IPAC2019 - List of Keywords (electron)

Paper	Title	Other Keywords	Page
MOXPLM2	From Dreams to Reality: Prospects for Applying Advanced Accelerator Technology to Next Generation Scientific User Facilities	plasma, laser, acceleration, wakefield	1
	M. Ferrario INFN/LNF, Frascati, Italy R.W. Aßmann DESY, Hamburg, Germany
	Recent years have seen spectacular progress in the development of innovative acceleration methods that are not based on traditional RF accelerating structures. These novel developments are at the interface of laser, plasma and accelerator physics and may potentially lead to much more compact and economical accelerator facilities. While primarily focusing on the ability to accelerate charged particles with much larger gradients than traditional RF, these new techniques have yet to demonstrate comparable performances to RF in terms of both beam parameters or reproducibility. To guide the developments beyond the necessary basic R&D and concept validations, a common understanding and definition of required performance and beam parameters for an operational user facility is now needed. These innovative user facilities can include "table-top" light sources, medical accelerators, industrial accelerators or even high-energy colliders. The talk will review the most promising developments in new acceleration methods, it will present the status of ongoing projects including the EU project EuPRAXIA and will identify the set of required specifications for the application under consideration.
	Slides MOXPLM2 [16.331 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOXPLM2
About •	paper received ※ 19 May 2019 paper accepted ※ 16 June 2019 issue date ※ 21 June 2019
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MOZPLS2	Ion Collider Precision Measurements With Different Species	target, operation, experiment, collider	28
	G.J. Marr, E.N. Beebe, I. Blackler, W. Christie, K.A. Drees, P.S. Dyer, A.V. Fedotov, W. Fischer, C.J. Gardner, H. Huang, T. Kanesue, N.A. Kling, V. Litvinenko, C. Liu, Y. Luo, D. Maffei, B. Martin, A. Marusic, K. Mernick, M.G. Minty, C. Naylor, M. Okamura, I. Pinayev, G. Robert-Demolaize, T. Roser, P. Sampson, V. Schoefer, T.C. Shrey, D. Steski, P. Thieberger, J.E. Tuozzolo, K. Zeno, I.Y. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC, under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Precedent to electron cooling commissioning and collisions of Gold at various energies at RHIC in 2018, the STAR experiment desired an exploration of the chiral magnetic effect in the quark gluon plasma (QGP) with an isobar run, utilizing Ruthenium and Zirconium. Colliding Zr-96 with Zr-96 and Ru-96 with Ru-96 create the same QGP but in a different magnetic field due to the different charges of the Zr (Z=40) and Ru (Z=44) ions. Since the charge difference is only 10%, the experimental program requires exacting store conditions for both ions. These systematic error concerns presented new challenges for the Collider, including frequent reconfiguration of the Collider for the different ion species, and maintaining level amounts of instantaneous and integrated luminosity between two species. Moreover, making beams of Zr-96 and Ru-96 is challenging since the natural abundances of these isotopes are low. Creating viable enriched source material for Zr-96 required assistance processing from RIKEN, while Ru-96 was provided by a new enrichment facility under commissioning at Oak Ridge National Laboratory.
	Slides MOZPLS2 [4.758 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOZPLS2
About •	paper received ※ 11 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOZZPLM2	A Bunch Structure Measurement of Muons Accelerated by RFQ Using a Longitudinal Beam-Profile Monitor With High Time Resolution	rfq, experiment, linac, background	37
	Y. Sue, K. Inami Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, M. Otani, T. Yamazaki KEK, Ibaraki, Japan K. Hasegawa, R. Kitamura, T. Morishita JAEA/J-PARC, Tokai-mura, Japan T. Iijima KMI, Nagoya, AIchi Prefecture, Japan H. Iinuma, Y. Nakazawa Ibaraki University, Hitachi, Ibaraki, Japan K. Ishida RIKEN Nishina Center, Wako, Japan Y. Kondo JAEA, Ibaraki-ken, Japan N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan Y. Takeuchi Kyoto ICR, Uji, Kyoto, Japan T. Ushizawa Sokendai, Ibaraki, Japan H.Y. Yasuda University of Tokyo, Tokyo, Japan M. Yotsuzuka Nagoya University, Nagoya, Japan
	Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP15H05742, JP16H03987, JP16J07784, JP18H03707 and JP18H05226. J-PARC E34 experiment intends to measure the anomalous magnetic moment and electric dipole moment of muon precisely by a different way from the previous experiment. In this experiment, a low-emittance muon beam is provided using the muons with the thermal energy and the four-stage linac. The demonstration of the first muon RF acceleration with an RFQ linac was conducted and the transverse profile of the accelerated muons was measured last year. As one of the remaining issues for the beam-diagnostic system, the longitudinal beam profile after the RFQ should be measured to match the profile to the designed acceptance of the subsequent accelerator. For this purpose, the new longitudinal beam monitor using the micro-channel plate is under development. The time resolution aims to be around 30 to 40 ps corresponding to 1 % of a period of an operation frequency of the accelerator, which is 324 MHz. On November 2018, the bunch structure of accelerated muons of 89 keV with the RFQ was measured using this monitor at the J-PARC MLF. The latest analysis result of this measurement will be reported in this poster.
	Slides MOZZPLM2 [2.618 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOZZPLM2
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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MOZZPLS1	eRHIC Design Overview	hadron, proton, storage-ring, luminosity	45
	C. Montag, G. Bassi, J. Beebe-Wang, J.S. Berg, M. Blaskiewicz, A. Blednykh, J.M. Brennan, S.J. Brooks, K.A. Brown, K.A. Drees, A.V. Fedotov, W. Fischer, D.M. Gassner, W. Guo, A. Hershcovitch, C. Hetzel, D. Holmes, H. Huang, W.A. Jackson, J. Kewisch, Y. Li, C. Liu, H. Lovelace III, Y. Luo, F. Méot, M.G. Minty, R.B. Palmer, B. Parker, S. Peggs, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, S. Seletskiy, V.V. Smaluk, K.S. Smith, S. Tepikian, P. Thieberger, D. Trbojevic, N. Tsoupas, S. Verdú-Andrés, W.-T. Weng, F.J. Willeke, H. Witte, Q. Wu, W. Xu, A. Zaltsman, W. Zhang BNL, Upton, Long Island, New York, USA E. Gianfelice-Wendt Fermilab, Batavia, Illinois, USA Y. Hao FRIB, East Lansing, Michigan, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The Electron-Ion Collider (EIC) is being envisioned as the next facility to be constructed by the DOE Nuclear Physics program. Brookhaven National Laboratory is proposing eRHIC, a facility based on the existing RHIC complex as a cost effective realization of the EIC project with a peak luminosity of 10³⁴ cm^-2 sec^-1. An electron storage ring with an energy range from 5 to 18 GeV will be added in the existing RHIC tunnel. A spin-transparent rapid-cycling synchrotron (RCS) will serve as a full-energy polarized electron injector. Recent design improvements include reduction of the IR magnet strengths to avoid the necessity for Nb₃Sn magnets, and a novel hadron injection scheme to maximize the integrated luminosity. We will provide an overview of this proposed project and present the current design status.
	Slides MOZZPLS1 [5.428 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOZZPLS1
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW017	Feedback Design for Control of the Micro-Bunching Instability based on Reinforcement Learning	bunching, storage-ring, feedback, controls	104
	T. Boltz, T. Asfour, M. Brosi, E. Bründermann, B. Härer, P. Kaiser, A.-S. Müller, C. Pohl, P. Schreiber, M. Yan KIT, Karlsruhe, Germany
	The operation of ring-based synchrotron light sources with short electron bunches increases the emission of coherent synchrotron radiation (CSR) in the THz frequency range. However, the micro-bunching instability resulting from self-interaction of the bunch with its own radiation field limits stable operation with constant intensity of CSR emission to a particular threshold current. Above this threshold, the longitudinal charge distribution and thus the emitted radiation vary rapidly and continuously. Therefore, a fast and adaptive feedback system is the appropriate approach to stabilize the dynamics and to overcome the limitations given by the instability. In this contribution, we discuss first efforts towards a longitudinal feedback design that acts on the RF system of the KIT storage ring KARA (Karlsruhe Research Accelerator) and aims for stabilization of the emitted THz radiation. Our approach is based on methods of adaptive control that were developed in the field of reinforcement learning and have seen great success in other fields of research over the past decade. We motivate this particular approach and comment on different aspects of its implementation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW017
About •	paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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MOPGW018	Perturbation of Synchrotron Motion in the Micro-Bunching Instability	bunching, synchrotron, storage-ring, radiation	108
	T. Boltz, M. Brosi, E. Bründermann, B. Härer, A.-S. Müller, P. Schreiber, P. Schönfeldt, M. Yan KIT, Karlsruhe, Germany
	Short electron bunches in a storage ring are subject to complex longitudinal dynamics due to self-interaction with their own CSR. Above a particular threshold current, this leads to the formation of dynamically changing micro-structures within the bunch, generally known as the micro-bunching instability. The longitudinal dynamics of this phenomenon can be simulated by solving the Vlasov-Fokker-Planck equation, where the CSR self-interaction can be added as a perturbation to the Hamiltonian. This contribution particularly focuses on the comprehension of synchrotron motion in the micro-bunching instability and how it relates to the formation of the occurring micro-structures. Therefore, we adopt the perspective of a single particle and comment on its implications for collective motion. We explicitly show how the shape of the parallel plates CSR wake potential breaks homogeneity in longitudinal phase space and propose a quadrupole-like mode as potential seeding mechanism of the micro-bunching instability. The gained insights are verified using the passive particle tracking method of the Vlasov-Fokker-Planck solver Inovesa.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW018
About •	paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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MOPGW021	Symplectic Tracking for the Robinson Wiggler	wiggler, storage-ring, dynamic-aperture, linear-dynamics	120
	J. Li, J. Feikes, T. Mertens, Y. Petenev, M. Ries, A. Schälicke HZB, Berlin, Germany
	A Robinson wiggler (RW) is considered to be installed in the Metrology Light Source (MLS) to lengthen the bunch and improve the Touschek lifetime by manipulating the damping partitions. Symplectic tracking is crucial to study the impact of the nonlinear field components introduced by the Robinson wiggler. This paper introduces a tracking method based on an implicit symplectic integrator to solve the exact Hamiltonian equations of particle motion in the wiggler. In addition, a numerical generating function method is implemented as an approach to realize fast tracking.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW021
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW027	Design Considerations for Permenant Magnetic Quadrupole Triplet for Matching Into Laser Driven Wake Field Acceleration Experiment at SINBAD	laser, plasma, experiment, acceleration	143
	S. Yamin, R.W. Aßmann, U. Dorda, F. Lemery, B. Marchetti, E. Panofski, P.A. Walker DESY, Hamburg, Germany
	SINBAD (Short and INnovative Bunches and Accelerators at DESY) facility aims to produce ultrashort bunches (sub-fs) at ~100 MeV, suitable for injection into novel accelerators e.g. dielectric Laser acceleration (DLA) and Laser Driven Wakefield acceleration (LWFA). The LWFA experiment demands β functions to be of the order of 1 mm to reduce energy spreads and emittance growth from nonlinearities. Matching such a space charge dominated beam to such constraints with conventional electromagnets is challenging. A Permanent Magnetic Quadrupole (PMQ) triplet is one promising focusing strategy. In this paper, we investigate the performance of a PMQ triplet to fit the requirements of the electron beam properties in a plasma cell and discuss the realizable phase spaces for the LWFA experiment planned at SINBAD.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW027
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW028	Study for the Alignment of Focusing Solenoid of ARES RF Gun and Effect of Misalignment of Solenoid on Emittance of Space Charge Dominated Electron Beam	solenoid, alignment, emittance, gun	147
	S. Yamin, R.W. Aßmann, B. Marchetti DESY, Hamburg, Germany
	SINBAD (Short and INnovative Bunches and Accelerators at DESY) facility will host multiple experiments relating to ultra-short high brightness beams and novel experiments with ultra-high gradient. ARES (Accelerator Research Experiment at SINBAD) Linac is an S-band photo injector to produce such electron bunches at around 100 MeV. The Linac will be commissioned in stages with the first stage corresponding to gun commissioning. In this paper, we present studies about the scheme adopted for the alignment of focusing solenoid for the ARES gun. The method is bench marked using ASTRA simulations. Moreover the effect of misalignment of the solenoid on the emittance of space charge dominated scheme and its compensation is also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW028
About •	paper received ※ 26 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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MOPGW029	Preliminary Study of Bunch Compression in the Hefei Light Source	lattice, storage-ring, radiation, synchrotron-radiation	151
	W. Li, Z.H. Bai, W. Li, J.G. Wang, D.R. Xu, Z. Zhao USTC/NSRL, Hefei, Anhui, People’s Republic of China
	Funding: This work was supported by the Fundamental Research Funds for the Central Universities (Grant No.WK2310000082 and WK2310000077), and the National Natural Science Foundation of China(GrantNo.11475167). Short electron bunch has interesting applications in the synchrotron radiation light sources, such as the production of powerful coherent THz radiation, time resolving spectrum analysis, etc. In this work, we are interested in acquiring the short bunch in the storage ring with a small circumference like Hefei Light Source. In this paper, we tried to approach the short bunch in two separate methods: by increasing the higher harmonic cavity voltage and by reducing the momentum compaction factor. The preliminary result and observations are shown and discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW029
About •	paper received ※ 16 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW053	Residual Gas Lifetime In High Energy Photon Source (HEPS)	scattering, dynamic-aperture, vacuum, photon	210
	S.K. Tian, H.S. Xu IHEP, Beijing, People’s Republic of China
	High vacuum has always been mandatory in particle accelerators. This is especially true for circular machines, where the beam makes thousands or millions turns, and beam lifetime is heavily affected by the residual gas scattering. At the beginning of storage ring operation the lifetime was very short mostly dominated by residual gas scattering. The residual gas lifetime is comprised of the elastic and inelastic scattering on electrons and elastic and inelastic scattering on nuclei. One usually calculates only the elastic scattering on nuclei (single Coulomb scattering) and inelastic scattering on nuclei (bremsstrahlung) of the residual gas scattering lifetime component. The analytic calculation the residual gas scattering lifetime and simulations of the beam interaction with the residual gas with code will be shown in this presentation
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW053
About •	paper received ※ 15 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
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MOPGW054	Study on Spherical Aberration Correction of Solenoid Lens in Ultrafast Electron Diffraction	induction, solenoid, emittance, focusing	213
	Y.T. Yang, K. Fan, J.J. Li HUST, Wuhan, People’s Republic of China Y. Song Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China
	High electron beam quality is required in Ultrafast Electron Diffraction (UED) to achieve high spatial resolution. However, aberrations mainly induced by solenoid lens will deteriorate the beam quality and limit the resolution. Spherical aberration introduces the largest distortion which is unavoidable in the case of static cylindrically symmetric electromagnetic fields on the basis of Scherzer’s theorem. In order to reduce the spherical aberrations, different models have been designed which are composed of three symmetrical lens and one asymmetrical lens. We obtain the magnetic field distribution and calculate the aberration of each model by OPERA, and the result is that the solenoid without poles has the minimum aberration and meets the design requirement best.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW054
About •	paper received ※ 13 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019
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MOPGW058	Towards a Sextupole-Free Electron Storage Ring	vacuum, impedance, storage-ring, feedback	217
	T.-Y. Lee, T. Ha PAL, Pohang, Kyungbuk, Republic of Korea
	This paper studies if it is possible to build an electron storage ring with no or a small number of sextupole mag-nets. If it is possible, the electron storage ring will be great-ly simplified. For the purpose, two methods are presented in the paper to handle head-tail instability: One is to use dielectric vacuum chamber made of such materials as ceramic or glass to reduce broadband impedance signifi-cantly. Then head-tail instability would be extremely weak. The other method is to install a bunch-by-bunch feedback system to suppress the already weak head-tail instability due to the dielectric vacuum chamber.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW058
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW062	Radiation of a Charge Moving in a Wire Structure	radiation, FEL, simulation, lattice	231
	S.N. Galyamin, A.V. Tyukhtin, V.V. Vorobev Saint Petersburg State University, Saint Petersburg, Russia A.I. Benediktovitch EuXFEL, Hamburg, Germany A.I. Benediktovitch BSU, Minsk, Belarus, Belarus
	Funding: This work is supported by the grant from Russian Foundation for Basic Research (No. 17-52-04107). In the X-ray frequency region, interaction of relativistic electrons with crystals results in parametric X-ray radiation (PXR), with its frequency being determined by distance between crystallographic planes and direction of electron motion. If instead of crystal one considers an artificial periodic structure with periods of the order of mm, one can expect emission of radiation of a similar nature at terahertz (THz) frequencies. This frequency range is of significant interest during last decade due to its prospective applications. Moreover, artificial wire-like structures are considered as a promising alternative to conventional dielectric structures for wakefield acceleration. Here we consider electromagnetic (EM) field produced by a charged particle bunch moving through a lattice of parallel conducting wires. We present several approaches for analysis of EM field in the described wire structure. First, conventional two-wave approximation for describing the "short-wave response" is developed. Second, we use the effective medium approach and describe the "long-wave" part of the spectrum. Third, we develop a method based on vibrator antenna theory which can be useful for finite length wire structure. P.D. Hoang, et al., Phys. Rev. Lett., V. 120, P. 164801 (2018).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW062
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW073	Beam Manipulation Using Self-Induced Fields at the SwissFEL Injector	FEL, simulation, experiment, wakefield	266
	S. Bettoni, P. Craievich, E. Ferrari, R. Ganter, F. Marcellini, E. Prat, S. Reiche PSI, Villigen PSI, Switzerland A.A. Lutman SLAC, Menlo Park, California, USA G. Penco Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	In the past years wakefield sources have been used to manipulate electron beams in accelerators. We recently installed corrugated structures for a total length of 2~m at the SwissFEL injector to test novel schemes for beam manipulations. We present simulations and early experimental results. We compare the model predictions with the measured data for the bunch energy losses and the kick factor, and show early results for the longitudinal phase space linearization and the production of current spikes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW073
About •	paper received ※ 09 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW086	Intensity Dependent Effects at ATF2, KEK	simulation, collider, linear-collider, wakefield	308
	P. Korysko, A. Latina CERN, Geneva, Switzerland P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom A. Faus-Golfe LAL, Orsay, France K. Kubo, T. Okugi KEK, Ibaraki, Japan
	The Accelerator Test Facility 2 (ATF2) at KEK is a prototype for the Final Focus Systems of the future e⁺e⁻ linear colliders, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC). In this paper both simulation and experimental results are presented with special emphasis on intensity-dependent effects. The importance of these effects is shown using the PLACET code and realistic ATF2 machine simulations (including beam jitter, misalignment, wakefield, Beam Based Alignment (BBA) correction, …). The latest experimental results are also presented, in particular the impact of the beam intensity on the beam size at the IP.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW086
About •	paper received ※ 23 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW104	Equilibria and Synchrotron Stability in Two Energy Storage Rings	storage-ring, damping, simulation, focusing	364
	B. Dhital, J.R. Delayen, G.A. Krafft ODU, Norfolk, Virginia, USA J.R. Delayen, Y.S. Derbenev, D. Douglas, G.A. Krafft, F. Lin, V.S. Morozov, Y. Zhang JLab, Newport News, Virginia, USA
	In a dual energy storage ring, the electron beam passes through two loops at markedly different energies E_L, and E_H, i.e., energies for low energy loop and high energy loop respectively. These loops use a common beamline where a superconducting linac at first accelerates the beam from EL to EH and then decelerates the beam from EH to EL in the next pass. There are two basic solutions to the equilibrium problems possible, i.e., ’Storage Ring’ (SR) equilibrium and ’Energy Recovery Linac’ (ERL) equilibrium. SR equilibrium mode more resembles the usual single loop storage ring with strong synchrotron motion and ERL equilibrium mode is the case where RF in two beam passes nearly cancels. Calculations based on linear transfer matrix formalism show that longitudinal stability exists for both SR mode and ERL mode in two energy storage rings.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW104
About •	paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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MOPGW111	Start to End Simulation on Beam Dynamics in Coherent Electron Cooling Accelerator	FEL, bunching, emittance, cavity	379
	Y.C. Jing, V. Litvinenko, I. Petrushina, I. Pinayev, K. Shih, Y.H. Wu BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA I. Petrushina SUNY SB, Stony Brook, New York, USA K. Shih SBU, Stony Brook, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A Coherent electron Cooling (CeC) has a potential of substantial reducing cooling time of the high-energy hadrons and hence to boost luminosity in high-intensity hadron-hadron and electron-hadron colliders. In a CeC system, a high quality electron beam is generated, propagated and optimized through a beam line which was carefully designed with consideration of space charge effect, wakefields and nonlinear dynamics such as coherent synchrotron radiation and chromatic aberration. In this paper, we present our study on the beam dynamics of such a beam line and compare the simulation result with what was measured in experiment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW111
About •	paper received ※ 17 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW112	Design of a Bunch Compressor with CSR Suppression to Achieve Hundreds of kA Peak Current	emittance, optics, site, dipole	382
	Y.C. Jing, V. Litvinenko BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A four dipole magnetic chicane is usually used to compress electron bunch to very short in modern accelerators which requires electron beams to have high peak current. The coherent synchrotron radiation (CSR) originated from the strong bending magnets in the chicane could greatly degrade the quality of the electron beam. In this paper, we present our design for a bunch compressing system with 30 to 100 fold in bunch length reduction and at the mean time suppress the effect of CSR on the e-beam’s quality. We discuss and detail the performance of such a compressor for potential FACET-II upgrade.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW112
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW116	Validation of a Novel Method for the Calculation of Near-Field Synchrotron Radiation	acceleration, radiation, cyclotron, synchrotron	397
	F.Y. Li, B.E. Carlsten, R. Garimella, C. Huang, T.J. Kwan LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the LDRD program at LANL. The phenomenon of synchrotron radiation (SR) from electrons is at the core of modern accelerator based light sources. While SR in the far field has been well characterized, the near-field SR and its impacts on self-consistent electron beam dynamics remain an ongoing topic. Since it is difficult to experimentally characterize the near fields, it is desirable to develop accurate and efficient numerical methods for the design of these light sources. Here, we investigate a novel method, originally proposed by Shintake and which potentially has both high efficiency and accuracy. We focus on the field calculation of this method and show that the original idea has missed the important terms of fields due to electron acceleration and therefore only applies to a linear motion. To correct this limitation we developed a modified algorithm that gives consistent fields with direct calculations using the Liénard-Wiechert equation. Some basic signatures of the near-field SR fields are also drawn for a cyclotron motion by using this modified approach.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW116
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPMP002	Linac and Damping Ring Designs for the FCC-ee	linac, emittance, positron, gun	420
	S. Ogur, K. Oide, Y. Papaphilippou, L. Rinolfi, F. Zimmermann CERN, Geneva, Switzerland A.M. Barnyakov, A.E. Levichev, P.V. Martyshkin, D.A. Nikiforov BINP SB RAS, Novosibirsk, Russia I. Chaikovska, R. Chehab LAL, Orsay, France K. Furukawa, N. Iida, T. Kamitani, F. Miyahara, K. Oide KEK, Ibaraki, Japan E.V. Ozcan Bogazici University, Bebek / Istanbul, Turkey S.M. Polozov MEPhI, Moscow, Russia L. Rinolfi ESI, Archamps, France F. Yaman IZTECH, Izmir, Turkey
	We report the design of the pre-injector chain for the Future Circular e⁺ e⁻ Collider (FCC-ee) system. The electron beam from a low-emittance RF gun is accelerated by an S-band linac up to 6 GeV. A damping ring at 1.54 GeV is required for emittance cooling of the positron beam. The intermediate energy step from the exit of the S-band linac at 6 GeV to the 20 GeV injection energy of the top-up booster can be provided by the modified Super Proton Synchrotron (SPS), serving as a pre-booster ring (PBR). An alternative option to reach 20 GeV energy would be to extend the S-band linac with a C- or X-band linac. An overall cost optimisation will determine the choice of the final configuration. Beam loss and emittance dilution in the linac due to space charge effects, wakefields, and misalignment of accelerator components can be mitigated by RF phasing and orbit steering. Start-to-end simulations examine the beam transport through the linac up to either 6 GeV or 20 GeV. The results indicate large design margins. Simulations of the beam dynamics in the damping ring (DR) demonstrate a sufficiently large momentum acceptance. Effects of intrabeam scattering and electron cloud instability in the DR are also studied.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP002
About •	paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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MOPMP003	Positron Source for FCC-ee	positron, target, linac, collider	424
	I. Chaikovska, R. Chehab, A. Faus-Golfe, Y. Han LAL, Orsay, France A. Apyan ANSL, Yerevan, Armenia Y. Enomoto, K. Furukawa, T. Kamitani, F. Miyahara, M. Satoh, Y. Seimiya, T. Suwada KEK, Ibaraki, Japan P.V. Martyshkin BINP SB RAS, Novosibirsk, Russia S. Ogur, K. Oide, Y. Papaphilippou, L. Rinolfi, P. Sievers, F. Zimmermann CERN, Geneva, Switzerland
	The FCC-ee is a high-luminosity, high-precision circular collider to be constructed in a new 100 km tunnel in the Geneva area. The physics case is well established and the FCC-ee operation is foreseen at 91 GeV (Z-pole), 160 GeV (W pair production threshold), 240 GeV (Higgs resonance) and 365 GeV (t-tbar threshold). Due to the large 6D production emittance and important thermal load in the production target, the positron injector, in particular the positron source, is one of the key elements of the FCC-ee, requiring special attention. To ensure high reliability of the positron source, conventional and hybrid targets are currently under study. The final choice of the positron target will be made based on the estimated performances. In this framework, we present a preliminary design of the FCC-ee positron source, with detailed simulation studies of positron production, capture and primary acceleration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP003
About •	paper received ※ 03 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP012	Concepts of Longitudinally Polarized Electron and Positron Colliding Beams in the Circular Electron Positron Collider	polarization, positron, resonance, wiggler	445
	Z. Duan, J. Gao, X.P. Li, D. Wang, Y. Wang, W.H. Xia, Q.J. Xu, C.H. Yu, Y. Zhang IHEP, Beijing, People’s Republic of China
	Funding: Work supported by National Key Research and Development Program of China (No.2018YFA0404300). This paper reports some preliminary study into the imple- mentation of longitudinally polarized e⁺/e⁻ colliding beams in the Circular Electron Positron Collider, at a center of mass energy of 91 GeV as a Z factory and energies beyond.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP012
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP044	Improving the Luminosity for Beam Energy Scan II at RHIC	cavity, operation, space-charge, luminosity	540
	C. Liu, M. Blaskiewicz, K.A. Drees, A.V. Fedotov, W. Fischer, C.J. Gardner, H. Huang, D. Kayran, Y. Luo, G.J. Marr, A. Marusic, K. Mernick, M.G. Minty, C. Montag, I. Pinayev, S. Polizzo, V.H. Ranjbar, D. Raparia, G. Robert-Demolaize, T. Roser, J. Sandberg, V. Schoefer, T.C. Shrey, S. Tepikian, P. Thieberger, A. Zaltsman, K. Zeno, I.Y. Zhang, W. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The QCD (Quantum Chromodynamics) phase diagram has many uncharted territories, particularly the nature of the transformation from Quark-Gluon plasma (QGP) to the state of Hadronic gas. The Beam Energy Scan I (BES-I) at the Relativistic Heavy Ion Collider (RHIC) was completed but measurements had large statistical errors. To improve the statistical error and expand the search for first-order phase transition and location of the critical point, Beam Energy Scan II will commence in 2019 with a goal of improving the luminosity by a factor of 3-4. The beam lifetime at low energies was and will be limited by some physical effects of which the most significant are intrabeam scattering, space charge, beam-beam, persistent current effects. This article will review these potential limiting factors and introduce the countermeasures which will be in place to improve BES-II luminosity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP044
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP049	6 T Cable-in-conduit Dipole to Double the Ion Energy for JLEIC	dipole, collider, injection, luminosity	556
	P.M. McIntyre, J. Breitschopf, J. Gerity Texas A&M University, College Station, USA J. Breitschopf, D.C.V. Chavez, J.N. Kellams, A. Sattarov ATC, College Station, Texas, USA
	The proposed electron-ion collider JLEIC would make high-luminosity collisions of polarized ions and polarized electrons with electron energy up to 12 GeV and ion energy up to 40 GeV/u. Both the luminosity and the collision energy could be increased by doubling the dipole field in the ion ring from 3 T to 6 T, and the enhanced performance would access the full range of parameters for the physics objectives of the project. The Texas A&M group has developed the large-aperture 3 T dipoles for the baseline project, based upon a novel superconducting cable-in-conduit. (CIC). A closely similar 6 T design is being developed, utilizing a 2-layer CIC. Details of the magnet design and development of the 2-layer CIC will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP049
About •	paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPMP050	Performance of CeC PoP Accelerator	FEL, gun, SRF, hadron	559
	I. Pinayev, Z. Altinbas, J.C. Brutus, A.J. Curcio, A. Di Lieto, T. Hayes, R.L. Hulsart, P. Inacker, Y.C. Jing, V. Litvinenko, J. Ma, G.J. Mahler, M. Mapes, K. Mernick, K. Mihara, T.A. Miller, M.G. Minty, G. Narayan, F. Severino, K. Shih, Z. Sorrell, J.E. Tuozzolo, E. Wang, G. Wang, A. Zaltsman BNL, Upton, Long Island, New York, USA I. Petrushina SUNY SB, Stony Brook, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Coherent electron cooling experiment is aimed for demonstration of the proof-of-principle demonstration of reduction energy spread of a single hadron bunch circulating in RHIC. The electron beam should have the required parameters and its orbit and energy should be matched to the hadron beam. In this paper we present the achieved electron beam parameters including emittance, energy spread, and other critical indicators. The operational issues as well as future plans are also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP050
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB013	Focusing of High-Brightness Electron Beams with Active-Plasma Lenses	plasma, emittance, focusing, experiment	601
	R. Pompili INFN/LNF, Frascati, Italy
	Plasma-based technology promises a tremendous reduction in size of accelerators used for research, medical, and industrial applications, making it possible to develop tabletop machines accessible for a broader scientific community. By overcoming current limits of conventional accelerators and pushing particles to larger and larger energies, the availability of strong and tunable focusing optics is mandatory also because plasma-accelerated beams usually have large angular divergences. In this regard, active-plasma lenses represent a compact and affordable tool to generate radially symmetric magnetic fields several orders of magnitude larger than conventional quadrupoles and solenoids. However, it has been recently proved that the focusing can be highly nonlinear and induce a dramatic emittance growth. Here, we present experimental results showing how these nonlinearities can be minimized and lensing improved. These achievements represent a major breakthrough toward the miniaturization of next-generation focusing devices.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB013
About •	paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB031	Progress of Conceptual Study for the Accelerators of a 2-7GeV Super Tau Charm Facility at China	collider, luminosity, factory, operation	643
	Q. Luo, W. Li, D.R. Xu USTC/NSRL, Hefei, Anhui, People’s Republic of China W.W. Gao, J.Q. Lan Fujian University of Technology, Fuzhou, People’s Republic of China
	Funding: Supported by National Natural Science Foundation of China U1832169 and the Double Fist-Class University Project Foundation of USTC. This paper shows the progress of the conceptual study for the accelerators of a super tau charm facility in China. Since the BEPCII will finish its historical mission in 5~10 years and its upgrade plan will only achieve a small luminosity enhancement of 3~5 times, a new next generation tau-charm collider will play an irreplaceable role in future high energy physics study. The luminosity of this successor is about 5×10³⁴cm⁻²s⁻¹ pilot and 1×10³⁵cm⁻²s⁻¹ nominal, with the electron beam longitudinally polarized at the IP. The general scheme of the accelerators and the beam pa-rameters are shown. Several key technologies such as beam polarization and beam emittance diagnostics are also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB031
About •	paper received ※ 14 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019
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MOPRB052	Gamma Factory at CERN: Design of a Proof-of-Principle Experiment	photon, laser, experiment, cavity	685
	Y. Dutheil, R. Alemany-Fernández, H. Bartosik, N. Biancacci, R. Bruce, P. Czodrowski, V. Fedosseev, B. Goddard, S. Hirlaender, J.M. Jowett, R. Kersevan, M. Kowalska, M. Lamont, D. Manglunki, J. Molson, A.V. Petrenko, M. Schaumann, F. Zimmermann CERN, Geneva, Switzerland S.E. Alden, A. Bosco, S.M. Gibson, L.J. Nevay JAI, Egham, Surrey, United Kingdom A. Apyan ANSL, Yerevan, Armenia E.G. Bessonov LPI, Moscow, Russia A. Bosco, S.M. Gibson, L.J. Nevay Royal Holloway, University of London, Surrey, United Kingdom F. Castelli Università degli Studi di Milano, Milano, Italy F. Castelli, C. Curatolo, L. Serafini INFN-Milano, Milano, Italy K. Kroeger FSU Jena, Jena, Germany A. Martens LAL, Orsay, France V. Petrillo Universita’ degli Studi di Milano, Milano, Italy M. Sapinski, T. Stöhlker GSI, Darmstadt, Germany G. Weber IOQ, Jena, Germany Y.K. Wu FEL/Duke University, Durham, North Carolina, USA
	The Gamma Factory (GF) initiative proposes to create novel research tools at CERN by producing, accelerating and storing highly relativistic partially stripped ion beams in the LHC rings and by exciting their atomic degrees of freedom by lasers, to produce high-energy photon beams. Their intensity would be several orders of magnitude higher than those of the presently operating light sources in the particularly interesting gamma-ray energy domain reaching up to 400 MeV. In this energy domain, the high-intensity photon beams can be used to produce secondary beams of polarized electrons, polarized positrons, polarized muons, neutrinos, neutrons and radioactive ions. Over the years 2017-2018 we have demonstrated that these partially stripped ion beams can be successfully produced, accelerated and stored in the CERN accelerator complex, including the LHC. The next step of the project is to build a proof of principle experiment in the SPS to validate the principal GF concepts. This contribution will present the initial conceptual design of this experiment along with its main challenge - the demonstration of the fast cooling method of partially stripped ion beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB052
About •	paper received ※ 19 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB056	THz Radiator Based on Photonic Band Gap Crystal for SwissFEL	photon, GUI, experiment, FEL	693
	L. Shi, R. Ischebeck, S. Reiche PSI, Villigen PSI, Switzerland
	Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 701647. The electromagnetic radiation in 1-20 THz has many unique properties when it interacts with matter due to its non-ionizing excitation in matter. Especially the dynamics of the excited matter can be probed with the help of X-ray pulses at a free electron laser facility, e.g. SwissFEL, to deepen our understanding of a wide range of phenomena. Due to its high research potential, various means of THz generation have been proposed and demonstrated. We investigate preliminarily here its generation based on a relativistic electron bunch and a photonic band gap crystal (PBG) made of dielectric rods. The PBG provides additional degrees of freedom for the THz pulse tuning. Additionally, the unwanted radiation parts can be damped by the structure in order to minimize the deleterious beam dynamics effects. The crystal also promises the integration of generation, filtering and coupling for transport into a single piece.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB056
About •	paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPRB060	Simulating Novel Collimation Schemes for High-Luminosity LHC With Merlin++	proton, scattering, collimation, simulation	708
	S.C. Tygier, R.B. Appleby UMAN, Manchester, United Kingdom R.J. Barlow, S. Rowan IIAA, Huddersfield, United Kingdom
	Due to the large stored beam energy in the HL-LHC new collimation technologies must be used to protect the machine. Active halo control of the proton beam halo with a Hollow Electron Lens can give a kick to protons at the edge of the beam without effecting the core. Various modes of operation are possible for example the electron lens can have a continuous current or it can be pulsed to different amplitudes for each passage of the proton beam. In this article we use Merlin++ simulations to show the performance of these modes for HL-LHC parameters. We also present recent simulations comparing scattering models in Merlin++.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB060
About •	paper received ※ 08 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB061	Simulations and Measurements of Coherent Synchrotron Radiation at the MAX-IV Short Pulse Facility	radiation, detector, simulation, dipole	712
	B.S. Kyle University of Manchester, Manchester, United Kingdom R.B. Appleby UMAN, Manchester, United Kingdom M. Brandin, E. Mansten, S. Thorin MAX IV Laboratory, Lund University, Lund, Sweden T.H. Pacey STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom J. Wolfenden The University of Liverpool, Liverpool, United Kingdom
	The Coherent Synchrotron Radiation (CSR) interaction is a source of unwanted correlated energy spread in short-bunch Free-Electron Lasers (FEL), diluting the desired FEL spectrum and reducing the total brightness of the light source. Many accelerator codes make use of 1-dimensional approximations in the calculation of the CSR-wake, which breaks down for bunch dimensions typical within bunch compressor dipoles in FELs. General Particle Tracer simulations of the CSR interaction make use of the 3-dimensional bunch distribution, making it advantageous in modelling the short-bunch, high aspect ratio regimes typical of modern 4th-generation light sources. Measurements of THz CSR emitted from the final bunch compressor dipole of the SP02 beamline at the MAX-IV Short Pulse Facility (SPF) were used, alongside start-to-end GPT and Elegant simulations, to characterize coherent radiation emission across a broad range of bunch lengths.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB061
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB067	High-gradient Single Cycle Terahertz Accelerating Structures	GUI, gun, acceleration, cathode	731
	S.P. Antipov, E. Gomez, S.V. Kuzikov Euclid TechLabs, LLC, Solon, Ohio, USA A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia
	Recently, gradients on the order of 1 GV/m level have been obtained in a form of single cycle (~1 ps) THz pulses produced by conversion of a high peak power laser radiation in nonlinear crystals (~1 mJ, 1 ps, up to 3% conversion efficiency). These pulses however are broadband (0.1-5 THz) and therefore a new accelerating structure type is required. For electron beam acceleration with such pulses we propose arrays of parabolic focusing micro-mirrors with common central. These novel structures could be produced by a femtosecond laser ablation system developed at Euclid Techlabs. This technology had already been tested for production of several millimeters long, multi-cell structure which has been testing with electron beam. We also propose using of structures where necessary GV/m E-fields are excited by a drive bunch travelling in the corrugated waveguide. The radiated by drive bunch sequence of short range delayed wakes are guided in this case by metallic disks and reflected back being focused exactly at time when the witness bunch arrives.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB067
About •	paper received ※ 21 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPRB072	eRHIC in Electron-Ion Operation	operation, collider, heavy-ion, hadron	738
	W. Fischer, E.C. Aschenauer, E.N. Beebe, M. Blaskiewicz, K.A. Brown, D. Bruno, K.A. Drees, C.J. Gardner, H. Huang, T. Kanesue, C. Liu, M. Mapes, G.T. McIntyre, M.G. Minty, C. Montag, S.K. Nayak, M. Okamura, V. Ptitsyn, D. Raparia, J. Sandberg, K.S. Smith, P. Thieberger, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, A. Zaltsman, A. Zelenski BNL, Upton, Long Island, New York, USA
	Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy. The design effort for the electron-ion collider eRHIC has concentrated on electron-proton collisions at the highest luminosities over the widest possible energy range. The present design also provides for electron-nucleon peak luminosities of up to 4.7·10³³ cm^-2s⁻¹ with strong hadron cooling, and up to 1.7·10³³ cm^-2s⁻¹ with stochastic cooling. Here we discuss the performance limitations and design choices for electron-ion collisions that are different from the electron-proton collisions. These include the ion bunch preparation in the injector chain, acceleration and intrabeam scattering in the hadron ring, path length adjustment and synchronization with the electron ring, stochastic cooling upgrades, machine protection upgrades, and operation with polarized electron beams colliding with either unpolarized ion beams or polarized He-3.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB072
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB075	Radiation Limits on Permanent Magnets in CBETA	radiation, vacuum, permanent-magnet, focusing	745
	V.O. Kostroun, C.M. Gulliford Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The Cornell Brookhaven Energy Recovery Linac Test Accelerator (CBETA), under construction at Cornell, uses Fixed Field Alternating Gradient (FFAG) Halbach magnets made from grade N35EH NdFeB. To reduce the 1% level magnetization errors in fabricated blocks to magnets with better than 0.001 field accuracy, iron wire shimming is necessary. This also limits magnetization changes by external influences to the ~1% level. The ambient radiation field present during CBETA operation can induce permanent magnet demagnetization. The radiation field arises from electrons in the beam halo hitting the vacuum chamber and from residual gas, Touschek and Intra-Beam scattering. The radiation dose rate due to electrons striking the vacuum chamber of a 4 cell straight section of CBETA FFAG magnets was calculated using the many particle Monte Carlo radiation code MCNP6.2. MCNP6.2 has a track-length heating tally for different particles and a collision heating tally that gives energy deposition/mass from all particles in the problem. Calculations show that electron loss has to be a fraction of a watt/m to keep the dose rate at an acceptable level during the accelerator lifetime.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB075
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPRB076	CBETA Beam Commissioning Results	linac, MMI, permanent-magnet, lattice	748
	C.M. Gulliford, N. Banerjee, A.C. Bartnik, I.V. Bazarov, J.A. Crittenden, K.E. Deitrick, A. Galdi, G.H. Hoffstaetter, P. Quigley, K.W. Smolenski Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J.S. Berg, S.J. Brooks, R.J. Michnoff, D. Trbojevic BNL, Upton, Long Island, New York, USA
	We report on the first results of commissioning CBETAwith a fully closed return loop. We repeat much of our early commissioning from the fractional arc test, namely setting up the injection system, calibrating the main linac, and steering the beam through the first splitter line. Most importantly, first results from sending the beam all the way through the FixedField Alternating gradient permanent magnet return arc are described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB076
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPRB080	Transient Beam Loading and Mitigation in JLEIC Collider Rings	cavity, klystron, luminosity, beam-loading	758
	J. Guo, R.A. Rimmer, H. Wang, S. Wang JLab, Newport News, Virginia, USA J.D. Fox Stanford University, Stanford, California, USA T. Mastoridis CalPoly, San Luis Obispo, California, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, with additional support from U.S. DOE Award Number DE-SC-0019287 The Jefferson Lab Electron-Ion Collider (JLEIC) is an asymmetric high luminosity ring-ring collider proposed as the next major R&D facility for the nuclear physics community. Both of JLEIC’s electron and ion collider rings have high beam current with gaps serving the pur-poses of beam abort, ion clearing, etc. Such a time-varying beam loading in the RF cavities would generate modulation in cavity RF phase/voltage, causing cyclic shift of collision point and potential luminosity loss. We studied a few approaches to mitigate the RF phase modu-lation and IP shift, such as correcting the RF phase/voltage modulation with traditional LLRF feed-back, one-turn feedback (OTFB), or RF feedforward (FF); optimizing the bunch fill pattern to limit the RF phase/voltage modulation to a small fraction of the bunch trains in the collider ring; or matching the RF phase modulation in the two rings. The preliminary re-sults are discussed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB080
About •	paper received ※ 23 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019
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MOPRB081	Electron Beam’s Closed Orbit in the Crab Crossing Scheme of Future Electron-Ion Colliders	closed-orbit, luminosity, cavity, simulation	762
	Y. Hao, V. Ptitsyn BNL, Upton, Long Island, New York, USA J. Qiang LBNL, Berkeley, California, USA
	In crab-crossing collision geometry the closed orbit of the electron beam will be altered by the beam-beam interaction and the tilted head and tail of the ion beam. We will present the linear model to determine the closed orbit and compare with the simulation. Also, the relation of the closed orbit and the synchro-betatron resonance will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB081
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB082	Scaling Properties of the Synchro-Beta Resonance in Crab Crossing Scheme of Future Electron Ion Collider	luminosity, resonance, simulation, cavity	766
	Y. Hao, Y. Luo, V. Ptitsyn BNL, Upton, Long Island, New York, USA J. Qiang LBNL, Berkeley, California, USA
	The synchro - beta resonance due to the beam-beam interaction was predicted by the strong-strong simulation in the future electron-ion collider designs. In this paper, we study the scaling properties of the degradation rate of this unwanted resonance. These studies motivated the possible countermeasures of the luminosity degradation associated with the resonance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB082
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB085	First Results from Commissioning of Low Energy RHIC Electron Cooler (LEReC)	cavity, MMI, gun, cathode	769
	D. Kayran, Z. Altinbas, D. Bruno, M.R. Costanzo, K.A. Drees, A.V. Fedotov, W. Fischer, M. Gaowei, D.M. Gassner, X. Gu, R.L. Hulsart, P. Inacker, J.P. Jamilkowski, Y.C. Jing, J. Kewisch, C.J. Liaw, C. Liu, J. Ma, K. Mernick, T.A. Miller, M.G. Minty, L.K. Nguyen, M.C. Paniccia, I. Pinayev, V. Ptitsyn, V. Schoefer, S. Seletskiy, F. Severino, T.C. Shrey, L. Smart, K.S. Smith, A. Sukhanov, P. Thieberger, J.E. Tuozzolo, E. Wang, G. Wang, A. Zaltsman, H. Zhao, Z. Zhao BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The brand new non-magnetized bunched beam electron cooler (LEReC) [1] has been built to provide luminosity improvement for Beam Energy Scan II (BES-II) physics program at the Relativistic Heavy Ion Collider (RHIC) BES-II [2]. The LEReC accelerator includes a photocathode DC gun, a laser system, a photocathode delivery system, magnets, beam diagnostics, a SRF booster cavity, and a set of Normal Conducting RF cavities to provide sufficient flexibility to tune the beam in the longitudinal phase space. This high-current high-power accelerator was successfully commissioned in period of March -September 2018. Beam quality suitable for cooling has been demonstrated. In this paper we discuss beam commissioning results and experience learned during commissioning. [1] A. Fedotov et al., ’Status of bunched beam electron cooler LEReC’ in these proceedings. [2] C.Liu et al., ’Improving luminosity of Beam Energy Scan II at RHIC’ in these proceedings.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB085
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB087	Proposal for a High Transformer Ratio CW Dielectric Accelerator	SRF, experiment, wakefield, operation	773
	V. Litvinenko Stony Brook University, Stony Brook, USA J.C. Brutus, Y.C. Jing, I. Pinayev, G. Wang BNL, Upton, Long Island, New York, USA M.E. Conde, C.-J. Jing, J.G. Power ANL, Argonne, Illinois, USA A. Kanareykin Euclid Beamlabs LLC, Bolingbrook, USA N. Vafaei-Najafabadi UCLA, Los Angeles, California, USA
	Advanced CW accelerators are one of high priority directions identified by Advanced Accelerator Concepts Research Roadmap Workshop Report . High transformer ratio of beam-driven accelerators is critically important for cost-effective FEL systems. We present a proposed experiment for demonstrating a high transformer ratio CW dielectric accelerator using operational SRF accelerator built for Coherent electron Cooling experiment. This accelerator operates with CW electron beam comprised of 78 kHz train of electron bunches. Electron bunches with controllable longitudinal and charge up to 10 nC per bunch are generated in 1.25 MV SRF photo-electron gun. This bunches are ballistically compressed to duration of 10-to-30 psec and accelerated to 15 MeV in SRF linac. Such bunches would be excellent drivers of high-transformer ratio DWA accelerators. In this paper we present expected performance of proposed CW DWA accelerator. Advanced Accelerator Concepts Research Roadmap Workshop Report, 2016, *V.N. Litvinenko et al., In proc.of FEL’17, Santa Fe, NM, USA, August 20-25, 2017, p. 132
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB087
About •	paper received ※ 19 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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MOPRB088	Study of Fluctuations in Undulator Radiation in the IOTA Ring at Fermilab	experiment, undulator, radiation, photon	777
	I. Lobach University of Chicago, Chicago, Illinois, USA A. Halavanau, Z. Huang, V. Yakimenko SLAC, Menlo Park, California, USA K. Kim ANL, Argonne, Illinois, USA V.A. Lebedev, S. Nagaitsev, A.L. Romanov, G. Stancari, A. Valishev Fermilab, Batavia, Illinois, USA A.Y. Murokh RadiaBeam, Los Angeles, California, USA T.V. Shaftan BNL, Upton, Long Island, New York, USA
	We study turn-by-turn fluctuations in the number of emitted photons in an undulator, installed in the IOTA electron storage ring at Fermilab with an InGaAs PIN photodiode and an integrating circuit. Our study was motivated by the previous experiment . We propose a theoretical model for the experimental data from and in our own experiment we attempted to verify the model in an independent and more systematic way. Moreover, these fluctuations are an interesting subject for a study by itself, since they act as a seed for SASE in FELs. We improve the precision of the measurements from * by subtracting the average signal amplitude using a comb filter with a one-turn IOTA delay, and by using a special algorithm for noise subtraction. We obtain a reasonable agreement between our theoretical model and experiment. Along with repeating the experiment from , which was performed at a constant beam current, we also collect data for fluctuations in undulator light at different beam current values. Lastly, in our experiment we were able to see the transition from Poisson statistics to Super-Poisson statistics for undulator light, whereas in only the latter statistics was observed. * M. Teich et al., PRL, vol. 65, no. 27, p. 3393 (1990).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB088
About •	paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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MOPRB089	Experimental Study of a Single Electron in a Storage Ring via Undulator Radiation	photon, undulator, experiment, radiation	781
	S. Nagaitsev, A.L. Romanov, G. Stancari Fermilab, Batavia, Illinois, USA A. Arodzero, A.Y. Murokh, M. Ruelas RadiaBeam, Santa Monica, California, USA I. Lobach University of Chicago, Chicago, Illinois, USA T.V. Shaftan BNL, Upton, Long Island, New York, USA
	A single electron orbiting around a ring and emitting single quanta at the rate of about one event per hundred turns could produce a wealth of information about physical processes in large traps (i.e. storage rings) for charged particles. It should be noted that Paul and Penning traps in the 1980s led to the Nobel prize for studying state and motion of single quantum particles, and just recently the Penning trap technique has enabled the measurement of a single proton magnetic moment with an unprecedented precision of 10 decimal places. The information from the storage ring traps could also be used for characterization of a quantum system as well as the "trap" itself, i.e. measuring properties of the storage ring lattice and electron interaction with the laser fields. Although, the interest in single electron quantum processes today is mostly academic in nature, the diagnostics and methodology developed for single electron radiation studies could find subsequent applications in a variety of applied disciplines in quantum technology, including quantum communications and quantum computing.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB089
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB090	Simulation Challenges for eRHIC Beam-Beam Study	proton, simulation, damping, emittance	785
	Y. Luo, F.J. Willeke BNL, Upton, Long Island, New York, USA Y. Hao FRIB, East Lansing, Michigan, USA J. Qiang LBNL, Berkeley, California, USA Y. Roblin, H. Zhang JLab, Newport News, Virginia, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The 2015 Nuclear Science Advisory Committee Long Rang Plan identified the need for an electron-ion collider (EIC) facility as a gluon microscope with capabilities beyond those of any existing accelerator complex. To reach the required high energy, high luminosity, and high polarization, the eRHIC design, based on the existing heavy ion and polarized proton collider RHIC, adopts a very small \beta-function at the interaction points, a high collision repetition rate, and a novel hadron cooling scheme. A full crossing angle of 22 mrad and crab cavities for both electron and proton rings are required. In this article, we will present the high priority R\&D items related to the beam-beam interaction studies for the current eRHIC design, the simulation challenges, and our plans and methods to address them. Recent progresses on this project are reported too.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB090
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB091	Combined Strong-Strong and Weak-Strong Beam-Beam Simulations for Crabbed Collision in eRHIC	proton, simulation, luminosity, cavity	788
	Y. Luo, G. Bassi, M. Blaskiewicz, W. Fischer, Y. Hao, C. Montag, V. Ptitsyn, V.V. Smaluk, F.J. Willeke BNL, Upton, Long Island, New York, USA K. Ohmi KEK, Ibaraki, Japan J. Qiang LBNL, Berkeley, California, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In the eRHIC, to compensate the geometric luminosity loss, local crab cavities on both sides of the interaction points are to adopted. The previous strong-strong beam-beam simulations showed that the luminosity degradation depends on the crab cavity frequency, proton synchrotron tune, proton bunch length and so on. In this article, we apply a combined strong-strong and weak-strong beam-beam simulation to investigate the incoherent and coherent beam motions with crabbed collison, and to calculate more realistic beam emittance growth rates and luminosity degradation rate.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB091
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB092	Symplectic and Exact Tracking of Low Energy 197Au⁷⁸⁺ in the Relativistic Heavy Ion Collider	quadrupole, simulation, storage-ring, lattice	791
	Y. Luo, W. Fischer, F. Méot, G. Robert-Demolaize BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In the coming RHIC low energy scan, the electron cooling technique is to be used to cool the ions 197Au⁷⁹⁺ with its energy range between 3.85~GeV/nucleon to 5.75~GeV/nucleon. To overlap the electron beam and the 197Au⁷⁹⁺ beam at the cooling section, a recombination monitor is to be used to detect the maximum flux of 197Au⁷⁸⁺ ions generated in the cooling section. In the previous studies, we tracked 197Au⁷⁸⁺ ions through the RHIC lattice defined with 197Au⁷⁹⁺ with an equivalent momentum deviation. In the article, we explode different symplectic ways to track 197Au⁷⁸⁺ ions exactly. We calculate and compare the trajectories and loss map of 197Au⁷⁸⁺ ions through the RHIC ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB092
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB093	eRHIC Electron Ring Design Status	polarization, storage-ring, solenoid, radiation	794
	C. Montag, M. Blaskiewicz, C. Hetzel, D. Holmes, Y. Li, H. Lovelace III, V. Ptitsyn, K.S. Smith, S. Tepikian, F.J. Willeke, H. Witte, W. Xu BNL, Upton, Long Island, New York, USA E. Gianfelice-Wendt Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. For the proposed electron-ion collider eRHIC, an electron storage ring will be installed in the existing RHIC tunnel. To reach the high luminosity of up to 10³⁴ cm^-2 sec^-1, beam currents up to 2.5A have to be stored. Besides high luminosity the physics program requires spin polarization levels of 70 percent, with both spin "up" and spin "down" orientations present in the fill. This is only feasible by using a full-energy spin polarized injector that replaces bunches faster than the depolarization rate. To limit the repetition rate of that injector to about one hertz, the polarization lifetime in the storage ring has to be maximized by proper spin matching and countermeasures for the machine misalignments. We will give an overview of the electron storage ring design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB093
About •	paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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MOPRB098	An Increased Extraction Energy Booster Complex for the Jefferson Lab Electron Ion Collider	booster, collider, extraction, proton	797
	E.A. Nissen JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, world-wide license to publish or reproduce this manuscript. The proposed Jefferson Lab Electron Ion Collider (JLE-IC) envisions an ion complex composed of an ion linac, two booster synchrotrons and a collider ring. The evolving design of the JLEIC booster required an increase in the extraction energy of the booster from 8 to 12.1 GeV kinetic energy, necessitating two machines instead of one. The decision was also made to switch to warm magnets, thus increasing the total radius of the 8 GeV booster. The second booster is now the same size as the collider rings. In this work we present the new designs for JLEIC’s Low Energy Booster (LEB) and High Energy Booster (HEB).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB098
About •	paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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MOPRB100	An Improved eRHIC Interaction Region Design Without High Field Nb₃Sn Magnets	hadron, quadrupole, dipole, proton	799
	B. Parker, R.B. Palmer, H. Witte BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The IR magnets for the eRHIC Collider proposed at BNL must provide strong fields for the high momentum hadron beam and yet protect the nearby electron beam focusing channel from these fields. In our initial design the electron and hadron magnets were staggered so their respective cold masses did not overlap; however, this restricts the longitudinal space for the first hadron quadrupole and led to the challenge of making a high-field Nb₃Sn main coil structure fit inside limited radial space within an external field active shield coil. In our new layout the crossing angle increased from 22 to 25 mrad and the electron and hadron cold masses are now side-by-side. This layout allows longer magnetic lengths for reducing the coil peak fields; NbTi conductor can now be used everywhere. Of course we must take care to control magnetic cross talk between neighboring apertures. One trick we will use to accomplish this is to maximize the yoke material thickness between the beams by tapering (i.e. change coil radius as a function of longitudinal position) some of the electron coils. The new eRHIC IR layout and magnet design is reported in this paper along with ongoing R&D to wind tapered coils.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB100
About •	paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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MOPRB106	3D Theory of Microbunched Electron Cooling for Electron-Ion Colliders	hadron, kicker, simulation, betatron	814
	G. Stupakov, P. Baxevanis SLAC, Menlo Park, California, USA
	Funding: This work was supported by the Department of Energy, Contract No. DE-AC02-76SF00515. The Microbunched Electron Cooling (MBEC) * is a promising cooling technique that can find applications in future hadron and electron-ion colliders. A 1D model of MBEC has been recently developed in Ref. *. This model predicts the cooling time below two hours for eRHIC 255 GeV proton beams, when two amplification sections are used in the cooling system. In this work, we go beyond the 1D model of Ref. and develop a realistic 3D theory of MBEC. Our approach is based on the analysis of the dynamics of microscopic 3D fluctuations in the electron and hadron beams during their interaction and propagation through the system. We derive an analytical expression for the cooling rate and optimize it for the parameters of eRHIC. Our analytical results are in reasonable agreement with simulations. * D. Ratner. Phys. Rev. Lett. 111, 084802 (2013). ** G. Stupakov. PRAB 21, 114402 (2018)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB106
About •	paper received ※ 29 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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MOPRB109	Cavity Design for the Updated eRHIC Crabbing System	cavity, proton, operation, hadron	818
	S. Verdú-Andrés, Q. Wu BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates LLC under contract no. DE-SC0012704 with the U.S. Department of Energy. The electron-ion collider eRHIC proposed by Brookhaven National Laboratory includes a crabbing system to reestablish head-on collisions for a maximum geometric overlap of the colliding bunches. Since the last cavity design, the crossing angle has increased from 22 to 25 mrad to relax the field strength requirement in one of the IR magnets - increasing the deflecting kick required to collider the bunches head on - and one of the considered options is to have both proton and electron crab cavities work at 200 MHz. The present paper discusses the RF design of the 200 MHz crab cavities for the electron and hadron beams of eRHIC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB109
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB110	Simulation Study of the Emittance Measurements in Magnetized Electron Beam	solenoid, emittance, cathode, gun	822
	S.A.K. Wijethunga, J.R. Delayen, G.A. Krafft ODU, Norfolk, Virginia, USA J.F. Benesch, F.E. Hannon, G.A. Krafft, M.A. Mamun, G.G. Palacios Serrano, M. Poelker, R. Suleiman, S. Zhang JLab, Newport News, Virginia, USA
	Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC05-06OR23177 Electron cooling of the ion beam is key to obtaining the required high luminosity of proposed electron-ion colliders. For the Jefferson Lab Electron Ion Collider, the expected luminosity of 10³⁴ 〖 cm〗^-2 s^-1 will be achieved through so-called ’magnetized electron cooling’, where the cooling process occurs inside a solenoid field, which will be part of the collider ring and facilitated using a circulator ring and Energy Recovery Linac (ERL). As an initial step, we generated magnetized electron beam using a new compact DC high voltage photogun biased at -300 kV employing an alkali-antimonide photocathode. This contribution presents the characterization of the magnetized electron beam (emittance variations with the magnetic field strength for different laser spot sizes) and a comparison to GPT simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB110
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPTS002	Linac Energy Jitter Measurements with SPARK BPMs at ALBA	linac, electronics, klystron, operation	833
	R. Muñoz Horta, D. Lanaia, E. Marín, A. Olmos, F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	At ALBA four Beam Position Monitors (BPMs) measure the beam position along the Linac to Booster Transfer Line. The BPM electronics (Libera Spark type) have been recently upgraded in order to be sensitive to single-pass beam detection. As a result, the position resolution measured in LTB BPMs has been increased by a factor 10 with respect to the former electronics. The increased resolution enables us to resolve the energy jitter of the Linac beam, providing an on-line measurement of the Linac energy during regular operation. In this paper a study of the Linac energy jitter is presented as well as its correlation with the jitter sources.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS002
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPTS014	The Experimental Area at the ARES LINAC	experiment, laser, linac, acceleration	867
	F. Burkart, R.W. Aßmann, U. Dorda, J. Hauser, S. Lederer, F. Lemery, B. Marchetti, F. Mayet, E. Panofski, P. Wiesener DESY, Hamburg, Germany M. Trunk University of Hamburg, Hamburg, Germany
	The ARES (Accelerator Research Experiment at SINBAD) linac at the accelerator R&D facility SINBAD (Short innovative bunches and accelerators at DESY) will drive multiple independent experiments including the acceleration of ultrashort electron bunches. In addition the linac will host an experimental area, open for transnational access, to study advanced high gradient, laser driven, acceleration concepts, like the ones studied within the ACHIP (accelerator on a chip) project. The area will be operational mid-2019. This paper will report on the current status of the experimental area, including hardware parameters, beam optics, achievable beam parameters, design of the experimental chamber and commissioning plans. The modification plans for a micro-bunching experiment in the frame of the ACHIP experiment and future upgrade plans will be shown and discussed in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS014
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPTS018	First Electron Beam at the Linear Accelerator FLUTE at KIT	laser, MMI, linac, klystron	882
	M.J. Nasse, A. Bernhard, E. Bründermann, A. Böhm, S. Funkner, B. Härer, I. Križnar, A. Malygin, S. Marsching, W. Mexner, A.-S. Müller, G. Niehues, R. Ruprecht, T. Schmelzer, M. Schuh, N.J. Smale, P. Wesolowski, M. Yan KIT, Karlsruhe, Germany
	Funding: The SRR project has received funding from the European Union’s Horizon 2020 Research and Innovation program under Grant Agreement No 730871. The first electron beams were generated in the 7 MeV section of the short-pulse linear accelerator test facility FLUTE (Ferninfrarot Linac- Und Test-Experiment) at the Karlsruhe Institute of Technology (KIT). In this contribution we show images of the electron beam on a YAG-screen (yttrium aluminum garnet) as well as signals from an integrating current transformer (ICT) and a Faraday cup. Furthermore, the progress of tuning the FLUTE electron bunches for experiments is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS018
About •	paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPTS023	Conditioning of the Frontline Cavities of the MYRRHA Injector	rfq, cavity, multipactoring, MMI	895
	S. Lamprecht, T. Conrad, K. Kümpel, N.F. Petry, H. Podlech IAP, Frankfurt am Main, Germany J. Belmans, D. Davin, W. De Cock, F. Pompon, D. Vandeplassche SCK•CEN, Mol, Belgium
	The MYRRHA Project (Multi-purpose hYbrid Research Reactor for High-tech Applications) in Mol, Belgium, is an upcoming accelerator driven system (ADS) for the transmutation of long-living radioactive waste. In the injector section of the accelerator, consisting of a 4-rod RFQ and a normal conducting CH-cavity section, the protons will be accelerated up to 17 MeV before entering the superconducting gap-spoke cavity section with an output energy of 600 MeV. A shortened test-injector with an output energy of 5.9 MeV is currently being installed at the SCK. CEN in Louvein-la- Neuve, Belgium. This test-injector serves the purpose of testing the reliability of the planned injector. When commissioning a cavity, it first has to be fed very little power to avoid damage to the structure by flashovers, discharges and multipacting. The power is then slowly increased up to full operation level. In this process, the surfaces are cleaned by heating/outgasing so that the effects disturbing operation described above do no longer occur. This paper will report on the status of the conditioning of the 176.1 MHz 4-rod RFQ up to 120 kW of the MYRRHA-injector and additional measurements concerning the gap voltage which are currently being performed at the SCK. CEN.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS023
About •	paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPTS025	Overview of the ARES Bunch Compressor at SINBAD	laser, plasma, linac, simulation	902
	F. Lemery University of Hamburg, Hamburg, Germany R.W. Aßmann, U. Dorda, K. Flöttmann, J. Hauser, M. Hüning, G. Kube, M. Lantschner, S. Lederer, B. Marchetti, N. Mildner, M. Pelzer, M. Rosan, J. Tiessen, K. Wittenburg DESY, Hamburg, Germany
	Funding: This project has received funding from the European Unions Horizon 2020 Research and Innovation programme under Grant Agreement No 730871. Bunch compressors are essential for the generation of short bunches with applications in e.g. colliders, free electron lasers, and advanced accelerator concepts. The up-and-coming ARES accelerator located at SINBAD, DESY will support the formation of ~100~MeV, pC, sub-fs electron bunches for LWFA research and development. We give an overview on the ARES bunch compressor, providing start-to-end simulations of the machine and an update on its technical design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS025
About •	paper received ※ 17 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPTS026	Status Report of the SINBAD-ARES RF Photoinjector and LINAC Commissioning	gun, linac, laser, experiment	906
	E. Panofski, R.W. Aßmann, F. Burkart, U. Dorda, K. Flöttmann, M. Hüning, B. Marchetti, D. Marx, F. Mayet, P.A. Walker, S. Yamin DESY, Hamburg, Germany
	The accelerator R&D facility SINBAD (Short innovative bunches and accelerators at DESY) will drive multiple independent experiments including the acceleration of ultrashort electron bunches and the test of advanced high gradient acceleration concepts. The SINBAD-ARES (Accelerator Research Experiment at SINBAD) setup hosts a normal conducting RF photoinjector generating a low charge electron beam that is afterwards accelerated to 100 MeV by an S-band linac section. The linac as well as a magnetic chicane allow the production of ultrashort pulses with an excellent arrival-time stability. The high brightness beam has then the potential to serve as a test beam for next generation compact acceleration schemes. The setup of the SINBAD-ARES facility will proceed in stages. We report on the current status of the ARES RF gun and linac commissioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS026
About •	paper received ※ 22 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPTS054	Status of the CLEAR Electron Beam User Facility at CERN	experiment, radiation, plasma, operation	983
	K.N. Sjobak, E. Adli, C.A. Lindstrøm University of Oslo, Oslo, Norway M. Bergamaschi, S. Burger, R. Corsini, A. Curcio, S. Curt, S. Döbert, W. Farabolini, D. Gamba, L. Garolfi, A. Gilardi, I. Gorgisyan, E. Granados, H. Guerin, R. Kieffer, M. Krupa, T. Lefèvre, S. Mazzoni, G. McMonagle, N. Nadenau, H. Panuganti, S. Pitman, V. Rude, A. Schlogelhofer, P.K. Skowroński, M. Wendt, A.P. Zemanek CERN, Geneva, Switzerland A. Lyapin UCL, London, United Kingdom
	The CERN Linear Electron Accelerator for Research (CLEAR) has now finished its second year of operation, providing a testbed for new accelerator technologies and a versatile radiation source. Hosting a varied experimental program, this beamline provides a flexible test facility for users both internal and external to CERN, as well as being an excellent accelerator physics training ground. The energy can be varied between 60 and 220 MeV, bunch length between 1 and 4 ps, bunch charge in the range 10 pC to 2 nC, and number of bunches in the range 1 to 200, at a repetition rate of 0.8 to 10 Hz. The status of the facility with an overview of the recent experimental results is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS054
About •	paper received ※ 12 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPTS065	Alternative Design of CEPC LINAC	linac, positron, booster, collider	1005
	C. Meng, J. Gao, X.P. Li, G. Pei, J.R. Zhang IHEP, Beijing, People’s Republic of China
	Circular Electron-Positron Collider (CEPC) is a 100 km ring e⁺ e⁻ collider for a Higgs factory. The injector is composed of a Linac and a Booster. The baseline design of CEPC Linac is a normal conducting S-band linear accelerator with frequency in 2860 MHz, which can provide electron and positron beam at an energy up to 10 GeV and bunch charge up to 3 nC. To reduce the design difficulty of booster and booster magnet at low energy part, an alternative design of the Linac with C-band accelerating structure at high energy part is proposed and the energy is up to 20 GeV. The compre-hensive consideration of Linac design and damping ring design will be discussed. In this paper, the physics design of this scheme is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS065
About •	paper received ※ 16 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
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MOPTS067	The Progress in Physics Design of HEPS LINAC	linac, wakefield, bunching, emittance	1008
	C. Meng, D.Y. He, X. He, J.Y. Li, Y.M. Peng, S.C. Wang, O. Xiao, J.R. Zhang, S.P. Zhang IHEP, Beijing, People’s Republic of China
	The High Energy Photon Source (HEPS) is a 6-GeV, ultralow-emittance light source to be built in China. The injector is composed of a 500-MeV Linac and a full energy booster. According to the study and com-missioning consideration of on-axis swap-out injec-tion system, a high bunch charge injector is desirable and a Linac that can provide 7nC per bunch electron beam to booster is needed. This paper present different bunching system schemes and the performance of different schemes are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS067
About •	paper received ※ 14 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019
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MOPTS073	Bunching System Optimization Based on MOGA	bunching, linac, emittance, solenoid	1018
	S.P. Zhang, J.Y. Li, C. Meng IHEP, Beijing, People’s Republic of China
	Multiobjective Genetic Algorithms (MOGA) is effective in dealing with optimization problems with multiple objectives. The bunching system of the High Energy Photon Source (HEPS) linac adopts a traditional bunching system for compressing electron beams with a pulse charge of 4 nC. The bunching system is optimized using MOGA. The optimization include minimizing the normalized emittance and maximizing transmission efficiency. The optimization results have reached the design target, and are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS073
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPTS089	Transverse Beam Dynamics Studies With High Intensity LHC Beams in the SPS	injection, octupole, emittance, impedance	1062
	M. Carlà, H. Bartosik, M.S. Beck, L.R. Carver, V. Kain, G. Kotzian, K.S.B. Li, G. Rumolo, C. Zannini CERN, Geneva, Switzerland
	In order to reach the target beam parameters of the LHC injectors upgrade (LIU), about twice the presently operational intensity of LHC type beams has to be achieved. Although the planned upgrade of the main RF system will occur during the long shutdown, a series of measurements have been performed to assess the beam dynamics challenges with these very high intensity beams on the long SPS injection plateau. Bunch-by-bunch transverse emittance blow-up measurements suggested the presence of electron-cloud. After a period of running with the high intensity beam for a couple of days, a clear improvement of beam quality was observed which is attributed to scrubbing. In addition, a horizontal headtail instability is encountered for the usual operational settings of chromaticity and transverse damper. The stability limit as a function of chromaticity and Landau octupole settings has been explored and will be discussed, together with possible sources of the instability and mitigation strategies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS089
About •	paper received ※ 06 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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MOPTS098	A Primary Electron Beam Facility at CERN	linac, injection, emittance, proton	1098
	Y. Papaphilippou, R. Corsini, Y. Dutheil, L.R. Evans, B. Goddard, A. Grudiev, A. Latina, S. Stapnes CERN, Meyrin, Switzerland T.P.Å. Åkesson Lund University, Department of Physics, Lund, Sweden
	This paper describes the concept of a primary electron beam facility at CERN, to be used for dark gauge force and light dark matter searches. The electron beam is produced in three stages: A Linac accelerates electrons from a photo-cathode up to 3.5 GeV. This beam is injected into the Super Proton Synchrotron, SPS, and accelerated up to a maximum energy of 16 GeV. Finally, the accelerated beam is slowly extracted to an experiment, possibly followed by a fast dump of the remaining electrons to another beamline. The beam parameters are optimized using the requirements of the Light Dark Matter eXperiment, LDMX, as benchmark.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS098
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPTS099	The Development Programme of Cathodes and Electron Guns for the Hollow Electron Lenses of the High Luminosity LHC Project	cathode, gun, luminosity, proton	1102
	D. Perini, G. Gobbi CERN, Geneva, Switzerland D.J. Crawford, J. Ruan, G. Stancari, L.R. Valerio Fermilab, Batavia, Illinois, USA J. Feng, Z. Li, W. Shao, K. Zhang BVERI, Beijing, People’s Republic of China W. Liu, J. Wang, Y. Wang, Y. Yang Beijing University of Technology, Beijing, People’s Republic of China
	Funding: Research supported by the HL-LHC project The High Luminosity LHC project (HL-LHC) foresees the construction and installation of important new equipment to increase the performance of the LHC machine. The Hollow Electron Lens (HEL) is a promising system to control the beam halo. It improves the beam collimation system of the HL-LHC and mitigates possible equipment damage in case of failure scenarios from halo losses. The halo can store up to 30 MJ energy. The specifications for this new device are quite demanding. The source, an electron gun with an annular shaped cathode, has to deliver a current up to 5 A. This is five times higher than the current in the existing electron lenses in Fermi and Brookhaven national laboratories. This note describes the programme carried out to design and test high-perveance guns equipped with two types of high-performance scandate cathodes. The size of the final gun is now considerably smaller than the one of the first prototype, allowing a reduction of diameter and cost of the superconducting magnet system used to steer the electron beam. The tests carried out at FNAL, BVERI and BJUT demonstrated that the developed cathodes fulfil the specifications and can supply a 5 A fully Space Charge Limited (SCL) current.
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About •	paper received ※ 17 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPTS104	A Toolkit for Tracing Electron Beam Envelope at Low Energy Section of TPS Linac	simulation, linac, operation, gun	1122
	H.H. Chen, H.C. Chen, K.-K. Lin, Y.K. Lin NSRRC, Hsinchu, Taiwan
	Based on calculated Bz of solenoids installed at the TPS linac low energy section, the electron beam envelope along beam centerline has been explored in this work using the initial and boundary conditions provided in the linac specifications. Concept of magnetic flux compression is adopt to analyze the beam size variation along linac centerline. The calculated result of selected checkpoints has been experimentally verified using screen monitors. In order to benefit tuning capability in routine operation, the display of beam size variation along centerline is integrated into the previously developed toolkit ’linac’. It is hope that it will provide an interactive approach for linac tune-up process and would be helpful to its routine operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS104
About •	paper received ※ 23 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPTS105	The High Brightness Photo-injector for THz CUR/VUV FEL at NSRRC	radiation, emittance, quadrupole, linac	1125
	A.P. Lee, M.C. Chou, H.P. Hsueh, J.-Y. Hwang, W.K. Lau NSRRC, Hsinchu, Taiwan P. Wang NTHU, Hsinchu, Taiwan
	A high brightness photo-injector has been build for THz coherent undulator radiation and VUV free electron laser test facility at NSRRC. In the first phase, the photo-injector was used to produce ultra-short electron bunches for THz CUR generation. The electron beam is generated form a photocathode rf gun followed by a solenoid for emittance compensation. Then A 5.2 m S-band linac accelerates the electron beam and compresses the beam by velocity bunching. Since the beam emittance will grow during the velocity bunching process, a solenoid system was installed to reduce the emmitance growth. Downstream the linac, a quadruple magnet was use for emittance measurement by quadruple scan method and the bunch length was measured by the coherent transition radiation. Finally, the ultra-short electron bunch with about few hundreds picoseconds passes through a U100 planer undulator can produce THz coherent undulator radiation. The instrument setup and results of measurement are presented in this paper.
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About •	paper received ※ 14 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019
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MOPTS117	Exploration of High-Gradient Structures for 4th Generation Light Sources	cavity, FEL, linac, cryogenics	1155
	S.J. Smith, S. Biedron, S.I. Sosa Guitron University of New Mexico, Albuquerque, USA T.B. Bolin Element Aero, Chicago, USA B.E. Carlsten, F.L. Krawczyk LANL, Los Alamos, New Mexico, USA J.R. Cary, D.M. Cheatham Tech-X, Boulder, Colorado, USA
	As the energy, scale and therefore the cost of large-scale accelerator projects, such as X-ray free-electron lasers (XFELs) increases, new technologies must be developed in order to minimize costs and maximize efficiency wherever possible. One obvious way to reduce costs is to reduce the length of accelerating sections by utilizing higher accelerating gradients. Here we present the results of a study into the various structure options for FEL linacs, contrasting different frequencies, geometries and operating modes. An investigation into the possibility of using cryo-cooled travelling wave (TW) electron structures which allow for higher gradient operation by exploiting the anomalous skin effect is also detailed. Finally, we give simulation results from a number of commercial codes including VSim 9, for a hypothetical TW high gradient C-band structure design employing cryo-cooled technology. Breakdown effects, pulsed heating, tolerances, efficiencies and potential rf sources are also explored, all within the framework of typical FELs and their requirements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS117
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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TUXXPLM3	First Operation of a Hybrid e-Gun at the Schlesinger Center for Compact Accelerators in Ariel University	gun, laser, solenoid, klystron	1171
	A.N. Nause, A. Fukasawa, J.B. Rosenzweig, R.J. Roussel UCLA, Los Angeles, USA A. Friedman Ariel University, Ariel, Israel B. Spataro INFN/LNF, Frascati, Italy
	Funding: Israel Ministry of Defence Israel Ministry of Science A novel hybrid photo injector was designed and partially tested at the UCLA Particle Beam Physics Laboratory. It was later commissioned at Ariel University in Israel as an on-going collaboration between the two universities. This unique, new generation design provides a radically simpler approach to RF feeding of a gun/buncher system, leading to a much shorter beam via velocity bunching owed to an attached traveling wave section of the photo-injector. This design results in better performance in beam parameters, providing a high quality electron beam, with energy of 6 MeV, emittance of app 3 μm, and a 150 fs pulse duration at up to 1 nC per pulse. The Hybrid gun is driven by a SLAC XK5 Klystron as the high power RF source, and third harmonic of a fs level IR Laser amplifier (266 nm) to drive the Cathode. The unique e-gun will produce an electron pulse for a THz FEL, which will operate at the super-radiance regime, and therefore requires extraordinary beam properties. This paper briefly describes the gun and presents initial operational results from the gun and its sub-systems.
	Slides TUXXPLM3 [9.526 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUXXPLM3
About •	paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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TUXXPLS2	Negative Muonium Ion Production With a C12A7 Electride Film	target, experiment, positron, acceleration	1175
	M. Otani, Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, K. Shimomura, T. Yamazaki KEK, Tsukuba, Japan K. Hasegawa, Y. Kondo, T. Morishita JAEA/J-PARC, Tokai-mura, Japan T. Iijima, Y. Sue Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan H. Iinuma, Y. Nakazawa Ibaraki University, Ibaraki, Japan K. Inami, M. Yotsuzuka Nagoya University, Nagoya, Japan K. Ishida RIKEN Nishina Center, Wako, Japan R. Kitamura, H.Y. Yasuda University of Tokyo, Tokyo, Japan N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Funding: This work was supported by OSPS KAKENHI Grant Numbers JP15H03666, JP 16H03987, JP18H03707. Negative muonium ion production is one of methods to cool muons. Since its discovery in 1987 by interactions of muons with a metal foil, it has been discussed that the production efficiency would be improved using a low-work function material. C12A7 (12CaO·7AlO3) was a well-known insulator as a constituent of alumina cement, but was recently confirmed to exhibit electric conductivity by electron doping. The C12A7 electride has lower work function (2.9 eV) and it was reported that nearly the same negative current signal as that with a bi-alkali material coated metal were observed in H⁻ formation. In this poster, the negative muonium production measurement with a Al foil and C12A7 electride film will be presented.
	Slides TUXXPLS2 [2.680 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUXXPLS2
About •	paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUYPLM1	XFEL Performance Achieved at PAL-XFEL	FEL, undulator, photon, emittance	1182
	H. Heo, M.-H. Cho, J.H. Han, H.-S. Kang, C. Kim, G. Kim, M.J. Kim, J.H. Ko, H.-S. Lee, C.-K. Min, I.H. Nam, K.-H. Park, C.H. Shim, H. Yang PAL, Pohang, Kyungbuk, Republic of Korea
	The hard X-ray free electron laser at Pohang Accelerator Laboratory (PAL-XFEL) successfully completed the commissioning of SASE and started user operation in late 2016. Since then, the facility has demonstrated excellent stability with very small timing jitter of about 20 fs, and commissioned the self-seeding system over a wide range of photon energies, etc. The talk will provide an overview of the last three years at the PAL-XFEL, including some detailed experimental results, as well as future prospects for the laboratory.
	Slides TUYPLM1 [7.516 MB]

Paper

Title

Other Keywords

Page

From Dreams to Reality: Prospects for Applying Advanced Accelerator Technology to Next Generation Scientific User Facilities

plasma, laser, acceleration, wakefield

1

M. Ferrario
INFN/LNF, Frascati, Italy
R.W. Aßmann
DESY, Hamburg, Germany

Recent years have seen spectacular progress in the development of innovative acceleration methods that are not based on traditional RF accelerating structures. These novel developments are at the interface of laser, plasma and accelerator physics and may potentially lead to much more compact and economical accelerator facilities. While primarily focusing on the ability to accelerate charged particles with much larger gradients than traditional RF, these new techniques have yet to demonstrate comparable performances to RF in terms of both beam parameters or reproducibility. To guide the developments beyond the necessary basic R&D and concept validations, a common understanding and definition of required performance and beam parameters for an operational user facility is now needed. These innovative user facilities can include "table-top" light sources, medical accelerators, industrial accelerators or even high-energy colliders. The talk will review the most promising developments in new acceleration methods, it will present the status of ongoing projects including the EU project EuPRAXIA and will identify the set of required specifications for the application under consideration.

Slides MOXPLM2 [16.331 MB]

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MOZPLS2

Ion Collider Precision Measurements With Different Species

target, operation, experiment, collider

28

G.J. Marr, E.N. Beebe, I. Blackler, W. Christie, K.A. Drees, P.S. Dyer, A.V. Fedotov, W. Fischer, C.J. Gardner, H. Huang, T. Kanesue, N.A. Kling, V. Litvinenko, C. Liu, Y. Luo, D. Maffei, B. Martin, A. Marusic, K. Mernick, M.G. Minty, C. Naylor, M. Okamura, I. Pinayev, G. Robert-Demolaize, T. Roser, P. Sampson, V. Schoefer, T.C. Shrey, D. Steski, P. Thieberger, J.E. Tuozzolo, K. Zeno, I.Y. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC, under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Precedent to electron cooling commissioning and collisions of Gold at various energies at RHIC in 2018, the STAR experiment desired an exploration of the chiral magnetic effect in the quark gluon plasma (QGP) with an isobar run, utilizing Ruthenium and Zirconium. Colliding Zr-96 with Zr-96 and Ru-96 with Ru-96 create the same QGP but in a different magnetic field due to the different charges of the Zr (Z=40) and Ru (Z=44) ions. Since the charge difference is only 10%, the experimental program requires exacting store conditions for both ions. These systematic error concerns presented new challenges for the Collider, including frequent reconfiguration of the Collider for the different ion species, and maintaining level amounts of instantaneous and integrated luminosity between two species. Moreover, making beams of Zr-96 and Ru-96 is challenging since the natural abundances of these isotopes are low. Creating viable enriched source material for Zr-96 required assistance processing from RIKEN, while Ru-96 was provided by a new enrichment facility under commissioning at Oak Ridge National Laboratory.

Slides MOZPLS2 [4.758 MB]

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MOZZPLM2

A Bunch Structure Measurement of Muons Accelerated by RFQ Using a Longitudinal Beam-Profile Monitor With High Time Resolution

rfq, experiment, linac, background

37

Y. Sue, K. Inami
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, M. Otani, T. Yamazaki
KEK, Ibaraki, Japan
K. Hasegawa, R. Kitamura, T. Morishita
JAEA/J-PARC, Tokai-mura, Japan
T. Iijima
KMI, Nagoya, AIchi Prefecture, Japan
H. Iinuma, Y. Nakazawa
Ibaraki University, Hitachi, Ibaraki, Japan
K. Ishida
RIKEN Nishina Center, Wako, Japan
Y. Kondo
JAEA, Ibaraki-ken, Japan
N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Takeuchi
Kyoto ICR, Uji, Kyoto, Japan
T. Ushizawa
Sokendai, Ibaraki, Japan
H.Y. Yasuda
University of Tokyo, Tokyo, Japan
M. Yotsuzuka
Nagoya University, Nagoya, Japan

Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP15H05742, JP16H03987, JP16J07784, JP18H03707 and JP18H05226.
J-PARC E34 experiment intends to measure the anomalous magnetic moment and electric dipole moment of muon precisely by a different way from the previous experiment. In this experiment, a low-emittance muon beam is provided using the muons with the thermal energy and the four-stage linac. The demonstration of the first muon RF acceleration with an RFQ linac was conducted and the transverse profile of the accelerated muons was measured last year. As one of the remaining issues for the beam-diagnostic system, the longitudinal beam profile after the RFQ should be measured to match the profile to the designed acceptance of the subsequent accelerator. For this purpose, the new longitudinal beam monitor using the micro-channel plate is under development. The time resolution aims to be around 30 to 40 ps corresponding to 1 % of a period of an operation frequency of the accelerator, which is 324 MHz. On November 2018, the bunch structure of accelerated muons of 89 keV with the RFQ was measured using this monitor at the J-PARC MLF. The latest analysis result of this measurement will be reported in this poster.

Slides MOZZPLM2 [2.618 MB]

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MOZZPLS1

eRHIC Design Overview

hadron, proton, storage-ring, luminosity

45

C. Montag, G. Bassi, J. Beebe-Wang, J.S. Berg, M. Blaskiewicz, A. Blednykh, J.M. Brennan, S.J. Brooks, K.A. Brown, K.A. Drees, A.V. Fedotov, W. Fischer, D.M. Gassner, W. Guo, A. Hershcovitch, C. Hetzel, D. Holmes, H. Huang, W.A. Jackson, J. Kewisch, Y. Li, C. Liu, H. Lovelace III, Y. Luo, F. Méot, M.G. Minty, R.B. Palmer, B. Parker, S. Peggs, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, S. Seletskiy, V.V. Smaluk, K.S. Smith, S. Tepikian, P. Thieberger, D. Trbojevic, N. Tsoupas, S. Verdú-Andrés, W.-T. Weng, F.J. Willeke, H. Witte, Q. Wu, W. Xu, A. Zaltsman, W. Zhang
BNL, Upton, Long Island, New York, USA
E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA
Y. Hao
FRIB, East Lansing, Michigan, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The Electron-Ion Collider (EIC) is being envisioned as the next facility to be constructed by the DOE Nuclear Physics program. Brookhaven National Laboratory is proposing eRHIC, a facility based on the existing RHIC complex as a cost effective realization of the EIC project with a peak luminosity of 10³⁴ cm^-2 sec^-1. An electron storage ring with an energy range from 5 to 18 GeV will be added in the existing RHIC tunnel. A spin-transparent rapid-cycling synchrotron (RCS) will serve as a full-energy polarized electron injector. Recent design improvements include reduction of the IR magnet strengths to avoid the necessity for Nb₃Sn magnets, and a novel hadron injection scheme to maximize the integrated luminosity. We will provide an overview of this proposed project and present the current design status.

Slides MOZZPLS1 [5.428 MB]

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MOPGW017

Feedback Design for Control of the Micro-Bunching Instability based on Reinforcement Learning

bunching, storage-ring, feedback, controls

104

T. Boltz, T. Asfour, M. Brosi, E. Bründermann, B. Härer, P. Kaiser, A.-S. Müller, C. Pohl, P. Schreiber, M. Yan
KIT, Karlsruhe, Germany

The operation of ring-based synchrotron light sources with short electron bunches increases the emission of coherent synchrotron radiation (CSR) in the THz frequency range. However, the micro-bunching instability resulting from self-interaction of the bunch with its own radiation field limits stable operation with constant intensity of CSR emission to a particular threshold current. Above this threshold, the longitudinal charge distribution and thus the emitted radiation vary rapidly and continuously. Therefore, a fast and adaptive feedback system is the appropriate approach to stabilize the dynamics and to overcome the limitations given by the instability. In this contribution, we discuss first efforts towards a longitudinal feedback design that acts on the RF system of the KIT storage ring KARA (Karlsruhe Research Accelerator) and aims for stabilization of the emitted THz radiation. Our approach is based on methods of adaptive control that were developed in the field of reinforcement learning and have seen great success in other fields of research over the past decade. We motivate this particular approach and comment on different aspects of its implementation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW017

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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MOPGW018

Perturbation of Synchrotron Motion in the Micro-Bunching Instability

bunching, synchrotron, storage-ring, radiation

108

T. Boltz, M. Brosi, E. Bründermann, B. Härer, A.-S. Müller, P. Schreiber, P. Schönfeldt, M. Yan
KIT, Karlsruhe, Germany

Short electron bunches in a storage ring are subject to complex longitudinal dynamics due to self-interaction with their own CSR. Above a particular threshold current, this leads to the formation of dynamically changing micro-structures within the bunch, generally known as the micro-bunching instability. The longitudinal dynamics of this phenomenon can be simulated by solving the Vlasov-Fokker-Planck equation, where the CSR self-interaction can be added as a perturbation to the Hamiltonian. This contribution particularly focuses on the comprehension of synchrotron motion in the micro-bunching instability and how it relates to the formation of the occurring micro-structures. Therefore, we adopt the perspective of a single particle and comment on its implications for collective motion. We explicitly show how the shape of the parallel plates CSR wake potential breaks homogeneity in longitudinal phase space and propose a quadrupole-like mode as potential seeding mechanism of the micro-bunching instability. The gained insights are verified using the passive particle tracking method of the Vlasov-Fokker-Planck solver Inovesa.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW018

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paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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MOPGW021

Symplectic Tracking for the Robinson Wiggler

wiggler, storage-ring, dynamic-aperture, linear-dynamics

120

J. Li, J. Feikes, T. Mertens, Y. Petenev, M. Ries, A. Schälicke
HZB, Berlin, Germany

A Robinson wiggler (RW) is considered to be installed in the Metrology Light Source (MLS) to lengthen the bunch and improve the Touschek lifetime by manipulating the damping partitions. Symplectic tracking is crucial to study the impact of the nonlinear field components introduced by the Robinson wiggler. This paper introduces a tracking method based on an implicit symplectic integrator to solve the exact Hamiltonian equations of particle motion in the wiggler. In addition, a numerical generating function method is implemented as an approach to realize fast tracking.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW021

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPGW027

Design Considerations for Permenant Magnetic Quadrupole Triplet for Matching Into Laser Driven Wake Field Acceleration Experiment at SINBAD

laser, plasma, experiment, acceleration

143

S. Yamin, R.W. Aßmann, U. Dorda, F. Lemery, B. Marchetti, E. Panofski, P.A. Walker
DESY, Hamburg, Germany

SINBAD (Short and INnovative Bunches and Accelerators at DESY) facility aims to produce ultrashort bunches (sub-fs) at ~100 MeV, suitable for injection into novel accelerators e.g. dielectric Laser acceleration (DLA) and Laser Driven Wakefield acceleration (LWFA). The LWFA experiment demands β functions to be of the order of 1 mm to reduce energy spreads and emittance growth from nonlinearities. Matching such a space charge dominated beam to such constraints with conventional electromagnets is challenging. A Permanent Magnetic Quadrupole (PMQ) triplet is one promising focusing strategy. In this paper, we investigate the performance of a PMQ triplet to fit the requirements of the electron beam properties in a plasma cell and discuss the realizable phase spaces for the LWFA experiment planned at SINBAD.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW027

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPGW028

Study for the Alignment of Focusing Solenoid of ARES RF Gun and Effect of Misalignment of Solenoid on Emittance of Space Charge Dominated Electron Beam

solenoid, alignment, emittance, gun

147

S. Yamin, R.W. Aßmann, B. Marchetti
DESY, Hamburg, Germany

SINBAD (Short and INnovative Bunches and Accelerators at DESY) facility will host multiple experiments relating to ultra-short high brightness beams and novel experiments with ultra-high gradient. ARES (Accelerator Research Experiment at SINBAD) Linac is an S-band photo injector to produce such electron bunches at around 100 MeV. The Linac will be commissioned in stages with the first stage corresponding to gun commissioning. In this paper, we present studies about the scheme adopted for the alignment of focusing solenoid for the ARES gun. The method is bench marked using ASTRA simulations. Moreover the effect of misalignment of the solenoid on the emittance of space charge dominated scheme and its compensation is also discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW028

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paper received ※ 26 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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MOPGW029

Preliminary Study of Bunch Compression in the Hefei Light Source

lattice, storage-ring, radiation, synchrotron-radiation

151

W. Li, Z.H. Bai, W. Li, J.G. Wang, D.R. Xu, Z. Zhao
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: This work was supported by the Fundamental Research Funds for the Central Universities (Grant No.WK2310000082 and WK2310000077), and the National Natural Science Foundation of China(GrantNo.11475167).
Short electron bunch has interesting applications in the synchrotron radiation light sources, such as the production of powerful coherent THz radiation, time resolving spectrum analysis, etc. In this work, we are interested in acquiring the short bunch in the storage ring with a small circumference like Hefei Light Source. In this paper, we tried to approach the short bunch in two separate methods: by increasing the higher harmonic cavity voltage and by reducing the momentum compaction factor. The preliminary result and observations are shown and discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW029

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paper received ※ 16 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPGW053

Residual Gas Lifetime In High Energy Photon Source (HEPS)

scattering, dynamic-aperture, vacuum, photon

210

S.K. Tian, H.S. Xu
IHEP, Beijing, People’s Republic of China

High vacuum has always been mandatory in particle accelerators. This is especially true for circular machines, where the beam makes thousands or millions turns, and beam lifetime is heavily affected by the residual gas scattering. At the beginning of storage ring operation the lifetime was very short mostly dominated by residual gas scattering. The residual gas lifetime is comprised of the elastic and inelastic scattering on electrons and elastic and inelastic scattering on nuclei. One usually calculates only the elastic scattering on nuclei (single Coulomb scattering) and inelastic scattering on nuclei (bremsstrahlung) of the residual gas scattering lifetime component. The analytic calculation the residual gas scattering lifetime and simulations of the beam interaction with the residual gas with code will be shown in this presentation

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW053

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paper received ※ 15 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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MOPGW054

Study on Spherical Aberration Correction of Solenoid Lens in Ultrafast Electron Diffraction

induction, solenoid, emittance, focusing

213

Y.T. Yang, K. Fan, J.J. Li
HUST, Wuhan, People’s Republic of China
Y. Song
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China

High electron beam quality is required in Ultrafast Electron Diffraction (UED) to achieve high spatial resolution. However, aberrations mainly induced by solenoid lens will deteriorate the beam quality and limit the resolution. Spherical aberration introduces the largest distortion which is unavoidable in the case of static cylindrically symmetric electromagnetic fields on the basis of Scherzer’s theorem. In order to reduce the spherical aberrations, different models have been designed which are composed of three symmetrical lens and one asymmetrical lens. We obtain the magnetic field distribution and calculate the aberration of each model by OPERA, and the result is that the solenoid without poles has the minimum aberration and meets the design requirement best.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW054

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paper received ※ 13 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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MOPGW058

Towards a Sextupole-Free Electron Storage Ring

vacuum, impedance, storage-ring, feedback

217

T.-Y. Lee, T. Ha
PAL, Pohang, Kyungbuk, Republic of Korea

This paper studies if it is possible to build an electron storage ring with no or a small number of sextupole mag-nets. If it is possible, the electron storage ring will be great-ly simplified. For the purpose, two methods are presented in the paper to handle head-tail instability: One is to use dielectric vacuum chamber made of such materials as ceramic or glass to reduce broadband impedance signifi-cantly. Then head-tail instability would be extremely weak. The other method is to install a bunch-by-bunch feedback system to suppress the already weak head-tail instability due to the dielectric vacuum chamber.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW058

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPGW062

Radiation of a Charge Moving in a Wire Structure

radiation, FEL, simulation, lattice

231

S.N. Galyamin, A.V. Tyukhtin, V.V. Vorobev
Saint Petersburg State University, Saint Petersburg, Russia
A.I. Benediktovitch
EuXFEL, Hamburg, Germany
A.I. Benediktovitch
BSU, Minsk, Belarus, Belarus

Funding: This work is supported by the grant from Russian Foundation for Basic Research (No. 17-52-04107).
In the X-ray frequency region, interaction of relativistic electrons with crystals results in parametric X-ray radiation (PXR), with its frequency being determined by distance between crystallographic planes and direction of electron motion. If instead of crystal one considers an artificial periodic structure with periods of the order of mm, one can expect emission of radiation of a similar nature at terahertz (THz) frequencies. This frequency range is of significant interest during last decade due to its prospective applications. Moreover, artificial wire-like structures are considered as a promising alternative to conventional dielectric structures for wakefield acceleration*. Here we consider electromagnetic (EM) field produced by a charged particle bunch moving through a lattice of parallel conducting wires. We present several approaches for analysis of EM field in the described wire structure. First, conventional two-wave approximation for describing the "short-wave response" is developed. Second, we use the effective medium approach and describe the "long-wave" part of the spectrum. Third, we develop a method based on vibrator antenna theory which can be useful for finite length wire structure.
* P.D. Hoang, et al., Phys. Rev. Lett., V. 120, P. 164801 (2018).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW062

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPGW073

Beam Manipulation Using Self-Induced Fields at the SwissFEL Injector

FEL, simulation, experiment, wakefield

266

S. Bettoni, P. Craievich, E. Ferrari, R. Ganter, F. Marcellini, E. Prat, S. Reiche
PSI, Villigen PSI, Switzerland
A.A. Lutman
SLAC, Menlo Park, California, USA
G. Penco
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

In the past years wakefield sources have been used to manipulate electron beams in accelerators. We recently installed corrugated structures for a total length of 2~m at the SwissFEL injector to test novel schemes for beam manipulations. We present simulations and early experimental results. We compare the model predictions with the measured data for the bunch energy losses and the kick factor, and show early results for the longitudinal phase space linearization and the production of current spikes.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW073

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paper received ※ 09 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPGW086

Intensity Dependent Effects at ATF2, KEK

simulation, collider, linear-collider, wakefield

308

P. Korysko, A. Latina
CERN, Geneva, Switzerland
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
A. Faus-Golfe
LAL, Orsay, France
K. Kubo, T. Okugi
KEK, Ibaraki, Japan

The Accelerator Test Facility 2 (ATF2) at KEK is a prototype for the Final Focus Systems of the future e⁺e⁻ linear colliders, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC). In this paper both simulation and experimental results are presented with special emphasis on intensity-dependent effects. The importance of these effects is shown using the PLACET code and realistic ATF2 machine simulations (including beam jitter, misalignment, wakefield, Beam Based Alignment (BBA) correction, …). The latest experimental results are also presented, in particular the impact of the beam intensity on the beam size at the IP.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW086

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paper received ※ 23 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPGW104

Equilibria and Synchrotron Stability in Two Energy Storage Rings

storage-ring, damping, simulation, focusing

364

B. Dhital, J.R. Delayen, G.A. Krafft
ODU, Norfolk, Virginia, USA
J.R. Delayen, Y.S. Derbenev, D. Douglas, G.A. Krafft, F. Lin, V.S. Morozov, Y. Zhang
JLab, Newport News, Virginia, USA

In a dual energy storage ring, the electron beam passes through two loops at markedly different energies E_L, and E_H, i.e., energies for low energy loop and high energy loop respectively. These loops use a common beamline where a superconducting linac at first accelerates the beam from EL to EH and then decelerates the beam from EH to EL in the next pass. There are two basic solutions to the equilibrium problems possible, i.e., ’Storage Ring’ (SR) equilibrium and ’Energy Recovery Linac’ (ERL) equilibrium. SR equilibrium mode more resembles the usual single loop storage ring with strong synchrotron motion and ERL equilibrium mode is the case where RF in two beam passes nearly cancels. Calculations based on linear transfer matrix formalism show that longitudinal stability exists for both SR mode and ERL mode in two energy storage rings.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW104

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paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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MOPGW111

Start to End Simulation on Beam Dynamics in Coherent Electron Cooling Accelerator

FEL, bunching, emittance, cavity

379

Y.C. Jing, V. Litvinenko, I. Petrushina, I. Pinayev, K. Shih, Y.H. Wu
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
I. Petrushina
SUNY SB, Stony Brook, New York, USA
K. Shih
SBU, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A Coherent electron Cooling (CeC) has a potential of substantial reducing cooling time of the high-energy hadrons and hence to boost luminosity in high-intensity hadron-hadron and electron-hadron colliders. In a CeC system, a high quality electron beam is generated, propagated and optimized through a beam line which was carefully designed with consideration of space charge effect, wakefields and nonlinear dynamics such as coherent synchrotron radiation and chromatic aberration. In this paper, we present our study on the beam dynamics of such a beam line and compare the simulation result with what was measured in experiment.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW111

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paper received ※ 17 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPGW112

Design of a Bunch Compressor with CSR Suppression to Achieve Hundreds of kA Peak Current

emittance, optics, site, dipole

382

Y.C. Jing, V. Litvinenko
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A four dipole magnetic chicane is usually used to compress electron bunch to very short in modern accelerators which requires electron beams to have high peak current. The coherent synchrotron radiation (CSR) originated from the strong bending magnets in the chicane could greatly degrade the quality of the electron beam. In this paper, we present our design for a bunch compressing system with 30 to 100 fold in bunch length reduction and at the mean time suppress the effect of CSR on the e-beam’s quality. We discuss and detail the performance of such a compressor for potential FACET-II upgrade.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW112

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPGW116

Validation of a Novel Method for the Calculation of Near-Field Synchrotron Radiation

acceleration, radiation, cyclotron, synchrotron

397

F.Y. Li, B.E. Carlsten, R. Garimella, C. Huang, T.J. Kwan
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the LDRD program at LANL.
The phenomenon of synchrotron radiation (SR) from electrons is at the core of modern accelerator based light sources. While SR in the far field has been well characterized, the near-field SR and its impacts on self-consistent electron beam dynamics remain an ongoing topic. Since it is difficult to experimentally characterize the near fields, it is desirable to develop accurate and efficient numerical methods for the design of these light sources. Here, we investigate a novel method, originally proposed by Shintake and which potentially has both high efficiency and accuracy. We focus on the field calculation of this method and show that the original idea has missed the important terms of fields due to electron acceleration and therefore only applies to a linear motion. To correct this limitation we developed a modified algorithm that gives consistent fields with direct calculations using the Liénard-Wiechert equation. Some basic signatures of the near-field SR fields are also drawn for a cyclotron motion by using this modified approach.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW116

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPMP002

Linac and Damping Ring Designs for the FCC-ee

linac, emittance, positron, gun

420

S. Ogur, K. Oide, Y. Papaphilippou, L. Rinolfi, F. Zimmermann
CERN, Geneva, Switzerland
A.M. Barnyakov, A.E. Levichev, P.V. Martyshkin, D.A. Nikiforov
BINP SB RAS, Novosibirsk, Russia
I. Chaikovska, R. Chehab
LAL, Orsay, France
K. Furukawa, N. Iida, T. Kamitani, F. Miyahara, K. Oide
KEK, Ibaraki, Japan
E.V. Ozcan
Bogazici University, Bebek / Istanbul, Turkey
S.M. Polozov
MEPhI, Moscow, Russia
L. Rinolfi
ESI, Archamps, France
F. Yaman
IZTECH, Izmir, Turkey

We report the design of the pre-injector chain for the Future Circular e⁺ e⁻ Collider (FCC-ee) system. The electron beam from a low-emittance RF gun is accelerated by an S-band linac up to 6 GeV. A damping ring at 1.54 GeV is required for emittance cooling of the positron beam. The intermediate energy step from the exit of the S-band linac at 6 GeV to the 20 GeV injection energy of the top-up booster can be provided by the modified Super Proton Synchrotron (SPS), serving as a pre-booster ring (PBR). An alternative option to reach 20 GeV energy would be to extend the S-band linac with a C- or X-band linac. An overall cost optimisation will determine the choice of the final configuration. Beam loss and emittance dilution in the linac due to space charge effects, wakefields, and misalignment of accelerator components can be mitigated by RF phasing and orbit steering. Start-to-end simulations examine the beam transport through the linac up to either 6 GeV or 20 GeV. The results indicate large design margins. Simulations of the beam dynamics in the damping ring (DR) demonstrate a sufficiently large momentum acceptance. Effects of intrabeam scattering and electron cloud instability in the DR are also studied.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP002

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paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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MOPMP003

Positron Source for FCC-ee

positron, target, linac, collider

424

I. Chaikovska, R. Chehab, A. Faus-Golfe, Y. Han
LAL, Orsay, France
A. Apyan
ANSL, Yerevan, Armenia
Y. Enomoto, K. Furukawa, T. Kamitani, F. Miyahara, M. Satoh, Y. Seimiya, T. Suwada
KEK, Ibaraki, Japan
P.V. Martyshkin
BINP SB RAS, Novosibirsk, Russia
S. Ogur, K. Oide, Y. Papaphilippou, L. Rinolfi, P. Sievers, F. Zimmermann
CERN, Geneva, Switzerland

The FCC-ee is a high-luminosity, high-precision circular collider to be constructed in a new 100 km tunnel in the Geneva area. The physics case is well established and the FCC-ee operation is foreseen at 91 GeV (Z-pole), 160 GeV (W pair production threshold), 240 GeV (Higgs resonance) and 365 GeV (t-tbar threshold). Due to the large 6D production emittance and important thermal load in the production target, the positron injector, in particular the positron source, is one of the key elements of the FCC-ee, requiring special attention. To ensure high reliability of the positron source, conventional and hybrid targets are currently under study. The final choice of the positron target will be made based on the estimated performances. In this framework, we present a preliminary design of the FCC-ee positron source, with detailed simulation studies of positron production, capture and primary acceleration.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP003

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paper received ※ 03 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP012

Concepts of Longitudinally Polarized Electron and Positron Colliding Beams in the Circular Electron Positron Collider

polarization, positron, resonance, wiggler

445

Z. Duan, J. Gao, X.P. Li, D. Wang, Y. Wang, W.H. Xia, Q.J. Xu, C.H. Yu, Y. Zhang
IHEP, Beijing, People’s Republic of China

Funding: Work supported by National Key Research and Development Program of China (No.2018YFA0404300).
This paper reports some preliminary study into the imple- mentation of longitudinally polarized e⁺/e⁻ colliding beams in the Circular Electron Positron Collider, at a center of mass energy of 91 GeV as a Z factory and energies beyond.

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP044

Improving the Luminosity for Beam Energy Scan II at RHIC

cavity, operation, space-charge, luminosity

540

C. Liu, M. Blaskiewicz, K.A. Drees, A.V. Fedotov, W. Fischer, C.J. Gardner, H. Huang, D. Kayran, Y. Luo, G.J. Marr, A. Marusic, K. Mernick, M.G. Minty, C. Montag, I. Pinayev, S. Polizzo, V.H. Ranjbar, D. Raparia, G. Robert-Demolaize, T. Roser, J. Sandberg, V. Schoefer, T.C. Shrey, S. Tepikian, P. Thieberger, A. Zaltsman, K. Zeno, I.Y. Zhang, W. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The QCD (Quantum Chromodynamics) phase diagram has many uncharted territories, particularly the nature of the transformation from Quark-Gluon plasma (QGP) to the state of Hadronic gas. The Beam Energy Scan I (BES-I) at the Relativistic Heavy Ion Collider (RHIC) was completed but measurements had large statistical errors. To improve the statistical error and expand the search for first-order phase transition and location of the critical point, Beam Energy Scan II will commence in 2019 with a goal of improving the luminosity by a factor of 3-4. The beam lifetime at low energies was and will be limited by some physical effects of which the most significant are intrabeam scattering, space charge, beam-beam, persistent current effects. This article will review these potential limiting factors and introduce the countermeasures which will be in place to improve BES-II luminosity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP044

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP049

6 T Cable-in-conduit Dipole to Double the Ion Energy for JLEIC

dipole, collider, injection, luminosity

556

P.M. McIntyre, J. Breitschopf, J. Gerity
Texas A&M University, College Station, USA
J. Breitschopf, D.C.V. Chavez, J.N. Kellams, A. Sattarov
ATC, College Station, Texas, USA

The proposed electron-ion collider JLEIC would make high-luminosity collisions of polarized ions and polarized electrons with electron energy up to 12 GeV and ion energy up to 40 GeV/u. Both the luminosity and the collision energy could be increased by doubling the dipole field in the ion ring from 3 T to 6 T, and the enhanced performance would access the full range of parameters for the physics objectives of the project. The Texas A&M group has developed the large-aperture 3 T dipoles for the baseline project, based upon a novel superconducting cable-in-conduit. (CIC). A closely similar 6 T design is being developed, utilizing a 2-layer CIC. Details of the magnet design and development of the 2-layer CIC will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP049

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paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPMP050

Performance of CeC PoP Accelerator

FEL, gun, SRF, hadron

559

I. Pinayev, Z. Altinbas, J.C. Brutus, A.J. Curcio, A. Di Lieto, T. Hayes, R.L. Hulsart, P. Inacker, Y.C. Jing, V. Litvinenko, J. Ma, G.J. Mahler, M. Mapes, K. Mernick, K. Mihara, T.A. Miller, M.G. Minty, G. Narayan, F. Severino, K. Shih, Z. Sorrell, J.E. Tuozzolo, E. Wang, G. Wang, A. Zaltsman
BNL, Upton, Long Island, New York, USA
I. Petrushina
SUNY SB, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron cooling experiment is aimed for demonstration of the proof-of-principle demonstration of reduction energy spread of a single hadron bunch circulating in RHIC. The electron beam should have the required parameters and its orbit and energy should be matched to the hadron beam. In this paper we present the achieved electron beam parameters including emittance, energy spread, and other critical indicators. The operational issues as well as future plans are also discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP050

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB013

Focusing of High-Brightness Electron Beams with Active-Plasma Lenses

plasma, emittance, focusing, experiment

601

R. Pompili
INFN/LNF, Frascati, Italy

Plasma-based technology promises a tremendous reduction in size of accelerators used for research, medical, and industrial applications, making it possible to develop tabletop machines accessible for a broader scientific community. By overcoming current limits of conventional accelerators and pushing particles to larger and larger energies, the availability of strong and tunable focusing optics is mandatory also because plasma-accelerated beams usually have large angular divergences. In this regard, active-plasma lenses represent a compact and affordable tool to generate radially symmetric magnetic fields several orders of magnitude larger than conventional quadrupoles and solenoids. However, it has been recently proved that the focusing can be highly nonlinear and induce a dramatic emittance growth. Here, we present experimental results showing how these nonlinearities can be minimized and lensing improved. These achievements represent a major breakthrough toward the miniaturization of next-generation focusing devices.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB013

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paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB031

Progress of Conceptual Study for the Accelerators of a 2-7GeV Super Tau Charm Facility at China

collider, luminosity, factory, operation

643

Q. Luo, W. Li, D.R. Xu
USTC/NSRL, Hefei, Anhui, People’s Republic of China
W.W. Gao, J.Q. Lan
Fujian University of Technology, Fuzhou, People’s Republic of China

Funding: Supported by National Natural Science Foundation of China U1832169 and the Double Fist-Class University Project Foundation of USTC.
This paper shows the progress of the conceptual study for the accelerators of a super tau charm facility in China. Since the BEPCII will finish its historical mission in 5~10 years and its upgrade plan will only achieve a small luminosity enhancement of 3~5 times, a new next generation tau-charm collider will play an irreplaceable role in future high energy physics study. The luminosity of this successor is about 5×10³⁴cm⁻²s⁻¹ pilot and 1×10³⁵cm⁻²s⁻¹ nominal, with the electron beam longitudinally polarized at the IP. The general scheme of the accelerators and the beam pa-rameters are shown. Several key technologies such as beam polarization and beam emittance diagnostics are also discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB031

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paper received ※ 14 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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MOPRB052

Gamma Factory at CERN: Design of a Proof-of-Principle Experiment

photon, laser, experiment, cavity

685

Y. Dutheil, R. Alemany-Fernández, H. Bartosik, N. Biancacci, R. Bruce, P. Czodrowski, V. Fedosseev, B. Goddard, S. Hirlaender, J.M. Jowett, R. Kersevan, M. Kowalska, M. Lamont, D. Manglunki, J. Molson, A.V. Petrenko, M. Schaumann, F. Zimmermann
CERN, Geneva, Switzerland
S.E. Alden, A. Bosco, S.M. Gibson, L.J. Nevay
JAI, Egham, Surrey, United Kingdom
A. Apyan
ANSL, Yerevan, Armenia
E.G. Bessonov
LPI, Moscow, Russia
A. Bosco, S.M. Gibson, L.J. Nevay
Royal Holloway, University of London, Surrey, United Kingdom
F. Castelli
Università degli Studi di Milano, Milano, Italy
F. Castelli, C. Curatolo, L. Serafini
INFN-Milano, Milano, Italy
K. Kroeger
FSU Jena, Jena, Germany
A. Martens
LAL, Orsay, France
V. Petrillo
Universita’ degli Studi di Milano, Milano, Italy
M. Sapinski, T. Stöhlker
GSI, Darmstadt, Germany
G. Weber
IOQ, Jena, Germany
Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

The Gamma Factory (GF) initiative proposes to create novel research tools at CERN by producing, accelerating and storing highly relativistic partially stripped ion beams in the LHC rings and by exciting their atomic degrees of freedom by lasers, to produce high-energy photon beams. Their intensity would be several orders of magnitude higher than those of the presently operating light sources in the particularly interesting gamma-ray energy domain reaching up to 400 MeV. In this energy domain, the high-intensity photon beams can be used to produce secondary beams of polarized electrons, polarized positrons, polarized muons, neutrinos, neutrons and radioactive ions. Over the years 2017-2018 we have demonstrated that these partially stripped ion beams can be successfully produced, accelerated and stored in the CERN accelerator complex, including the LHC. The next step of the project is to build a proof of principle experiment in the SPS to validate the principal GF concepts. This contribution will present the initial conceptual design of this experiment along with its main challenge - the demonstration of the fast cooling method of partially stripped ion beams.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB052

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paper received ※ 19 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB056

THz Radiator Based on Photonic Band Gap Crystal for SwissFEL

photon, GUI, experiment, FEL

693

L. Shi, R. Ischebeck, S. Reiche
PSI, Villigen PSI, Switzerland

Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 701647.
The electromagnetic radiation in 1-20 THz has many unique properties when it interacts with matter due to its non-ionizing excitation in matter. Especially the dynamics of the excited matter can be probed with the help of X-ray pulses at a free electron laser facility, e.g. SwissFEL, to deepen our understanding of a wide range of phenomena. Due to its high research potential, various means of THz generation have been proposed and demonstrated. We investigate preliminarily here its generation based on a relativistic electron bunch and a photonic band gap crystal (PBG) made of dielectric rods. The PBG provides additional degrees of freedom for the THz pulse tuning. Additionally, the unwanted radiation parts can be damped by the structure in order to minimize the deleterious beam dynamics effects. The crystal also promises the integration of generation, filtering and coupling for transport into a single piece.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB056

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPRB060

Simulating Novel Collimation Schemes for High-Luminosity LHC With Merlin++

proton, scattering, collimation, simulation

708

S.C. Tygier, R.B. Appleby
UMAN, Manchester, United Kingdom
R.J. Barlow, S. Rowan
IIAA, Huddersfield, United Kingdom

Due to the large stored beam energy in the HL-LHC new collimation technologies must be used to protect the machine. Active halo control of the proton beam halo with a Hollow Electron Lens can give a kick to protons at the edge of the beam without effecting the core. Various modes of operation are possible for example the electron lens can have a continuous current or it can be pulsed to different amplitudes for each passage of the proton beam. In this article we use Merlin++ simulations to show the performance of these modes for HL-LHC parameters. We also present recent simulations comparing scattering models in Merlin++.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB060

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paper received ※ 08 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB061

Simulations and Measurements of Coherent Synchrotron Radiation at the MAX-IV Short Pulse Facility

radiation, detector, simulation, dipole

712

B.S. Kyle
University of Manchester, Manchester, United Kingdom
R.B. Appleby
UMAN, Manchester, United Kingdom
M. Brandin, E. Mansten, S. Thorin
MAX IV Laboratory, Lund University, Lund, Sweden
T.H. Pacey
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom
J. Wolfenden
The University of Liverpool, Liverpool, United Kingdom

The Coherent Synchrotron Radiation (CSR) interaction is a source of unwanted correlated energy spread in short-bunch Free-Electron Lasers (FEL), diluting the desired FEL spectrum and reducing the total brightness of the light source. Many accelerator codes make use of 1-dimensional approximations in the calculation of the CSR-wake, which breaks down for bunch dimensions typical within bunch compressor dipoles in FELs. General Particle Tracer simulations of the CSR interaction make use of the 3-dimensional bunch distribution, making it advantageous in modelling the short-bunch, high aspect ratio regimes typical of modern 4th-generation light sources. Measurements of THz CSR emitted from the final bunch compressor dipole of the SP02 beamline at the MAX-IV Short Pulse Facility (SPF) were used, alongside start-to-end GPT and Elegant simulations, to characterize coherent radiation emission across a broad range of bunch lengths.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB061

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB067

High-gradient Single Cycle Terahertz Accelerating Structures

GUI, gun, acceleration, cathode

731

S.P. Antipov, E. Gomez, S.V. Kuzikov
Euclid TechLabs, LLC, Solon, Ohio, USA
A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

Recently, gradients on the order of 1 GV/m level have been obtained in a form of single cycle (~1 ps) THz pulses produced by conversion of a high peak power laser radiation in nonlinear crystals (~1 mJ, 1 ps, up to 3% conversion efficiency). These pulses however are broadband (0.1-5 THz) and therefore a new accelerating structure type is required. For electron beam acceleration with such pulses we propose arrays of parabolic focusing micro-mirrors with common central. These novel structures could be produced by a femtosecond laser ablation system developed at Euclid Techlabs. This technology had already been tested for production of several millimeters long, multi-cell structure which has been testing with electron beam. We also propose using of structures where necessary GV/m E-fields are excited by a drive bunch travelling in the corrugated waveguide. The radiated by drive bunch sequence of short range delayed wakes are guided in this case by metallic disks and reflected back being focused exactly at time when the witness bunch arrives.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB067

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paper received ※ 21 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPRB072

eRHIC in Electron-Ion Operation

operation, collider, heavy-ion, hadron

738

W. Fischer, E.C. Aschenauer, E.N. Beebe, M. Blaskiewicz, K.A. Brown, D. Bruno, K.A. Drees, C.J. Gardner, H. Huang, T. Kanesue, C. Liu, M. Mapes, G.T. McIntyre, M.G. Minty, C. Montag, S.K. Nayak, M. Okamura, V. Ptitsyn, D. Raparia, J. Sandberg, K.S. Smith, P. Thieberger, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, A. Zaltsman, A. Zelenski
BNL, Upton, Long Island, New York, USA

Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy.
The design effort for the electron-ion collider eRHIC has concentrated on electron-proton collisions at the highest luminosities over the widest possible energy range. The present design also provides for electron-nucleon peak luminosities of up to 4.7·10³³ cm^-2s⁻¹ with strong hadron cooling, and up to 1.7·10³³ cm^-2s⁻¹ with stochastic cooling. Here we discuss the performance limitations and design choices for electron-ion collisions that are different from the electron-proton collisions. These include the ion bunch preparation in the injector chain, acceleration and intrabeam scattering in the hadron ring, path length adjustment and synchronization with the electron ring, stochastic cooling upgrades, machine protection upgrades, and operation with polarized electron beams colliding with either unpolarized ion beams or polarized He-3.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB072

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB075

Radiation Limits on Permanent Magnets in CBETA

radiation, vacuum, permanent-magnet, focusing

745

V.O. Kostroun, C.M. Gulliford
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The Cornell Brookhaven Energy Recovery Linac Test Accelerator (CBETA), under construction at Cornell, uses Fixed Field Alternating Gradient (FFAG) Halbach magnets made from grade N35EH NdFeB. To reduce the 1% level magnetization errors in fabricated blocks to magnets with better than 0.001 field accuracy, iron wire shimming is necessary. This also limits magnetization changes by external influences to the ~1% level. The ambient radiation field present during CBETA operation can induce permanent magnet demagnetization. The radiation field arises from electrons in the beam halo hitting the vacuum chamber and from residual gas, Touschek and Intra-Beam scattering. The radiation dose rate due to electrons striking the vacuum chamber of a 4 cell straight section of CBETA FFAG magnets was calculated using the many particle Monte Carlo radiation code MCNP6.2. MCNP6.2 has a track-length heating tally for different particles and a collision heating tally that gives energy deposition/mass from all particles in the problem. Calculations show that electron loss has to be a fraction of a watt/m to keep the dose rate at an acceptable level during the accelerator lifetime.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB075

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPRB076

CBETA Beam Commissioning Results

linac, MMI, permanent-magnet, lattice

748

C.M. Gulliford, N. Banerjee, A.C. Bartnik, I.V. Bazarov, J.A. Crittenden, K.E. Deitrick, A. Galdi, G.H. Hoffstaetter, P. Quigley, K.W. Smolenski
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.S. Berg, S.J. Brooks, R.J. Michnoff, D. Trbojevic
BNL, Upton, Long Island, New York, USA

We report on the first results of commissioning CBETAwith a fully closed return loop. We repeat much of our early commissioning from the fractional arc test, namely setting up the injection system, calibrating the main linac, and steering the beam through the first splitter line. Most importantly, first results from sending the beam all the way through the FixedField Alternating gradient permanent magnet return arc are described.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB076

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPRB080

Transient Beam Loading and Mitigation in JLEIC Collider Rings

cavity, klystron, luminosity, beam-loading

758

J. Guo, R.A. Rimmer, H. Wang, S. Wang
JLab, Newport News, Virginia, USA
J.D. Fox
Stanford University, Stanford, California, USA
T. Mastoridis
CalPoly, San Luis Obispo, California, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, with additional support from U.S. DOE Award Number DE-SC-0019287
The Jefferson Lab Electron-Ion Collider (JLEIC) is an asymmetric high luminosity ring-ring collider proposed as the next major R&D facility for the nuclear physics community. Both of JLEIC’s electron and ion collider rings have high beam current with gaps serving the pur-poses of beam abort, ion clearing, etc. Such a time-varying beam loading in the RF cavities would generate modulation in cavity RF phase/voltage, causing cyclic shift of collision point and potential luminosity loss. We studied a few approaches to mitigate the RF phase modu-lation and IP shift, such as correcting the RF phase/voltage modulation with traditional LLRF feed-back, one-turn feedback (OTFB), or RF feedforward (FF); optimizing the bunch fill pattern to limit the RF phase/voltage modulation to a small fraction of the bunch trains in the collider ring; or matching the RF phase modulation in the two rings. The preliminary re-sults are discussed in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB080

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paper received ※ 23 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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MOPRB081

Electron Beam’s Closed Orbit in the Crab Crossing Scheme of Future Electron-Ion Colliders

closed-orbit, luminosity, cavity, simulation

762

Y. Hao, V. Ptitsyn
BNL, Upton, Long Island, New York, USA
J. Qiang
LBNL, Berkeley, California, USA

In crab-crossing collision geometry the closed orbit of the electron beam will be altered by the beam-beam interaction and the tilted head and tail of the ion beam. We will present the linear model to determine the closed orbit and compare with the simulation. Also, the relation of the closed orbit and the synchro-betatron resonance will be presented.

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB082

Scaling Properties of the Synchro-Beta Resonance in Crab Crossing Scheme of Future Electron Ion Collider

luminosity, resonance, simulation, cavity

766

Y. Hao, Y. Luo, V. Ptitsyn
BNL, Upton, Long Island, New York, USA
J. Qiang
LBNL, Berkeley, California, USA

The synchro - beta resonance due to the beam-beam interaction was predicted by the strong-strong simulation in the future electron-ion collider designs. In this paper, we study the scaling properties of the degradation rate of this unwanted resonance. These studies motivated the possible countermeasures of the luminosity degradation associated with the resonance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB082

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB085

First Results from Commissioning of Low Energy RHIC Electron Cooler (LEReC)

cavity, MMI, gun, cathode

769

D. Kayran, Z. Altinbas, D. Bruno, M.R. Costanzo, K.A. Drees, A.V. Fedotov, W. Fischer, M. Gaowei, D.M. Gassner, X. Gu, R.L. Hulsart, P. Inacker, J.P. Jamilkowski, Y.C. Jing, J. Kewisch, C.J. Liaw, C. Liu, J. Ma, K. Mernick, T.A. Miller, M.G. Minty, L.K. Nguyen, M.C. Paniccia, I. Pinayev, V. Ptitsyn, V. Schoefer, S. Seletskiy, F. Severino, T.C. Shrey, L. Smart, K.S. Smith, A. Sukhanov, P. Thieberger, J.E. Tuozzolo, E. Wang, G. Wang, A. Zaltsman, H. Zhao, Z. Zhao
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The brand new non-magnetized bunched beam electron cooler (LEReC) [1] has been built to provide luminosity improvement for Beam Energy Scan II (BES-II) physics program at the Relativistic Heavy Ion Collider (RHIC) BES-II [2]. The LEReC accelerator includes a photocathode DC gun, a laser system, a photocathode delivery system, magnets, beam diagnostics, a SRF booster cavity, and a set of Normal Conducting RF cavities to provide sufficient flexibility to tune the beam in the longitudinal phase space. This high-current high-power accelerator was successfully commissioned in period of March -September 2018. Beam quality suitable for cooling has been demonstrated. In this paper we discuss beam commissioning results and experience learned during commissioning.
[1] A. Fedotov et al., ’Status of bunched beam electron cooler LEReC’ in these proceedings.
[2] C.Liu et al., ’Improving luminosity of Beam Energy Scan II at RHIC’ in these proceedings.

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB087

Proposal for a High Transformer Ratio CW Dielectric Accelerator

SRF, experiment, wakefield, operation

773

V. Litvinenko
Stony Brook University, Stony Brook, USA
J.C. Brutus, Y.C. Jing, I. Pinayev, G. Wang
BNL, Upton, Long Island, New York, USA
M.E. Conde, C.-J. Jing, J.G. Power
ANL, Argonne, Illinois, USA
A. Kanareykin
Euclid Beamlabs LLC, Bolingbrook, USA
N. Vafaei-Najafabadi
UCLA, Los Angeles, California, USA

Advanced CW accelerators are one of high priority directions identified by Advanced Accelerator Concepts Research Roadmap Workshop Report *. High transformer ratio of beam-driven accelerators is critically important for cost-effective FEL systems. We present a proposed experiment for demonstrating a high transformer ratio CW dielectric accelerator using operational SRF accelerator built for Coherent electron Cooling experiment. This accelerator operates with CW electron beam comprised of 78 kHz train of electron bunches. Electron bunches with controllable longitudinal and charge up to 10 nC per bunch are generated in 1.25 MV SRF photo-electron gun. This bunches are ballistically compressed to duration of 10-to-30 psec and accelerated to 15 MeV in SRF linac**. Such bunches would be excellent drivers of high-transformer ratio DWA accelerators. In this paper we present expected performance of proposed CW DWA accelerator.
*Advanced Accelerator Concepts Research Roadmap Workshop Report, 2016,
*V.N. Litvinenko et al., In proc.of FEL’17, Santa Fe, NM, USA, August 20-25, 2017, p. 132

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paper received ※ 19 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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MOPRB088

Study of Fluctuations in Undulator Radiation in the IOTA Ring at Fermilab

experiment, undulator, radiation, photon

777

I. Lobach
University of Chicago, Chicago, Illinois, USA
A. Halavanau, Z. Huang, V. Yakimenko
SLAC, Menlo Park, California, USA
K. Kim
ANL, Argonne, Illinois, USA
V.A. Lebedev, S. Nagaitsev, A.L. Romanov, G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA
A.Y. Murokh
RadiaBeam, Los Angeles, California, USA
T.V. Shaftan
BNL, Upton, Long Island, New York, USA

We study turn-by-turn fluctuations in the number of emitted photons in an undulator, installed in the IOTA electron storage ring at Fermilab with an InGaAs PIN photodiode and an integrating circuit. Our study was motivated by the previous experiment *. We propose a theoretical model for the experimental data from * and in our own experiment we attempted to verify the model in an independent and more systematic way. Moreover, these fluctuations are an interesting subject for a study by itself, since they act as a seed for SASE in FELs. We improve the precision of the measurements from * by subtracting the average signal amplitude using a comb filter with a one-turn IOTA delay, and by using a special algorithm for noise subtraction. We obtain a reasonable agreement between our theoretical model and experiment. Along with repeating the experiment from *, which was performed at a constant beam current, we also collect data for fluctuations in undulator light at different beam current values. Lastly, in our experiment we were able to see the transition from Poisson statistics to Super-Poisson statistics for undulator light, whereas in * only the latter statistics was observed.
* M. Teich et al., PRL, vol. 65, no. 27, p. 3393 (1990).

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paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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MOPRB089

Experimental Study of a Single Electron in a Storage Ring via Undulator Radiation

photon, undulator, experiment, radiation

781

S. Nagaitsev, A.L. Romanov, G. Stancari
Fermilab, Batavia, Illinois, USA
A. Arodzero, A.Y. Murokh, M. Ruelas
RadiaBeam, Santa Monica, California, USA
I. Lobach
University of Chicago, Chicago, Illinois, USA
T.V. Shaftan
BNL, Upton, Long Island, New York, USA

A single electron orbiting around a ring and emitting single quanta at the rate of about one event per hundred turns could produce a wealth of information about physical processes in large traps (i.e. storage rings) for charged particles. It should be noted that Paul and Penning traps in the 1980s led to the Nobel prize for studying state and motion of single quantum particles, and just recently the Penning trap technique has enabled the measurement of a single proton magnetic moment with an unprecedented precision of 10 decimal places. The information from the storage ring traps could also be used for characterization of a quantum system as well as the "trap" itself, i.e. measuring properties of the storage ring lattice and electron interaction with the laser fields. Although, the interest in single electron quantum processes today is mostly academic in nature, the diagnostics and methodology developed for single electron radiation studies could find subsequent applications in a variety of applied disciplines in quantum technology, including quantum communications and quantum computing.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB089

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB090

Simulation Challenges for eRHIC Beam-Beam Study

proton, simulation, damping, emittance

785

Y. Luo, F.J. Willeke
BNL, Upton, Long Island, New York, USA
Y. Hao
FRIB, East Lansing, Michigan, USA
J. Qiang
LBNL, Berkeley, California, USA
Y. Roblin, H. Zhang
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The 2015 Nuclear Science Advisory Committee Long Rang Plan identified the need for an electron-ion collider (EIC) facility as a gluon microscope with capabilities beyond those of any existing accelerator complex. To reach the required high energy, high luminosity, and high polarization, the eRHIC design, based on the existing heavy ion and polarized proton collider RHIC, adopts a very small \beta-function at the interaction points, a high collision repetition rate, and a novel hadron cooling scheme. A full crossing angle of 22 mrad and crab cavities for both electron and proton rings are required. In this article, we will present the high priority R\&D items related to the beam-beam interaction studies for the current eRHIC design, the simulation challenges, and our plans and methods to address them. Recent progresses on this project are reported too.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB090

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB091

Combined Strong-Strong and Weak-Strong Beam-Beam Simulations for Crabbed Collision in eRHIC

proton, simulation, luminosity, cavity

788

Y. Luo, G. Bassi, M. Blaskiewicz, W. Fischer, Y. Hao, C. Montag, V. Ptitsyn, V.V. Smaluk, F.J. Willeke
BNL, Upton, Long Island, New York, USA
K. Ohmi
KEK, Ibaraki, Japan
J. Qiang
LBNL, Berkeley, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the eRHIC, to compensate the geometric luminosity loss, local crab cavities on both sides of the interaction points are to adopted. The previous strong-strong beam-beam simulations showed that the luminosity degradation depends on the crab cavity frequency, proton synchrotron tune, proton bunch length and so on. In this article, we apply a combined strong-strong and weak-strong beam-beam simulation to investigate the incoherent and coherent beam motions with crabbed collison, and to calculate more realistic beam emittance growth rates and luminosity degradation rate.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB091

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB092

Symplectic and Exact Tracking of Low Energy 197Au⁷⁸⁺ in the Relativistic Heavy Ion Collider

quadrupole, simulation, storage-ring, lattice

791

Y. Luo, W. Fischer, F. Méot, G. Robert-Demolaize
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the coming RHIC low energy scan, the electron cooling technique is to be used to cool the ions 197Au⁷⁹⁺ with its energy range between 3.85~GeV/nucleon to 5.75~GeV/nucleon. To overlap the electron beam and the 197Au⁷⁹⁺ beam at the cooling section, a recombination monitor is to be used to detect the maximum flux of 197Au⁷⁸⁺ ions generated in the cooling section. In the previous studies, we tracked 197Au⁷⁸⁺ ions through the RHIC lattice defined with 197Au⁷⁹⁺ with an equivalent momentum deviation. In the article, we explode different symplectic ways to track 197Au⁷⁸⁺ ions exactly. We calculate and compare the trajectories and loss map of 197Au⁷⁸⁺ ions through the RHIC ring.

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB093

eRHIC Electron Ring Design Status

polarization, storage-ring, solenoid, radiation

794

C. Montag, M. Blaskiewicz, C. Hetzel, D. Holmes, Y. Li, H. Lovelace III, V. Ptitsyn, K.S. Smith, S. Tepikian, F.J. Willeke, H. Witte, W. Xu
BNL, Upton, Long Island, New York, USA
E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
For the proposed electron-ion collider eRHIC, an electron storage ring will be installed in the existing RHIC tunnel. To reach the high luminosity of up to 10³⁴ cm^-2 sec^-1, beam currents up to 2.5A have to be stored. Besides high luminosity the physics program requires spin polarization levels of 70 percent, with both spin "up" and spin "down" orientations present in the fill. This is only feasible by using a full-energy spin polarized injector that replaces bunches faster than the depolarization rate. To limit the repetition rate of that injector to about one hertz, the polarization lifetime in the storage ring has to be maximized by proper spin matching and countermeasures for the machine misalignments. We will give an overview of the electron storage ring design.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB093

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paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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MOPRB098

An Increased Extraction Energy Booster Complex for the Jefferson Lab Electron Ion Collider

booster, collider, extraction, proton

797

E.A. Nissen
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, world-wide license to publish or reproduce this manuscript.
The proposed Jefferson Lab Electron Ion Collider (JLE-IC) envisions an ion complex composed of an ion linac, two booster synchrotrons and a collider ring. The evolving design of the JLEIC booster required an increase in the extraction energy of the booster from 8 to 12.1 GeV kinetic energy, necessitating two machines instead of one. The decision was also made to switch to warm magnets, thus increasing the total radius of the 8 GeV booster. The second booster is now the same size as the collider rings. In this work we present the new designs for JLEIC’s Low Energy Booster (LEB) and High Energy Booster (HEB).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB098

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paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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MOPRB100

An Improved eRHIC Interaction Region Design Without High Field Nb₃Sn Magnets

hadron, quadrupole, dipole, proton

799

B. Parker, R.B. Palmer, H. Witte
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The IR magnets for the eRHIC Collider proposed at BNL must provide strong fields for the high momentum hadron beam and yet protect the nearby electron beam focusing channel from these fields. In our initial design the electron and hadron magnets were staggered so their respective cold masses did not overlap; however, this restricts the longitudinal space for the first hadron quadrupole and led to the challenge of making a high-field Nb₃Sn main coil structure fit inside limited radial space within an external field active shield coil. In our new layout the crossing angle increased from 22 to 25 mrad and the electron and hadron cold masses are now side-by-side. This layout allows longer magnetic lengths for reducing the coil peak fields; NbTi conductor can now be used everywhere. Of course we must take care to control magnetic cross talk between neighboring apertures. One trick we will use to accomplish this is to maximize the yoke material thickness between the beams by tapering (i.e. change coil radius as a function of longitudinal position) some of the electron coils. The new eRHIC IR layout and magnet design is reported in this paper along with ongoing R&D to wind tapered coils.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB100

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paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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MOPRB106

3D Theory of Microbunched Electron Cooling for Electron-Ion Colliders

hadron, kicker, simulation, betatron

814

G. Stupakov, P. Baxevanis
SLAC, Menlo Park, California, USA

Funding: This work was supported by the Department of Energy, Contract No. DE-AC02-76SF00515.
The Microbunched Electron Cooling (MBEC) * is a promising cooling technique that can find applications in future hadron and electron-ion colliders. A 1D model of MBEC has been recently developed in Ref. **. This model predicts the cooling time below two hours for eRHIC 255 GeV proton beams, when two amplification sections are used in the cooling system. In this work, we go beyond the 1D model of Ref. * and develop a realistic 3D theory of MBEC. Our approach is based on the analysis of the dynamics of microscopic 3D fluctuations in the electron and hadron beams during their interaction and propagation through the system. We derive an analytical expression for the cooling rate and optimize it for the parameters of eRHIC. Our analytical results are in reasonable agreement with simulations.
* D. Ratner. Phys. Rev. Lett. 111, 084802 (2013).
** G. Stupakov. PRAB 21, 114402 (2018)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB106

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paper received ※ 29 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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MOPRB109

Cavity Design for the Updated eRHIC Crabbing System

cavity, proton, operation, hadron

818

S. Verdú-Andrés, Q. Wu
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates LLC under contract no. DE-SC0012704 with the U.S. Department of Energy.
The electron-ion collider eRHIC proposed by Brookhaven National Laboratory includes a crabbing system to reestablish head-on collisions for a maximum geometric overlap of the colliding bunches. Since the last cavity design, the crossing angle has increased from 22 to 25 mrad to relax the field strength requirement in one of the IR magnets - increasing the deflecting kick required to collider the bunches head on - and one of the considered options is to have both proton and electron crab cavities work at 200 MHz. The present paper discusses the RF design of the 200 MHz crab cavities for the electron and hadron beams of eRHIC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB109

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB110

Simulation Study of the Emittance Measurements in Magnetized Electron Beam

solenoid, emittance, cathode, gun

822

S.A.K. Wijethunga, J.R. Delayen, G.A. Krafft
ODU, Norfolk, Virginia, USA
J.F. Benesch, F.E. Hannon, G.A. Krafft, M.A. Mamun, G.G. Palacios Serrano, M. Poelker, R. Suleiman, S. Zhang
JLab, Newport News, Virginia, USA

Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC05-06OR23177
Electron cooling of the ion beam is key to obtaining the required high luminosity of proposed electron-ion colliders. For the Jefferson Lab Electron Ion Collider, the expected luminosity of 10³⁴ 〖 cm〗^-2 s^-1 will be achieved through so-called ’magnetized electron cooling’, where the cooling process occurs inside a solenoid field, which will be part of the collider ring and facilitated using a circulator ring and Energy Recovery Linac (ERL). As an initial step, we generated magnetized electron beam using a new compact DC high voltage photogun biased at -300 kV employing an alkali-antimonide photocathode. This contribution presents the characterization of the magnetized electron beam (emittance variations with the magnetic field strength for different laser spot sizes) and a comparison to GPT simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB110

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPTS002

Linac Energy Jitter Measurements with SPARK BPMs at ALBA

linac, electronics, klystron, operation

833

R. Muñoz Horta, D. Lanaia, E. Marín, A. Olmos, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

At ALBA four Beam Position Monitors (BPMs) measure the beam position along the Linac to Booster Transfer Line. The BPM electronics (Libera Spark type) have been recently upgraded in order to be sensitive to single-pass beam detection. As a result, the position resolution measured in LTB BPMs has been increased by a factor 10 with respect to the former electronics. The increased resolution enables us to resolve the energy jitter of the Linac beam, providing an on-line measurement of the Linac energy during regular operation. In this paper a study of the Linac energy jitter is presented as well as its correlation with the jitter sources.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS002

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPTS014

The Experimental Area at the ARES LINAC

experiment, laser, linac, acceleration

867

F. Burkart, R.W. Aßmann, U. Dorda, J. Hauser, S. Lederer, F. Lemery, B. Marchetti, F. Mayet, E. Panofski, P. Wiesener
DESY, Hamburg, Germany
M. Trunk
University of Hamburg, Hamburg, Germany

The ARES (Accelerator Research Experiment at SINBAD) linac at the accelerator R&D facility SINBAD (Short innovative bunches and accelerators at DESY) will drive multiple independent experiments including the acceleration of ultrashort electron bunches. In addition the linac will host an experimental area, open for transnational access, to study advanced high gradient, laser driven, acceleration concepts, like the ones studied within the ACHIP (accelerator on a chip) project. The area will be operational mid-2019. This paper will report on the current status of the experimental area, including hardware parameters, beam optics, achievable beam parameters, design of the experimental chamber and commissioning plans. The modification plans for a micro-bunching experiment in the frame of the ACHIP experiment and future upgrade plans will be shown and discussed in detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS014

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPTS018

First Electron Beam at the Linear Accelerator FLUTE at KIT

laser, MMI, linac, klystron

882

M.J. Nasse, A. Bernhard, E. Bründermann, A. Böhm, S. Funkner, B. Härer, I. Križnar, A. Malygin, S. Marsching, W. Mexner, A.-S. Müller, G. Niehues, R. Ruprecht, T. Schmelzer, M. Schuh, N.J. Smale, P. Wesolowski, M. Yan
KIT, Karlsruhe, Germany

Funding: The SRR project has received funding from the European Union’s Horizon 2020 Research and Innovation program under Grant Agreement No 730871.
The first electron beams were generated in the 7 MeV section of the short-pulse linear accelerator test facility FLUTE (Ferninfrarot Linac- Und Test-Experiment) at the Karlsruhe Institute of Technology (KIT). In this contribution we show images of the electron beam on a YAG-screen (yttrium aluminum garnet) as well as signals from an integrating current transformer (ICT) and a Faraday cup. Furthermore, the progress of tuning the FLUTE electron bunches for experiments is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS018

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paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPTS023

Conditioning of the Frontline Cavities of the MYRRHA Injector

rfq, cavity, multipactoring, MMI

895

S. Lamprecht, T. Conrad, K. Kümpel, N.F. Petry, H. Podlech
IAP, Frankfurt am Main, Germany
J. Belmans, D. Davin, W. De Cock, F. Pompon, D. Vandeplassche
SCK•CEN, Mol, Belgium

The MYRRHA Project (Multi-purpose hYbrid Research Reactor for High-tech Applications) in Mol, Belgium, is an upcoming accelerator driven system (ADS) for the transmutation of long-living radioactive waste. In the injector section of the accelerator, consisting of a 4-rod RFQ and a normal conducting CH-cavity section, the protons will be accelerated up to 17 MeV before entering the superconducting gap-spoke cavity section with an output energy of 600 MeV. A shortened test-injector with an output energy of 5.9 MeV is currently being installed at the SCK. CEN in Louvein-la- Neuve, Belgium. This test-injector serves the purpose of testing the reliability of the planned injector. When commissioning a cavity, it first has to be fed very little power to avoid damage to the structure by flashovers, discharges and multipacting. The power is then slowly increased up to full operation level. In this process, the surfaces are cleaned by heating/outgasing so that the effects disturbing operation described above do no longer occur. This paper will report on the status of the conditioning of the 176.1 MHz 4-rod RFQ up to 120 kW of the MYRRHA-injector and additional measurements concerning the gap voltage which are currently being performed at the SCK. CEN.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS023

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPTS025

Overview of the ARES Bunch Compressor at SINBAD

laser, plasma, linac, simulation

902

F. Lemery
University of Hamburg, Hamburg, Germany
R.W. Aßmann, U. Dorda, K. Flöttmann, J. Hauser, M. Hüning, G. Kube, M. Lantschner, S. Lederer, B. Marchetti, N. Mildner, M. Pelzer, M. Rosan, J. Tiessen, K. Wittenburg
DESY, Hamburg, Germany

Funding: This project has received funding from the European Unions Horizon 2020 Research and Innovation programme under Grant Agreement No 730871.
Bunch compressors are essential for the generation of short bunches with applications in e.g. colliders, free electron lasers, and advanced accelerator concepts. The up-and-coming ARES accelerator located at SINBAD, DESY will support the formation of ~100~MeV, pC, sub-fs electron bunches for LWFA research and development. We give an overview on the ARES bunch compressor, providing start-to-end simulations of the machine and an update on its technical design.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS025

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paper received ※ 17 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPTS026

Status Report of the SINBAD-ARES RF Photoinjector and LINAC Commissioning

gun, linac, laser, experiment

906

E. Panofski, R.W. Aßmann, F. Burkart, U. Dorda, K. Flöttmann, M. Hüning, B. Marchetti, D. Marx, F. Mayet, P.A. Walker, S. Yamin
DESY, Hamburg, Germany

The accelerator R&D facility SINBAD (Short innovative bunches and accelerators at DESY) will drive multiple independent experiments including the acceleration of ultrashort electron bunches and the test of advanced high gradient acceleration concepts. The SINBAD-ARES (Accelerator Research Experiment at SINBAD) setup hosts a normal conducting RF photoinjector generating a low charge electron beam that is afterwards accelerated to 100 MeV by an S-band linac section. The linac as well as a magnetic chicane allow the production of ultrashort pulses with an excellent arrival-time stability. The high brightness beam has then the potential to serve as a test beam for next generation compact acceleration schemes. The setup of the SINBAD-ARES facility will proceed in stages. We report on the current status of the ARES RF gun and linac commissioning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS026

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paper received ※ 22 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPTS054

Status of the CLEAR Electron Beam User Facility at CERN

experiment, radiation, plasma, operation

983

K.N. Sjobak, E. Adli, C.A. Lindstrøm
University of Oslo, Oslo, Norway
M. Bergamaschi, S. Burger, R. Corsini, A. Curcio, S. Curt, S. Döbert, W. Farabolini, D. Gamba, L. Garolfi, A. Gilardi, I. Gorgisyan, E. Granados, H. Guerin, R. Kieffer, M. Krupa, T. Lefèvre, S. Mazzoni, G. McMonagle, N. Nadenau, H. Panuganti, S. Pitman, V. Rude, A. Schlogelhofer, P.K. Skowroński, M. Wendt, A.P. Zemanek
CERN, Geneva, Switzerland
A. Lyapin
UCL, London, United Kingdom

The CERN Linear Electron Accelerator for Research (CLEAR) has now finished its second year of operation, providing a testbed for new accelerator technologies and a versatile radiation source. Hosting a varied experimental program, this beamline provides a flexible test facility for users both internal and external to CERN, as well as being an excellent accelerator physics training ground. The energy can be varied between 60 and 220 MeV, bunch length between 1 and 4 ps, bunch charge in the range 10 pC to 2 nC, and number of bunches in the range 1 to 200, at a repetition rate of 0.8 to 10 Hz. The status of the facility with an overview of the recent experimental results is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS054

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paper received ※ 12 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPTS065

Alternative Design of CEPC LINAC

linac, positron, booster, collider

1005

C. Meng, J. Gao, X.P. Li, G. Pei, J.R. Zhang
IHEP, Beijing, People’s Republic of China

Circular Electron-Positron Collider (CEPC) is a 100 km ring e⁺ e⁻ collider for a Higgs factory. The injector is composed of a Linac and a Booster. The baseline design of CEPC Linac is a normal conducting S-band linear accelerator with frequency in 2860 MHz, which can provide electron and positron beam at an energy up to 10 GeV and bunch charge up to 3 nC. To reduce the design difficulty of booster and booster magnet at low energy part, an alternative design of the Linac with C-band accelerating structure at high energy part is proposed and the energy is up to 20 GeV. The compre-hensive consideration of Linac design and damping ring design will be discussed. In this paper, the physics design of this scheme is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS065

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paper received ※ 16 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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MOPTS067

The Progress in Physics Design of HEPS LINAC

linac, wakefield, bunching, emittance

1008

C. Meng, D.Y. He, X. He, J.Y. Li, Y.M. Peng, S.C. Wang, O. Xiao, J.R. Zhang, S.P. Zhang
IHEP, Beijing, People’s Republic of China

The High Energy Photon Source (HEPS) is a 6-GeV, ultralow-emittance light source to be built in China. The injector is composed of a 500-MeV Linac and a full energy booster. According to the study and com-missioning consideration of on-axis swap-out injec-tion system, a high bunch charge injector is desirable and a Linac that can provide 7nC per bunch electron beam to booster is needed. This paper present different bunching system schemes and the performance of different schemes are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS067

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paper received ※ 14 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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MOPTS073

Bunching System Optimization Based on MOGA

bunching, linac, emittance, solenoid

1018

S.P. Zhang, J.Y. Li, C. Meng
IHEP, Beijing, People’s Republic of China

Multiobjective Genetic Algorithms (MOGA) is effective in dealing with optimization problems with multiple objectives. The bunching system of the High Energy Photon Source (HEPS) linac adopts a traditional bunching system for compressing electron beams with a pulse charge of 4 nC. The bunching system is optimized using MOGA. The optimization include minimizing the normalized emittance and maximizing transmission efficiency. The optimization results have reached the design target, and are presented in this paper.

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPTS089

Transverse Beam Dynamics Studies With High Intensity LHC Beams in the SPS

injection, octupole, emittance, impedance

1062

M. Carlà, H. Bartosik, M.S. Beck, L.R. Carver, V. Kain, G. Kotzian, K.S.B. Li, G. Rumolo, C. Zannini
CERN, Geneva, Switzerland

In order to reach the target beam parameters of the LHC injectors upgrade (LIU), about twice the presently operational intensity of LHC type beams has to be achieved. Although the planned upgrade of the main RF system will occur during the long shutdown, a series of measurements have been performed to assess the beam dynamics challenges with these very high intensity beams on the long SPS injection plateau. Bunch-by-bunch transverse emittance blow-up measurements suggested the presence of electron-cloud. After a period of running with the high intensity beam for a couple of days, a clear improvement of beam quality was observed which is attributed to scrubbing. In addition, a horizontal headtail instability is encountered for the usual operational settings of chromaticity and transverse damper. The stability limit as a function of chromaticity and Landau octupole settings has been explored and will be discussed, together with possible sources of the instability and mitigation strategies.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS089

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paper received ※ 06 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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MOPTS098

A Primary Electron Beam Facility at CERN

linac, injection, emittance, proton

1098

Y. Papaphilippou, R. Corsini, Y. Dutheil, L.R. Evans, B. Goddard, A. Grudiev, A. Latina, S. Stapnes
CERN, Meyrin, Switzerland
T.P.Å. Åkesson
Lund University, Department of Physics, Lund, Sweden

This paper describes the concept of a primary electron beam facility at CERN, to be used for dark gauge force and light dark matter searches. The electron beam is produced in three stages: A Linac accelerates electrons from a photo-cathode up to 3.5 GeV. This beam is injected into the Super Proton Synchrotron, SPS, and accelerated up to a maximum energy of 16 GeV. Finally, the accelerated beam is slowly extracted to an experiment, possibly followed by a fast dump of the remaining electrons to another beamline. The beam parameters are optimized using the requirements of the Light Dark Matter eXperiment, LDMX, as benchmark.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS098

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPTS099

The Development Programme of Cathodes and Electron Guns for the Hollow Electron Lenses of the High Luminosity LHC Project

cathode, gun, luminosity, proton

1102

D. Perini, G. Gobbi
CERN, Geneva, Switzerland
D.J. Crawford, J. Ruan, G. Stancari, L.R. Valerio
Fermilab, Batavia, Illinois, USA
J. Feng, Z. Li, W. Shao, K. Zhang
BVERI, Beijing, People’s Republic of China
W. Liu, J. Wang, Y. Wang, Y. Yang
Beijing University of Technology, Beijing, People’s Republic of China

Funding: Research supported by the HL-LHC project
The High Luminosity LHC project (HL-LHC) foresees the construction and installation of important new equipment to increase the performance of the LHC machine. The Hollow Electron Lens (HEL) is a promising system to control the beam halo. It improves the beam collimation system of the HL-LHC and mitigates possible equipment damage in case of failure scenarios from halo losses. The halo can store up to 30 MJ energy. The specifications for this new device are quite demanding. The source, an electron gun with an annular shaped cathode, has to deliver a current up to 5 A. This is five times higher than the current in the existing electron lenses in Fermi and Brookhaven national laboratories. This note describes the programme carried out to design and test high-perveance guns equipped with two types of high-performance scandate cathodes. The size of the final gun is now considerably smaller than the one of the first prototype, allowing a reduction of diameter and cost of the superconducting magnet system used to steer the electron beam. The tests carried out at FNAL, BVERI and BJUT demonstrated that the developed cathodes fulfil the specifications and can supply a 5 A fully Space Charge Limited (SCL) current.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS099

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paper received ※ 17 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPTS104

A Toolkit for Tracing Electron Beam Envelope at Low Energy Section of TPS Linac

simulation, linac, operation, gun

1122

H.H. Chen, H.C. Chen, K.-K. Lin, Y.K. Lin
NSRRC, Hsinchu, Taiwan

Based on calculated Bz of solenoids installed at the TPS linac low energy section, the electron beam envelope along beam centerline has been explored in this work using the initial and boundary conditions provided in the linac specifications. Concept of magnetic flux compression is adopt to analyze the beam size variation along linac centerline. The calculated result of selected checkpoints has been experimentally verified using screen monitors. In order to benefit tuning capability in routine operation, the display of beam size variation along centerline is integrated into the previously developed toolkit ’linac’. It is hope that it will provide an interactive approach for linac tune-up process and would be helpful to its routine operation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS104

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paper received ※ 23 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPTS105

The High Brightness Photo-injector for THz CUR/VUV FEL at NSRRC

radiation, emittance, quadrupole, linac

1125

A.P. Lee, M.C. Chou, H.P. Hsueh, J.-Y. Hwang, W.K. Lau
NSRRC, Hsinchu, Taiwan
P. Wang
NTHU, Hsinchu, Taiwan

A high brightness photo-injector has been build for THz coherent undulator radiation and VUV free electron laser test facility at NSRRC. In the first phase, the photo-injector was used to produce ultra-short electron bunches for THz CUR generation. The electron beam is generated form a photocathode rf gun followed by a solenoid for emittance compensation. Then A 5.2 m S-band linac accelerates the electron beam and compresses the beam by velocity bunching. Since the beam emittance will grow during the velocity bunching process, a solenoid system was installed to reduce the emmitance growth. Downstream the linac, a quadruple magnet was use for emittance measurement by quadruple scan method and the bunch length was measured by the coherent transition radiation. Finally, the ultra-short electron bunch with about few hundreds picoseconds passes through a U100 planer undulator can produce THz coherent undulator radiation. The instrument setup and results of measurement are presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS105

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paper received ※ 14 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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MOPTS117

Exploration of High-Gradient Structures for 4th Generation Light Sources

cavity, FEL, linac, cryogenics

1155

S.J. Smith, S. Biedron, S.I. Sosa Guitron
University of New Mexico, Albuquerque, USA
T.B. Bolin
Element Aero, Chicago, USA
B.E. Carlsten, F.L. Krawczyk
LANL, Los Alamos, New Mexico, USA
J.R. Cary, D.M. Cheatham
Tech-X, Boulder, Colorado, USA

As the energy, scale and therefore the cost of large-scale accelerator projects, such as X-ray free-electron lasers (XFELs) increases, new technologies must be developed in order to minimize costs and maximize efficiency wherever possible. One obvious way to reduce costs is to reduce the length of accelerating sections by utilizing higher accelerating gradients. Here we present the results of a study into the various structure options for FEL linacs, contrasting different frequencies, geometries and operating modes. An investigation into the possibility of using cryo-cooled travelling wave (TW) electron structures which allow for higher gradient operation by exploiting the anomalous skin effect is also detailed. Finally, we give simulation results from a number of commercial codes including VSim 9, for a hypothetical TW high gradient C-band structure design employing cryo-cooled technology. Breakdown effects, pulsed heating, tolerances, efficiencies and potential rf sources are also explored, all within the framework of typical FELs and their requirements.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS117

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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TUXXPLM3

First Operation of a Hybrid e-Gun at the Schlesinger Center for Compact Accelerators in Ariel University

gun, laser, solenoid, klystron

1171

A.N. Nause, A. Fukasawa, J.B. Rosenzweig, R.J. Roussel
UCLA, Los Angeles, USA
A. Friedman
Ariel University, Ariel, Israel
B. Spataro
INFN/LNF, Frascati, Italy

Funding: Israel Ministry of Defence Israel Ministry of Science
A novel hybrid photo injector was designed and partially tested at the UCLA Particle Beam Physics Laboratory. It was later commissioned at Ariel University in Israel as an on-going collaboration between the two universities. This unique, new generation design provides a radically simpler approach to RF feeding of a gun/buncher system, leading to a much shorter beam via velocity bunching owed to an attached traveling wave section of the photo-injector. This design results in better performance in beam parameters, providing a high quality electron beam, with energy of 6 MeV, emittance of app 3 μm, and a 150 fs pulse duration at up to 1 nC per pulse. The Hybrid gun is driven by a SLAC XK5 Klystron as the high power RF source, and third harmonic of a fs level IR Laser amplifier (266 nm) to drive the Cathode. The unique e-gun will produce an electron pulse for a THz FEL, which will operate at the super-radiance regime, and therefore requires extraordinary beam properties. This paper briefly describes the gun and presents initial operational results from the gun and its sub-systems.

Slides TUXXPLM3 [9.526 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUXXPLM3

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUXXPLS2

Negative Muonium Ion Production With a C12A7 Electride Film

target, experiment, positron, acceleration

1175

M. Otani, Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, K. Shimomura, T. Yamazaki
KEK, Tsukuba, Japan
K. Hasegawa, Y. Kondo, T. Morishita
JAEA/J-PARC, Tokai-mura, Japan
T. Iijima, Y. Sue
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
H. Iinuma, Y. Nakazawa
Ibaraki University, Ibaraki, Japan
K. Inami, M. Yotsuzuka
Nagoya University, Nagoya, Japan
K. Ishida
RIKEN Nishina Center, Wako, Japan
R. Kitamura, H.Y. Yasuda
University of Tokyo, Tokyo, Japan
N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Funding: This work was supported by OSPS KAKENHI Grant Numbers JP15H03666, JP 16H03987, JP18H03707.
Negative muonium ion production is one of methods to cool muons. Since its discovery in 1987 by interactions of muons with a metal foil, it has been discussed that the production efficiency would be improved using a low-work function material. C12A7 (12CaO·7AlO3) was a well-known insulator as a constituent of alumina cement, but was recently confirmed to exhibit electric conductivity by electron doping. The C12A7 electride has lower work function (2.9 eV) and it was reported that nearly the same negative current signal as that with a bi-alkali material coated metal were observed in H⁻ formation. In this poster, the negative muonium production measurement with a Al foil and C12A7 electride film will be presented.

Slides TUXXPLS2 [2.680 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUXXPLS2

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paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUYPLM1

XFEL Performance Achieved at PAL-XFEL

FEL, undulator, photon, emittance

1182

H. Heo, M.-H. Cho, J.H. Han, H.-S. Kang, C. Kim, G. Kim, M.J. Kim, J.H. Ko, H.-S. Lee, C.-K. Min, I.H. Nam, K.-H. Park, C.H. Shim, H. Yang
PAL, Pohang, Kyungbuk, Republic of Korea

The hard X-ray free electron laser at Pohang Accelerator Laboratory (PAL-XFEL) successfully completed the commissioning of SASE and started user operation in late 2016. Since then, the facility has demonstrated excellent stability with very small timing jitter of about 20 fs, and commissioned the self-seeding system over a wide range of photon energies, etc. The talk will provide an overview of the last three years at the PAL-XFEL, including some detailed experimental results, as well as future prospects for the laboratory.

Slides TUYPLM1 [7.516 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUYPLM1

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paper received ※ 20 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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TUYPLM3

Status of the MAX IV Accelerators

storage-ring, sextupole, linac, vacuum

1185

P.F. Tavares, E. Al-Dmour, Å. Andersson, J. Breunlin, F.J. Cullinan, E. Mansten, S. Molloy, D.K. Olsson, D. Olsson, M. Sjöström, S. Thorin
MAX IV Laboratory, Lund University, Lund, Sweden

The MAX IV facility in Lund, Sweden, consists of three electron accelerators and their respective synchrotron radiation beamlines: a 3 GeV ring, which is the first implementation worldwide of a multi-bend achromat lattice, a 1.5 GeV ring optimized for soft X-Rays and UV radiation production and a 3 GeV linear accelerator that acts as a full-energy injector into both rings and provides electron pulses as short as 100 fs that produce X-rays by spontaneous emission in the undulators of the short-pulse facility (SPF). In this paper, we review the latest achieved accelerator performance and operational results.

Slides TUYPLM3 [9.108 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUYPLM3

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUZPLM1

Adding Data Science and More Intelligence to Our Accelerator Toolbox

controls, network, laser, simulation

1191

S. Biedron
University of New Mexico, Albuquerque, USA
S. Biedron
Element Aero, Chicago, USA

Requirements for recent accelerators are becoming more and more stringent and sophisticated machine tuning is necessary. A large amount of data is acquired from accelerator components as an assistant of machine tuning. It is hard for operators to utilize all the accelerator data for machine tuning. Therefore, machine learning, data mining and big data handling are recently applied to accelerators. For instance, Bayesian optimization is used for maximizing a target performance, a clustering algorithm is used for anomaly detection, and hidden correlation finding is utilized for discovering new aspects of a machine. This talk reviews recent progress of machine learning applications and big data handling in accelerators.

Slides TUZPLM1 [11.978 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZPLM1

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paper received ※ 20 May 2019 paper accepted ※ 16 June 2019 issue date ※ 21 June 2019

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TUZZPLM2

Status of Automated Optimization Procedures at the European XFEL Accelerator

FEL, feedback, undulator, status

1212

S. Tomin
EuXFEL, Schenefeld, Germany
L. Fröhlich, M. Scholz
DESY, Hamburg, Germany

The European XFEL is in the operational stage since fall 2017. Since then, tuning of the FEL performance (e.g. of the photon pulse energy) has become increasingly important. Due to a large number of parameters to which FEL facilities are highly sensitive and their complex correlations, controlling and optimizing them in a speedy manner is becoming a very important and challenging task. Several automated optimization procedures were developed to optimize the FEL beam quality. In this work, we present the status and the results of these activities, as well as the optimization statistics.

Slides TUZZPLM2 [5.882 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZZPLM2

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paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUZZPLS3

New Method of Calculation of the Wake due to Radiation and Space Charge Forces in Relativistic Beams

radiation, wakefield, space-charge, synchrotron-radiation

1223

G. Stupakov
SLAC, Menlo Park, California, USA

Funding: This work was supported by the Department of Energy, Contract No. DE-AC02-76SF00515.
Radiation reaction force in a relativistic beam, also known as a CSR wakefield, is often computed using a 1D model of a line charge beam. While this model can serve as a useful tool for a quick calculation, in some cases, it may not be sufficiently accurate. In particular, this model misses the so-called compression effects associated with the change of the electromagnetic energy when the beam is compressed longitudinally or transversely. The existing 3D simulation codes that take this effect into account are often slow and are not easy to use. In this work, we propose a new approach to the calculations of radiation and space charge longitudinal forces based on the use of the integrals for the retarded potentials. Our main result expresses the rate of change of particles energy through 2D (in a 2D model) or 3D integrals for a given orbit of the beam. It generalizes the 1D model and includes the transient effects of at the entrance and the exit from the magnet. For a given beam line with known magnetic lattice, and a known distribution function of the beam, the calculation reduces to taking 2D or 3D integrals along the orbit.

Slides TUZZPLS3 [2.080 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZZPLS3

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paper received ※ 29 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPMP003

Development of Remote Handleable Axially Decoupled Radiation Resistant Vacuum Seal

vacuum, target, interface, operation

1233

R.R. Nagimov, Y. Bylinskii, L. Egoriti, A. Gottberg, G.W. Hodgson, A.N. Koveshnikov, D. Yosifov
TRIUMF, Vancouver, Canada

Funding: ARIEL is funded by the Canada Foundation for Innovation (CFI), the Provinces of AB, BC, MA, ON, QC, and TRIUMF. TRIUMF receives federal funding via a contribution agreement with the NRC of Canada.
Advanced Rare IsotopE Laboratory (ARIEL) facility is a major expansion of TRIUMF’s rare isotope research program. Aiming to triple the production of rare isotopes, ARIEL facility includes the new electron linac driver and two target stations for electron and proton beams. Particularities of ARIEL target stations design define the requirements for vacuum interfaces with both primary electron and proton beamlines and rare-isotope beamlines. None of the existing products fully met the requirements, driving the development of custom vacuum interfaces. The design of new vacuum seals is driven both by unique design specifications (limited amount of allowed axial forces, extreme radiation resistance, remote handleability and high repeatability) as well as limitations of the proposed design of beamline infrastructure in the target hall (limited available space and the choice of materials for certain components). This paper discusses preliminary results of the vacuum seal development and presents first results of prototype testing.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP003

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPMP004

Dynamic Pressure in the LHC - Influence of Ions Induced by Ionization of Residual Gas by Both the Proton Beam and the Electron Cloud

proton, vacuum, experiment, ECR

1236

S. Bilgen, C. Bruni, B. Mercier, G. Sattonnay
LAL, Orsay, France
V. Baglin
CERN, Geneva, Switzerland

Funding: work supported by FCC project (CERN & LAL-CNRS-IN2P3)
Ultra-High Vacuum is an essential requirement to reach design performances in high-energy particle colliders. For the future HL-LHC or FCC study, the understanding of the beam interactions with the vacuum chamber is fundamental to provide solutions to mitigate the pressure rises induced by electronic, photonic and ionic molecular desorption. Studies were performed on the ions, produced by molecular ionization generated by the proton beam and the electron cloud, and stimulating molecular desorption by the surface bombardment. In-situ measurements were carried out, on the LHC Vacuum Pilot Sector (VPS)*, to monitor the dynamic pressure, and to collect the electrical signals due to the electron cloud and to the ions interacting with the vacuum chamber walls. Experimental measurements of electrical signals recorded by copper electrodes were compared to calculations taking into account both the Secondary Electron Yield of copper and electron energy distribution. Finally, it seems that copper electrodes were not fully conditioned and an ion current could be estimated.
* THE LHC VACUUM PILOT-SECTOR PROJECT
B. Henrist, V. Baglin, G. Bregliozzi, and P. Chiggiato, CERN, Geneva, Switzerland
Proceedings of IPAC2014, Dresden, Germany.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP004

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paper received ※ 01 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPMP007

DYVACS (DYnamic VACuum Simulation) Code: Calculation of Gas Density Profiles in Presence of Electron Cloud

vacuum, proton, photon, experiment

1244

G. Sattonnay, S. Bilgen, B. Mercier
LAL, Orsay, France
V. Baglin
CERN, Meyrin, Switzerland

The computation of residual gas density profiles in particle accelerators is an essential task to optimize beam pipes and vacuum system design. In a hadron collider such as the LHC, the beam induces dynamic effects due to ion, electron and photon-stimulated gas desorption. The well-known VASCO* code developed at CERN in 2004 (and then PyVASCO**) is already used to estimate vacuum stability and density profiles in steady state conditions. Nevertheless, some phenomena are not taken into account such as the ionization of residual gas by the electron clouds. Therefore, we propose an upgrade of this code by introducing electron cloud maps*** to estimate the electron density and the ionization of gas by electrons, leading to an increase of both electron- and ion-induced desorption. Results obtained with the new code (called DYVACS for DYnamic VACuum Simulation) will be compared to pressure measurements in the VPS sector**** of the LHC.
* A. Rossi, Tech. Rep., LHC Proj. Note 341
** I. Aichinger, et al arXiv:1707.07525
*** T. Demma et al Phys. Rev. Acceler. and Beams 10, 114401 (2007)
**** B. Henrist et al, Proc. IPAC2014, Dresden

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP007

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPMP021

Comparison of TiZrV Non-evaporable Getter Films Deposited by DC Magnetron Sputtering or Quantitative Deposition

vacuum, site, target, interface

1283

X.Q. Ge, W. Li, J.Q. Shao, S. Wang, Y.G. Wang, Y. Wang, W. Wei, B. Zhang, Y.X. Zhang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Ti-Zr-V non-evaporable getter (NEG) films have been widely used in vacuum chambers of various accelerators since their discovery. Recently, we have used a new method called ’quantitative deposition’ to deposit Ti-Zr-V NEG films on nichrome substrates. The surface morphology and surface chemical bonding information were collected by scanning electron microscopy. Although the film deposited by DC magnetron sputtering has more uniform grain growth, smoother grain boundaries and higher porosity, the two films all have porous network structure and can be used as getter films.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP021

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paper received ※ 24 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPMP029

Establishing a Laser Treatment to Suppress the Secondary Electron Emission

laser, experiment, synchrotron, focusing

1303

Y.G. Wang, X.Q. Ge, X.T. Pei, S.W. Wang, Y. Wang, B. Zhang, B.L. Zhu
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Laser treatment has a significant inluent on suppressing the secondary electron emission(SEE). The new synchrotron radiation light source, the Hefei Advanced Light Source(HALS) has a strict requirement on the SEE. In this paper, we used a 355nm laser to process copper sample. After the laser treatment, the secondary electron yield(SEY) reduced from 2.05 to 0.86. We used the scanning electron microscope(SEM) to analysis the surface of sample after the laser treatment.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP029

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paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPMP031

Research on Secondary Electron Emission Characteristics of Diamond-like Carbon Thin Films

vacuum, experiment, laser, gun

1306

Y.X. Zhang, X.Q. Ge, W. Li, J.Q. Shao, S. Wang, Y.G. Wang, Y. Wang, W. Wei, B. Zhang, B.L. Zhu
USTC/NSRL, Hefei, Anhui, People’s Republic of China

In modern particle accelerators, the build-up of electron cloud is a main limiting factor for the achievement of high-quality beam. Among the techniques to mitigate it, coating the internal walls of the beam pipes with a thin film which has a low secondary electron yield (SEY) is considered to be one of the most effective means. From several earlier studies, it was found that diamond-like carbon (DLC) thin films are potential coatings. This paper is mainly about the research on secondary electron emission characteristics of DLC thin films. The secondary electron emission (SEE) tests were done at temperature of 298 K and vacuum pressure of 2×10^-9 Torr. Here, we obtained the characteristics of the SEE from DLC film coatings with different thickness under ultrahigh-vacuum (UHV) conditions. The maximum secondary electron yield (SEY), δmax, of the DLC thin films under different primary electron doses were also obtained, respectively.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP031

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paper received ※ 26 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPMP034

A Modular Optical Firing Interface for CERN’s Generic Power Converter Control Platform

controls, interface, ISOL, status

1315

M. Di Cosmo, T.G. Gaime, B. Todd
CERN, Geneva, Switzerland

The power converters group at CERN has developed a third generic converter controller (FGC3) and regulation platform (RegFGC3), capable of controlling any of CERN’s power converters. This platform provides electrical connections to the low-level control elements of power converters, and in some cases a galvanic isolation is required between the converter controller output, and the power converter under control. To meet these requirements, a generic modular optical firing platform has been developed, which converts the electrical firing pulses from the RegFGC3 and FGC3 platforms into optical drive signals. Designed to be fully scalable, this platform provides various protection mechanisms to verify the integrity of the firing information. For example, checking for illegal firing states, dead-time, and drive errors. This paper describes the modular optical firing interface, the basic principles, and the configurations which are in use, or are planned to be used at CERN.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP034

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paper received ※ 15 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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TUPMP036

Results on the FCC-hh Beam Screen Sawtooth at the Kit Electron Storage Ring Kararesults on the Fcc-Hh Beam Screen Sawtooth at the Kit Electron Storage Ring Kara

photon, radiation, vacuum, experiment

1323

L.A. Gonzalez, V. Baglin, I. Bellafont, P. Chiggiato, C. Garion, R. Kersevan
CERN, Geneva, Switzerland
I. Bellafont, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
S. Casalbuoni, E. Huttel
KIT, Eggenstein-Leopoldshafen, Germany

Funding: * The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 654305.
In the framework of the EuroCirCol collaboration (work package 4 "Cryogenic Beam Vacuum System"), the fabrication of the FCC-hh beam screen (BS) prototype has been carried out with the aim of testing it at room temperature on the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator) light source. The BS prototype was tested on a beamline installed by the collaboration, named as BEam Screen TEstbench EXperiment (BESTEX). KARA has been chosen because its synchrotron radiation (SR) spectrum, photon flux and power match quite well the one foreseen for the 50+50 TeV FCC-hh proton collider. The BS prototype (2 m in length) was manufactured according to the base line design (BD) of the FCC-hh BS. It implements a saw-tooth profile designed to absorb the SR generated at the bending magnets. Also, a laser-ablated anti-electron cloud surface texturing [2] was applied at the BS inner walls. We present here the results obtained at BESTEX and the comparison of the results obtained during irradiation of the saw-tooth profile at different geometric configurations.
This activity has been carried out in the framework of the EuroCirCol* collaboration (work package 4 "Cryogenic Beam Vacuum System").

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP036

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paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPMP038

Summary of Modelling Studies on the Beam Induced Vacuum Effects in the FCC-hh

vacuum, photon, collider, synchrotron

1331

I. Bellafont, R. Kersevan, L. Mether
CERN, Geneva, Switzerland

Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 654305.
EuroCirCol is a conceptual design study of a Future Circular Collider (FCC-hh) which aims to expand the current energy and luminosity frontiers that the LHC has established. The vacuum chamber of this 50 TeV, 100 km collider, will have to cope with unprecedented levels of synchrotron radiation power for proton colliders, dealing simultaneously with a tighter magnet aperture. Since the high radiation power and photon flux will release large amounts of gas into the system, the difficulty to keep a low level of residual gas density increases considerably compared with the LHC. This article presents a study of the beam induced vacuum effects for the FCC-hh novel conditions, the different phenomena which, owing to the presence of the beam, have an impact on the vacuum level of the accelerator. To achieve this, a novel beam screen has been proposed, featuring specific mitigating measures aimed at dealing with the beam induced effects. It is concluded that thanks to the new beam screen design, the vacuum level in the FCC-hh shall be adequate, allowing to reach the molecular density requirement of better than 10¹⁵ H₂/m3 with baseline beam parameters within the first months of conditioning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP038

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paper received ※ 10 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPMP048

Current Status of Turkish Accelerator and Radiation Laboratory

radiation, cavity, FEL, status

1359

A.A. Aksoy, O.F. Elçim
Ankara University Institute of Accelerator Technologies, Golbasi, Turkey
Ö. Karslı, C. Kaya, B. Koc
Ankara University, Accelerator Technologies Institute, Golbasi, Turkey

Funding: T.R. Presidency Strategy and Budget Office Grand No: 2006K-120470
Turkish Accelerator and Radiation Laboratory (TARLA) which is designed to deliver various accelerator based radiation sources, aims to be outstanding research instrument for users from both Turkey and region. Within the current scope of TARLA its superconducting accelerator will drive two of free electron laser (FEL) beamlines in order to provide Continuous Wave (CW) tunable radiation of high brightness in the mid- and far-infrared range as well as a Bremmstrahlung radiation station. Main components of TARLA, such as injector, superconducting accelerating modules and cryoplant are under commissioning currently. In this paper commissioning results and current status of facility are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP048

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPMP051

MULTIPACTOR SUPPRESSION BY LASER ABLATION SURFACE ENGINEERING FOR SPACE APPLICATIONS

laser, multipactoring, GUI, controls

1365

R. Valizadeh, A.N. Hannah, O.B. Malyshev, B.S. Sian
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J.S. Colligon
University of Huddersfield, Huddersfield, United Kingdom
Y. Dan
Hitachi High-Technologies Corp., Ibaraki-ken, Japan
V.R. Dhanak
The University of Liverpool, Liverpool, United Kingdom
J. Mutch
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
B.S. Sian
UMAN, Manchester, United Kingdom
N. Sykes
Micronanics Laser Solution Center, Didcot, United Kingdom

Developing a surface with low Secondary Electron Yield (SEY) is one of the main ways of mitigating electron cloud and beam-induced electron multipacting in high-energy charged particle accelerators and space-borne RF equipment for communication purposes. In this study we report on the secondary electron yield (SEY) measured from silver coated aluminium alloy as-received and after laser ablation surface engineering (LASE). Analysis shows the SEY can be reduced by 43% using LASE. EDX and SEM analysis shows it is possible to reduce the SEY whilst maintaining the original surface composition.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP051

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPGW006

Measurements of the Momentum Compaction Factor of the ESRF Storage Ring

radiation, undulator, SRF, synchrotron

1392

N. Carmignani, W. De Nolf, A. Franchi, C. Sahle, L. Torino
ESRF, Grenoble, France
B. Nash
RadiaSoft LLC, Boulder, Colorado, USA

In a storage ring, the momentum compaction factor can be obtained by measuring the variation of the beam energy as a function of the RF frequency. In this paper we present the measurement of the momentum compaction factor from two different methods. With the first, we measure the variation of the undulator spectra for different RF frequencies. With the second, we measure the variation of the hard x-rays flux produced by a dipole for different RF frequencies.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW006

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paper received ※ 29 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPGW024

Pulse Shaping Methods for Laser-Induced Generation of THz Radiation at the Delta Storage Ring

laser, radiation, storage-ring, experiment

1453

C. Mai, B. Büsing, A. Glaßl, S. Khan, D. Krieg, A. Meyer auf der Heide
DELTA, Dortmund, Germany

At DELTA, a 1.5-GeV electron storage ring operated as a synchrotron light source by the TU Dortmund University, a dedicated beamline is used for experiments with (sub-)THz radiation. Here, an interaction of short laser pulses with electron bunches to give rise to coherently emitted broadband as well as tunable narrowband radiation from 75 GHz to 5.6 THz. For the narrowband operation of the source, a laser pulse with periodic intensity modulation is used. An interferometric approach, the chirped-pulse beating technique, is routinely employed for this purpose. Recently, pulse shaping techniques using spatial light modulators are investigated to gain more flexible control of the laser pulse shape and the spectrotemporal properties of the resulting THz pulses.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW024

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPGW025

The DELTA Short-Pulse Source: Upgrade Plans from CHG to EEHG

laser, undulator, radiation, optics

1457

A. Meyer auf der Heide, B. Büsing, S. Khan, D. Krieg, C. Mai, F. Teutenberg
DELTA, Dortmund, Germany

At the synchrotron light source DELTA operated by the TU Dortmund University, coherent harmonic generation (CHG) is employed to provide ultrashort pulses in the vacuum ultraviolet and terahertz (THz) regime. Here, a modulation of the electron energy induced by an interaction of an ultrashort laser pulse with an electron bunch is transformed into a density modulation by a magnetic chicane. This results in coherent emission at harmonics of the laser wavelength as well as THz radiation. With the planned upgrade towards echo-enabled harmonic generation (EEHG), much higher harmonics can be achieved by adding a second laser-electron interaction. The necessary major modifications of the DELTA storage ring and investigations of the laser-electron interaction will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW025

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPGW033

Status of Test-Accelerator as Coherent THz Source (t-ACTS) at ELPH, Tohoku University

radiation, undulator, polarization, FEM

1475

S. Kashiwagi, H. Hama, F. Hinode, K. Kanomata, S. Miura, N.M. Morita, T. Muto, I. Nagasawa, K. Nanbu, S. Ninomiya, H. Saito, K. Takahashi, H. Yamada
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

A test-Accelerator as Coherent Terahertz Source (t-ACTS) has been under development at the Research Center for Electron Photon Science (ELPH), Tohoku University, in which an intense coherent terahertz radiation is generated from the femtosecond electron pulses. Velocity bunching scheme in a traveling accelerating structure is employed to generate femtosecond electron pulses, and the generation of femtosecond electron pulses was confirmed by spectrum analysis of coherent transition radiation using Michelson interferometer. Coherent transition radiation and coherent undulator radiation in the terahertz (THz) region from the short electron pulses has been demonstrated, and their characteristics such as frequency spectrum, spatial distribution and polarization were measured and compared with theoretical calculations. We have succeeded to generate the coherent transition radiation up to approximately 5 THz and the coherent undulator radiation with narrow bandwidth from 2.6 to 3.4 THz. At present, development of a variable polarized THz light source using a crossed-undulator system is being carried out. In addition, we are developing a nondestructive beam monitor using Cherenkov radiation emitted from the electron pulses. The status of t-ACTS will be presented in this conference.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW033

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paper received ※ 17 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPGW037

Systematic Measurements of the Coherent THz Spectra by Magnetic Bunch Compression at the Compact ERL

optics, radiation, sextupole, linac

1486

M. Shimada, Y. Honda, R. Kato, T. Miyajima, N. Nakamura, T. Obina, T. Uchiyama
KEK, Ibaraki, Japan
T. Hotei
Sokendai, Ibaraki, Japan

Short electron bunch beam is one of the key elements of a Free Electron Laser (FEL) or intense THz coherent light source. The Energy Recovery Linac (ERL) has the strong advantage of operation of such an electron bunch at high repetition rate and is expected to increase the photon flux. At the Compact ERL in KEK site, we have demonstrated the magnetic bunch compression at the 180-degree return arc and measured the THz spectra of the Coherent Transition Radiation (CTR). This paper reports the revamped THz beamline and the improvement of the beam tuning as well as the systematic measurements of the THz spectra by magnetic bunch compression.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW037

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPGW038

Study on Coherent THz Radiation Using Tilt Control of Electron Beam

radiation, solenoid, target, experiment

1489

Y. Tadenuma, M. Brameld, T. Murakami, K. Sakaue, M. Washio
Waseda University, Tokyo, Japan

Funding: This work was supported by a research granted from JSPS KAKENHI 17H02821.
The terahertz wave is located in the intermediate frequency band between radio waves and light waves, and researches on the light sources such as terahertz quantum cascade laser and femtosecond laser based THz sources are being conducted*. As a new terahertz light source, we are studying coherent Cherenkov radiation by using the tilt control of electron beam and irradiating the target medium. Since the radiation intensity of Cherenkov radiation depends on the target medium, comparison of three kinds of medium with different refractive index and density, and optimization of the target shape were performed. In addition, we are going to try quasi monochromatization of radiation by using multi slit to control the form factor of the electron beam. In this presentation, we will report the experimental results of target optimization and quasi monochromatization and the future prospects.
*S. S. Dhillon, et al., The 2017 terahertz science and technology roadmap, J. Phys. D: Appl. Phys., 50 (2017) 043001.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW038

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paper received ※ 12 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPGW045

Lattice Design for the Reversible SSMB

radiation, emittance, storage-ring, bunching

1507

C.L. Li
SINAP, Shanghai, People’s Republic of China
A. Chao
SLAC, Menlo Park, California, USA
C. Feng, B.C. Jiang
Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China

Steady State Microbunching (SSMB) aiming at producing high average power radiation in the electron storage ring has been proposed by Ratner and Chao years ago. Reversible seeding scheme is one of the promising scenarios with less challenges on the storage ring lattice design. The key problem for reversible SSMB is the precise cancelation of the laser modulation which will allow producing turn-by-turn coherent radiation without spoiling the transverse emittances and energy spread. In this paper the lattice design for the microbunching generation and its cancelation will be presented. Also a storage ring lattice design will be shown.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW045

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPGW051

Generation of Two Terahertz Radiation Pulses with Continuously Tunable Frequency and Time Delay

radiation, laser, cathode, gun

1518

W.X. Wang, Z.G. He, S.M. Jiang, H.R. Zhang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

We propose to generate two narrow band terahertz pulses radiated from two temporally modulated relativistic electron beams, which are generated in a photo-injector. The temporal profile of the drive laser is modulated by means of the paired chirped pulses beating technique, leading to the generation of two pre-bunched electron beams. Coherent transient radiation (CTR) is considered as the mechanism for terahertz radiation generation. The frequencies of the two terahertz pulses can be independently tuned by adjusting the paired beating frequencies, and the interval between the two terahertz pulses can be adjusted by the optical delay line.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW051

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paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPGW059

Studies of The Electron Beam Lifetime in Solaris Electron Storage Ring

storage-ring, cavity, scattering, vacuum

1541

R. Panas, A.M. Marendziak, A.I. Wawrzyniak, M. Wisniowski
Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland

Solaris storage ring is a recently constructed and commissioned machine operated in decay mode. With total accumulated beam dose near to 1000 A.h the measured total lifetime has reached 16 h for 270mA of a stored current. In this paper, the beam lifetime studies are presented using measured residual gas analysis and vertical scraper position for tuned and detuned Landau cavities. It shows that for stable beam the lifetime is dominated by the interaction of the electron with residual gas (vacuum lifetime) and between electrons interaction within a bunch (Touschek lifetime). The estimated vacuum, Touschek and total beam lifetimes from theoretical analysis are also compared with the measured beam lifetime.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW059

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPGW085

A Hard X-Ray Compact Compton Source at CBETA

laser, photon, scattering, brilliance

1604

K.E. Deitrick, C. Franck, G.H. Hoffstaetter, V.O. Kostroun, K.W. Smolenski
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J. Crone, H.L. Owen
UMAN, Manchester, United Kingdom
B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Compton backscattering at energy recovery linacs (ERLs) promises high flux, high energy x-ray sources in the future, made possible by high quality, high repetition rate electron beams produced by ERLs. CBETA, the Cornell-BNL ERL Test Accelerator currently being built and commissioned at Cornell, is an SRF multi-turn ERL using Non-Scaling Fixed Field Alternating-gradient (NS-FFA) arcs. CBETA has high quality design parameters with an anticipated top energy of 150 MeV on the fourth pass. The expected parameters of a Compton source at CBETA include a top x-ray energy of over 400 keV with a flux on the order of 10¹² ph/s. In this paper, we present anticipated parameters and potential applications in science and engineering for this source.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW085

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPGW086

Energy and RF Cavity Phase Symmetry Enforcement in Multi-Turn ERL Models

cavity, linac, acceleration, target

1606

R.M. Koscica, N. Banerjee, C.M. Gulliford, G.H. Hoffstaetter, W. Lou
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

In a multi-pass Energy Recovery Linac (ERL), each cavity must regain all energy expended from beam acceleration during beam deceleration, and the beam should achieve specific energy targets during each loop that returns it to the linac. For full energy recovery, and for every returning beam to meet loop energy requirements, we must optimize the phase and voltage of cavity fields in addition to selecting adequate flight times. If we impose symmetry in time and energy during acceleration and deceleration, fewer parameters are needed, simplifying the optimization. As an example, we present symmetric models of the Cornell BNL ERL Test Accelerator (CBETA) with solutions that satisfy the optimization targets of loop energy and zero cavity loading.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW086

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paper received ※ 14 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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TUPGW098

Fabrication & Cold Tests of a Millimeter-Period RF Undulator

undulator, laser, FEL, GUI

1643

F. Toufexis, B.J. Angier, D. Gamzina, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
To reduce the linac energy required for an FEL radiating at a given wavelength, and hence its size, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424GHz, using a corrugated cylindrical waveguide operating at the HE11 modes. We have designed a mm-wave undulator cavity at 91.392GHz* with an equivalent undulator period of 1.75 mm. This undulator requires 1.4 MW for sub microsecond pulses for an equivalent K value of 0.1. In this work we present the mechanical design and fabrication of this 91.392 GHz RF Undulator, as well as preliminary cold test data.
* F. Toufexis and S.G. Tantawi, "A 1.75-mm Period RF-Driven Undulator", Proceedings of IPAC17.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW098

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paper received ※ 10 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPGW102

CBETA - Novel Superconducting ERL

linac, MMI, operation, cryomodule

1651

R.J. Michnoff, J.S. Berg, S.J. Brooks, J. Cintorino, Y. Hao, C. Liu, G.J. Mahler, F. Méot, S. Peggs, V. Ptitsyn, T. Roser, P. Thieberger, S. Trabocchi, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, H. Witte
BNL, Upton, Long Island, New York, USA
N. Banerjee, J. Barley, A.C. Bartnik, I.V. Bazarov, D.C. Burke, J.A. Crittenden, L. Cultrera, J. Dobbins, S.J. Full, F. Furuta, R.E. Gallagher, M. Ge, C.M. Gulliford, B.K. Heltsley, G.H. Hoffstaetter, D. Jusic, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, W. Lou, J.R. Patterson, P. Quigley, D.M. Sabol, D. Sagan, J. Sears, C.H. Shore, E.N. Smith, K.W. Smolenski, V. Veshcherevich, D. Widger
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
D. Douglas
Douglas Consulting, York, Virginia, USA
M. Dunham, C.E. Mayes
SLAC, Menlo Park, California, USA

Funding: New York State Research&Development Authority - NYSERDA agreement number 102192
We are successfully commissioning a unique Cornell University and Brookhaven National Laboratory Electron Recovery Linac (ERL) Test Accelerator ’CBETA’ [1]. The ERL has four accelerating passes through the supercon-ducting linac with a single Fixed Field Alternating Linear Gradient (FFA-LG) return beam line built of the Halbach type permanent magnets. CBETA ERL accelerates elec-trons from 42 MeV to 150 MeV, with the 6 MeV injec-tor. The novelties are that four electron beams, with ener-gies of 42, 78, 114, and 150 MeV, are merged by spreader beam lines into a single arc FFA-LG beam line. The elec-tron beams from the Main Linac Cryomodule (MLC) pass through the FFA-LG arc and are adiabatically merged into a single straight line. From the straight section the beams are brought back to the MLC the same way. This is the first 4 pass superconducting ERL and the first single permanent magnet return line.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW102

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB002

The Conceptual Design of a 36 GHz RF Undulator

undulator, cavity, GUI, photon

1676

D. Zhu
ASCo, Clayton, Victoria, Australia
A.W. Cross, L. Zhang
USTRAT/SUPA, Glasgow, United Kingdom
Y.E. Tan
AS - ANSTO, Clayton, Australia

The CompactLight project supported by European H₂020 is to design a hard X-ray FEL facility beyond today’s state of the art. The project integrates photo injector, X-band acceleration and innovative compact short-period undulators together to make the machine more compact. RF undulator has an extraordinary advantage of working at very short undulator period. A conceptual design for a RF undulator at 36 GHz using a corrugated cylindrical waveguide operating in the HE11 mode is presented in this paper. Based on beam dynamics simulation and photon beam radiation simulations, the possibility of RF undulator to be used in CompactLight project is evaluated.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB002

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB008

LUXE - a QED Experiment at the European XFEL

experiment, FEL, laser, photon

1694

F. Burkart, R.W. Aßmann, R. Brinkmann, W. Decking, N. Golubeva, B. Heinemann, M. Hüning, J. List, M. Wing
DESY, Hamburg, Germany
M. Wing
UCL, London, United Kingdom

The proposed experiment aims to measure QED in the presence of strong fields and above the Schwinger critical field. An experiment is being considered at the European XFEL, which should be able to measure non-perturbative QED and its transition from the perturbative regime. This paper presents the current status of the LUXE (Laser und XFEL Experiment) design study. First layout considerations; accelerator beam line design, electron and laser beam parameters, radioprotection issues and first results of the start to end simulations will be presented and discussed in detail. An outlook concerning the implementation into the XFEL schedule and timeline of this experiment will be given.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB008

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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TUPRB012

Design of High Power CW IR-THz Source for the Radiation Source ELBE Upgrade

undulator, radiation, FEL, linac

1702

P.E. Evtushenko, T.E. Cowan, U. Lehnert, P. Michel
HZDR, Dresden, Germany

The Radiation Source ELBE at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) is a user facility based on a 1 mA - 40 MeV CW SRF LINAC. Presently HZDR is considering upgrade options for the ELBE or its replacement with a new CW, SRF LINAC-based user facility. A part of the user requirements is the capability to generate IR and THz pulse in the frequency range from 0.1 through 30 THz, with pulse energies in the range from 100 uJ through a few mJ, at the repetition rate between 100 kHz and 1 MHz. This corresponds to the pulse energy increase, dependent on the wavelength by a factor from 100 through 1000. In this contribution, we outline key aspects of a concept, which would allow to achieve such parameters. Such key aspects are: 1 - use of a beam with longitudinal density modulation and bunching factor of about 0.5 at the fundamental frequency; 2 - achieving the density modulation through the mechanism similar to the one used in optical klystron (OK) and HGHG FEL; 3 - generating necessary for the modulation optical beam by an FEL oscillator, and 4 - using two electron injectors, where one injector provides beam for the FEL oscillator while second high charge injector provides beam for the high energy per pulse generation for user experiments. All-in-all the concept of the new radiation source is very similar to an OK, but operating with two beams simultaneously.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB012

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paper received ※ 21 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB013

Simulation Studies for a EEHG seeded FEL in the XUV

laser, bunching, FEL, simulation

1705

V. Grattoni, S. Ackermann, R.W. Aßmann, B. Faatz, T. Lang, C. Lechner, M.M. Mohammad Kazemi, G. Paraskaki, J. Zemella
DESY, Hamburg, Germany
W. Hillert
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
S. Reiche
PSI, Villigen PSI, Switzerland

Echo-enabled harmonic generation (EEHG) is a promising technique for seeded free electron lasers (FELs) not only to go down to wavelengths of 4 nm, but also to simplify the schemes that are currently used to achieve a similar wavelength range (double cascade HGHG). Thus a study optimizing the EEHG performance in the wavelength range from 60 to §I{4}{nm} has been performed. The more critical working point, at 4 nm, is here analyzed in terms of seed laser energy stability for two different seed laser frequencies: visible and UV.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB013

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paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB018

Design Studies of a Proof-of-Principle Experiment on THz SASE FEL at PITZ

FEL, undulator, laser, experiment

1713

X. Li, P. Boonpornprasert, Y. Chen, J.D. Good, M. Groß, H. Huck, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, O. Lishilin, G. Loisch, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, G. Shu, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany

A free-electron laser based THz source is undergoing design studies at the Photo Injector Test facility at DESY in Zeuthen (PITZ). It is considered as a prototype for pump-probe experiments at the European XFEL, benefiting from the fact that the electron beam from the PITZ facility has an identical pulse train structure as the XFEL pulses. In the proposed proof-of-principle experiment, the electron beam (up to 4 nC bunch charge and 200 A peak current) will be accelerated to 16-22 MeV/c to generate SASE radiations in an LCLS-I undulator in the THz range between 60 and 100 µm with an expected energy of up to ~1 mJ/pulse. In this paper, we report our simulations on the optimization of the photo-injector and the design of the transport and matching beamline. Experimental investigations on the generation, characterization and matching of the high charge beam in the existing 22-m-long beamline will also be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB018

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paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB020

Status of the European XFEL

FEL, operation, photon, MMI

1721

W. Decking, F. Brinker, L. Fröhlich, R. Kammering, T. Limberg, S. Liu, D. Nölle, M. Omet, M. Scholz, T. Wamsat
DESY, Hamburg, Germany

The European XFEL is a Hard X-ray Free Electron Laser based on superconducting accelerator technology. In operation since 2017, it now serves 3 FEL beamlines simultaneously for user experiments. We will report on the present operation of the linear accelerator, the beam distribution to the various beamlines and the performance of the FEL radiators.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB020

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paper received ※ 15 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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TUPRB023

Considerations for the Ultrahard X-ray Undulator Line of the European XFEL

undulator, FEL, photon, operation

1732

E. Schneidmiller, V. Balandin, W. Decking, M. Dohlus, N. Golubeva, D. Nölle, M.V. Yurkov, I. Zagorodnov
DESY, Hamburg, Germany
G. Geloni, Y. Li, S. Molodtsov, J. Pflüger, S. Serkez, H. Sinn, T. Tanikawa, S. Tomin
EuXFEL, Schenefeld, Germany

The European XFEL is a multi-user X-ray FEL facility based on superconducting linear accelerator. Presently, three undulators (SASE1, SASE2, SASE3) routinely deliver high-brightness soft- and hard- X-ray beams for users. There are two empty undulator tunnels that were originally designed to operate with spontaneous radiators in the range 20-90 keV. We consider, instead a possible installation of two FEL undulators. One of them (SASE4) is proposed for operation in a standard (7-25 keV) range as well as in ultrahard (25-100 keV) regime. We discuss a possible location and length of SASE4, modifications of electron beam transport, beam dynamics, choice of undulator technology, different operation modes (SASE and advanced lasing concepts) etc.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB023

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB024

A Concept for Upgrade of FLASH2 Undulator Line

undulator, FEL, polarization, operation

1736

E. Schneidmiller, B. Faatz, I. Hartl, S. Schreiber, M. Tischer, M. Vogt, M.V. Yurkov, J. Zemella
DESY, Hamburg, Germany
W. Wurth
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

FLASH is the first soft X-ray FEL user facility, routinely providing brilliant photon beams for users since 2005. There are plans to upgrade both existing undulator lines of this facility, FLASH1 and FLASH2. FLASH1 will mainly operate in XUV range in seeding and SASE modes, while FLASH2 will use the standard SASE regime as well as new lasing concepts aiming at production of brilliant photon beams on the fundamental and harmonics down to 1nm. In this paper we present a concept for FLASH2 upgrade, and discuss different advanced options.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB024

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paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB026

Optics & Compression Schemes for a Possible FLASH Upgrade

FEL, emittance, laser, simulation

1744

J. Zemella, M. Vogt
DESY, Hamburg, Germany

The proposed FLASH upgrade will rely on high quality electron beams provided to all undulator beamlines. Here we describe possible modifications to the FLASH lattice and the compression scheme that aim at improving the beam quality and the ability to control critical beam properties along the machine - simultaneously and independently for all beamlines.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB026

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paper received ※ 11 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB027

Upgrade Plans for FLASH for the Years After 2020

laser, FEL, undulator, operation

1748

M. Vogt, K. Honkavaara, J. Rönsch-Schulenburg, S. Schreiber, J. Zemella
DESY, Hamburg, Germany

FLASH is a unique superconducting soft X-ray FEL capable of producing up to 8000 photon pulses per second. A substantial upgrade is planned to keep FLASH attractive and competitive. Several upgrade scenarios are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB027

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paper received ※ 14 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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TUPRB031

FERMI Configuration for the Echo Enabled Harmonic Generation Experiment

laser, FEL, experiment, photon

1752

E. Allaria, D. Castronovo, M. Cautero, I. Cudin, M.B. Danailov, B. Diviacco, L. Giannessi, M. Veronese, M. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The FERMI FEL-2 undulator line, normally operated in the double stage high gain harmonic generation with the fresh bunch (HGHG-FB) has been temporary modified to allow operating the FEL in the Echo Enabled Harmonic Generation (EEHG) scheme. An increase of the dispersion in the delay-line was required together with a replacement of the second stage modulator allowing the electron beam to resonantly interact with a second seed laser. Another critical component of the EEHG setup is a new manipulator installed in the delay-line chicane and hosting additional diagnostic components. In this work we describe in some detail these new components that allowed a successful demonstration of the EEHG at harmonics as high as 101.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB031

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paper received ※ 17 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB032

The CompactLight Design Study Project

FEL, linac, undulator, brightness

1756

G. D’Auria, S. Di Mitri, R.A. Rochow
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
M. Aicheler
HIP, University of Helsinki, Finland
A.A. Aksoy
Ankara University, Accelerator Technologies Institute, Golbasi, Turkey
D. Alesini, M. Bellaveglia, B. Buonomo, F. Cardelli, M. Croia, M. Diomede, M. Ferrario, A. Gallo, A. Giribono, L. Piersanti, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati, Italy
R. Apsimon, A. Castilla
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
J.M. Arnesano, F. Bosco, L. Ficcadenti, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
A. Bernhard, J. Gethmann
KIT, Karlsruhe, Germany
G. Burt
Lancaster University, Lancaster, United Kingdom
M. Calvi, T. Schmidt, K. Zhang
PSI, Villigen PSI, Switzerland
H.M. Castaneda Cortes, J.A. Clarke, D.J. Dunning, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A.W. Cross, L. Zhang
USTRAT/SUPA, Glasgow, United Kingdom
G. Dattoli, F. Nguyen, A. Petralia
ENEA C.R. Frascati, Frascati (Roma), Italy
R.T. Dowd, D. Zhu
AS - ANSTO, Clayton, Australia
W.D. Fang
SINAP, Shanghai, People’s Republic of China
A. Faus-Golfe, Y. Han
LAL, Orsay, France
E.N. Gazis, N. Gazis
National Technical University of Athens, Athens, Greece
R. Geometrante, M. Kokole
KYMA, Trieste, Italy
V.A. Goryashko, M. Jacewicz, R.J.M.Y. Ruber
Uppsala University, Uppsala, Sweden
X.J.A. Janssen, J.M.A. Priem
VDL ETG, Eindhoven, The Netherlands
A. Latina, X. Liu, C. Rossi, D. Schulte, S. Stapnes, X.W. Wu, W. Wuensch
CERN, Geneva, Switzerland
O.J. Luiten, P.H.A. Mutsaers, X.F.D. Stragier
TUE, Eindhoven, The Netherlands
J. Marcos, E. Marín, R. Muñoz Horta, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
G. Taylor
The University of Melbourne, Melbourne, Victoria, Australia

Funding: This project has received funding from the European Union’s Horizon2020 research and innovation programme under grant agreement No 777431
The H₂020 CompactLight Project (www. CompactLight.eu) aims at designing the next generation of compact X-rays Free-Electron Lasers, relying on very high gradient accelerating structures (X-band, 12 GHz), the most advanced concepts for bright electron photo injectors, and innovative compact short-period undulators. Compared to existing facilities, the proposed facility will benefit from a lower electron beam energy, due to the enhanced undulators performance, and will be significantly more compact, with a smaller footprint, as a consequence of the lower energy and the high-gradient X-band structures. In addition, the whole infrastructure will also have a lower electrical power demand as well as lower construction and running costs.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB032

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB033

Fixed-gap Undulators for Elettra and FERMI

undulator, polarization, FEL, operation

1760

B. Diviacco, R. Bracco, D. Millo
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

In the context of an R&D program on alternative undulator schemes, two fixed-gap, linearly polarised, adjustable-phase undulators (APUs) were built and successfully tested, the first on the FERMI free electron laser, the second on the Elettra storage ring. The latter is now in regular operation for the ALOISA surface science beam line. As a further elaboration on the fixed-gap concept, two elliptically polarised undulators (EPUs) are now being developed for FERMI and for Elettra. We have also started the construction of a double period APU providing an extended tuning range to the TwinMic soft X-Ray microscopy beam line. We present here the main design and construction aspects of the new undulators under development.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB033

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paper received ※ 09 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB035

Stimulated Emission of THz Coherent Diffraction Radiation in an Optical Cavity by a Multibunch Electron Beam

cavity, experiment, radiation, resonance

1763

Y. Honda, A. Aryshev, R. Kato, T. Miyajima, T. Obina, M. Shimada, R. Takai, T. Uchiyama, N. Yamamoto
KEK, Ibaraki, Japan

Funding: JSPS KAKENHI
Accelerator-based terahertz (THz) radiation has been expected to realize a high-power broad-band source. Employing a low-emittance and short-bunch electron beam at a high repetition rate, a scheme to resonantly excite optical cavity modes of THz spectrum range via coherent diffraction radiation has been proposed. The confocal cavity design is the special case that resonance conditions of all the eigen modes coincide, resulting in realizing broad-band excitation. But in general cases of non-confocal cavities, the resonance condition depends on the mode, and the resonance peak becomes wide and weak. We performed an experiment with a non-confocal cavity as a follow-up experiment of that we have done with a confocal cavity. The result confirmed that the confocal design is the key for a broad-band source.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB035

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paper received ※ 26 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB038

Characteristics of Polarized Coherent Radiation in Thz Region From a Crossed-Undulator

undulator, radiation, polarization, experiment

1769

H. Saito, H. Hama, F. Hinode, K. Kanomata, S. Kashiwagi, S. Miura, N.M. Morita, T. Muto, I. Nagasawa, K. Nanbu, S. Ninomiya, K. Takahashi, H. Yamada
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

A variable polarized THz light source using a crossed-undulator configuration has been developed at Research Center for Electron Photon Science (ELPH), Tohoku University. It consists of two planar undulators of which deflecting planes cross at right angles and a phase shifter for phase adjustment. Polarization of the crossed-undulator has observation angle dependence due to that of radiation wavelength and optical path length difference between two radiations. That limits an angular range maintaining the identical polarization state. Assuming undulator parameters for our experiment (a fundamental frequency 1.9 THz and a number of periods seven) degree of circular polarization larger than 0.9 can be obtained only in the range of 2.2 mrad, i. e. 13% of the radiation angular spread.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB038

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB039

Research of Coherent Edge Radiation Generated by Electron Beams Oscillating Free-Electron Lasers

FEL, radiation, cavity, experiment

1772

N. Sei, H. Ogawa
AIST, Tsukuba, Ibaraki, Japan
K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, Y. Sumitomo, Y. Takahashi, T. Tanaka
LEBRA, Funabashi, Japan
H. Ohgaki, H. Zen
Kyoto University, Kyoto, Japan

Funding: JSPS KAKENHI Grant Number JP16H03912
We have studied far-infrared coherent radiation with an S-band linac at Laboratory for Electron Beam Research and Application (LEBRA) at Nihon University. We have already developed a couple of terahertz-wave sources based on coherent synchrotron radiation and coherent transition radiation*, which have been applied to spectroscopic research**. Moreover, we developed coherent edge radiation (CER) at the downstream bending magnets in the FEL sections. Because the edge radiation has an annular shape distribution characterized by the asymmetric first-order Laguerre-Gaussian mode, the CER can be extracted from an optical cavity of the FEL system without a diffraction loss of the FEL beam***. The root-mean-squared bunch length of the electron beam was evaulated by measuring the CER spectra, which was about the same level as the FEL micropulse width. Although the infrared FELs at LEBRA had a long slippage length, the CER intensity can be a guidepost enhancing the FEL power because of the existence of their correlation. In this presentation, the characteristics of the CER including correlation between the CER and the FEL will be reported.
* N. Sei et al., Jpn. J. Appl. Phys. 56, (2017) 032401.
** N. Sei et al., J. Opt. Soc. Am. B, 31, (2014) 2150.
*** N. Sei et al., Phys. Lett. A in press.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB039

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paper received ※ 19 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB040

Development of Coherent Terahertz Wave Sources and Transport Systems at LEBRA Linac

FEL, linac, radiation, vacuum

1775

T. Sakai, K. Hayakawa, Y. Hayakawa, K. Nogami, Y. Sumitomo, T. Tanaka
LEBRA, Funabashi, Japan
H. Ogawa, N. Sei
AIST, Tsukuba, Ibaraki, Japan

Funding: This work was supported by JSPS KAKENHI (Grant-in-Aid for Young Scientists (B)) Grant Number JP16K17539 and JP16H03912.
Development of a 125 MeV S-band electron linac for the generation of Free Electron Laser (FEL), Parametric X-ray Radiation (PXR) and coherent terahertz waves (THz waves) has been underway at LEBRA of Nihon University as a joint research with KEK and National Institute of Advanced Industrial Science and Technology (AIST). The high power coherent transition radiation (CTR), coherent edge radiation (CER) and the coherent synchrotron radiation (CSR) wave sources development has been carried out since 2011 at LEBRA. The transport systems of the each THz wave were installed in the vacuum chamber on the downstream side of the 45 degrees bending magnet of the PXR and FEL beam-line. In particular, a CER of the generated the FEL beam line can also be guided without disturbing the FEL oscillations. Additionally, a part of the mirror of the transport optical system is constructed using Indium Tin Oxide (ITO) mirror with the optimized for the transport of the THz wave. In this report, construction of the THz transport beam lines and the property of the THz lights are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB040

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paper received ※ 19 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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TUPRB041

Simulation of Short-Pulse Generation from a Dynamically Detuned IR-FEL Oscillator and Pulse Stacking at an External Cavity

FEL, cavity, simulation, radiation

1778

Y. Sumitomo, Y. Hayakawa, T. Sakai
LEBRA, Funabashi, Japan
R. Hajima
QST, Tokai, Japan

Funding: Q-LEAP program supported by Ministry of Education, Culture, Sports, Science and Technology, Japan
At the LEBRA facility of Nihon U., we have an IR-FEL oscillator to generate radiations in the range of wavelengths 1-6 um for various experiments. A research program has been established to explore the application of the IR-FEL to generate attosecond UV and X-ray pulses through the high harmonic generation (HHG) in noble gases, where the IR-FEL pulses must have a high-peak power and a short-pulse duration. The property of generated FEL pulse is affected by the cavity length detuning of FEL oscillator as well as the small signal gain and the cavity loss. The operation at a small- or zero-detuning length is necessary to generate a FEL pulse shorter than the bunch length, although it requires a long macro-pulse to reach the saturation. For the short FEL pulse generation within a limited macro-pulse length at the LEBRA LINAC, we apply a dynamical modulation to the electron bunch repetition, that is equivalent to a dynamical detuning of the FEL cavity length. We illustrate the potential performance of the IR-FEL with the dynamical detuning by time-dependent 3D FEL simulations. We also evaluate the enhancement of the FEL pulses by an external cavity stacking for the sake of the HHG application.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB041

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paper received ※ 29 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB042

Design Study of Nonlinear Energy Chirp Correction Using Sextupole Magnets at the Soft X-Ray Free-Electron Laser Beamline of SACLA

sextupole, FEL, linac, cavity

1782

K. Togawa, T. Hara, H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

At the x-ray free-electron laser (FEL) facility, SACLA, a soft x-ray FEL beamline (SCSS+) is driven by a dedicated 800-MeV electron accelerator and being operated in parallel with two hard x-ray FEL beamlines. Responding to the demands of short laser pulses from users, a nonlinearity correction system using sextupole magnets is under consideration to obtain shorter electron bunches. Since the frequency of the SCSS+ injector is S-band, the nonlinearity correction of a bunch compression process using a harmonic correction cavity is not so efficient as the SACLA injector, whose frequency of the injector is L-band. Instead of a complex and costly correction cavity system, the sextupole magnets are simply installed in a dispersive section of the first bunch compressor chicane. In this report, we will present the basic design concept and some detail studies of the nonlinear correction.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB042

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB045

Stimulated Excitation by Seeding With Cherenkov Radiation in an Optical Cavity

radiation, cavity, GUI, ion-source

1785

S.M. Jiang, Z.G. He, Q.K. Jia, W.W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People’s Republic of China
D. He
Anhui Electrical Engineering Professional Technique College, Hefei, People’s Republic of China

Funding: Work supported by National Foundation of Natural Sciences of China (11775216, 11705198, 11675178), and Fundamental Research Funds for the Central Universities (WK2310000061).
By seeding with narrow-band Cherenkov radiation from a dielectric loaded waveguide(DLW), stimulated excitation in an optical cavity is presented. The evolution and energy loss of the field oscillating in optical cavity is analysed by the theoretical and numerical calculation. The results show that the high order TM modes of the Cherenkov radiation can be better preserved after a large number of roundtrips in the optical cavity and this scheme offers a potential method of realizing high power Terahertz radiation source in a compact facility.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB045

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paper received ※ 30 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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TUPRB046

Second Order Intensity Correlation and Statistical Properties of a Soft X-Ray Free Electron Laser

laser, FEL, radiation, simulation

1788

C.L. Li, J.H. Chen, Z.C. Chen, X.T. Wang, H.L. Wu
SINAP, Shanghai, People’s Republic of China
B. Liu, T. Liu
SARI-CAS, Pudong, Shanghai, People’s Republic of China

High degree of transverse field coherence is one of the unique properties of an FEL compared with a 3rd gen-eration storage ring light source. As a result, the FEL advances the development of innovative research and technology that was not previously feasible. A truly coherent source should be coherent in all orders de-scribed from the intensity correlation functions. In this paper, second order intensity correlation of FEL radia-tion is investigated based on the Hanbury Brown-Twiss intensity correlation method. The statistical properties of radiation produced from SASE was also investigated and compared with the statistical proper-ties of a phase-locked laser. The results show that the statistical properties of a SASE mode behave as a cha-otic source, which is significantly different from the properties of a phase-locked laser beam.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB046

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB050

The Optical Resonator of CTFEL for Range of 1 to 2 THz

FEL, GUI, radiation, coupling

1795

X.J. Shu, Y.H. Dou
Institute of Applied Physics and Computational Mathematics, People’s Republic of China

A high power THz free electron laser (FEL) facility is under construction at China Academy of Engineering Physics (CTFEL). The radiation frequency of the FEL facility will be tuned in range of 1~3 THz and the average output power is about 10 W. The system mainly consists of a GaAs photoemission DC gun, superconductor accelerator, hybrid wiggler, optical cavity. The first lasing is obtained on Aug. 29, 2017, and CTFEL is operated in range of 2-4THz, but cannot lasing at the frequency below 1.8 THz. The optical resonator of CTFEL must be optimized to ensure lasing in range of 1 to 2 THz.. The lasing strongly depends on the performance of the optical resonator including output efficiency, gain and round-trip loss. The optical resonator consists of metal-coated reflect mirror, the centre-hole output mirror, waveguide. The influence of waveguide on the quality of optical cavity is evaluated by the 3D OSIFEL code. The waveguide size and output hole radius is optimized to different frequencies between 1 THz to 2 THz.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB050

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paper received ※ 13 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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TUPRB052

The Mini-Period Permanent Magnet Staggered Undulator for Compact X-Ray Free Electron Laser

undulator, FEL, permanent-magnet, radiation

1797

L.G. Yan, D.R. Deng, J. Wang
CAEP/IAE, Mianyang, Sichuan, People’s Republic of China

Funding: Work supported by National Natural Science Foundation of China under grant of 11505174, 11505173 and 11605190.
Miniaturization of X-ray free electron laser requires reduction of undulator period length. In this proceeding, a mini-period permanent magnet staggered undulator was proposed, which is free of superconducting solenoid and thus has advantages of easy-manufacture and low-cost. After optimization, it can generate periodic field of peak field 0.71 T with period length 10 mm and pole gap 2 mm, which has been verified on a prototype. Combined with X-band linac, the length of 1 nm XFEL facility using the permanent magnet staggered undulator can be confined within 44 m.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB052

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paper received ※ 30 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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TUPRB053

Injector Physics Design at SHINE

laser, feedback, FEL, emittance

1801

Z. Wang, M.H. Zhao
SINAP, Shanghai, People’s Republic of China
Q. Gu
SSRF, Shanghai, People’s Republic of China
G.L. Wang
DICP, Dalian, People’s Republic of China

As a CW x-ray free electron laser facility, SHINE has a high requirement on the electron beam quality in the linac, as well as in the injector. SHINE injector consists of a 162.5 MHz normal conducting VHF gun, a NC 1.3 GHz RF buncher, a one cavity SC cryomodule, an eight cavity SC cryomodule and 3 solenoids along the injector layout. Some beam diagnostic element are inserted in the layout as well. In this paper, we try to introduce the injector physics design at shine.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB053

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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TUPRB054

The Beam-Based Alignment Simulation and Preliminary Experiment at SXFEL

FEL, alignment, quadrupole, undulator

1804

L. Zeng, H.X. Deng, C. Feng, D. Gu, B. Liu, Z.T. Zhao
SINAP, Shanghai, People’s Republic of China
G.L. Wang
DICP, Dalian, People’s Republic of China

The Shanghai soft X-ray Free-electron Laser facility (SXFEL) is now serving as an experimental platform for fundamental free-electron laser (FEL) principle tests. The machine puts very tight tolerance on the straightness of the electron beam orbit. It is hard to achieve the required trajectory due to the off-axis field of the misaligned quadrupoles and undulator segments especially for the SXFEL driven by low energy linac (840MeV). This tight requirement on electron beam straightness can only be met through the beam-based alignment (BBA) technology which achieved great success at LCLS, PAL-XFEL, European-XFEL and SCALA with high electron beam energies. But there has been no report about satisfactory BBA experiment results on soft X-ray FEL facility driven by relatively low energy linacs (on the order of 2 GeV or less) up to now. Here, we report the simulation results and preparatory experiment progress of the BBA at SXFEL with the method of dispersion-free steering (DFS). The experiment results show some improvements of the electron beam orbit and the phenomenon of the dispersion-free. The entire BBA experiment and a feedback system of electron beam trajectory may also be included.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB054

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paper received ※ 18 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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TUPRB057

THz-Pump and UV-Probe Scheme Based on Storage Ring

laser, radiation, bunching, storage-ring

1811

H.R. Zhang, Z.G. He, S.M. Jiang, W.X. Wang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

We propose a THz-pump and UV-probe scheme based on storage ring for ultra-fast dynamics experiment. In which, two sequential laser pulses, one of which has a periodic intensity envelope, simultaneously interact with different parts of the long electron beam in a modulator; after a chicane, the part that interacts with the periodic pulse will bunch at THz domain and radiate through a bend magnet, another based on high-harmonic generation will bunch at UV domain and radiate at a radiator. The electron beam can be utilized circularly in the storage ring, which will increase its average power. The feasibility of this THz-pump and UV-probe scheme is verified in both theory and simulation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB057

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paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB061

Seeded Free-Electron Lasers Driven by a Transverse Tilted Electron Bunch

laser, FEL, undulator, radiation

1817

Z. Zhao, Q.K. Jia, H.T. Li
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Work supported by the China Postdoctoral Science Foundation (No. 2018M642542) and the Fundamental Research Funds for the Central Universities (WK2310000081).
A transverse tilt of the electron bunch is normally unwanted in free-electron laser (FEL) since only a portion of the bunch can contribute to the FEL radiation. However, the recent researches demonstrate that the tilted bunch can be used to generate FEL with some special features. In this work we investigate the generation of a large tilt of the bunch by using a corrugated structure and a dogleg separately. Based on the tilted bunch, the creation of ultra-short pulse and multi-color pulses are demonstrated in high-gain harmonic generation (HGHG) FEL.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB061

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB062

Coherence Time Characterization for Self-Amplified Spontaneous Emission Free-Electron Lasers

FEL, laser, free-electron-laser, radiation

1820

G. Zhou, Y. Jiao, J.Q. Wang
IHEP, Beijing, People’s Republic of China
T.O. Raubenheimer, J. Wu
SLAC, Menlo Park, California, USA
C.-Y. Tsai
HUST, Wuhan, People’s Republic of China
C. Yang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

One of the key challenges in scientific researches based on free-electron lasers (FELs) is the characterization of the coherence time of the ultra-fast hard x-ray pulse, which fundamentally influences the interaction process between x-ray and materials. Conventional optical methods, based on autocorrelation, is very difficult to realize due to the lack of mirrors. Here, we experimentally demonstrate a conceptually new coherence time characterization method and a coherence time of 174.7 attoseonds has been measured for the 6.92 keV FEL pulses at Linac Coherent Light Source. In our experiment, a phase shifter is adopted to control the cross-correlation between x-ray and microbunched electrons. This approach provides critical temporal coherence diagnostics for x-ray FELs, and is decoupled from machine parameters, applicable for any photon energy, radiation brightness, repetition rate and FEL pulse duration, etc.
The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB062

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paper received ※ 01 May 2019 paper accepted ※ 28 May 2019 issue date ※ 21 June 2019

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TUPRB069

Study of FEL Operation Using Collimator without X-band Linearizer in HX Line at PAL-XFEL

FEL, operation, linac, simulation

1824

H. Yang, C.-K. Min, I.H. Nam
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This work is supported by MSIP, Korea.
A Hard X-ray (HX) line in PAL-XFEL consists of an e-gun, a Laser Heater (LH), S-band accelerators, an X-band LINearizer (XLIN), three Bunch Compressors (BC), a dog-leg, and an undulator line. It generates 2.5 - 15-keV FEL with over than 1-mJ pulse energy. The XLIN before BC1 is used for linearizing the energy chirp in the longitudinal phase space and provides the flexibility for FEL optimization and operation. However, it causes the instability of FEL by large jitters and drift because of higher frequency. We study the FEL operation without XLIN. The collimator in the center of BC1 is used removing the slices to cause nonlinear compression. We optimize the FEL by short electron bunch with under 30 fs. In this paper, we present details of the optimizing sequence and performance for the FEL operation without XLIN.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB069

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB070

A Peak Finding Algorithm for FEL Spectra Characterization

FEL, bunching, laser, background

1827

M.A. Pop
MAX IV Laboratory, Lund University, Lund, Sweden
E. Allaria
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

We present a software tool aimed at investigating the spectra of photon sources in order to detect any instabilities in the electron beam that have a clear effect on the spectrum. The method has been developed for FERMI@Elettra but with a general approach on the particularities of FEL machines such as a high repetition frequency and significant shot to shot fluctuations. The software has two operating options: a mode, aimed at online usage, which only detects peaks and their corresponding valleys, offering no information about the peaks themselves; and a more comprehensive mode that fits peak functions (Gaussian, Lorentzian etc…) to the spectrum based on initial guesses of the fitting parameters. The algorithm can provide a collection of simple but valuable variables such as number of peaks, peak separation and ratio between peak heights, as well as more specialized variables like peak width statistics and decomposition of the raw spectrum in basic components.
Project done in collaboration with FERMI@Elettra

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB070

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB071

Considerations on Implementing EEHG with a Strong Linear Chirp

bunching, FEL, linac, radiation

1830

M.A. Pop, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden

As the ECHO enabled harmonic generation (EEHG) scheme draws such intense focus from the FEL community, we conduct simulations to evaluate the challenges of implementing said scheme in different FEL layouts. Nonlinear processes such as this require extensive simulations to harmonize all system specific properties like seed lasers and electron beam properties. Along with optimizing the original EEHG scheme* one can consider, for example, altering the seed laser pulse to optimize the bunching for a machine specific chirp. We study the EEHG as a possible seeding method aimed at increasing coherence of the photon beam for the prospective SXL FEL beamline at MAXIV. The particular chirp of the electron beam through the MAXIV LINAC generates some specific requirements in implementing EEHG but may also offer an opportunity for exotic operation modes of this FEL.
* Xiang D. and Stupakov G. Echo-enabled harmonic generation free electron laser 10.1103/PhysRevSTAB.12.030702

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB071

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB074

Start-to-End Simulations of the Compact Light Project Based on an S-Band Injector and an X-Band LINAC

lattice, linac, FEL, cavity

1836

E. Marín, R. Muñoz Horta, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
A.A. Aksoy
Ankara University, Accelerator Technologies Institute, Golbasi, Turkey
S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
A. Latina
CERN, Geneva, Switzerland
S.B. van der Geer
Pulsar Physics, Eindhoven, The Netherlands

Funding: This project has received funding from the European Union’s Horizon2020 research and innovation programme under grant agreement No 777431
In this paper we report the start-to-end simulation results of one of the options under consideration for the CompactLight Project (XLS). The XLS is a hard X-ray Free Electron Laser under design, using the latest concepts for bright electron photo injectors, very high-gradient X-band structures, and innovative short-period undulators. Presently there exist various tracking codes to conduct the design process. Therefore identifying the most convenient code is of notable importance. This paper compares the tracking codes, Placet and General Particle Tracer, using the XLS lattice based on a S and X-band Injector. The calculation results in terms of beam quality and tracking performance of a full 6-D simulation are presented.
[*] The CompactLight Design Study Project, IPAC2019 proceedings.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB074

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPRB075

Higher Order Mode Spectra Study of 3.9 GHz Superconducting Radio Frequency Cavities for the European XFEL

cavity, HOM, simulation, FEL

1840

L. Shi, S. Reiche
PSI, Villigen PSI, Switzerland
N. Baboi, A. Sulimov, E. Vogel, T. Wamsat
DESY, Hamburg, Germany
R.M. Jones, N.Y. Joshi
UMAN, Manchester, United Kingdom
P. Pierini
ESS, Lund, Sweden

Funding: The work is part of EuCARD2 and was partly funded by the European Commission, GA 312453.
It is important to verify both by simulation and experiments the wakefields in superconducting radio frequency (SRF) cavities, which can degrade the electron beam quality considerably or impose excessive heat load if left undamped. In this paper, we investigate the Higher Order Mode (HOM) spectra of the 3.9 GHz SRF cavities, which are assembled in a cryogenic module and are used to linearize the longitudinal phase space of the electron beam in the injector of the European XFEL. The HOM spectra are significantly different from the ones from a single cavity due to the coupling of the modes amongst cavities. The measurements not only provide direct input for the beam dynamics studies but also for the beam instrumentation utilizing these modes. The mode spectra are also investigated with a number of numerical simulations and the comparison with measurements shows favorable agreement.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB075

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB076

Free Electron Laser Driven by a High-Energy High-Current Energy-Recovery Linac

FEL, radiation, linac, undulator

1844

F. Zimmermann
CERN, Geneva, Switzerland
H. Aksakal
KMSIU, Onikisubat / Kahramanmaras, Turkey
A.A. Aksoy
Ankara University, Accelerator Technologies Institute, Golbasi, Turkey
Z. Nergiz
Nigde University, Nigde University Science & Art Faculty, Nigde, Turkey

Funding: This work was supported by the European Commission under the HORIZON 2020 project ARIES, grant agreement no. 730871.
The proposed electron-hadron collider LHeC, based on an energy recovery linac, employs an electron beam of 20 mA current at an energy of tens of GeV. This electron beam could also be used to drive a free electron laser (FEL) operating at sub-Angstrom wavelengths. Here we demonstrate that such FEL would have the potential to provide orders of magnitude higher peak power, peak brilliance and average brilliance, than any other FEL, either existing or proposed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB076

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paper received ※ 10 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB086

Four X-ray Pulses within 10 ns at LCLS

laser, experiment, FEL, gun

1859

F.-J. Decker, W.S. Colocho, S.H. Glenzer, A.A. Lutman, A. Miahnahri, D.F. Ratner, J.C. Sheppard, S. Vetter
SLAC, Menlo Park, California, USA

The X-Ray FEL at SLAC or LCLS delivers typically one bunch at the time. Different schemes of two bunches have been developed: Two bucket, Twin bunch, split undulator, and fresh slice. Here we discuss a four bunch or even eight bunch setup, separated by 2 RF buckets or 0.7 ns. . The demand comes from MEC (Matter in Extreme Conditions) experiments, where high-power laser beams with Joule-class energies create impulsive pressure waves compressing materials on time scales of the order of ns. Eight snapshots for a single experiment will allow measuring the compression history, structural phase transitions into new high-pressure material states, and have the potential to resolve the transition kinetics time scales.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB086

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paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB088

Generation of High Peak Power Hard X-Rays at LCLS-II with Double Bunch Self-seeding

FEL, photon, laser, undulator

1863

A. Halavanau, F.-J. Decker, Y. Ding, C. Emma, Z. Huang, J. Krzywiński, A.A. Lutman, G. Marcus, C. Pellegrini, D. Zhu
SLAC, Menlo Park, California, USA

Funding: This work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515.
We propose to use existing LCLS copper S-band linac double bunch infrastructure to significantly improve LCLS-II hard X-ray performance. In our setup, we use the first bunch to generate a strong seeding X-ray signal, and the second bunch, initially traveling off-axis, to interact with the seed in the amplifier undulator and generate a near TW, 15 fs duration X-ray pulse in the 4 to 8 keV photon energy range. We investigate, via numerical simulations, the required transverse beam dynamics and the four crystals X-ray monochromator to be added to the existing LCLS-II beamline and discuss the final properties of the hard X-ray pulses and their potential application in high intensity, high-field physics experiments, including QED above the Schwinger critical field.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB088

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB089

Undulator Radiation Generated by a Single Electron

undulator, photon, experiment, radiation

1867

A. Halavanau, Z. Huang, C. Pellegrini, T.O. Raubenheimer
SLAC, Menlo Park, California, USA
I. Lobach
University of Chicago, Chicago, Illinois, USA
S. Nagaitsev
Fermilab, Batavia, Illinois, USA
D. Seipt
HZDR, Dresden, Germany

Funding: This work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515.
The facilities providing single electron beams are currently being commissioned at Fermilab and will be at SLAC. Recently, Fermilab’s IOTA ring routinely demonstrated circulation of a single electron at 100 MeV beam energy. Alternatively, SLAC is working on constructing LCLS-II an X-ray FEL driven by a 4 GeV SRF linac. A parasitic beamline, S30XL, is planned that will extract 4 GeV dark current from between the primary LCLS-II electron bunches. The dark current will be delivered to End Station A and can work independently of LCLS-II experiments. The dark current will be bunched at a frequency of 46 MHz while extracted current varied from single electrons to 10’s of nA. In the present paper, we estimate the feasibility of propagating single electron beams through a conventional undulator, placed in the IOTA and S30XL beamlines. We explore the possible observable effects and experimental parameters range. In addition, we focus on potential applications of such beams in systems for high fidelity quantum measurements.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB089

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB092

Cherenkov Radiation in Periodic Wire Medium Formed by Transversely Modulated Electron Beams

radiation, laser, cathode, experiment

1878

A. Halavanau
SLAC, Menlo Park, California, USA
A.I. Benediktovitch
EuXFEL, Hamburg, Germany
E.A. Gurnevich
Belarussian State University, Scientific Research Institute of Nuclear Problems, Minsk, Belarus

Funding: Work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515.
We investigate the properties of Cherenkov, quasi-Cherenkov (parametric) and diffraction radiation generated in the periodic conducting wire medium by transversely modulated electron beams. Such beams were recently obtained at Argonne Wakefield Accelerator (AWA) facility using microlens array (MLA) laser shaping technique. We consider in details the case of one dimensional periodic tungsten wire structure and transverse electron beamlets separation of mm scale. We look at possible enhancements of the radiation field due to transverse periodicity of the electron beam.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB092

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paper received ※ 14 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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TUPRB095

Superconducting Undulators for the Advanced Photon Source Upgrade

undulator, vacuum, photon, operation

1884

M. Kasa, E.R. Anliker, J.D. Fuerst, Q.B. Hasse, Y. Ivanyushenkov, I. Kesgin, Y. Shiroyanagi, E. Trakhtenberg
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The magnetic devices group at the Advanced Photon Source (APS) is in the process of designing and developing superconducting undulators (SCUs) for the APS upgrade. While similar in some aspects to previous SCU systems currently in operation at the existing APS, the new SCU systems will include two undulators installed in one cryostat which occupies an entire straight section of the storage ring. Straight sections containing planar undulators will either be configured as ’in-line’, where the two undulators behave as one source, or canted, where the two undulators are operated independently. Also under development is a superconducting arbitrary polarizing emitter (SCAPE) which can produce planar, elliptical, and helical undulator fields.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB095

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paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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TUPRB096

Test of an X-ray Cavity using Double-Bunches from the LCLS Cu-Linac

FEL, cavity, laser, free-electron-laser

1887

K.-J. Kim, L. Assoufid, R.R. Lindberg, X. Shi, D. Shu, Yu. Shvyd’ko, M. White
ANL, Argonne, Illinois, USA
F.-J. Decker, Z. Huang, G. Marcus, T.O. Raubenheimer, D. Zhu
SLAC, Menlo Park, California, USA

Funding: This work is supported by U.S. DOE, Office of Science, Office of BES, under Contract No. DE-AC02-06CH11357 (ANL) and DE-AC02-76SF00515 (SLAC).
We discuss a proposal to test the operation of an X-ray cavity consisting of Bragg reflectors. The test will con-stitute a major step demonstrating the feasibility of either an X-ray regenerative amplifier FEL or an X-ray FEL Oscillator. These cavity-based X-ray FELs will provide the full temporal coherence lacking in the SA-SE FELs. An X-ray cavity of rectangular path will be constructed around the first seven LCLS-II undulator units. The Cu-linac will produce a pair of electron bunches separated by the cavity-round-trip distance during each linac cycle. The X-ray pulse produced by the first bunch is deflected into the cavity and returns to the undulator where it is amplified due to the presence of the second bunch. The key challenges are: the preci-sion of the cavity mechanical construction, the quality of the diamond crystals, and the electron beam stability. When the LCLS-II super-conducting linac becomes available, the cavity can then be used for high-repetition rate studies of the X-ray RAFEL and XFELO concepts.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB096

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB097

Recent Progress on the Design of Normal Conducting APEX-II VHF CW Electron Gun

cavity, gun, cathode, brightness

1891

D. Li, H.Q. Feng, D. Filippetto, M.J. Johnson, A.R. Lambert, T.H. Luo, C.E. Mitchell, J. Qiang, F. Sannibale, J.W. Staples, S.P. Virostek, R.P. Wells
LBNL, Berkeley, California, USA
H.Q. Feng
TUB, Beijing, People’s Republic of China

Funding: Director of Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
We report recent progress on the design of a normal conducting CW electron gun, APEX-II (Advanced Photo-injector EXperiment-II) at Lawrence Berkeley National Laboratory. APEX-II is an upgrade of the successful APEX gun and the LCLS-II (Linac Coherent Light Source-II) injector, aiming at applications for Free electron laser (FEL) such as LCLS-II High Energy upgrade, UED (Ultrafast Electron Diffraction) and UEM (Ultrafast Electron Microscopy). The APEX-II adopted a two-cell cavity design with resonant frequency of 162.5 MHz. The APEX-II gun is targeting to achieve exceeding 30 MV/m of launch gradient at the cathode and output energy above 1.5 MeV with transverse emittance of 0.1 um at 100 pC. Advanced MOGA optimization technique has been used for both the RF cavity design and extensive beam dynamics studies using APEX-like and LCLS-II like injector layout. Detailed RF designs, beam dynamics studies, preliminary engineering design and FEA analysis will be presented, with cavity features that were demonstrated to be crucial in the operation of the APEX gun.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB097

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB102

Numerical Study of the Delta II Polarizing Undulator for LCLS II

undulator, simulation, polarization, laser

1899

K. Tian, H.-D. Nuhn
SLAC, Menlo Park, California, USA

Funding: Work supported by US Department of Energy Contract DE-AC03-76SF00515.
The Delta undulator has been operated successfully in LCLS with full control of the polarization mode and K value of the device. In LCLS II, a new Delta II undulator will be based on a similar design but with some differences. In this paper, we will present numerical simulation results that provide guidance to choose the geometric shape of the magnet poles and define the required tolerance for assembling the undulator magnets.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB102

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paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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TUPRB106

Status of the Superconducting Soft X-Ray Free-Electron Laser User Facility Flash at DESY

experiment, laser, operation, undulator

1909

J. Rönsch-Schulenburg, K. Honkavaara, M. Kuhlmann, S. Schreiber, R. Treusch, M. Vogt
DESY, Hamburg, Germany

FLASH, the free electron laser user facility at DESY (Hamburg, Germany), delivers high brilliance XUV and soft x-ray FEL radiation to photon experiments with different parameters at two undulator beamlines simultaneously. FLASH’s superconducting linac can produce bunch trains of up to 800 bunches within a 0.8 ms RF flat top at a repetition rate of 10 Hz. In standard operation during 2018, FLASH supplied up to 500 bunches in two bunch trains with independent fill patterns and compression schemes to each of the two beamlines. In 2018 first successful plasma accelerating experiments could be reported by the FLASHForward plasma wakefield acceleration experiment situated in a third beamline. We report on the highlights of FLASH operation in 2018/2019.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB106

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB108

Mechanical Design of a Dielectric Wakefield Dechirper System for CLARA

vacuum, FEL, wakefield, alignment

1912

M. Colling, D.J. Dunning, B.D. Fell, T.H. Pacey, Y.M. Saveliev
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

STFC Daresbury Laboratory are developing a compact electron beam energy dechirper system, based on dielectric wakefield structure, for the on-site electron accelerator CLARA (Compact Linear Accelerator for Research and Applications). CLARA will be an experimental free electron laser (FEL) facility operating at 250MeV and will be a test bed for a variety of novel FEL schemes. The dechirper dielectric quartz plates will induce wakefields within the structure which can remove the beam chirp that is initially introduced to compress the electron bunch longitudinally. Removing or adjusting the amount of chirp enables researchers to reduce or adjust the bunch energy/momentum spread, expanding the FEL capabilities. The attachment and alignment of the quartz plates present numerous mechanical design challenges that require high precision manufacturing and quartz plate positioning via fiducialisation. This paper will review the dechirper specifications, the chosen design solutions, measured mechanical performance, and the expected effect of the dechirper on CLARA FEL operation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB108

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB112

JLEIC: A High Luminosity Polarized Electron-Ion Collider at Jefferson Lab

collider, luminosity, proton, emittance

1916

Y. Zhang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The recent National Academies of Science Review concluded the science questions that could be answered by an electron-ion collider are significant to advancing our understanding of the atomic nuclei that make up all visible matter in the universe. To meet this science need, a high luminosity polarized electron-ion collider (JLEIC) was envisioned at Jefferson Lab, based on the existing CEBAF recirculated SRF electron linac. Over the past 16 years, Jefferson Lab has been actively engaged in the design study and accelerator R&D for JLEIC, a comprehensive Pre-Conceptual Design Report has been completed recently. The JLEIC baseline design has also been continuously optimized including extending the CM energy to 100 GeV. In this paper, we present a summary of the JLEIC baseline design and also briefly discuss the accelerator R&D.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB112

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paper received ※ 07 June 2019 paper accepted ※ 07 June 2019 issue date ※ 21 June 2019

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TUPRB113

Dynamic Aperture of JLEIC Electron Collider Ring with Errors and Correction

alignment, multipole, optics, quadrupole

1920

Y.M. Nosochkov, Y. Cai
SLAC, Menlo Park, California, USA
F. Lin, V.S. Morozov, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: * This work is supported by the U.S. Department of Energy, Office of Science, and Office of Nuclear Physics under Contracts DE-AC05-06OR23177, DE-AC02-06CH11357, and DE-AC02-76SF00515.
Design of the Jefferson Lab Electron-Ion Collider (JLEIC) includes low-beta Interaction Region (IR) and spin rotator optics for high luminosity and polarization. Magnet errors, especially in the high-beta final focus quadrupoles, result in optics perturbations which need to be corrected in order to attain sufficient dynamic aperture (DA). We present design of orbit correction system for the electron ring and evaluate its performance. The DA is then studied including misalignment, magnet strength errors, non-linear field errors, and corrections.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB113

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paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPTS004

Development of a Penning Ion Source Test Stand for Production of Alpha Particles

ion-source, cathode, plasma, cyclotron

1932

N. Savard
UBC, Vancouver, B.C., Canada
M.P. Dehnel, P.T. Jackle, S.V. Melanson, D.E. Potkins, J.E. Theroux
D-Pace, Nelson, British Columbia, Canada
G.M. Marcoux
Carleton University, College of Natural Sciences, Ottawa, Ontario, Canada

Medical cyclotron manufacturers are seeking less-costly and more compact ion sources than Electron Cyclotron Resonance Ion Sources (ECRIS) for alpha particle production, which are currently capable of generating beam currents up to 2 mA at energies of 30 keV for axial injection into these cyclotrons. Penning Ion Sources by comparison are relatively old technologies mostly used for cheap singly-charged ion production. However, these ion sources have been used in the past for high-current multiply-charged state ion production of heavy ions up to a few mA of current, and are much smaller, cheaper, and less complex than ECRISs. Therefore, we are developing a Penning Ion source test stand to produce high-current alpha-particles for medical cyclotrons. This requires designs and simulations of all the primary components of the ion source. This system will be used to fully characterize the output beam current and internal plasma properties as a function of varying gas pressure, ion source geometries, magnetic field strength, arc voltage/current, and material properties. The result will be a source optimized for maximum alpha particle beam currents, to be used as a prototype for a commercial Penning Ion Source.
* J. Bennet. A Review of PIG Sources for Multiply Charged Heavy Ions. IEEE Transactions on Nuclear Science, 1972.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS004

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPTS009

Operating the SNS RF H⁻ Ion Source with a 10% Duty Factor

ion-source, plasma, neutron, LEBT

1951

M.P. Stockli, M.E. Clemmer, S.M. Cousineau, B. Han, T.A. Justice, Y.W. Kang, S.N. Murray, T.R. Pennisi, C. Piller, R.F. Welton
ORNL, Oak Ridge, Tennessee, USA
I.N. Draganic, R.W. Garnett, D. Kleinjan, G. Rouleau
LANL, Los Alamos, New Mexico, USA
V.G. Dudnikov
Muons, Inc, Illinois, USA
C. Stinson
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work was performed at Oak Ridge National Laboratory under contract DE-AC05-00OR22725 and at Los Alamos National Laboratory under contract DE-AC52-06NA25396 for the U.S. Department of Energy.
The SNS (Spallation Neutron Source) (radio-frequency) RF-driven, H⁻ ion source injects ~50 mA of H⁻ beam into the SNS accelerator at 60 Hz with a 6% duty factor. It injects up to 7 A·hrs of H⁻ ions during its ~14-week service cycles, which is an unprecedented lifetime for small-emittance, high-current pulsed H⁻ ion sources. The SNS source also features unprecedented low cesium consumption and can be installed and started up in <10 h. Presently, the LANSCE (Los Alamos Neutron Science CEnter) accelerator complex in Los Alamos is fed by a filament-driven, biased converter-type H⁻ source that operates with a high plasma duty factor of 10%. It needs to be replaced every 4 weeks with a ~4 day startup phase. The measured negative beam current of 16-18 mA falls below the desired 21 mA acceptance of LANSCE’s accelerator especially since the beam contains several mA of electrons. LANSCE and SNS are exploring the possibility of using the SNS RF H⁻ source at LANSCE to increase the H⁻ beam current and the ion source lifetime while decreasing the startup time. For this purpose, the SNS H⁻ source has been tested at a 10% duty factor by operating it at 120 Hz with 840 µs plasma pulses generated with ~30 kW of 2 MHz RF power, and extracting ~25 mA around-the-clock for 28 days. This, and additional tests and other considerations are discussed in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS009

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPTS011

Vacuum Lifetime and Surface Charge Limit Investigations Concerning High Intensity Spin-polarized Photoinjectors

cathode, vacuum, laser, experiment

1954

S. Friederich, K. Aulenbacher, C. Matejcek
IKP, Mainz, Germany
K. Aulenbacher
GSI, Darmstadt, Germany
K. Aulenbacher
HIM, Mainz, Germany

Funding: DFG excellence initiative PRISMA+, Bundesministerium für Bildung und Forschung "Verbundforschung FKZ 05K16UMA"
The Small Thermalized Electron Source at Mainz (STEAM) is a dc photoemission source. It is designed to operate at up to 200kV bias voltage with an accelerating field of up to 5 MV/m at the cathode surface. In several experiments, the properties of GaAs operating under the conditions of spin-polarized photoemission were investigated. Its performance, quantum efficiency lifetime and surface charge limit observations for bulk-GaAs will be discussed.

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paper received ※ 29 April 2019 paper accepted ※ 28 May 2019 issue date ※ 21 June 2019

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TUPTS013

Characterization of an Electron Gun Test Setup Based on Multipacting

cavity, cathode, multipactoring, gun

1961

C. Henkel, W. Hillert, V. Miltchev
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
K. Flöttmann
DESY, Hamburg, Germany

A multipacting electron gun (MEG) is a micro-pulse electron source, based on secondary electron emission in a resonant microwave cavity structure, for the generation of low emittance electron bunches in continuous wave operation. Based on numerical simulations, an experimental test setup for low-energy electron beams at 3 GHz has been established. In this contribution we show a detailed description and characterization of the RF test stand, supported by first results on charge collection measurements of the output current with respect to important operational parameters like power transmission and modifiable mechanical dimensions in the assembly of the experiment. This is a milestone in the development of a MEG setup for higher energetic electron beams and subsequent investigation of essential beam characteristics like emittance and energy distribution for the optimization with regard to best possible beam quality and future fields of application.

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paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPTS014

SINGLE SHOT CATHODE TRANSVERSE MOMENTUM IMAGING IN PHOTOINJECTORS

cathode, solenoid, emittance, simulation

1964

P.W. Huang, Y. Chen, J.D. Good, M. Groß, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, X. Li, O. Lishilin, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
D. Filippetto, F. Sannibale
LBNL, Berkeley, California, USA
C.-X. Tang
TUB, Beijing, People’s Republic of China
W. Wan
ShanghaiTech University, Shanghai, People’s Republic of China

In state of the art photoinjector electron sources, cathode performance determines the lower limit of achievable beam emittance. Measuring the thermal emittance at the photocathodes in electron guns is of vital importance for improving the injectors. Traditional methods, like solenoid scan, pepper-pot, need multi-shots and are time-consuming, therefore suffer from machine stability. Here we propose a new method, named cathode transverse momentum imaging. By tuning the gun solenoid focusing, the electrons’ transverse momentum at the cathode is imaged to a downstream screen, which enables a single shot measurement. Several experiments have been done at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) with a Cs2Te cathode. Measurements of cathode transverse momentum, the corresponding spectra, cathode transverse momentum map and its correlation with surface electric field are presented.

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPTS015

Design Steps Towards an Electron Source for Ultrafast Electron Diffraction at DELTA

laser, cavity, gun, space-charge

1968

D. Krieg, S. Khan
DELTA, Dortmund, Germany
T.J. Albert, K. Sokolowski-Tinten
Universität Duisburg-Essen, Duisburg, Germany

Funding: MERCUR Pr-2017-0002
Ultrafast electron diffraction (UED) is a pump-probe technique to explore the structural dynamics of matter, combining sub-angstrom De-Broglie wavelength of electrons with femtosecond time resolution. UED experiments require ultrashort laser pulses to pump a sample, electron bunches with small emittance and ultrashort length to analyze the state of the sample and excellent control of the delay between them. Electrons accelerated to a few MeV in a photocathode gun offer significant advantages compared to keV electrons from electrostatic electron sources regarding emittance, bunch length and, due to the reduction of space charge effects, bunch charge. Furthermore, thicker samples and hence a wider range of possible materials are enabled by the longer mean free path of MeV electrons. In this paper, design steps towards a university-based UED facility with ultrashort and low-emittance MeV electron bunches are presented, including the transverse and longitudinal focusing schemes, which minimize space charge effects and nonlinearities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS015

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPTS025

Arc and Convertor Current Transient Studies for Multi-cusp Cesiated Surface Conversion H⁻ Source at Lansce

ion-source, operation, plasma, extraction

1983

D. Kleinjan
LANL, Los Alamos, New Mexico, USA

The Multi-cusp Cesiated Surface Conversion H⁻ Ion Source at the Los Alamos Neutron Science Center (LANSCE) has provided beam at ~14 mA, 120 Hz, and 10% D.F. for many years of neutron science research. Recently, random high current transients were discovered in the arc current used to ionize hydrogen in the LANSCE H⁻ ion source, and in the convertor current used to convert protons to H⁻ ions. Most have no effect, but more severe transients can cripple beam output. Hypothesized causes are related to cesiation effects, plasma potential changes, tungsten filament vaporation/sputtering, or from the pulsed power system. A dedicated study was recently done on the LANSCE H⁻ Ion source test stand to determine the cause of these transients. Current understanding indicates that the more severe transients come from a combination of cesiation effects and plasma potential changes. The status of these current transient studies on the LANSCE H⁻ ion source will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS025

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPTS026

Negative Electron Affinity GaAs Cathode Activation With CsKTe Thin Film

cathode, photon, vacuum, gun

1986

M. Kuriki
KEK, Ibaraki, Japan
K. Masaki
HU/AdSM, Higashi-Hiroshima, Japan

Funding: This work is partly supported by Japan-US Cooperative grant for scientific studies, Grant aid for scientific study by MEXT Japan (KAKENHI).
Negative Electron Affinity (NEA) GaAs cathode is an unique device which can generate a highly polarized electron beam with circularly polarized light. The NEA surface is conventionally made by Cs and \rm O/NF₃ adsorption on the cleaned p-doped GaAs crystal, but the robustness of the cathode is very limited, so that the electron emission is easily lost by residual gas adsorption, ion back-bombardment, etc. To improve the cathode robustness, NEA activation with a stable thin-film on GaAs surface according to Hetero junction hypothesis has been proposed by the author. An experiment of the NEA activation with CsKTe thin film was carried out at Hiroshima University and a significant electron emission with 1.43 eV photon was observed which strongly suggested NEA activation. The cathode showed 16 to 20 times improvement of lifetime comparing to GaAs activated with Cs and O.

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paper received ※ 26 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS047

Improvement of 6D Brightness by a 1.4-cell Photocathode RF Gun for MeV Ultrafast Electron Diffraction

gun, emittance, cathode, brightness

2033

Y. Song
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China
K. Fan, C.-Y. Tsai, Y.T. Yang
HUST, Wuhan, People’s Republic of China
J. Yang
ISIR, Osaka, Japan

Recent research indicates that ultrafast electron diffraction and microscopy (UED/M) have unprecedented potential in probing ultrafast dynamic processes, especially in organic and biological materials. However, reaching the required brightness while maintaining high spatiotemporal resolution requires new design of electron source. In order to produce ultrashort electron beam with extreme high brightness, a 1.4-cell RF gun is being developed to reach higher acceleration gradient near the photocathode and thus suppress the space charge effect in the low energy region. Simulation of the 1.4-cell RF photocathode gun shows considerable improvement in bunch length, emittance and energy spread, which all lead to better temporal and spatial resolution comparing to traditional 1.6-cell RF photocathode gun. The results demonstrate the feasibility of sub-ps temporal resolution with normalized emittance less than 0.1 πmm·mrad while maintaining 1 pC electron pulse.

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paper received ※ 24 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS050

Design and Analysis of the Cold Cathode Ion Source for 200 MeV Superconducting Cyclotron

cathode, ion-source, proton, cyclotron

2040

S.W. Xu
USTC, Hefei, Anhui, People’s Republic of China
L. Calabretta
INFN/LNS, Catania, Italy
G. Chen, M. Xu
ASIPP, Hefei, People’s Republic of China
O. Karamyshev, G.A. Karamysheva, G. Shirkov
JINR, Dubna, Moscow Region, Russia

SC200 is a superconducting isochronous cyclotron which generates 200 MeV, 400 nA proton beam for particle therapy. The cold-cathode-type Penning ion gauge (PIG) ion source for the internal ion source of SC200 has been selected as an alternative and preliminary designed. In this paper, design of ion source and test bench are demonstrated. Currently, the properties of ion source have been simulated for a variety of electric field distributions and magnetic field strengths. The secondary electron emission in electromagnetic field has been simulated. It provides reference for the optimization design of arc chamber. In addition, the sample of cold-cathode-type ion source has been tested on the test bench and extracted beam intensity has been measured over 200 μA.

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paper received ※ 30 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS052

Conceptual Design of a High-Performance Injector Based on Rf-Gated Gridded Thermionic Gun for Thz Fel

gun, linac, cathode, bunching

2046

P. Yang, H.M. Chen, T. Hu, J.J. Li, Y. Lu
HUST, Wuhan, People’s Republic of China
G.Y. Feng, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Free-Electron Laser (FEL) has higher requirements on electron beam properties, for example, low transverse emittance, small energy spread, short bunch length and high peak current. Taking compactness and economy into account, we aim to design a high-performance linear accelerator based on a RF-gated gridded thermionic electron gun, which will be used as the injector of the oscillator-type THz FEL facility at Huazhong University of Science and Technology of China. The RF-gated grid will be modulated with the fundamental and 3rd harmonic microwave of the LINAC frequency, which will be very helpful to get high electron capture efficiency and short bunch length. Concerning velocity bunching effect in the LINAC, electron bunch with good symmetry of current profile and bunch length less than 10 ps can be obtained at the exit of the injector. In this paper, design and beam dynamics simulation for the high-performance injector are presented.

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paper received ※ 26 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS053

Design of a 217 MHz VHF Gun at Tsinghua University

gun, cathode, cavity, simulation

2050

L.M. Zheng, H. Chen, Y.C. Du, W.-H. Huang, R.K. Li, Z.Z. Li, C.-X. Tang
TUB, Beijing, People’s Republic of China
B. Gao
IHEP, Beijing, People’s Republic of China

A 217 MHz VHF gun operating in CW mode is designing at Tsinghua University. The cathode gradient is designed to be 30 MV/m to accelerate the electron bunches up to 878 keV. The cavity profile is optimized in CST to minimize the input power, peak surface electric field, and peak wall power density. The multipacting analysis and the thermal analysis are also presented in this paper. Further gun shape optimization and mechanical design are ongoing.

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paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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TUPTS054

1st+2nd Harmonic Photocathode Bimodal Gun R&D

gun, emittance, cathode, cavity

2054

L. Wang
SINAP, Shanghai, People’s Republic of China
W. Fang, Z.T. Zhao
SSRF, Shanghai, People’s Republic of China
J.L. Hirshfield
Yale University, Physics Department, New Haven, CT, USA
J.L. Hirshfield, S.V. Shchelkunov
Omega-P, Inc., New Haven, Connecticut, USA
Y. Jiang, S.V. Shchelkunov
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
L. Wang
University of Chinese Academy of Sciences, Beijing, People’s Republic of China

Funding: U.S. Dept. of Energy
A novel Bimodal Electron Gun is designed to apply microwaves at two harmonically-related frequency in a 0.6 cell RF gun to increase the RF breakdown threshold and enhance the beam quality. This stratagem is intended to allow the RF gun structure to support a high accelera-tion gradient as well as to manipulate the emittance evolution in the half cell. By selecting a proper ampli-tude ratio and phase relationship between the first and second harmonic RF field components in the gun cavity, the superposition of the harmonic field components can provide a flat-top like RF profile to omitting the RF emittance component in the gun, while increase the RF breakdown threshold. The recent status of the Bimodal Electron Gun R&D is presented, including the designs of the novel two frequency RF structure and the simulation of the beam dynamic.

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPTS066

Re-optimisation of the ALICE Gun Upgrade Design for the 500-pC Bunch Charge Requirements of PERLE

cathode, gun, operation, laser

2071

B. Hounsell, M. Klein, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
B. Hounsell, B.L. Militsyn, T.C.Q. Noakes, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
B. Hounsell, W. Kaabi
LAL, Orsay, France
B.L. Militsyn, T.C.Q. Noakes
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The injector for PERLE, a planned ERL test facility, must be capable of delivering 500 pC bunches at a repetition rate of 40.1 MHz to provide a beam with 20 mA average current with a projected rms emittance of less than 6 mm mrad. This must be achieved at two different operational voltages 350 kV and 220 kV for unpolarised and polarised operation respectively. The PERLE injector will be based on an upgrade of a DC photocathode electron gun operated previously at ALICE ERL at Daresbury. The upgrade will add a load lock system for photocathode interchange. This paper presents the results of a re-optimisation of the electrode system as ALICE operated with a bunch charge of around 80 pC while PERLE needs a bunch charge of 500 pC. This re-optimisation was done using the many-objective genetic algorithm NSGAIII to minimise both the slice emittance and transverse beam size for both required operational voltages.

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPTS070

Systematic Benchmarking of a Planar (N)UNCD Field Emission Cathode

cathode, gun, experiment, ECR

2083

J.H. Shao, M.E. Conde, W. Liu, J.G. Power, E.E. Wisniewski
ANL, Argonne, Illinois, USA
S.V. Baryshev, M.S. Schneider
Michigan State University, East Lansing, Michigan, USA
G. Chen
IIT, Chicago, Illinois, USA
K. Kovi
Euclid TechLabs, LLC, Solon, Ohio, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Planar nitrogen-incorporated ultrananocrystalline diamond, (N)UNCD, is a unique and attractive field emission source because of the capability to generate high charge beam, the simplicity of production without shaped emitters, and the ease of handling with moderate vacuum requirement. In the presented study using an L-band normal conducting single-cell rf gun, a (N)UNCD cathode has been conditioned to 42 MV/m with a well-controlled manner and reached a maximum charge of 15 nC and an average emission current of 6~mA during a 2.5 us emission period. The systematic study of emission properties during the rf conditioning process illustrates the tunability of (N)UNCD in a wide range of surface gradients. This research demonstrates the versatility of (N)UNCD cathode which could enable multiple designs of field emission rf injector for industrial and scientific applications.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS070

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paper received ※ 20 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPTS073

Analysis of Electron Beam Divergence in Diamond Field Emitter Array Cathodes

cathode, focusing, experiment, simulation

2090

D. Kim, H.L. Andrews, R.L. Fleming, C. Huang, J.W. Lewellen, K.E. Nichols, V.N. Pavlenko, E.I. Simakov
LANL, Los Alamos, New Mexico, USA
B.K. Choi
Cheju Halla University, Jeju-si, Republic of Korea

Funding: Los Alamos National Laboratory (LANL) Laboratory Directed Research and Development (LDRD) program (Contract DE-AC52-06NA25396) and Sandia National Laboratories (Contract DE-NA-0003525).
At Los Alamos National Laboratory (LANL), we have recently established a capability to fabricate diamond array cathodes for electron beam sources. Our fabricated diamond field emitter arrays (DFEAs) are the arrays of micrometer-scale diamond pyramids with nanometer-scale sharp tips and produce high per-tip current (> 15 μA per-tip) in DC testing. For the beam divergence measurements, we designed and assembled a test stand consisting of a DFEA cathode, a mesh aperture of 0.375-inch for an anode, and AZO (ZnO:Al2O3) screen coated on a sapphire substrate for beam visualization. A negative voltage of about 40 kV is applied to the cathode, and the mesh and the screen are kept at ground. We measure a size of the electron beam on the AZO screen at different mesh to screen distances at a fixed cathode-mesh gap in order to calculate the beam divergence angles. We also perform the beam dynamics simulations with Computer Simulation Technology (CST) Studio and General Particle Tracer (GPT) using a single pyramidal shape with a nanowire tip model. In this presentation, the measured experimental results of the beam divergences will be compared to the beam dynamic simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS073

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS076

RF Design of APEX2 Cavities

gun, cavity, cathode, brightness

2094

T.H. Luo, H.Q. Feng, D. Filippetto, M.J. Johnson, A.R. Lambert, D. Li, C.E. Mitchell, F. Sannibale, J.W. Staples, S.P. Virostek, R.P. Wells
LBNL, Berkeley, California, USA
H.Q. Feng
TUB, Beijing, People’s Republic of China

Funding: Director of Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
APEX2 is a proposed high repetition rate, high brightness electron source based on CW normal conducting RF cavities, aiming to further extend the brightness performance for FEL and UED/UEM beyond APEX. APEX2 consists of two cavities, one gun cavity for generating photo-electrons and one following cavity for beam energy boosting. In this paper, we present the RF design of the APEX2 cavities. The design has considered both beam dynamics requirements and engineering feasibility. A novel geometry optimization method with Genetic Algorithm has been implemented in the design procedure.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS076

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPTS077

Design of a High Gradient THz-Driven Electron Gun

gun, acceleration, experiment, FEL

2098

S.M. Lewis, V.A. Dolgashev, A.A. Haase, E.A. Nanni, M.A.K. Othman, A.V. Sy, S.G. Tantawi
SLAC, Menlo Park, California, USA
D. Kim, E.I. Simakov
LANL, Los Alamos, New Mexico, USA

Funding: This work was supported by Department of Energy contract DE-AC02-76SF00515. This work was also supported by NSF grants PHY-1734015.
We present the design of a high-gradient electron gun. The goal of this gun is to generate relativistic electrons using GV/m accelerating fields. The initial design is a standing-wave field-emission gun operating in the pi-mode with a cavity frequency of 110.08 GHz. A pulsed 110 GHz gyrotron oscillator will be used to drive the structure with power coupled in through a TM01 circular waveguide mode. The gun is machined in two halves which are bonded. This prototype will be used to characterize the electron beam and study RF breakdown at 110 GHz.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS077

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS078

Coherent Electron Cooling (CeC) Experiment at RHIC: Status and Plans

FEL, experiment, SRF, simulation

2101

V. Litvinenko, K. Mihara
Stony Brook University, Stony Brook, USA
Z. Altinbas, J.C. Brutus, A. Di Lieto, D.M. Gassner, T. Hayes, P. Inacker, J.P. Jamilkowski, Y.C. Jing, R. Kellermann, J. Ma, G.J. Mahler, M. Mapes, R.J. Michnoff, T.A. Miller, M.G. Minty, G. Narayan, M.C. Paniccia, D. Phillips, I. Pinayev, S.K. Seberg, F. Severino, J. Skaritka, L. Smart, K.S. Smith, Z. Sorrell, R. Than, J.E. Tuozzolo, E. Wang, G. Wang, Y.H. Wu, B.P. Xiao, T. Xin, A. Zaltsman
BNL, Upton, Long Island, New York, USA
I. Petrushina
SUNY SB, Stony Brook, New York, USA
K. Shih
SBU, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and NSF Grant No. PHY-141525
We will present currents status of the CeC experiment at RHIC and discuss plans for future. Special focus will be given to unexpected experimental results obtained during RHIC Run 18 and discovery of a previously unknown type of microwave instability. We called this new phenomenon micro-bunching Plasma Cascade Instability (PCI). Our plan for future experiments includes suppressing this instability in the CeC accelerator and using it as a broad-band amplifier in the CeC system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS078

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paper received ※ 19 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPTS079

Overcoming Multipacting Barriers in SRF Photoinjectors

cavity, gun, cathode, SRF

2105

I. Petrushina
SUNY SB, Stony Brook, New York, USA
V. Litvinenko, G. Narayan, I. Pinayev, F. Severino, K.S. Smith
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Superconducting RF (SRF) photoinjectors are considered to be a potential breakthrough in the area of high brightness electron sources. However, there is always the very important question of the compatibility of SRF cavities and high quantum efficiency (QE) photocathodes. A deposition of active elements from high QE photocathodes on the surface of a cavity makes it more vulnerable to multipacting (MP) and could affect the operation of an SRF gun. On the other side, MP can significantly reduce the lifetime of a photocathode. It is well known in the SRF community that a strong coupling, high forward power and sufficient cleanliness of cavity walls are the key components to overcome a low-level MP zone. In this paper we present a theoretical model of passing a MP barrier which could help estimate the desirable conditions for successful operation of an SRF gun. We demonstrate our results for the 113 MHz SRF photo-injector for Coherent electron Cooling (CeC) alongside with the experimental observations and 3D simulations of the MP discharge in the cavity. The results of the theoretical model and simulations show good agreement with the experimental results, and demonstrate that, if approached carefully, MP zones can be easily passed without any harm to the photocathode.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS079

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPTS083

Simulations and Experimental Plans for a High-Repetition-Rate Field-Enhanced Conduction-Cooled Superconducting RF Electron Source

cavity, cathode, SRF, simulation

2113

O. Mohsen, A. McKeown, D. Mihalcea, P. Piot, I. Salehinia
Northern Illinois University, DeKalb, Illinois, USA
R. Dhuley, M.G. Geelhoed, D. Mihalcea, P. Piot, J.C.T. Thangaraj
Fermilab, Batavia, Illinois, USA

Funding: Work supported by DOE awards DE-SC0018367 with NIU and DE-AC02-07CH11359 with Fermilab.
We present a novel RF design for a field enhanced electron source driven by field emission cathodes. The proposed electron source relies on the enhanced high electric field gradients at the cathode to simultaneously extract and accelerate electrons. The system will be tested in a conduction-cooled superconducting radio-frequency cavity recently demonstrated at Fermilab. In this paper, we present electromagnetic and thermal simulations of the setup that support the feasibility of the design.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS083

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paper received ※ 18 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPTS084

Performances of Silicon-Based Field-Emission Cathodes Coated with UltraNano Crystalline Diamond

cathode, experiment, vacuum, simulation

2117

O. Mohsen, V. Korampally, A. Lueangaramwong, P. Piot, V. Valluri
Northern Illinois University, DeKalb, Illinois, USA
R. Divan, A.V. Sumant
Argonne National Laboratory, Argonne, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA

Funding: Work supported by NSF grant PHY-1535401 and DOE award DE-SC0018367 with NIU
Field-emission electron sources have been considered as possible candidates for the production of bright or high-current electron bunches. In this paper, we report on the experimental characterization of silicon-based field-emitter arrays (FEA) in a DC high voltage gap. The silicon cathodes are produced via a simple self-assembling process. The measurement reported in this paper especially compares the field-emission properties of a nanostructured and planar diamond-coated Si-based cathode.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS084

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paper received ※ 17 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPTS088

A Normal Conducting RF Gun as an Electron Source for JLEIC Cooling

gun, emittance, cathode, solenoid

2127

F.E. Hannon, R.A. Rimmer
JLab, Newport News, Virginia, USA

The baseline design for a magnetized injector for the bunched-beam electron cooler ring, as part of the Jeffer-son Lab Electron Ion Collider (JLEIC) uses a DC photo-cathode electron gun as the source. A challenging aspect of this concept is transporting a 3.2nC electron bunch at low energy and preserving the angular momentum. An RF gun source has been investigated to gauge the potential advantages of high gradient on the photocathode and higher exit energy. The design is presented and compared with the baseline results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS088

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS089

Observations of the Femtosecond Laser-Induced Emission From the Diamond Field Emitter Tips

laser, cathode, photon, experiment

2130

E.I. Simakov, H.L. Andrews, R.L. Fleming, D. Kim, V.N. Pavlenko
LANL, Los Alamos, New Mexico, USA
D.S. Black, K.J. Leedle
Stanford University, Stanford, California, USA

Funding: Los Alamos National Laboratory LDRD Program
We present the results of experimental observation of emission from single diamond field emitter tips when triggered by an ultra-short laser pulse. Diamond field emitter array (DFEA) cathodes were originally proposed for applications that require large current densities. DFEAs represent periodic arrays of diamond pyramids with micron-size dimensions and tips with diameters of the order of tens of nanometers. DFEAs are known to produce significant currents in field emission regime under direct current (DC) fields and in radio-frequency (RF) guns. It has been proposed that single diamond tip emitters can be employed for production of small tightly focused electron beams for dielectric laser accelerators (DLAs) that accelerate particles using the energy of light produced by infrared lasers. To generate short electron bunches required by DLAs diamond pyramids may be triggered with a laser. We have recently observed emission produced by a single diamond pyramid when triggered by a laser at different wavelengths from 256 nm to 2020 nm. We have conducted studies with the goal to understand mechanism of the emission. We clearly observed the change in emission mechanism when the wavelength changed from 256 nm to 512 nm. We believe that while the emission at 256 nm is a clear photoemission, the emission at longer wavelengths is likely the field emission caused by intense electric fields of the laser.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS089

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPTS091

Physics of Electron Beam Generation and Dynamics From Diamond Field Emitter Arrays

simulation, cathode, ECR, experiment

2137

C. Huang, H.L. Andrews, R.C. Baker, R.L. Fleming, D. Kim, T.J. Kwan, V.N. Pavlenko, A. Piryatinski, E.I. Simakov
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the LDRD program at Los Alamos National Laboratory
Many applications such as compact accelerators and electron microscopy demand high brightness electron beams with small beam size and low emittance. Electric-field-assisted diamond emitters manufactured from semiconductor processes are strong candidates for cathodes in such sources. The micro-scale pyramid structure of the emitter has the desirable attribute of significant field enhancement at the sharp interfaces (apex and edges) to facilitate electron emission. We use the LSP particle-in-cell code to simulate the diamond emitter in a diode setup and obtain the beam size and divergence. An empirical fit of the fields around the apex is extracted for detail study. The trend of the beam divergence observed in the simulation is further corroborated using electron’s trajectory in the empirical field model.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS091

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS093

Magnetized Gridded Thermionic Electron Source

gun, cathode, emittance, simulation

2140

M.S. Stefani
ODU, Norfolk, Virginia, USA
C.M. Gulliford, V.O. Kostroun, C.E. Mayes, K.W. Smolenski
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
F.E. Hannon, M. Poelker, R. Suleiman
JLab, Newport News, Virginia, USA

Funding: This manuscript has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy.
The study of magnetized electron beam has become a high priority for its use in ion beam cooling as part of Electron Ion Colliders and the potential of easily forming flat beams for various applications. The demand for high average current for effective ion beam cooling has caused consideration of using bunched magnetized electron beam produced by a gridded thermionic electron gun. This paper presents the design of a potential electron source for JCIEC first measurements characterizing the beam properties of a magnetized thermionic gun.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS093

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS095

Global Model of Multi-Chamber Negative Hydrogen Ion Sources with Updated Hydrogen Plasma Chemistry

simulation, plasma, ion-source, interface

2144

S.N. Averkin, S.A. Veitzer
Tech-X, Boulder, Colorado, USA

Funding: This work was performed under the auspices of the Department of Energy, Office of Basic Energy Sciences Award #DE-SC0009585.
Global models of plasma discharges are used to calculate volume averaged number densities and temperatures of plasma components. The wall fluxes are estimated based on heuristic expressions that "patch" together analytic and semi-analytic solutions covering from low-pressure to high-pressure regimes. Due to the nature of the wall fluxes estimation, the global models are limited to single chamber designs. We present the extension of the Global Enhanced Vibrational Kinetic Model (GEVKM) * for the multi-chamber design with the updated hydrogen plasma chemistry **. The extended GEVKM consists of separate global models for macroscopic parameters of all species in each chamber coupled through interface boundary conditions. We compare our model with fluid simulation results for a plasma composition and species temperatures in the negative hydrogen ion source developed at IPP Garching.
* Averkin S.N. et al, IEEE Trans. Plasma Sci., Vol. 43, N. 6, pp. 1926-1943, 2015.
** Yang W. et al, Phys. Plasmas, 25, 113509, 2018.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS095

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paper received ※ 21 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPTS096

Fluid Models of Inductively Coupled Plasma Sources for Negative Hydrogen Ion Sources

plasma, ion-source, simulation, neutron

2147

S.A. Veitzer, P. Stoltz
Tech-X, Boulder, Colorado, USA

Funding: This work was performed under the auspices of the Department of Energy, Office of Basic Energy Sciences Award #DE-SC0009585.
Negative hydrogen ion sources are widely used to produce neutron beams via spallation both for neutron science in its own right, and as neutron sources for fusion devices. Numerical modeling is a useful tool for trying to optimize negative hydrogen ion sources. However there are significant numerical and computational challenges that have to be overcome, including code performance and resolution of separation of time scales between ion and electron motions. One method is to utilize fluid models to simulate inductively coupled ion sources (ICPs). We have been developing algorithms to simulate negative hydrogen production in high-power, external-antenna ICP sources. We present simulation results using the USim*,** framework to model plasma chemistry that produces negative hydrogen, and model the effects of electron temperature on overall production rates. The numerical plasma chemistry models include processes of ionization, dissociation, recombination, as well as reactive dissociation of vibrationally resolved states and de-excitation of atomic hydrogen. We benchmark our plasma chemistry model results using plasma parameters relevant to experiments being carried out at the D-Pace Ion Source Test Facility. We have also been developing fluid-based drift/diffusion models for multi-component plasmas, such as those in negative hydrogen sources. These simulation results demonstrate enhancement of the effective diffusion rates in plasmas that contain both electrons and negative ions.
* J. Loverich and A. Hakim, J. Fusion Sci., 29(6), 2010.
** J. Loverich et al., AIAA, Vol. 4012, 2011.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS096

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paper received ※ 19 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS099

Predicting the Performances of Coherent Electron Cooling with Plasma Cascade Amplifier

plasma, kicker, space-charge, collider

2150

G. Wang, V. Litvinenko, J. Ma
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Recently, we proposed a new type of instability, Plasma Cascade Instability (PCI), to be used as the amplification mechanism of a Coherent Electron Cooling (CeC) system, which we call Plasma Cascade Amplifier (PCA). In this work, we present our analytical estimate of the cooling force as expected from a PCA- based CeC system and compare it with the simulation results. As examples, we apply our analysis to a few possible CeC systems and investigate the evolution of the circulating ion beams in the presence of cooling.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS099

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPTS101

Bi-Alkali Antimonide Photocathodes for LEReC DC Gun

cathode, gun, vacuum, laser

2154

E. Wang, A.V. Fedotov, M. Gaowei, D. Kayran, D. Lehn, C.J. Liaw, T. Rao, J.E. Tuozzolo, J. Walsh
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Low Energy RHIC electron cooling (LEReC) is a bunched electron cooler at RHIC. The Bi-alkali photocathodes are chosen as electron source due to its long lifetime and high QE at visible wavelength. Because the DC gun needs to produce 24/7 beams over several months, cathode production system and multiple cathodes transferring systems are designed, commissioned and in operation. In this report, we will describe our photocathodes production and discuss the cathode’s performance from cathode growth system to the DC gun.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS101

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPTS102

New Activation Techniques for Higher Charge Lifetime from GaAs Photocathodes

cathode, gun, laser, site

2157

O.H. Rahman, M. Gaowei, W. Liu, E. Wang
BNL, Upton, Long Island, New York, USA
J.P. Biswas
Stony Brook University, Stony Brook, USA

GaAs is the choice of photocathode material for polarized electron sources. The well established method of activating GaAs for beam extraction is to use Cs and Oxygen to create a ’Negative Electron Affinity’(NEA) layer. However, this layer is highly sensitive to vacuum and gets damaged due to ion back bombardment in DC guns. In this work, we explore activation methods that used Tellurium in conjunction with the usual Cs and Oxygen. We report our method to activate GaAs and show charge lifetime results for our activation method. Our results show that the use of Te could potentially help with longer charge lifetimes from GaAs cathodes in DC guns.

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paper received ※ 14 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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TUPTS103

The Progress of High Current High Bunch Charge Polarized Electron HVDC Gun

cathode, gun, vacuum, high-voltage

2160

E. Wang, I. Ben-Zvi, R.F. Lambiase, W. Liu, O.H. Rahman, J. Skaritka, F.J. Willeke
BNL, Upton, Long Island, New York, USA
I. Ben-Zvi
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The high current and high bunch charge polarized electron source is essential for cost reduction of eRHIC. It aims to deliver electron beam with 10 mA average current and 5.3 nC bunch charge. We analyzed the mechanism of cathode degradation and proposed using a large strain superlattice GaAs photocathode in a high voltage DC gun to increase the charge lifetime above kilo Coulomb. The gun has been designed and fabricated and expected to start commissioning by the mid of this year. In this paper, we will present the modeling of ion back bombardment and cathode degrading. We proposed an anode offset scheme to increase cathode lifetime. Also, we will describe the details of gun design and the strategies to demonstrate high current high charge polarized electron beam from this source.

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS104

Spatio-Temporal Shaping of the Photocathode Laser Pulse for Low-Emittance Shaped Electron Bunches

laser, cathode, emittance, simulation

2163

T. Xu, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
C.-J. Jing, A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
P. Piot
Fermilab, Batavia, Illinois, USA
J.G. Power
ANL, Argonne, Illinois, USA

Funding: This work is supported by the U.S. DOE contract No. DE- SC0017750 with Euclid Techlabs LLC., No. DE-SC0018656 with NIU, and No. DE-AC02-06CH11357 with ANL.
Photocathode laser shaping techniques to generate temporally shaped electron bunches are appealing owing to their simplicity. Such technique is being considered to form shaped electron bunches to enhance the transformer ratio in beam-driven accelerators. At low energy (i.e. during the emission process) the transverse and longitudinal space charge effects are coupled so that attaining a low beam transverse emittance require the laser to be spatiotemporal shaped. In this paper, we explore the generation of a linearly-ramped bunch with optimized transverse emittance by temporally and radially shaping the laser pulse to provide an adequate initial distribution. We discuss a possible implementation of the optical shaping technique and describe a planned experiment.

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPTS105

High Current High Charge Magnetized and Bunched Electron Beam from a DC Photogun for JLEIC Cooler

cathode, laser, gun, emittance

2167

S. Zhang, P.A. Adderley, J.F. Benesch, D.B. Bullard, J.M. Grames, J. Guo, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, M.A. Mamun, M. Poelker, R. Suleiman, M.G. Tiefenback, Y.W. Wang
JLab, Newport News, Virginia, USA
J.R. Delayen, G.A. Krafft, Y.W. Wang, S.A.K. Wijethunga
ODU, Norfolk, Virginia, USA

Funding: This project was supported by the U.S. DOE Basic Energy Sciences under contract No. DE-AC05-060R23177. Additional support comes from Laboratory Directed Research and Development program.
A high current, high charge magnetized electron beamline that has been under development for fast and efficient cooling of ion beams for the proposed Jefferson Lab Electron Ion Collider (JLEIC). In this paper, we present the latest progress over the past year that include the generation of picosecond magnetized beam bunches at average currents up to 28 mA with exceptionally long photocathode lifetime, and the demonstrations of magnetized beam with high bunch charge up to 700 pC at 10s of kHz repetition rates. Detailed studies on a stable drive laser system, long lifetime photocathode, beam magnetization effect, beam diagnostics, and a comparison between experiment and simulations will also be reported. These accomplishes marked an important step towards the essential feasibility for the JLEIC cooler design using magnetized beams.
(To be inserted)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS105

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS106

First Commissioning of LCLS-II CW Injector Source

gun, cavity, operation, vacuum

2171

F. Zhou, C. Adolphsen, A.L. Benwell, G.W. Brown, W.S. Colocho, Y. Ding, M.P. Dunning, K. Grouev, B.T. Jacobson, X. Liu, T.J. Maxwell, J.F. Schmerge, T.J. Smith, T. Vecchione, F.Y. Wang, C.M. Zimmer
SLAC, Menlo Park, California, USA
G. Huang, F. Sannibale
LBNL, Berkeley, California, USA

Funding: The work is supported by DOE under grant No. DE-AC02-76SF00515
The LCLS-II injector source includes a 186MHz CW rf-gun, a 1.3 GHz CW rf-buncher, a loadlock system for photocathode change, two main solenoids, and a few essential diagnostics. The electron beam is designed to operate at a high repetition rate, up to 1-MHz. Since summer of 2018 we started LCLS-II injector source commissioning immediately after the major installation was completed. Initial commissioning showed the rf-gun was severely contaminated with hydrocarbons and very limited power <600W could be fed into the gun cavity. After a few significant processes, we eventually removed the hydrocarbons and successfully delivered desired rf power of 80 kW to the gun. This paper reports first com-missioning results including gun bakeout and vacuum processing, CW RF-gun and buncher operation with nom-inal power, and measurements of rf stability and dark current.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS106

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paper received ※ 10 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS111

Study on Improving Durability of Cs-Te Photocathode for an RF-gun

cathode, gun, vacuum, brightness

2182

T. Tamba, J. Miyamatsu, K. Sakaue, M. Washio
Waseda University, Tokyo, Japan

At Waseda University, we have been studying for high quality electron beam generation using 1.6 cell Cs-Te photocathode rf-gun. We use photocathode as the electron source, which can generate high- quality electron beam such as low emittance, and short bunch. The performance of photocathode is evaluated mainly in terms of quantum efficiency (Q.E.) and lifetime. Cs-Te photocathode used in the rf-gun is known for high Q.E. about 10% with UV light and relatively longer lifetime among semiconductor photocathodes. Since it is a hard environment for photocathode inside the gun, it is necessary to replace the photocathode every several months. In other words, in order to achieve long-term operation of rf-gun, it is necessary to find highly durable photocathode recipe. It has been reported that the Cs-Te photocathode by co-evaporation can produce a photocathode having a longer lifetime as compared with the sequential evaporation. Moreover, we have done studies to improve lifetime and durability of Cs-Te photocathode by coating the cathode surface with CsBr thin film. In this conference, we report the evaluation results of Cs-Te photocathode by co-evaporation, CsBr coating and future prospects.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS111

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paper received ※ 12 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPTS113

Microwave Thermionic Electron Gun for Synchrotron Light Sources

gun, cathode, cavity, coupling

2189

S.V. Kutsaev, R.B. Agustsson, R.D. Berry, D. Chao, O. Chimalpopoca, A.Yu. Smirnov, K.V. Taletski, A. Verma
RadiaBeam, Santa Monica, California, USA
M. Borland, A. Nassiri, Y. Sun, G.J. Waldschmidt, A. Zholents
ANL, Argonne, Illinois, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Basic Energy Science, under contracts DE-SC0015191 and DE- AC02-06CH11357.
Thermionic RF guns are the source of electrons used in many practical applications, such as drivers for synchrotron light sources, preferred for their compactness and efficiency. RadiaBeam Technologies has developed a new thermionic RF gun for the Advanced Photon Source at Argonne National Laboratory, which would offer substantial improvements in reliable operations with a robust interface between the thermionic cathode and the cavity, as well as better RF performance, compared to existing models. This improvement became possible by incorporating new pi-mode electromagnetic design, robust cavity back plate design, and a cooling system that will allow stable operation for up to 1 A of beam current and 100 Hz rep rate at 1.5 μs RF pulse length, and 70 MV/m peak on-axis field in the cavity. In this paper, we discuss the electromagnetic and engineering design of the cavity and provide the test results of the new gun.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS113

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paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPTS114

Electron Stimulated Desorption from Cryogenic NEG-Coated Surfaces

vacuum, cryogenics, experiment, site

2193

R. Sirvinskaite, M.D. Cropper
Loughborough University, Loughborough, Leicestershire, United Kingdom
A.N. Hannah, O.B. Malyshev, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S. Wang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Non-Evaporable Getter (NEG) coating has been used for years in many particle accelerators due to its advantages like evenly distributed pumping speed, low thermal outgassing, and low photon, electron and ion stimulated desorption yields. Although NEG coating has been tested at room temperatures intensively, there is little data on its behaviour at cryogenic temperatures. Tests in this environment are important for the Future Circular Collider (FCC) study and other accelerator facilities where the operational conditions of the beam screen are restricted to cryogenic temperatures. This work will provide some preliminary results on NEG properties at low temperatures, e.g. pumping speed and capacity, as well as its behaviour under electron bombardment, where electron stimulated desorption (ESD) yields will be calculated. The ternary Ti-Zr-V coating, deposited with dense and columnar structure, will be the first material to be tested at cryogenic temperatures in ASTeC Daresbury laboratory. The results were compared with the ones obtained at room temperature, offering an insight into the behaviour of NEG-coated cryogenic chambers when beam-induced effects are present.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS114

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPTS115

The Progress in Physical Start-Up of the NSC KIPT Subcritical Neutron Source Facility Driven by an Electron Linear Accelerator

neutron, target, detector, vacuum

2197

P. Gladkikh, O.V. Bykhun, I.M. Karnaukhov, A. Mytsykov, V. Stomin, I. Ushakov, A.Y. Zelinsky
NSC/KIPT, Kharkov, Ukraine

National Science Center ’Kharkov Institute of Physics &Technology’ (NSC KIPT), Kharkov, Ukraine and Argonne National Laboratory (ANL), Chicago, USA are jointly constructing and commissioning the Ukraine Neutron Source facility. The facility consists of a subcritical assembly driven by a 100MeV/100kW electron linear accelerator. The electron beam will be used for generating the neutrons for operating the subcritical assembly using tungsten or natural uranium target. The facility is planned to support the Ukraine nuclear industry, and provide a capability for performing reactor physics, material research, and basic science experiments, to produce medical isotopes, train young nuclear professionals. The integrating facility tests were completed at the end of 2018, and physical start-up operation began in 2019. The facility commissioning and current start-up results are presented and discussed in the paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS115

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paper received ※ 10 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS116

Adjustment and Improvement of 100 MeV/100 kW Electron Linear Accelerator Parameters for the NSC KIPT SCA Neutron Source

neutron, gun, operation, MMI

2200

P. Gladkikh, V.P. Androsov, O. Bezditko, O.V. Bykhun, V.V. Gevtsev, A.N. Gordienko, A. Gvozd, V.E. Ivashchenko, D.A. Kapliy, I.I. Karhaukhov, I.M. Karnaukhov, V.P. Lyashchenko, M. Moisieienko, A. Mytsykov, A.V. Reuzayev, A.B. Shevtsov, D.V. Tarasov, V.I. Trotsenko, A.Y. Zelinsky
NSC/KIPT, Kharkov, Ukraine

The NSC KIPT SCA Neutron Source uses 100 MeV/ 100 kW electron linear accelerator as a driver for the generation of the initial neutrons. The electron linear accelerator was designed and manufactured by the Institute of High Energy Physics (IHEP) of China. At present, the accelerator was assembled at NSC KIPT, all the components were tested, and the first beam commissioning results are obtained. The pilot operation of the accelerator was started in 2018. The progress in the accelerator system operations and electron beam performance improvement are described in the paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS116

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paper received ※ 10 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS117

Photocathode Activities at INFN LASA

cathode, operation, laser, gun

2203

D. Sertore, G. Guerini Rocco, P. Michelato, L. Monaco
INFN/LASA, Segrate (MI), Italy
S.K. Mohanty
DESY Zeuthen, Zeuthen, Germany
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy

We present the activity on alkali antimonide photocathodes at INFN LASA. The long term goal is to transfer to these photocathodes the know-how acquired in the successful development of cesium telluride photocathodes, nowadays used in many leading FEL facilities and accelerator complex. In this paper we present and discuss the results so far obtained on alkali antimonide films grown in our R&D system and the status of the new preparation system specifically designed for these sensitive materials.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS117

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paper received ※ 16 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEXPLM1

XFEL Operational Flexibility due to the Dechirper System

undulator, FEL, controls, laser

2219

A.A. Lutman, K.L.F. Bane, Y. Ding, C. Emma, M.W. Guetg, E. Hemsing, Z. Huang, J. Krzywiński, J.P. MacArthur, G. Marcus, A. Marinelli, T.J. Maxwell, A. Novokhatski
SLAC, Menlo Park, California, USA
G. Guo
Stanford University, Stanford, California, USA

Funding: U.S.Department of Energy, Office of Science, Laboratory Directed Research and Development (LDRD) program at SLAC National Accelerator Laboratory, under Contract No. DE-AC02-76SF00515.
The RadiaBeam/SLAC dechirper was installed to demonstrate the concept of using wakefields from a corrugated structure to change the energy profile along an electron bunch. Since installation, the system has allowed a large number of additional XFEL operating modes including fresh-slice two-color or three color operation, fresh-slice seeding, passive streaking, etc. This talk will discuss the results from using the dechirper system and possible implementation issues related to the high-rate LCLS-II.
Lutman, A. A. et al. Nat. Photon. 10, 745-750 (2016).; Nat. Photon. 10, 695-696 (2016); other papers in submission.

Slides WEXPLM1 [5.744 MB]

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paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEXPLS1

High Performance ECR Sources for Next-Generation Nuclear Science Facilities

ECR, plasma, ion-source, ECRIS

2224

D. Leitner
LBNL, Berkeley, California, USA

Modern heavy-ion accelerators require intense heavy-ion beams with high charge state. Electron Cyclotron Resonance (ECR) sources are the primary tool for generating such beams. Advances in magnet technology and an improved understanding of the ECR ion source plasma physics have led to significant improvements in ECR source performance over the last several decades. The current state of the art is represented by third-generation sources operating at frequencies around 28 GHz and peak coil fields of about 7 T using NbTi conductor. Fourth-generation ECR ion sources with an operating frequency above 40 GHz have the potential to quadruple the source output beam current. These sources will need to incorporate advanced conductor technologies and/or novel coil configurations in order to exceed the limitations of the present structures. This talk will present worldwide efforts currently underway to develop high-performance ECR sources using new design approaches in support of next-generation nuclear physics facilities.

Slides WEXPLS1 [8.012 MB]

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paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEXXPLM1

Amplified Emission of a Soft-X Ray Free-Electron Laser Based on Echo-Enabled Harmonic Generation

FEL, laser, experiment, free-electron-laser

2230

E. Allaria, L. Badano, G. De Ninno, S. Di Mitri, B. Diviacco, W.M. Fawley, N.S. Mirian, G. Penco, P. Rebernik Ribič, S. Spampinati, C. Spezzani, M. Trovò
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
G. De Ninno
University of Nova Gorica, Nova Gorica, Slovenia
E. Ferrari, E. Prat
PSI, Villigen PSI, Switzerland
D. Garzella
CEA, Gif-sur-Yvette, France
V. Grattoni
DESY, Hamburg, Germany
E. Hemsing
SLAC, Menlo Park, California, USA
M.A. Pop
MAX IV Laboratory, Lund University, Lund, Sweden
E. Roussel
PhLAM/CERLA, Villeneuve d’Ascq, France
D. Xiang
Shanghai Jiao Tong University, Shanghai, People’s Republic of China

We report the first evidence of substantial gain in a soft-X ray Free Electron Laser (FEL) based on Echo-Enabled Harmonic Generation (EEHG). The experiment was focused on harmonics 36 (~7.3nm) and 45 (5.8 nm) and clearly demonstrated the expected EEHG capability of generating powerful and coherent FEL pulses, with strongly reduced sensitivity to electron-beam fluctuations. The experiment was carried out at FERMI, the seeded FEL user facility at Elettra-Sincrotrone Trieste.

Slides WEXXPLM1 [11.410 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXXPLM1

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paper received ※ 17 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEXXPLS1

Magnetron R&D for High Efficiency CW RF Sources of Particle Accelerators

injection, cavity, controls, klystron

2233

H. Wang, R.M. Nelson, R.A. Rimmer
JLab, Newport News, Virginia, USA
B.R.L. Coriton, C.P. Moeller
GA, San Diego, California, USA
A. Dudas, M.L. Neubauer
Muons, Inc, Illinois, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, DOE OS/NP STTR Grant DE-SC0013203 and DOE OS/HEP Accelerator Stewardship award 2019-2021.
The scheme of using a high efficiency magnetron to drive a superconducting or normal conducting radio frequency accelerator cavity needs not only injection phase locking but also amplitude modulation to compensate for the cavity’s microphonics, frequency change, variations of cavity voltage and beam current. To be able to do a fast and efficient modulation and to compensate the frequency pushing effect due to the anode current change, the magnetron’s magnetic field has to be trimmed by an external coil*. To facilitate this, a low eddy current magnetron body has been designed and built**. This paper will present the experimental results of such modulation on a conventional 2.45 GHz magnetron at the R&D test stand. In addition, the progresses on the injection lock test to a new 1497 MHz, 13kW magnetron prototype aimed for the CEBAF klystron replacement with newly built low level RF (LLRF) controller for the amplitude modulation will be reported. Based on these R&D results, a 915MHz, 2×75kW CW industrial heating type magnetron system is being developed to be used for the high efficiency (>80%) RF source to the electron accelerator for industrial applications.
* H. Wang, et al,THPAL145, proceedings of IPAC 2018.
** M. Neubauer, et al,THPAL042, proceedings of IPAC 2018.

Slides WEXXPLS1 [8.033 MB]

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEXXPLS3

Is it Possible to Use Additive Manufacturing for Accelerator UHV Beam Pipes?

vacuum, laser, ECR, experiment

2240

G. Sattonnay, M. Alves, S. Bilgen, B.J. Bonnis, A. Gonnin, D. Grasset, S. Jenzer, F. Letellier-Cohen, B. Mercier, E. Mistretta
LAL, Orsay, France
F. Brisset
ICMMO, Orsay, France

Funding: Work supported by a grant from IN2P3/CNRS, program I3D metal
Recently, additive manufacturing (AM) has revolutionized mechanical engineering by allowing the quick production of mechanical components with complex shapes. AM by selective laser melting (SLM) is an advanced manufacturing process which uses lasers to melt metal powders one layer at a time to produce final 3D components. This technology could be also used to make Ultra High Vacuum components. Therefore, we investigated in this work the reproducibility of AM 316L stainless steel properties for different specimen supplied by several manufacturers with the same SLM process. Clearly, the microstructure and therefore the mechanical properties of the investigated AM samples are different as a function of manufacturers: indeed, they are largely influenced by processing parameters, which produces heterogeneous and anisotropic microstructures that differ from traditional wrought counterparts. Samples were also submitted to bake cycles at high temperature, in order to check the structural stability of material properties after heat treatments. The outgassing rates and the secondary emission yield of vacuum components constructed from AM 316L were also measured. Finally, the possibility to use AM for accelerator beam pipes will be discussed.

Slides WEXXPLS3 [9.009 MB]

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paper received ※ 01 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEYYPLS2

First Experimental Measurements of the Caustic Nature of Trajectories in Bunch Compressors

linac, FEL, experiment, sextupole

2270

T.K. Charles
The University of Melbourne, Melbourne, Victoria, Australia
J. Björklund Svensson
Lund University, Lund, Sweden
A. Latina
CERN, Geneva, Switzerland
S. Thorin
MAX IV Laboratory, Lund University, Lund, Sweden

Theoretical advancements describing density perturbations in accelerated charge particle beams, known as caustics, has been recently developed * This proceeding describes the first experimental measurements of the caustic nature of charged particle trajectories in a particle accelerator. Caustics by their nature are discontinuities that result from small continuous perturbations of an input. Under certain conditions, small density modulations will reliably produce striking changes in the corresponding output current profile. These current modulations can shift alone the bunch with varying higher-order longitudinal dispersion. The MAX IV linac double-bend achromats provide the perfect test bed for experimentally verifying how the caustic lines evolve. The natural amplification of small perturbations makes caustics an attractive diagnostic tool, and effective tool for characterise the bunch compressors. This approach also allows us to modify and improve the longitudinal charge profile, removing current spikes or creating tailor shaped current profiles.
* T.K.Charles et. al. Phys. Rev. Accel. Beams 19, 104402

Slides WEYYPLS2 [5.402 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLS2

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEZPLS1

Control of Laser Plasma Accelerated Electrons: A Route for Compact Free Electron Lasers

laser, undulator, radiation, FEL

2280

M.-E. Couprie, T. André, F. Blache, F. Bouvet, F. Briquez, Y. Dietrich, J.P. Duval, M. El Ajjouri, A. Ghaith, C. Herbeaux, N. Hubert, C.A. Kitegi, M. Labat, N. Leclercq, A. Lestrade, A. Loulergue, O. Marcouillé, F. Marteau, D. Oumbarek Espinos, P. Rommeluère, M. Sebdaoui, K.T. Tavakoli, M. Valléau
SOLEIL, Gif-sur-Yvette, France
I.A. Andriyash, S. Corde, J. Gautier, J.-P. Goddet, O.S. Kononenko, G. Lambert, K. Ta Phuoc, A. Tafzi, C. Thaury
LOA, Palaiseau, France
S. Bielawski, C. Evain, E. Roussel, C. Szwaj
PhLAM/CERLA, Villeneuve d’Ascq, France
V. Malka
Weizmann Institute of Science, Physics, Rehovot, Israel

The recent spectacular development of laser plasma ac- celerators that now can deliver GeV electron beams in an extremelyshortdistancemakesthemverypromising. Ap- plications for light sources based on undulator radiation and free electron laser appear as an intermediate step to move from an acceleration concept to an accelerator qual- ification. However, the presently achieved divergence and energy spread require some electron beam manipulations. The COXINEL test line was designed for enabling Free Elec- tron Laser operation with baseline reference parameters. It comprises variable permanent magnet quadrupoles for di- vergence handling, a magnetic chicane for electron energy sorting, a second set of quadrupole for chromatic focusing and an undulator for synchrotron radiation emission and/or free electron laser gain medium. The transport along the line is controlled [1]. The synchrotron radiation emitted by the undulator radiation is studied under different conditions of detection (CCD camera, spectrometer), electron beam manipulation and undulator parameters. These observations pave the way towards Laser Plasma Acceleration based Free Electron Laser.

[1] T. André et al., Control of laser plasma accelerated electrons for light sources, accepted in Nature Comm.

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEZZPLS3

Longitudinal-Phase-Space Manipulation for Efficient Beam-Driven Structure Wakefield Acceleration

wakefield, linac, simulation, acceleration

2296

W.H. Tan, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA
A. Zholents, A. Zholents
ANL, Argonne, Illinois, USA

Funding: This work is funded by the United States Department of Energy awards DE-SC0018656 with Northern Illinois University and DE-AC02-06CH11357 with Argonne National Laboratory.
Collinear beam-driven structure wakefield acceleration (SWFA) is an advanced acceleration technique that could support the compact generation of high-energy beams for future multi-user x-ray free-electron-laser facilities*. Producing an ideal shaped drive beam through phase space manipulation is crucial for an efficient SWFA. Controlling the final longitudinal-phase space of the drive beam necessitate staged beam manipulations during acceleration. This paper describes the preliminary design of an accelerator beamline capable of producing drive beam with tailored current distribution and longitudinal-phase-space correlation. The proposed design is based on simple analytical models combined in a 1-D longitudinal beam-dynamics simulation tracking program supporting forward and backward (time reversal) tracking.
* A. Zholents, et al., Dielectric wakefield accelerator to drive the future FEL light source

Slides WEZZPLS3 [2.869 MB]

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPMP010

8 Gev Slow Extraction Beam Test for Muon to Electron Conversion Search Experiment at J-PARC

kicker, extraction, timing, injection

2322

M. Tomizawa, Y. Arakaki, Y. Fukao, Y. Hashimoto, Y. Igarashi, T. Kimura, S. Mihara, M. Moritsu, S. Murasugi, R. Muto, H. Nishiguchi, K. Okamura, Y. Shirakabe, K. Ueno, E. Yanaoka
KEK, Ibaraki, Japan
Y. Fujii
Monash University, Faculty of Science, Clayton, Victoria, Australia
F. Tamura
JAEA/J-PARC, Tokai-mura, Japan

A muon to electron conversion search experiment (COMET) planned at J-PARC needs 8 GeV bunched proton beams with a continuous 1 MHz pulse structure. In this experiment, an intensity ratio of the residual to the main pulsed beam, which is expressed as extinction, should be less than the level of 10^-10. In RUN78 (Jan. to Feb., 2018), we have succeeded in slow extraction of 8 GeV protons with 7.3×1012 ppp, satisfies the COMET phase-I requirement, and the extinction derived from a timing measurement of secondary particles from the target shows a promising result. A mechanism to explain the measured extinction will be also described in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP010

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paper received ※ 01 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPMP029

Systematic Optics Studies for the Commissioning of the AWAKE Beamline

optics, plasma, experiment, quadrupole

2383

C. Bracco, B. Goddard, I. Gorgisyan, M. Turner, F.M. Velotti, L. Verra
CERN, Geneva, Switzerland
M. Aiba
PSI, Villigen PSI, Switzerland

The commissioning of the AWAKE electron beam line was successfully completed in 2018. Despite a modest length of about 15 m, this low-energy line is quite complex and several iterations were needed before finding satisfactory agreement between the model and the measurements. The work allowed to precisely predict the size and positioning of the electron beam at the merging point with the protons inside the plasma cell, where no direct measurement is possible. All the key aspects and corrections which had to be included in the model, precautions and systematic checks to apply for the correct setup of the line are presented. The sensitivity of the ~18 MeV electron beam to various perturbations, like different initial optics parameters and beam conditions, energy jitter and drifts, earth’s magnetic field etc., is described.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP029

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paper received ※ 10 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPMP049

Simulations of Beam Shaping for Dark Matter Experiments at LCLS-II

experiment, FEL, optics, quadrupole

2443

Y.M. Nosochkov, C. Hast, T.W. Markiewicz, L.Y. Nicolas, T.O. Raubenheimer, M. Santana-Leitner
SLAC, Menlo Park, California, USA

Funding: * Work supported by the U.S. DOE Contract DE-AC02-76SF00515.
A new transfer beamline, called S30XL, and an experimental facility are proposed to be built at SLAC, taking advantage of the LCLS-II free electron laser (FEL) under construction. The S30XL will operate parasitically to the FEL by extracting the unused low intensity 4-GeV LCLS-II bunches into the existing A-line and the End Station-A (ESA). This provides a unique capability of multi-GeV nearly continuous electron beam for a variety of HEP experiments, in particular the dark matter search experiments. The latter require a very low beam current ranging from pA to micro-A, as well as a large beam spot at the detector. The necessary beam shaping will be performed using spoilers and collimators in the A-line, and by optimizing the optics. FLUKA and elegant codes are used to generate and track the beam into the ESA.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP049

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paper received ※ 16 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPGW004

Wire Scanner for High Intensity Ion Beam*

quadrupole, focusing, LEBT, vacuum

2466

A. Beller, D. Bondoux, F. Bouly
LPSC, Grenoble Cedex, France

Funding: Part of this work supported by the European Atomic Energy Community (EURATOM) H₂020 Program under grant agreement n°662186 (MYRTE project).
The goal of the project is to develop a Wire-Scanner compatible with low energy - high intensity ion beams and adaptable to various beam chamber diameters. The purpose is to obtain the 2D beam profile by passing measurement wires through the beam. Thanks to a high speed passage of measurement wires, it allows to avoid "disrupting" the beam passage, and can be considered as a non-destructive diagnosis. Wires heating and measuring issues have been solved by using tungsten wires kept in tension by a mechanical system. All driving and signal measurements are performed by a PXI based system. The synchronization of the measurements is guaranteed by an analog input board recovering the wires current and the translator position, the latter being carried out by a laser sensor. Besides this technological aspect, an optimization algorithm for beam profile reconstruction from measured data under Gaussian hypothesis has been developed. The standalone system and first experimental results are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW004

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paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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WEPGW008

Fiber Beam Loss Monitors at MAMI

beam-losses, experiment, detector, FPGA

2477

M. Dehn, P. Achenbach, I. Beltschikow, O. Corell, P. Gülker, W. Lauth, M. Mauch
IKP, Mainz, Germany

Funding: Work supported by DFG (CRC 1044) and the German federal state of Rhineland-Palatinate
At the 14 MeV stage of the 1508 MeV cascaded racetrack microtron accelerator Mainz Microtron (MAMI) fiber beam loss monitors with multi-anode photomultipliers (ma-PMTs) have been successfully tested. The combination of individual fibers for each recirculation beam pipe with ma-PMTs allows to detect beam losses turn by turn in the order of 10^-4 or even lower which cannot be accomplished with the already existing beam diagnostics. This kind of beam loss monitor might be an alternative to ionisation chambers for the new Mainz Energy Recovering Superconducting Accelerator (MESA).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW008

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW009

DEVELOPMENT OF THE ELECTRON BEAM PROBE FOR HADRON SYNCHROTRONS.

simulation, hadron, proton, experiment

2480

M. Droba, C. Hübinger, O. Meusel, H. Podlech, K.I. Thoma
IAP, Frankfurt am Main, Germany
O.R. Jones, M. Wendt, F. Zimmermann
CERN, Meyrin, Switzerland

Funding: BMBF 05P18RFRB2
Non-invasive diagnostics is essential to get important information about intense hadron beams, e.g. the transverse beam profile, which is indispensable in order to attain high brilliance and luminosity for upgrades on present machines and for future projects. Furthermore, it can be used to optimise parameter settings in environment of the running machine. An electron beam probe (EBP) is a beam diagnostics instrument which scans a low energy, low current electron beam through a hadron beam and obtains information from the detected response. The electrons are shot perpendicular through the hadron beam to be examined, which causes deflection in the beam potential of the intense hadron bunch, that needs to be detected and further analysed. We propose to build the EBP scanning apparatus for synchrotrons under ultra-high vacuum condition. The results of multi particle simulations evaluating limitations the expected measurement potential and limitations are presented. This work will be performed in collaboration with CERN.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW009

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paper received ※ 11 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPGW010

Diagnostics and First Beam Measurements at FLUTE

laser, cathode, diagnostics, experiment

2484

T. Schmelzer, A. Bernhard, E. Bründermann, A. Böhm, S. Funkner, B. Härer, I. Križnar, A. Malygin, S. Marsching, W. Mexner, A.-S. Müller, M.J. Nasse, G. Niehues, R. Ruprecht, M. Schuh, N.J. Smale, P. Wesolowski, M. Yan
KIT, Karlsruhe, Germany

FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a compact versatile linear accelerator at the Karlsruhe Institute of Technology (KIT). It serves as a platform for a variety of accelerator studies as well as a source of strong ultra-short THz pulses for photon science. In the commissioning phase of the 7 MeV low energy section the electron bunches are used to test the different diagnostics systems installed in this section. An example is the split-ring-resonator-experiment. In this contribution we report on the commissioning status of the beam diagnostics and present first beam measurements at FLUTE.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW010

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPGW011

Development of a Silicon Strip Detector for Novel Accelerators at Sinbad

detector, simulation, acceleration, linac

2487

S. Jaster-Merz, R.W. Aßmann, F. Burkart, U. Dorda, U. Kraemer, E. Panofski, M. Stanitzki
DESY, Hamburg, Germany

At the SINBAD facility (DESY Hamburg), novel particle acceleration techniques like dielectric laser acceleration (DLA) structures will be tested using the ARES linac. Due to the small size of these structures, the accelerated electron beams only have a very low (sub-pC) charge. To determine the energy distribution of these beams, a silicon strip detector for the ARES linac spectrometer is currently under development. This detector fulfils the requirements of high spatial resolution for low charge density beams. The detector consists of two 1 cm x 1 cm silicon strip sensors and readout components. The design of the detector, its components and an estimate of its behaviour for a specific electron beam distribution are presented and discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW011

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paper received ※ 17 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPGW012

Vertical Beam Size Measurement Methods at the BESSY II Storage Ring and their Resolution Limits

diagnostics, storage-ring, polarization, detector

2491

M. Koopmans, F. Armborst, J.G. Hwang, A. Jankowiak, P. Kuske, M. Ries, G. Schiwietz
HZB, Berlin, Germany

With the VSR upgrade for the BESSY II electron storage ring* bunch resolved diagnostics are required for machine commissioning and to ensure the long-term quality and stability of operation. For transverse beam size measurements we are going to use an interferometric method, which will be combined with a fast gated intensified CCD camera at a subsequent stage. A double-slit interferometer method has already been verified successfully at BESSY II**. In addition first 2D bunch resolved measurement tests have been performed at the dedicated diagnostics beamline for bunch length measurements. Measurements of the interferometer and X-ray pinholes as function of a vertical electron beam excitation are compared in this paper.
* A. Jankowiak et al., Germany, June 2015. DOI: 10.5442/R0001
** M. Koopmans et al., in Proc. IPAC’17, paper MOPAB032, 2017

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW012

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paper received ※ 09 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPGW014

A Non-Invasive THz Spectrometer for Bunch Length Characterization at European XFEL

FEL, radiation, diagnostics, factory

2495

N.M. Lockmann, C. Gerth, P. Peier, B. Schmidt, S. Wesch
DESY, Hamburg, Germany

The European X-ray Free-Electron Laser provides one of the most powerful X-ray laser pulses to a wide range of experiments. These experiments strongly benefit from the exact knowledge of the electron bunch current profile and demand for stable and shortest-possible pulse lengths. During the 2018 summer shutdown, the 4-staged grating spectrometer CRISP* has been installed at a diffraction radiation (DR) beamline just upstream of the undulator beamline switchyard. The DR at final electron beam energies of up to 17.5 GeV enables non-invasive bunch length characterization based on form factor measurements down to a few micrometers. Fast detectors and electronics allow for the characterization of the whole bunch train with repetition rates above 1 MHz. This contribution will present commissioning results of the THz beamline as well as first measured form factors and reconstructed electron current profiles.
* S. Wesch et al., Nuclear Instruments and Methods in Physics Research Section A 665 (2011) pp. 40-47

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW014

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPGW018

An Ultra-Fast and Wide-Spectrum Linear Array Detector for High Repetition Rate and Pulsed Experiments

detector, experiment, radiation, synchrotron

2504

M.M. Patil, E. Bründermann, M. Caselle, S. Funkner, B. Kehrer, A.-S. Müller, G. Niehues, W. Wang, M. Weber
KIT, Karlsruhe, Germany
C. Gerth
DESY, Hamburg, Germany
D.R. Makowski, A. Mielczarek
TUL-DMCS, Łódź, Poland

Funding: "BMBF: is funded by the BMBF contract number: 05K16VKA" (2016-2018) ("NeoDyn")
Photon science research at accelerators is influenced radically by the developments of sensor and readout technologies for imaging. These technologies enable a wide range of applications in beam diagnostics, tomography and spectroscopy. The repetition rate of commercially available linear array detectors is a limiting factor for the emerging synchrotron applications. To overcome these limitations, KALYPSO(Karlsruhe Linear arraY detector for MHz rePetition rateSpectrOscopy), an ultra-fast and wide-field of view linear array detector operating at several mega-frames per second(Mfps), has been developed. A silicon micro-strip sensor is connected to custom cutting-edge front end ASICs to achieve unprecedented frame rate in continuous readout mode. In this contribution, the third generation of KALYPSO will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW018

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW022

A Numerical Analysis to Choose the Most Performing Optical Transition Radiation Screen

target, radiation, brightness, site

2518

F. Cioeta, D. Alesini, A. Variola
INFN/LNF, Frascati (Roma), Italy
M. Ciambrella, A. Mostacci
Sapienza University of Rome, Rome, Italy
D. Cortis, M. Marongiu, V. Pettinacci
INFN-Roma, Roma, Italy

Optical Transition Radiation (OTR) screen represents the most appropriate instrument to measure and verify the characteristics of a beam spot size produced by a particle accelerator. In order to measure such beam properties, OTR screens have to sustain thermal and mechanical stresses due to the energy that several bunches deposit. Owing to these requirements, it is essential to identify the more suitable material to optimize the OTR dimensions and to get reliable measures from the diagnostic system. In this paper, we describe a numerical procedure to choose the most performing material taking into account the physical requirements of a multi-bunch high brightness. The procedure is based on a dedicated ANSYS script able to evaluate the fatigue life time of the material considering a high number of thermal cycles generated by several bunches. The main characteristic of this script is the capability to simulate the real thermal and mechanical effect on the target that the hitting particle beam produces. The numerical procedure has been applied to compare the performance of three relevant materials-Aluminium, Silicon and Graphite simulating a beam hitting with well-known parameters.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW022

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paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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WEPGW027

Evaluation and Reduction of Influence of Filling Pattern on X-Ray Beam Position Monitors for SPring-8

space-charge, storage-ring, operation, undulator

2526

H. Aoyagi, Y. Furukawa, S. Takahashi
JASRI/SPring-8, Hyogo, Japan

SPring-8 constantly provides various several-bunch mode operations, which combine single bunches and train bunches. Recently, influence of filling pattern on the accuracy of the XBPMs became apparent, so that we started a systematic evaluation. It was found that the influence was caused by suppression of current signal due to space charge effect, which could be quantified by observing a behaviour of the current signal while changing the voltage of photoelectron collecting electrodes. In order to mitigate the space charge effect, we examined some methods, such as, changing operation parameters of the XBPMs and the undulators. As a result, we successfully reduced the influence of filling pattern.
* H. Aoyagi et al., Proc. of PASJ2018 WEOL06
http://www.pasj.jp/web_publish/pasj2018/proceedings/PDF/WEOL/WEOL06.pdf
http://www.pasj.jp/web_publish/pasj2018/proceedings/PDF/WEOL/WEOL06_oral.pdf

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW027

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paper received ※ 10 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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WEPGW030

Beam Profile Monitor for Slow Extracted Beam Using Multi-Layered Graphene at J-PARC

target, extraction, proton, real-time

2532

Y. Hashimoto, Y. Hori, R. Muto, M. Tomizawa, T. Toyama, M. Uota
KEK, Tokai, Ibaraki, Japan
M. Endo, H. Sakai
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
M. Murakami, K. Murashima, M. Tachibana, A. Tatami
KANEKA, Osaka, Japan

Extracted-beam profiles in slow extraction at J-PARC has been measured by using secondary electrons emitted from a target array made by multi-layered graphen, in real time during spill time of around 2 seconds. The target array consists of 20 ribbons with width of 1 mm, pitch of 2 mm, and thickness of 1.1 micron. Secondary-electron current at each channel is measured by a current amplifier having sensitivity more than 1 pA. These configuration produces useful information for beam dynamics in slow extraction. We have set this monitor at the entrance of a septum magnet, then we can also measure the last few-turns beam with the extracted beam simultaneously. We will discuss about features of this instrument and recent beam study with 51 kW extracted-beams.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW030

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW031

Measurement of Cherenkov Diffraction Radiation from a Short Electron Bunches at t-ACTS

radiation, experiment, photon, detector

2536

S. Ninomiya, H. Hama, F. Hinode, K. Kanomata, S. Kashiwagi, S. Miura, N.M. Morita, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, K. Takahashi, H. Yamada
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

Cherenkov Diffraction Radiation (ChDR) can be considered as a tool of non-destructive beam diagnostics. It also has the feature that the photon flux of ChDR is proportional to the thickness of the dielectric used as the radiator and can be much larger than ordinary diffraction radiation. An experimental set-up for the measurement of coherent ChDR from short electron bunches of about 100 fs is being prepared at t-ACTS, Tohoku University. Results of a basic experimental study about coherent ChDR will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW031

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paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPGW033

Development of the Bunch Shape Monitor Using the Carbon-Nano Tube Wire

high-voltage, vacuum, operation, DTL

2543

R. Kitamura, N. Hayashi, K. Hirano, Y. Kondo, K. Moriya, H. Oguri
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
K. Futatsukawa, T. Miyao, M. Otani
KEK, Ibaraki, Japan
S. Kosaka, Y. Nemoto
Nippon Advanced Technology Co., Ltd., Tokai, Japan

A bunch shape monitor (BSM) is one of the important instruments to measure the longitudinal phase space distribution. The information of the bunch length measured by the BSM is useful to tune phases of the accelerating cavities in the linear accelerator. For example, in the J-PARC linac, three BSM’s using the tungsten wire are installed and tested at the ACS section to measure the bunch shapes between the accelerating cavities. However, this conventional BSM is hard to measure the bunch shape of H⁻ beam with 3 MeV at the beam transport between the RFQ and DTL sections, because the wire is broken around the center region of the beam. The new BSM using the carbon-nano-tube (CNT) wire is being developed to be able to measure the bunch shape of the H⁻ beam with 3 MeV. One challenge to introduce the CNT wire for the BSM is the measure to the discharge. The careful attention should be paid to apply the high voltage of 10 kV to the CNT wire. The several measures are taken to suppress the discharge from the wire and operate the CNT-BSM. This presentation reports the current status of the development and future prospective for the CNT-BSM.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW033

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPGW034

Development of L-band Cavity BPM for STF

cavity, electronics, linac, simulation

2547

S.W. Jang, E.-S. Kim
KUS, Sejong, Republic of Korea
H. Hayano
KEK, Ibaraki, Japan

We developed a L-band beam position monitor with position resolution of few hundred nano meter for Superconducting Test Faciliy(STF) in KEK. The L-band BPM was developed to install inside the superconducting cryomodule of STF in KEK and it’s test was performed at Accelerator Test Facility in KEK. The three L-band BPM are fabricated and installed at the end of Linac of ATF. The position resolution measurement was performed with new L-band BPM electronics. In this talk, we will describe about the development of L-band BPM and its beam test results of nano meter level beam position resolution with new electronics system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW034

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paper received ※ 15 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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WEPGW037

Development of a Dense Gas Sheet Target for a 2D Beam Profile Monitor

experiment, simulation, vacuum, target

2554

N. Ogiwara, Y. Hori
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Hikichi, J. Kamiya, M. Kinsho
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
I. Yamada
Doshisha University, Graduate School of Engineering, Kyoto, Japan

We have been developing a dense gas sheet target to realize a non-destructive and fast-response beam profile monitor for the accelerators in J-PARC. The beaming effect in vacuum science and technology has been employed for making a gas sheet. The gas sheet with a thickness of ~ 1 mm and the density of 2 x 10^-4 Pa was successfully obtained. Then, we have successfully measured the profiles of the 400 MeV H⁻ ion beam in J-PARC linac by detecting the ions generated through the collision of this gas sheet to the H⁻ beam. This time, we have developed the gas sheet with the density of more than 10-3 Pa using a circular slit. The details of the new gas sheet generator will be shown.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW037

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paper received ※ 20 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPGW038

Beam Control and Monitors for the Spiral Injection Test Experiment

injection, experiment, solenoid, site

2557

M.A. Rehman
Sokendai, Ibaraki, Japan
K. Furukawa, H. Hisamatsu, T. Mibe, H. Nakayama, S. Ohsawa
KEK, Ibaraki, Japan
H. Iinuma
Ibaraki University, Hitachi, Ibaraki, Japan

A new experiment at J-PARC (E34) is under construction in order to measure the muon’s g-2 to unprecedented precision of 0.1 ppm and electric dipole moment up to the sensitivity of 10-21 e.cm in order to explore new physics beyond the standard model. A novel three-dimensional spiral injection scheme has been devised to inject and store the beam into a small diameter MRI-type storage magnet for E34. The new injection scheme features smooth injection with high storage efficiency for the compact storage magnet. However, spiral injection scheme is an unproven idea, therefore, a Spiral Injection Test Experiment (SITE) is underway to establish this injection scheme. The SITE is consist of 80 keV thermionic electron gun, two-meter-long beamline, and a solenoidal storage magnet. In order to match the beam with the solenoidal field, several optical elements have been placed on the beamline to control the beam phase space. The DC electron beam spiral track has been confirmed by the de-excitation of the nitrogen gas in the vacuum chamber of the storage magnet. A current monitor system has been developed in order to extract the beam current and geometrical information of three-dimensional trajectory. An electric chopper system to produce the pulsed beam and beam monitors to detect the pulsed beam will also be discussed in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW038

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paper received ※ 01 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW039

Multi-Ribbon Profile Monitor for High Power Proton Beam at J-PARC MR Abort Line

target, proton, extraction, emittance

2561

K. Sato
The University of Tokyo, Graduate School of Science, Tokyo, Japan
E. Hamada, Y. Hashimoto, S. Igarashi, T. Koseki, Y. Sato
KEK, Tsukuba, Japan

Japan Proton Accelerator Research Complex (J-PARC) Main Ring (MR), the world-class high intensity proton synchrotron, provides proton beam to two experimental facilities with two extraction modes: Fast extraction (FX) and Slow extraction (SX). The number of protons per pulse (ppp) in MR recorded the world highest value of 2.6×10¹⁴ in the FX mode. Now we are planning to increase the ppp further up to 3.3×10¹⁴ in near future. The beam profile is one of the most important parameters to discuss the high intensity beam dynamics in MR. Monitors using multi-wires / ribbons are effective to measure the beam profile with good accuracy and wide dynamic range. However, they cause significant beam losses by interactions with high-intensity circulating beam in synchrotrons. Recently, we installed new multi-ribbon profile monitor (MRPM) in an abort line in MR. The abort line is one of the extracted beam lines of the FX system. It has a quadrupole doublet which is called Abort Q and transports extracted beam to a beam dump. The FX system can extract the circulating beam in MR with an arbitrary energy. Performing the single-pass measurement with MRPM and changing the transfer matrix by sweeping field strength of Abort Q, the emittance of the extracted beam can be measured. In this paper, we present the design, manufacturing, and results of the first beam test of newly installed MRPM system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW039

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paper received ※ 01 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPGW041

Development of a Gas Distribution Measuring System for Gas Sheet Beam Profile Monitor

injection, experiment, detector, simulation

2567

I. Yamada
Doshisha University, Graduate School of Engineering, Kyoto, Japan
Y. Hikichi, J. Kamiya, M. Kinsho
JAEA/J-PARC, Tokai-mura, Japan
N. Ogiwara
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

The beam profile monitor is needed for measuring one of the beam parameters of high intensity accelerator to avoid radioactivating the systems. A monitor with sheet-shaped gas that can measure the beam profile nondestructively in two dimensions is developing. One of issues to introduce the monitor in accelerator is that the gas distribution is not uniform. Obtaining correct beam profile data needs to measure the gas distribution data because signal from the monitor is in proportion to beam intensity and gas distribution. A system analyzing distribution of ions produced from the gas using electron beam to measuring gas distribution in three dimensions is developing. An electron gun that produces ideal narrow beam, electrodes that forms parallel electric field toward micro-channel plate(MCP), and phosphor constitute the system. The electron beam that ionizes the gas which needs to be measured, produced ions are induced to MCP, and image on phosphor gives gas distribution data. In preliminary experiment for inspecting the measuring principle, experimental results agreed with simulation. The details of this system and the results of gas measuring experiment are reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW041

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paper received ※ 28 April 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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WEPGW044

Study on the Influence of Beam Transverse Position on the Cavity Bunch Length Measurement

cavity, simulation, dipole, laser

2578

Q. Wang, S.M. Jiang, Q. Luo, B.G. Sun
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Work supported by National Key R&D Program of China (Grant No. 2016YFA0401900 and No. 2016YFA0401903) and The National Natural Science Foundation of China (Grant No. U1832169 and No. 11575181).
Monopole modes in the resonant cavity are wildly used to obtain the beam current and the bunch length, while dipole modes are used to measure the beam transverse position. It is generally recognized that the monopole modes are independent of the beam transverse offset. In this paper, the influence of beam transverse offset on the bunch length measurement using monopole modes is analyzed. The simulation results show that the relative error of the bunch length measurement is less than 1 % when the beam offset is within 1 mm.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW044

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paper received ※ 25 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPGW045

Application of Clustering by Fast Search and Find of Density Peaks to Beam Diagnostics at SSRF

SRF, GUI, storage-ring, diagnostics

2581

R. Jiang, Y.B. Leng
SSRF, Shanghai, People’s Republic of China

With the increased technological complexity of accelera-tors, meeting the demand of beam diagnostics and opera-tion need more powerful and faster methods. And detect-ing the accuracy and stability of beam position moni-tors(BPMs) are important for all kinds of measurement systems and feedback systems in particle accelerator field. As an effective tool for data analysis and automa-tion, the machine learning methods had been used in accelerator physics field, recently. Among machine learn-ing methods, the clustering by fast search and find of density peaks as a typical unsupervised learning algo-rithms could be performed directly without training in arbitrary accelerator systems and could discover un-known patterns in the data. This paper used clustering by fast search and find of density peaks to detect faulty beam position monitor or monitoring beam orbit stability by analysis five typical parameters, that is beta oscilla-tion of X and Y direction(BetaX and BetaY), transverse oscillation of X and Y direction(AmpX and AmpY) and energy oscillation(AmpE). The results showed that cluster-ing by fast search and find of density peaks could classi-fy beam data into different clusters on the basis of their similarity. And that, aberrant run data points could be detected by decision graph. Morever, analysis results demonstrate the characteristic parameters AmpE, AmpX and BetaX amplitude have the same effect to distinguish the faulty BPMs and the AmpY and the BetaY amplitude are also.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW045

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW051

Designing of a Solenoid Lens for the Application to a Compact Electron Beam Testing Bench

solenoid, gun, space-charge, cathode

2591

S.Y. Lu, G. Feng, T. Hu, X.D. Tu, Y.Q. Xiong, P. Yang
HUST, Wuhan, People’s Republic of China

To calculate beams transport is vital for designing vacuum pipe and arranging focusing elements for each electron beam line system. Space charge effects of a low-energy, high-intensity DC electron beam focused by a solenoid lens with bucking coil are investigated theoretically in this paper. A second-order equation is numerical solved for the beam envelope focused by a short solenoid lens. In addition, a conventional transfer matrix of solenoid is not applicable to low-energy, high-intensity electron beams because the strong space charge effects are ignored. By cutting a solenoid into several segments, we have derived a micro-transfer matrix which takes space charge fields into account, and a complete beam envelope for a transport system. A simulation is used to verify our theoretical calculation results, and corresponding discussions are given in detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW051

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPGW053

Study with Wire Scanner and Beam Loss Monitor at CSNS-LINAC

MEBT, experiment, linac, neutron

2598

J.L. Sun, R.Y. Qiu, T. Yang
IHEP CSNS, Guangdong Province, People’s Republic of China
J.M. Tian, T.G. Xu, Zh.H. Xu, L. Zeng
IHEP, Beijing, People’s Republic of China

China Spallation Neutron Source (CSNS) consists of 80 MeV H⁻ LINAC, 1.6 GeV RCS, RTBT line and one target. Many wire scanners and beam loss monitors (BLM) distributed along the LINAC and the RTBT for the profile and beam loss measurement. For the wire scanner, signal on the wire induced by the secondary electron is used for the profile measurement. Signal lost may happen when the wire or the signal chain shorted, thus a backup readout chain is required for the accident condition. As for the BLM, it is difficult to do the online calibration to see how sensitive the monitor is. Based on the two requests above, a crosscheck study was carried out recently, one wire scanner and the BLM next to it were chose at LINAC and RTBT. Both wire signal and BLM signal were recorded while the wire scanner crossing the beam. We found these two type of signals have the same accuracy for the profile measurement, and ~ 1 μA beam loss induced by the wire disturbance can be detected. Also thermal electron emission suspected happening during the measurement. More detailed experiment will be carried out in December. Secondary electron emission efficiency of the tungsten wire and thermal electron emission rate will be verified then.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW053

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW055

Beam Longitudinal Distribution Reconstructed by GESPAR Method at CAEP THz FEL

radiation, FEL, laser, experiment

2602

D. Wu, T.H. He, P. Li, J. Liu, X. Luo, Q. Pan, L.J. Shan, X. Shen, J. Wang, D.X. Xiao, L.G. Yan, P. Zhang, K. Zhou
CAEP/IAE, Mianyang, Sichuan, People’s Republic of China

Funding: Work supported by National Natural Science Foundation of China with grant (11505173, 11505174, 11575264, and 11605190)
Coherent radiation can be used to measure the longitudinal distribution of the electron beam bunch of any length, as long as the coherent radiation spectrum can be measured. In many cases, the Kramers-Krönig relationship is used to reconstruct the temporal distribution of the beam from the coherent radiation spectrum. However, the extrapolation of the low frequency will introduce the uncertainty of the reconstruction. In this paper, GrEedy Sparse PhAse Retrieval (GESPAR) method was used to reconstruct the beam longitudinal distribution measured by coherent transition radiation on the THz FEL facility of China Academy of Engineering Physics. The results indicate that the GESPAR method works well for the complex and ultrashort distribution. It will be an effective tool to accurately measure the femtosecond bunch temporal structure.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW055

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paper received ※ 14 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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WEPGW060

Theoretical Analysis and Experimental Design of Terahertz Single-Pulse Picking based on Plasma Mirror

plasma, laser, target, FEL

2613

S.Y. Zhao, M. Li, P. Li, J. Wang, D. Wu, X. Yang
CAEP/IAE, Mianyang, Sichuan, People’s Republic of China

Funding: Work supported by National Natural Science Foundation of China with grant (11505173, 11505174, 11575264, and 11605190)
China Academy of Engineering Physics terahertz free electron laser (CTFEL) facility needs a terahertz switch for picking of single-pulse, which can facilitate the experiments that require high peak power but low average power. At present, many researches mainly focus on resonant tunneling effects, tunable metamaterials such as graphene and vanadium dioxide, nonlinear modulation based on the principle of all-optical switching, etc. However, the frequency range of these terahertz switches is generally not applicable to CTFEL(1.87-2.3THz). In this paper, self-induced plasma switching technology is applied to CTFEL. Single-pulse is reflected by a dense plasma in a Ge, Al or fused quartz slab that is photoexcited by laser system. Theoretical analysis and numerical simulation demonstrate the feasibility of the experiment. In addition, schematic layout of the experiment setup and specifications of the major instruments are given.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW060

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPGW063

Fiber-based Cherenkov Beam Loss and Beam Profile Monitor at BEPC II

linac, operation, instrumentation, beam-losses

2622

L. Yu, Y.F. Sui, L. Wang, D.C. Zhu
IHEP, Beijing, People’s Republic of China

A fiber-based Cherenkov beam loss monitor (CBLM) consisting of large core (400μm), long (50 m) multimode fibers, has been developed as an long-range detection tool for the BEPCII: primarily designed for radiation safety in order to limit the dose outside the shielding of the machine, this monitor also serves as an tool to measure beam profile with the wire sccaner. In this paper, principal of operation, instrumentation and programming of these CBLMs are discussed. Some results of beam loss and beam profile measurement with these CBLMs are also presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW063

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPGW067

The Study of Beam-Beam Effects on BINP Electron-Positron Colliders

injection, positron, detector, luminosity

2629

V.M. Borin, G.V. Karpov, O.I. Meshkov, D.N. Shatilov, D.B. Shwartz, M.V. Timoshenko
BINP SB RAS, Novosibirsk, Russia
V.L. Dorokhov
BINP, Novosibirsk, Russia

The beam-beam effects depending on the beams current and energy were studied at electron-positron colliders VEPP-2000 and VEPP-4M by the set of different diagnostics: the streak camera, optical dissector, BPM. The beam transverse profiles as well as longitudinal motion were acquired from the moment of a first collision of the beams in the interaction point up to the establishment of an equilibrium state. The spectra of the beams oscillation during this process as well as influence of the transverse feedback were studied. The obtained results are compared with a numerical simulations and discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW067

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW068

Measurements of Beam Parameters at the Last Track of the ERL-Based Novosibirsk Free Electron Laser

FEL, radiation, diagnostics, undulator

2632

V.M. Borin, Ya.V. Getmanov, A.S. Matveev, O.I. Meshkov, O.A. Shevchenko, N.A. Vinokurov
BINP SB RAS, Novosibirsk, Russia
V.L. Dorokhov
BINP, Novosibirsk, Russia
Ya.V. Getmanov
NSU, Novosibirsk, Russia
A.I. Mickailov
Budker INP & NSU, Novosibirsk, Russia

Parameters and dynamics of the electron beam of the Novosibirsk infrared Free Electron Laser are studied. The Novosibirsk FEL is based on the multi-turn energy recovery linac (ERL). The ERL operate in CW mode with an average beam current about 5 mA. Therefore non-destructive beam diagnostic methods are preferable. The beam energy at the last track of the ERL is 42 MeV. As a result, significant part of synchrotron radiation from bending magnets is in the visible range and can be used for diagnostic purposes. The transverse beam dimensions were measured with the optical diagnostics before (transition radiation) and after (synchrotron radiation from a bending magnet) the undulator applied for generation of middle-infrared coherent radiation. The obtained data are used to calculate the beam energy distribution and emittance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW068

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW072

Evaluation of Pilot-Tone Calibration Based BPM System at Elettra Sincrotrone Trieste

electronics, FPGA, injection, diagnostics

2638

P. Leban, M. Žnidarčič
I-Tech, Solkan, Slovenia
G. Brajnik, R. De Monte
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Stable and reliable beam position measurement is of paramount importance for the present and future light sources. Stabilization with a pilot-tone technique was developed by Elettra Sincrotrone Trieste and supported in the commercial BPM electronics Libera Spark. Both system components (the pilot-tone front-end and BPM electronics) are controlled through a common software interface which is compatible with TANGO, EPICS and LabVIEW/MATLAB clients. The system provides a reliable self-diagnostics, cable and button diagnostics and drift compensation. This paper presents results from beam measurements under different environmental and beam conditions.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW072

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paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW080

Design of Resonant Stripline BPM for an IR-FEL Project at NSRL

FEL, dipole, vacuum, emittance

2665

X.Y. Liu, B.G. Sun
USTC/NSRL, Hefei, Anhui, People’s Republic of China
M. Bopp, M.M. Dehler, X.Y. Liu, A. Scherer
PSI, Villigen PSI, Switzerland

Funding: Work supported by the National Science Foundation of China (11575181, 21327901, 11705203); X. Y. Liu was supported by the China Scholarship Council for a 2-year study at PSI (Grant No. 201706340057).
This paper presents the design of a 476MHz resonant stripline beam position monitor (BPM) for an IR-FEL machine at NSRL. This type of BPM was developed based on stripline BPM by moving the coupling feedthrough closer to the short end downstream. This modification introduces a resonance that gives this BPM a better capability to detect lower beam currents compared to broadband devices like button and stripline BPM. Meanwhile, the change is small enough to use the same type of electronics [1-3]. In the following sections, the basic principle, nonlinear effect, sensitivity, the filtered sum and difference signals, and the mechanical design of this BPM will be mainly discussed.
Email address: xiaoyu.liu@psi.ch

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW080

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paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPGW087

Control System Studio to Monitor Front End and Beamlines Status as well as Light Source Stability

status, operation, controls, photon

2687

W.Y. Lin, B.Y. Chen, C.S. Huang, C.H. Kuo, T.Y. Lee
NSRRC, Hsinchu, Taiwan

The primary task during a shift change at the Taiwan Photon Source Accelerator Operations team is to know the exact status of the machine, so that problems can be discovered immediately and solved when the machine behaves abnormal. To provide a stable beam during top-up operation, it is necessary to monitor closely the stability of the light source, of front end areas and beamlines. Should any abnormality occur, the operator would initiate initial troubleshooting and adjustments, inform users and sub-system staff members and perform subsequent first anal-yses and system optimizations. In this article, we describe how to sort through the nec-essary information with the Control System Studio (CSS) design page. There are currently seven beamlines in operation at the Taiwan Photon Source (05, 09, 21, 23, 25, 41, 45) and more new beamlines will be added in the future. Com-pared with other tools, CSS is intuitive and easy to revise. No matter weather adding new parameters or changing settings, the operation team can quickly get familiar with the machine status and perform an interface upgrade.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW087

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paper received ※ 27 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW089

Calibration of the AWAKE Electron Spectrometer with Electrons Derived from a Partially Stripped Ion Beam

proton, quadrupole, plasma, experiment

2694

D.A. Cooke, M. Cascella, J. Chappell, S. Jolly, F. Keeble, M. Wing
UCL, London, United Kingdom
R. Alemany-Fernández, J. Bauche, I. Gorgisyan, E. Gschwendtner, V. Kain, M.W. Krasny, S. Mazzoni, A.V. Petrenko
CERN, Meyrin, Switzerland
P. La Penna, M. Quattri
ESO, Garching bei Muenchen, Germany

The energy distribution of electrons accelerated in the wake of a self-modulated proton beam is measured using a magnetic spectrometer at AWAKE. The spectrometer was commissioned in 2017 and ran successfully throughout 2018. Imaging properties of the spectrometer system are studied via a combination of simulations and linear optics models and validated using mono-energetic electrons stripped from the partially stripped ion beam in the AWAKE beamline at CERN. These and other details of the calibration and performance will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW089

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPGW090

Emittance Evolution of Low Energy Antiproton Beams in the Presence of Deceleration and Cooling

emittance, proton, antiproton, closed-orbit

2697

J.R. Hunt, J. Resta-López, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
C. Carli, B. Dupuy, D. Gamba
CERN, Geneva, Switzerland
J.R. Hunt, J. Resta-López, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

The commissioning of the Extra Low Energy Antiproton (ELENA) ring has been completed before the start of the second long shutdown (LS2) at CERN. First beams to an experiment in a new experimental zone have as well already been delivered. ELENA will begin distributing 100 keV cooled antiproton beams to all antimatter experiments in 2021. This contribution presents measurements made using a novel scraping algorithm capable of determining the emittance of non-Gaussian beams in the presence of dispersive effects. The emittance is sampled during various sections of the ELENA deceleration cycle, investigating the efficiency of the electron cooler and extracting additional information from the beam. The electron cooler is shown to effectively reduce the transverse phase space after blow-up during deceleration. The beam is characterised before extraction for the purpose of tracking and optimisation of the new electrostatic transfer lines currently being installed. Finally, the application of the scraping algorithm to other machines with a scraper located in a dispersive region is discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW090

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPGW093

Commissioning of the Prototype for a New Gas Curtain Beam Profile Monitor Using Beam Induced Fluorescence for HL-LHC

photon, gun, background, experiment

2709

A. Salehilashkajani, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom
M. Ady, N. Chritin, J. Glutting, O.R. Jones, R. Kersevan, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness
CERN, Geneva, Switzerland
P. Forck, S. Udrea
GSI, Darmstadt, Germany
C.P. Welsch, H.D. Zhang
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work is supported by the HLLHCUK project and the STFC Cockcroft Institute core grant No. ST/G008248/1.
A new supersonic gas-jet curtain based beam profile monitor is under development for minimally invasive simultaneous transverse profile diagnostics of proton and electron beams, at pressures compatible with LHC. The monitor makes use of a thin gas-jet curtain angled at 45 degrees with respect to the charged particle beams. The fluorescence caused by the interaction between the curtain and the beam can then be detected using a dedicated imaging system to determine its transverse profile. This contribution details design features of the monitor, discusses the gas-jet curtain formation and presents various experimental tests, including profile measurements of an electron beam using nitrogen and neon curtains. The gas-jet density was estimated by correlating it with the number of photons detected by the camera. These measurements are then compared with results obtained using a movable pressure gauge. This monitor has been commissioned in collaboration with CERN, GSI and the University of Liverpool. It serves as a first prototype of a final design that will be placed in the LHC beam line to measure the profile of the proton beam.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW093

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPGW095

Coherent Transition Radiation Spatial Imaging as a Bunch Length Monitor

radiation, detector, simulation, focusing

2713

J. Wolfenden, R.B. Fiorito, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
M. Brandin, E. Mansten, S. Thorin
MAX IV Laboratory, Lund University, Lund, Sweden
R.B. Fiorito, C.P. Welsch, J. Wolfenden
Cockcroft Institute, Warrington, Cheshire, United Kingdom
B.S. Kyle, T.H. Pacey, T.H. Pacey
UMAN, Manchester, United Kingdom
B.S. Kyle
University of Manchester, Manchester, United Kingdom
E. Mansten
Lund University, Division of Atomic Physics, Lund, Sweden
T.H. Pacey
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A.G. Shkvarunets
UMD, College Park, Maryland, USA

Funding: This work was supported by the EU under Grant Agreement No. 624890 and the STFC Cockcroft Institute core Grant No. ST/G008248/1.
High-resolution bunch length measurement is a key component in the optimisation of beam quality in FELs, storage rings, and plasma-based accelerators. Simulations have shown that the profile of a coherent transition radiation (CTR) image produced by a charged particle beam is sensitive to bunch length and can thus be used as a diagnostic. This contribution presents the development progress of a novel bunch length monitor based on imaging the spatial distribution of CTR. Due to the bunch lengths studied, 10fs-100fs FWHM, the radiation of interest was in the THz range. This led to the development of a THz imaging system, which can be applied to both high and low energy electron beams. The associated benefits of this imaging distribution methodology over the typical angular distribution measurement are discussed. Building upon preliminary multi-shot proof of concept results last year, a new series of experiments have been conducted in the short pulse facility (SPF) at MAX IV. Single-shot measurements have been used to measure the exact point of maximum compression. Analysis from the proof of concept results last year, and initial results from the new measurements this year are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW095

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW096

Development of Supersonic Gas-Sheet-Based Beam Profile Monitors

photon, background, radiation, monitoring

2717

H.D. Zhang, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
M. Ady, J. Glutting, O.R. Jones, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness
CERN, Geneva, Switzerland
P. Forck, S. Udrea
GSI, Darmstadt, Germany
A. Salehilashkajani, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom

Funding: HL-LHC project funded by STFC and CERN, and the STFC Cockcroft core grant No. ST/G008248/1.
Non-destructive beam profile monitoring is very desirable, essentially for any particle accelerator but particularly for high-energy and high-intensity machines. Supersonic gas jet-based monitors, detecting either the ionization or fluorescence of a gas sheet interacting with the primary beam to be characterized, allow for minimally invasive measurements. They can also be used over a wide energy range, from keV to TeV beams. This contribution gives an overview of the jet-based ionization and fluorescence beam profile monitors which have been developed, built and tested at the Cockcroft Institute. It discusses gas sheet generation, vacuum considerations, choice of gas species and detection methods.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW096

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW099

Development of a Beam Halo Monitor

radiation, synchrotron-radiation, synchrotron, optics

2721

V.G. Dudnikov, R.P. Johnson, M. Popovic
Muons, Inc, Illinois, USA
M.A. Cummings
Northern Illinois University, DeKalb, Illinois, USA
R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA

Our innovative approach is to design the Beam Halo Monitor, where beam induced synchrotron radiation will be used to monitor the beam Halo. This involves an original scheme of light collection using a coronograph for measuring beam halo.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW099

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW103

Synchrotron Radiation Beam Diagnostics at IOTA - Commissioning Performance and Upgrade Efforts

optics, radiation, experiment, detector

2732

N. Kuklev, Y.K. Kim
University of Chicago, Chicago, Illinois, USA
J.D. Jarvis, A.L. Romanov, J.K. Santucci, G. Stancari
Fermilab, Batavia, Illinois, USA

Funding: Work supported by National Science Foundation award PHY-1549132, the Center for Bright Beams. Fermi Research Alliance operates Fermilab under Contract DE-AC02-07CH11359 with the US Dept. of Energy.
The Integrable Optics Test Accelerator is a research electron and proton storage ring recently commissioned at the Fermilab Accelerator Science and Technology facility. A key part of its beam diagnostics suite are synchrotron radiation monitors, used for measuring transverse beam profile, position, and intensity. In this paper, we report on the performance and uses of this system during the year 1 run. We demonstrate sub-100nm statistical beam position uncertainty and high dynamic range from 10⁹ electrons down to a single electron. Commissioning challenges and operational issues are discussed. We conclude by outlining current upgrade efforts, including improved modularity, small emittance measurements, and a multi-anode photomultiplier system for turn-by-turn acquisition.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW103

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paper received ※ 15 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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WEPGW104

The CBETA Beam Position Monitor (BPM) System Design and Strategy for Measuring Multiple Simultaneous Beams in the Common Beam Pipe

timing, injection, hardware, MMI

2736

R.J. Michnoff, R.L. Hulsart
BNL, Upton, Long Island, New York, USA
J. Dobbins
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
CBETA, a 4-pass electron Energy Recovery Linac (ERL) is presently under construction at Cornell University and is a collaboration between Brookhaven National Laboratory (BNL) and Cornell University. Beam commissioning began in March 2019 with a single pass ERL configuration. Commissioning of the complete 4-pass machine is scheduled to begin in fall 2019. The fixed field alternating gradient (FFA) return loop for CBETA uses Halbach permanent magnets with a common beam pipe for seven different energy beams (4 accelerating energies and 3 decelerating energies). One of the most challenging requirements for the CBETA BPM system is to independently measure the position of each of these beams. The overall design of the CBETA BPM system and the techniques planned to measure the position of each energy beam will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW104

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPGW108

Transverse Uncorrelated Emittance Diagnostic for Magnetized Electron Beams

emittance, diagnostics, simulation, cathode

2745

M.S. Stefani
ODU, Norfolk, Virginia, USA
F.E. Hannon
JLab, Newport News, Virginia, USA

Funding: This manuscript has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy.
The study of magnetized electron beam has become a high priority for its use in ion beam cooling as part of Electron Ion Colliders and the potential of easily forming flat beams for various applications. In this paper, a new diagnostic is described with the purpose of studying transverse magnetized beam properties. The device is a modification to the classic pepper-pot, used in this novel context to measure the uncorrelated components of transverse emittance in addition to the typical effective emittance. The limitations of traditional methods are discussed, and simulated demonstrations of the new technique shown.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW108

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW110

Feasibility Study of Beam Profile Measurements Using Interferometer and Diffractometer Techniques for ALS-U

synchrotron, storage-ring, radiation, lattice

2752

C. Sun, S. De Santis, D. Filippetto, F. Sannibale, C. Steier
LBNL, Berkeley, California, USA

Funding: Work supported by the Director Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
ALS-U is an ongoing upgrade of Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. The upgraded ALS will replace the existing Triple-Bend Achromat (TBA) storage ring lattice with a compact Multi-Bend Achromat (MBA) lattice. This MBA technology allows us to tightly focus electron beams down to about 10 μm to reach diffraction limit in a soft x-ray region. The beam size measurement is a challenging task for this tightly focused beam. The interferometer technique with visible light from synchrotron radiation has been developed in many facilities to measure their beam size at a micrometer-level accuracy. In this paper, we will present the feasibility study of this technique for the ALS-U storage ring beam size measurement.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW110

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW112

Energy Calibration of the Rea3 Accelerator by Time-of-Flight Technique*

dipole, cyclotron, linac, detector

2760

A.C.C. Villari, D.B. Crisp, A. Lapierre, S. Nash, T. Summers, Q. Zhao
NSCL, East Lansing, Michigan, USA

Funding: * This material is based upon work supported by the National Science Foundation under Grant No. PHY15-65546.
We report on a simple method to perform an absolute calibration of the magnetic beam analyser of the reaccelerator ReA3 at the National Superconducting Cyclotron Laboratory. The method is based on the time of flight between two beam stoppers 7.65 m apart. Based on two independent time-of-flight measurements at three different beam energies, the beam analyser magnet is calibrated with an accuracy of 0.12 %, corresponding to a beam energy accuracy of 0.24 %.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW112

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paper received ※ 25 April 2019 paper accepted ※ 28 May 2019 issue date ※ 21 June 2019

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WEPGW113

Propose a Non-Destructive Stern-Gerlach Apparatus for Measuring the Spin Polarization of Electron Beam

quadrupole, polarization, simulation, software

2763

W. Liu, E. Wang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Mott polarimeter is used for measuring the spin polarization of <10 MeV electron beam destructively. We propose a nondestructive spin polarization measurement device for electron beam based on Stern-Gerlach effect, which include a magnetic quadrupole, Lorenz force compensated electric quadrupole and Beam position monitor. The magnetic quadrupole provides a spin-magnetic interaction force (or Stern-Gerlach force) for the spin polarized electrons. The electric quadrupole provides an electric field force for electrons to offset the Lorentz force induced by the magnetic quadrupole. So that the polarized electron beam only experience the gradient force in the device, which has ability to split the spin polarized electron beam. By measuring the split spin polarized electrons using high resolution beam position monitor, the polarization of electron beam can be calculated. We will present the theoretical analysis and calculation of electron motion in this device.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW113

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paper received ※ 01 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPGW114

Interferometric Measurement of Bunch Length of a 3Mev Picocoulomb Electron Beam

laser, cathode, experiment, space-charge

2766

X. Yang, M. Babzien, B. Bacha, G.L. Carr, W.X. Cheng, L. Doom, M.G. Fedurin, B.N. Kosciuk, J.J. Li, D. Padrazo Jr, T.V. Shaftan, V.V. Smaluk, C. Swinson, L.-H. Yu, Y. Zhu
BNL, Upton, Long Island, New York, USA

Funding: BNL LDRD
We report the bunch length measurement of low-energy 3 MeV electron beams in picosecond regime with the charge from 1.0 to 14 pC. It is the first time that we demonstrate single-cycle nano-joule coherent terahertz (THz) radiation from 3MeV electron beam can be meas-ured via a far-infrared Michelson interferometer using a QOD. At this low energy range, when charge is about 1 pC, the signal from the conventional helium-cooled sili-con composite bolometer is too low. Compared to the bunch length measurement via the ultrafast-laser-pump and electron-beam-probe in the timescale 10^-14 to 10-12 s which is determined by the phase-transition dynamics in solids, the advantages are: there are no needs of pump laser and probe sample, greatly simplifying the experi-ment; the timing jitter between laser and electron beams contributes no error to the bunch length measurement; furthermore, the method can be extended to sub-picosecond regime enabling bunch length measurement in a much broader timescale 10-14 to 10-11 s for low-energy electron beams. In the current experiment the bunch length is limited to 1 ps only because the setup of driving laser to cathode with a large 70° incident angle, effective-ly lengthening the laser pulse to ≥1 ps.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW114

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPGW115

Radiation Robust RF Gas Beam Detector R&D for Intensity Frontier Experiments

detector, cavity, GUI, plasma

2770

K. Yonehara, A. Moretti
Fermilab, Batavia, Illinois, USA
M.A. Cummings, R.P. Johnson, G.M. Kazakevich
Muons, Inc, Illinois, USA

A novel radiation robust RF gas beam detector has been demonstrated by using the Main Injector beam at Fermilab. The detector demonstrated a stable signal gain, fast response time, and high radiation resistivity with intense proton beams. The plasma process in the detector is studied to validate the plasma physics model. The result suggests that the detector is applicable for Long Baseline Neutrino Facility at Fermilab. To prepare for the LBNF, a proto type detector will be made and applied for the Neutrino at Main Injector target system. Progress of the project will be given in the presentation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW115

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW121

Update on the JLEIC Electron Collider Ring Design

collider, optics, quadrupole, solenoid

2780

F. Lin, V.S. Morozov, Y. Zhang
JLab, Newport News, Virginia, USA
Y. Cai, Y.M. Nosochkov
SLAC, Menlo Park, California, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, and Office of Nuclear Physics under Contracts DE-AC05-06OR23177 and DE-AC02-76SF00515.
The design concept of electron collider ring in the Jefferson Lab Electron-Ion Collider (JLEIC) is based on a small beam size at the interaction point (IP) to boost the luminosity. With a chosen beta-star at the IP, electron beam size is determined by the equilibrium emittance obtained from the linear optics design. In this paper, we present an update on the lattice design of the electron ring considering not only preservation of low beam emittance, but also optimization of geometric arrangement. In particular, recent development of the lattice design has been focused on incorporating the vertical dogleg, which brings the electron beam to the ion beam plane for collisions, in the spin rotator design. The vertical dogleg is designed with no horizontal emittance growth, controlled vertical emittance and no first-order effect on the electron polarization.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW121

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paper received ※ 21 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPGW123

Full Acceptance Interaction Region Design of JLEIC

detector, dipole, coupling, interaction-region

2787

V.S. Morozov, R. Ent, Y. Furletova, F. Lin, T.J. Michalski, R. Rajput-Ghoshal, M. Wiseman, R. Yoshida, Y. Zhang
JLab, Newport News, Virginia, USA
Y. Cai, Y.M. Nosochkov, M.K. Sullivan
SLAC, Menlo Park, California, USA
G.L. Sabbi
LBNL, Berkeley, California, USA

Funding: This material is based upon work supported by the U.S. DoE under Contracts No. DE-AC05-06OR23177, DE-AC02-76SF00515, and DE-AC03-76SF00098.
Nuclear physics experiments envisioned at a proposed future Electron-Ion Collider (EIC) require high luminosity of 10³³-10³⁴ cm^-2s^-1 and a full-acceptance detector capable of reconstruction of a whole electron-ion collision event. Due to a large asymmetry in the electron and ion momenta in an EIC, the particles associated with the initial ion tend to go at very small angles and have small rigidity offsets with respect to the initial ion beam. They are detected after they pass through the apertures of the final focusing quadrupoles. Therefore, the apertures must be sufficiently large to provide the acceptance required by experiments. In addition, to maximize the luminosity, the final focusing quadrupoles must be placed as close to the interaction point as possible. A combination of these requirements presents serious detection, optics and engineering design challenges. We present a design of a full-acceptance interaction region of Jefferson Lab Electron-Ion Collider (JLEIC). The paper presents how this design addresses the above requirements up to an ion momentum of 200 GeV/c. We summarize the magnet parameters, which are kept consistent with the Nb-Ti superconducting magnet technology.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW123

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paper received ※ 23 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPRB008

Design Study of High Gradient Compact S-band TW Accelerating Structure for the ThomX LINAC Upgrade

linac, HOM, vacuum, emittance

2807

M. El Khaldi, M. Alkadi, C. Bruni, L. Garolfi, A. Gonnin, H. Monard
LAL, Orsay, France

ThomX is a Compton source project in the range of the hard X rays (45/90 keV). The machine is composed of a 50/70 MeV injector Linac and a storage ring where an electron bunch collides with a laser pulse accumulated in a Fabry-Perot resonator. The final goal is to provide an X-rays average flux of 10¹²-10¹³ ph/s. A demonstrator was funded and is being built on the Orsay university campus. The S-band injector Linac consists of 2.5 cell photocathode RF gun and a TW accelerating section. During the commissioning phase, a standard LIL S-band accelerating section is able to achieve around 50 MeV corresponding to around 45 keV X-rays energy. Since the maximum targeted X-ray energy is 90 keV, the development of a new S-band accelerating section, intended to replace the LIL structure, will provide an electron beam energy of 70 MeV. This requires essentially the development of more reliable high gradient compact S band accelerating section. Such design is tailored for high gradient operation, low breakdown rates. We present here the RF design of the LINAC upgrade and the performances obtained in terms of beam dynamics.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB008

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paper received ※ 02 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPRB020

Compact Ultra High-Gradient Ka-Band Accelerating Structure for Research, Medical and Industrial Applications

linac, accelerating-gradient, operation, gun

2842

L. Faillace
INFN-Milano, Milano, Italy
M. Behtouei
Sapienza University of Rome, Rome, Italy
V.A. Dolgashev
SLAC, Menlo Park, California, USA
B. Spataro, A. Variola
INFN/LNF, Frascati, Italy
G. Torrisi
INFN/LNS, Catania, Italy

Technological advancements are strongly required to fulfil demands for new accelerators devices from the compact or portable devices for radiotherapy to mo-bile cargo inspections and security, biology, energy and environmental applications, and ultimately for the next generation of colliders. In the frame of the collab-oration with INFN-LNF, SLAC (USA) we are working closely on design studies, fabrication and high-power operation of Ka-band accelerating structures. In par-ticular, new manufacturing techniques for hard-copper structures are being investigated in order to determine the maximum sustainable gradients above 150 MV/m and extremely low probability of RF breakdown. In this paper, the preliminary RF and mechanical design as well as beam dynamics estimations for a Ka-Band accelerating structure at 35 GHz are presented together with discussions on practical accelerating gradients and maximum average beam current throughput.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB020

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paper received ※ 08 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPRB024

Low Power RF Test of a Quadrupole-free X-Band Mode Launcher for High Brightness Applications

GUI, brightness, quadrupole, simulation

2856

G. Torrisi, L. Celona, S. Gammino, O. Leonardi, G. Sorbello
INFN/LNS, Catania, Italy
G. Castorina
Sapienza University of Rome, Rome, Italy
V.A. Dolgashev
SLAC, Menlo Park, California, USA
L. Faillace
INFN-Milano, Milano, Italy
G.S. Mauro
INFN/LNL, Legnaro (PD), Italy
G. Sorbello
University of Catania, Catania, Italy
B. Spataro
INFN/LNF, Frascati, Italy

In this work we present the low power RF characterization of a novel TM01 X-band mode launcher for the new generation of high brightness RF photo-injectors. The proposed mode launcher exploits a fourfold symmetry which minimizes both the dipole and the quadrupole fields in order to mitigate the emittance growth in the early stages of the acceleration process. Two identical aluminum mode launchers have been assembled and measured in back-to-back configurations for three different central waveguide lengths. From the back-to-back results we infer the performance of each mode launcher. The low power RF test, performed at the Istituto Nazionale di Fisica Nucleare Laboratori Nazionali del Sud (INFN-LNS), validate both the numerical simulations and the quality of fabrication. An oxygen-free high-conductivity copper version of the device is being manufactured for high power and ultra high vacuum tests that are planned to be conducted at SLAC

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB024

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paper received ※ 09 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPRB027

Electromagnetic Design and Characterization of an S-band 3-Cell RF Accelerating Cavity

cavity, emittance, simulation, acceleration

2867

G.R. Montoya Soto
Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
C. Duarte Galván, C.A. Valerio
ECFM-UAS, Culiacan, Sinaloa, Mexico
B. Yee-Rendón
JAEA/J-PARC, Tokai-mura, Japan

An S-Band (2998 MHz) RF cavity to accelerate electrons was developed taking into account the beam space charge, the relativistic change in velocity of the low energy beam particle distribution through the cavity and the emittance growth. The electromagnetic design and geometry optimization were done using the codes Poisson Superfish and CST Studio. In addition, beam dynamics simulations were done using the program Travel to optimize the emittance and take into account the space charge effect. The machining was done in a CNC machining center. Measurements of the cavity resonance frequencies were carried out and compared with the obtained by the simulations with good agreement between them.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB027

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paper received ※ 30 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPRB031

SRF Trip Caused by the Tuner in BEPCII

SRF, cavity, operation, collider

2880

J.P. Dai, Z.H. Mi, P. Sha, Y. Sun, Q.Y. Wang, L.G. Xiao
IHEP, Beijing, People’s Republic of China

Funding: Work support by Natural Science Foundation of China (11575216)
The stability and reliability of the Superconducting RF system (SRF) is generally a key issue in a large scale accelerator such as Beijing Electron Positron Collider II (BEPCII). In the past several years, SRF is one of the main factors limiting the availability of BEPCII, and many efforts have been made to fix the SCRF troubles. This paper focuses on the details of the SCRF trip caused by the tuner, which is one of the most persistent troubles and figured out till the summer of 2018.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB031

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paper received ※ 08 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPRB042

High Power Test of the First C-band Spherical Pulse Compressor Prototype

GUI, cavity, FEL, linac

2896

Z.B. Li
SINAP, Shanghai, People’s Republic of China
W. Fang, Q. Gu, X.X. Huang, J.H. Tan, Z.T. Zhao
SSRF, Shanghai, People’s Republic of China

Funding: National Natural Science Foundation of China (No. 11675249)
Recently, a new C-band (5712 MHz) compact spherical radio frequency (RF) pulse compressor was designed and tested for Shanghai Soft X-ray Free Electron Laser Facili-ty (SXFEL). This pulse compressor utilizes one high Q₀ spherical RF resonant cavity that works with two TE1, 1,3 modes and a dual-mode polarized coupler. The peak power multiply factor is 6.1 and average power gain 3.8 in theory. During the high power test, a peak power mul-tiply factor of 5.74 and average power gain of 3.77 was achieved. This paper presents the RF measurement of the C-band spherical pulse compressor and the high power test results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB042

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paper received ※ 19 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPRB045

Suppression of Secondary Electron Yield Effect in the 650MHz/800kW Klystron for CEPC

cavity, klystron, simulation, multipactoring

2906

X. He, C. Meng, S. Pei, J.L. Wang, O. Xiao, N. Zhou
IHEP, Beijing, People’s Republic of China

The circular electron positron collider (CEPC) is in pre-research, it will need more than two hundred 650MHz/800kW klystrons. The secondary electron yield (SEY) effect suppression is very important for the klystron working stable. The simulation uses an incident primary electron source and considers all the phases and power levels of the input microwave. Two methods are simulated for the SEY suppression. The groove cutting on the nose of cavities is much simple while the TiN coating can suppress better. The effect after groove cutting on nose is also simulated and the corresponding compensations are adopted. For simplify the fabrication progress as well as some experience that can be referenced, the groove cutting method is adopted finally for the first klystron prototype, which is expected to be available in the summer of 2019.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB045

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPRB048

Design, Fabricate, and Tuning of X-Band Deflecting Structure for CERN

simulation, cavity, GUI, free-electron-laser

2915

J.H. Tan, W. Fang, Q. Gu, X.X. Huang, Z.T. Zhao
SSRF, Shanghai, People’s Republic of China

A 20-cell x-band deflecting structure for CERN has been finished, and now is under high power conditioning at XBOX of CERN.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB048

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPRB049

HOM Analysis of the 4-cell Superconducting Cavity on CTFEL Facility

HOM, cavity, FEL, simulation

2918

X. Luo, T.H. He, C.L. Lao, L.J. Shan, X.M. Shen, D. Wu, K. Zhou
CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
F. Wang
PKU, Beijing, People’s Republic of China

The higher order modes (HOMs) of the 1.3GHz 4-cell cavity on CTFEL facility is analyzed in this paper. The passbands of the HOMs in the 4-cell cavity were simulat-ed, and the most harmful modes were determined. The power of the wakefields was estimated. By microwave test at room temperature, the frequencies of the HOMs were measured, as well as the external Q’s of the HOM cou-plers. Besides, a frequency distribution measurement system was built. The HOM signal excited by beam at 2 K temperature is measured, and some preliminary results are obtained. The measurement techniques and results of the HOM damping performance are presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB049

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPRB054

Design of the Multiplexing Optical Measurement System for a Pre-bunched THz Free Electron Laser

laser, radiation, detector, FEL

2931

Y.K. Zhao, W. Li, B.G. Sun, Y.G. Tang, F.F. Wu, T.Y. Zhou
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Work supported by the the Fundamental Research Funds for the Central Universities (WK2310000080, WK2310000057), and the National Science Foundation of China (11705203, 11575181)
A new and compact a pre-bunched terahertz (THz) free electron laser (FEL) at the National Synchrotron Radiation Laboratory, University of Science and Technology of China is being constructed and aims to generate the tunable radiation frequency ranges from 0.5 THz to 5 THz at 11-18 Mev electron energy. This system is expected to use for imaging, basic researches as well as industrial applications as a result of the significant merits of simple, compact and cost-effective. Due to the THz laser measurement system plays an important part in the pre-bunched THz FEL facility. Therefore, a multiplexing THz laser sensing measurement system model is developed for measuring the output laser power and the optical spectrum of THz radiation with the excellent advantages of robustness, high sensitivity and low-cost in this paper.
Corresponding author (email: tiany86@ustc.edu.cn)
Corresponding author (email: wufangfa@ustc.edu.cn)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB054

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPRB055

Design of 3 MeV S-band Electron Linac Structure With 2.5 Bunching Cells

bunching, linac, coupling, simulation

2934

Y. Joo, P. Buaphad, H.R. Lee
University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
Y. Kim
KAERI, Daejon, Republic of Korea
J.Y. Lee, S. Lee
Korea Atomic Energy Research Institute (KAERI), Daejeon, Republic of Korea

Funding: UST (University of Science and Technology), KAERI (Korea Atomic Energy Research Institute)
The Korea Atomic Energy Research Institute (KAERI) has been designing several 3 MeV S-band RF electron linear accelerators (linacs) for non-destructive testing. Until now, the bunching cell of the linac has a full-cell geometry. However, to maximize the acceleration of electrons after emission from the electron gun, the geometry of the first bunching cell is modified from a full-cell to a half cell. To accelerate electron beams more gently, recently, we increased the total number of bunching cells from 1.5 to 2.5. In this paper, we describe design concepts and detailed optimization processes of a 3 MeV linac with the 2.5 bunching cells to optimize RF parameters such as the quality factor, resonance frequency, and uniformity of electric field distribution along the linac. Lastly, we will discuss the application of 3 MeV linac.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB055

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paper received ※ 04 June 2019 paper accepted ※ 16 June 2019 issue date ※ 21 June 2019

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WEPRB058

Combined Field Emission and Multipactor Simulation in High Gradient RF Accelerating Structures

multipactoring, simulation, cavity, GUI

2940

D. Banon-Caballero
IFIC, Valencia, Spain
N. Catalán Lasheras, K.T. Szypula, W. Wuensch
CERN, Geneva, Switzerland
A. Faus-Golfe
LAL, Orsay, France
B. Gimeno
UVEG, Burjasot (Valencia), Spain

Field emitted electrons have important consequences in the operation of high-gradient RF accelerating structures both by generating so-called dark currents and initiating RF breakdown. The latter is an important limitation of the performance in such devices. Another kind of vacuum discharge that primarily affects the operation of lower-field RF components, for example those used in space applications, is multipactor. Theoretical simulations using CST Particle Studio, show that field emitted electrons generated in the high field regions of high-gradient accelerating cavities migrate to low field regions under ponderomotive forces potentially triggering multipactor there. This phenomenon is an interplay between high field and low field processes which may have as a consequence that multipactor actually affects to the performance of high-gradient cavities because field emitted electrons might reduce the timescales for the onset of multipactor.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB058

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paper received ※ 27 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPRB059

Dark Current Analysis at CERN’s X-band Facility

radiation, operation, ECR, linac

2944

D. Banon-Caballero, M. Boronat, V. Sánchez Sebastián, A. Vnuchenko
IFIC, Valencia, Spain
N. Catalán Lasheras, S. Pitman, M. Widorski, W. Wuensch, V. del Pozo Romano
CERN, Meyrin, Switzerland
A. Faus-Golfe
LAL, Orsay, France
B. Gimeno
UVEG, Burjasot (Valencia), Spain
T.G. Lucas, M. Volpi
The University of Melbourne, Melbourne, Victoria, Australia
W.L. Millar
Lancaster University, Lancaster, United Kingdom
J. Paszkiewicz
University of Oxford, Oxford, United Kingdom

Dark current is particularly relevant during operation in high-gradient linear accelerators. Resulting from the capture of field emitted electrons, dark current produces additional radiation that needs to be accounted for in experiments. In this paper, an analysis of dark current is presented for four accelerating structures that were tested and conditioned in CERN’s X-band test facility for CLIC. The dependence on power, and therefore on accelerating gradient, of the dark current signals is presented. The Fowler-Nordheim equation for field emission seems to be in accordance with the experimental data. Moreover, the analysis shows that the current intensity decreases as a function of time due to conditioning, but discrete jumps in the dark current signals are present, probably caused by breakdown events that change the emitters’ location and intensity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB059

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paper received ※ 10 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPRB062

Spatially Resolved Dark Current in High Gradient Traveling Wave Structures

linac, diagnostics, site, collider

2956

J. Paszkiewicz, W. Wuensch
CERN, Meyrin, Switzerland
P. Burrows
JAI, Oxford, United Kingdom
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

High-gradient accelerating structures are known to produce field-emitted current from regions of high surface field, which are captured and accelerated by the fields within the structure. This current is routinely measured in structures under test in the CLIC high-gradient test stands using Faraday cups. This paper presents a novel technique to spatially resolve the longitudinal distribution of field emitted current by analysing downstream Faraday cup signals when the structure is fed with RF pulses much shorter than its filling time. Results from this method applied to X-band cavities operating at 100 MV/m are presented, and are compared to breakdown position distributions. A decay in emitted current as conditioning progressed in regions with a low breakdown rate and large jumps in regions with a large breakdown rate are observed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB062

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paper received ※ 29 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPRB063

Connection of 12 GHz High Power RF from the XBOX 1 High Gradient Test Stand to the CLEAR Electron LINAC

LLRF, klystron, linac, software

2960

A.V. Edwards
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
N. Catalán Lasheras, S. Gonzalez Anton, G. McMonagle, S. Pitman, B.J. Woolley, V. del Pozo Romano
CERN, Meyrin, Switzerland

A new RF system is being established at XBOX1 to drive two §I{100}{MV/m} CLIC structures in the CLEAR electron linac. In the past, these structures had been powered by RF from PET structures excited by a drive beam. This drive beam is no longer available. The upgrade will reroute power from the §I{50}{MW} klystron and pulse compressor which was previously used to power the structure in XBOX1. During the upgrade, the LLRF system will be optimised to improve the modulation of the output signals and down-mixing of the returning signals to obtain accurate phase and amplitude information. The design of the improved LLRF and software, along with phase noise measurements and comparisons with the old system are made in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB063

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPRB072

Ultra-High Gradient Short RF Pulse Gun

gun, cathode, emittance, brightness

2987

S.P. Antipov, P.V. Avrakhov, S.V. Kuzikov, A. Liu
Euclid TechLabs, LLC, Solon, Ohio, USA
G. Ha, J.G. Power
ANL, Argonne, Illinois, USA

Funding: DOE SBIR DE-SC0018709
High brightness beams enable novel applications like x-ray free electron lasers and ultrafast electron microscopes. High brightness beams essentially consist of a large number of electrons in a small phase space volume, i.e. a high peak current. When such beams are generated from the cathode, there is a strong space charge force, which elongates the bunch and reduces its brightness. An optimal solution is to raise the accelerating voltage in the gun. However, the maximum gradient is limited by the effects of RF breakdown. The probability of RF breakdown is reduced as the RF pulse length decreases. We present a development of an electron photoinjector operating with short RF pulse, 10 ns scale. We have designed an X-band gun including the RF design, beam quality optimization, and engineering. The gun will be fed by 10 ns, 300 MW RF pulse generated at the Argonne Wakefield Accelerator Facility for two-beam acceleration experiments. We also manufactured an aluminum prototype and measured its microwave properties, most importantly, fill time. The proposed high brightness beam source can be used as the main beam in wakefield accelerators. It will find commercial applications in ultrafast electron diffraction and microscopy systems.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB072

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paper received ※ 21 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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WEPRB073

CW Room Temperature Accelerating Structures

impedance, operation, radiation, SRF

2990

S.P. Antipov, P.V. Avrakhov, E. Gomez, S.V. Kuzikov
Euclid TechLabs, LLC, Solon, Ohio, USA
A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

To this day CW linear electron accelerators were based only on expensive and bulky (embedded in a cryostat) superconducting accelerating structures. CW regime can in principle be realized with normal conducting structures provided the shunt impedance is high. Such structures can be designed using dielectrics (ultra-pure ceramics in C-band and diamond in mm-waves) with ultra-low loss tangent (~10-6). The use of dielectrics allows to concentrate the electromagnetic energy density in the dielectric region and thus minimize fields and ohmic loss on metallic walls. The thermal loss in dielectric can be relatively low given the loss tangent is small. We report here the design of structures with shunt impedance on the order of 10⁴ MOhm/m, which is several orders of magnitude higher than shut impedance in copper structures in GHz and THz range. High shunt impedance makes it possible to accelerate electrons to 1 MeV using kW-level CW RF sources like magnetrons in C-band and gyrotrons in THz range. Such CW accelerators will find applications in sterilization, food irradiation, industrial radiography and cargo inspection.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB073

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paper received ※ 21 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPRB076

Analysis of Higher Order Multipoles of the 952.6 Mhz RF-Dipole Crabbing Cavity for the Jefferson Lab Electron-Ion Collider

cavity, multipole, dipole, HOM

2996

S.U. De Silva, J.R. Delayen, S. Sosa
ODU, Norfolk, Virginia, USA
V.S. Morozov, H. Park
JLab, Newport News, Virginia, USA

The crabbing system is a key feature in the Jefferson Lab Electron-Ion Collider (JLEIC) required to increase the luminosity of the colliding bunches. A local crabbing system will be installed with superconducting rf-dipole crabbing cavities operating at 952.6 MHz. The field non-uniformity across the beam aperture in the crabbing cavities produces higher order multipole components, similar to that which are present in magnets. Knowledge of higher order mode multipole field effects is important for accurate beam dynamics study for the crabbing system. In this paper, we quantify the multipole components and analyse their effects on the beam dynamics.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB076

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paper received ※ 20 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPRB084

Mechanical Design and Analysis of the Proposed APEX2 VHF CW Electron Gun

cavity, gun, vacuum, cathode

3014

A.R. Lambert, H.Q. Feng, D. Filippetto, M.J. Johnson, D. Li, T.H. Luo, C.E. Mitchell, F. Sannibale, J.W. Staples, S.P. Virostek, R.P. Wells
LBNL, Berkeley, California, USA

Funding: Work supported by the Office of Science, U.S. Department of Energy under DOE contract number DEAC02-05CH11231
Normal conducting radio-frequency (RF) guns resonating in the very high frequency (VHF) range (30-300 MHz) and operating in continuous wave (CW) mode have successfully achieved the targeted brightness and reliability necessary for upgrading the performance of current lower repetition rate accelerator-based instruments such as X-ray free electron lasers (FELs), and ultra-fast electron diffraction (UED) and microscopy (UEM). The APEX2 (Advanced Photo-injector Experiment 2) electron gun is a proposed upgrade for the current LCLS-II injector, which was based on the original APEX design. In contrast, APEX2 is designed as a two-cell cavity operating at 162.5 MHz with a launching field at the cathode equal to 34 MV/m, producing a beam energy of 1.5 to 2 MeV, more than double APEX. Operation of the gun in this condition will require upwards of 200 kW of RF power, thus proper thermal management is crucial to achieve target performance. This paper describes the current design, thermal performance and tuning methods.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB084

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paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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WEPRB089

Theoretical Analysis of Quasiparticle Overheating, Positive Q-Slope, and Vortex Losses in SRF Cavities

cavity, SRF, niobium, experiment

3020

J.T. Maniscalco, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T. Arias, D. Liarte, J.P. Sethna, N. Sitaraman
Cornell University, Ithaca, New York, USA

The surface resistance of an SRF cavity is an important measure of its performance and utility: lower resistance leads directly to lower cryogenic losses and power consumption. This surface resistance comprises two components, namely the ‘‘BCS resistance’’, which depends strongly on the quasiparticle temperature, and a temperature-independent ‘‘residual resistance’’, which is often dominated by losses due to trapped magnetic vortices. Both components are generally dependent on the RF field strength. Here we present a summary of recent theoretical advances in understanding the microscopic mechanisms of the surface resistance, in particular addressing niobium hydride formation and quasiparticle overheating (using the tools of density functional theory) and discussing issues with existing models of the positive Q-slope, a field-dependent decrease in the BCS resistance, and possible paths for improvement of these models. We also discuss trapped flux losses using ideas from collective weak pinning theory.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB089

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paper received ※ 20 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPRB093

Design of a Proof-of-principle Crabbing Cavity for the Jefferson Lab Electron-ion Collider

cavity, HOM, collider, luminosity

3027

H. Park, S.U. De Silva, J.R. Delayen, S.I. Sosa Guitron
ODU, Norfolk, Virginia, USA
J.R. Delayen, H. Park
JLab, Newport News, Virginia, USA

The Jefferson Lab design for an electron-ion collider (JLEIC) requires crabbing of the electron and ion beams in order to achieve the design luminosity. A number of options for the crabbing cavities have been explored, and the one which has been selected for the proof-of-principle is a 952 MHz, 2-cell rf-dipole (RFD) cavity. This paper summarizes the electromagnetic design of the cavity and its HOM characteristics.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB093

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paper received ※ 22 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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WEPRB094

Measurements of the Electrical Axes of the CeC PoP RF Cavities

cavity, cathode, gun, SRF

3031

I. Petrushina
SUNY SB, Stony Brook, New York, USA
Y.C. Jing, V. Litvinenko, J. Ma, I. Pinayev, K. Shih, G. Wang
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
K. Shih
SBU, Stony Brook, New York, USA

It is common knowledge that every mode in an SRF cavity has a so-called electrical axis, and only in an ideal cavity would this axis align exactly with the geometrical axis of the device. The misalignment of the electrical axis creates an additional undesirable transverse kick to the beam, which has to be corrected to achieve the designed beam parameters. In this paper we present the two methods which have been used in order to determine the electrical axes in the RF cavities of the Coherent electron Cooling (CeC) Proof of Principle (PoP) accelerator. The electron accelerator for the CeC PoP consists of the three main RF components: the 113 MHz SRF gun, the two normal-conducting 500 MHz bunching cavities, and the 704 MHz SRF 5-cell elliptical cavity. We discuss, in detail, the specifics of the measurement for each cavity and provide the corresponding results. In addition, we describe the influence of the field asymmetry in the 500 MHz bunchers on the beam dynamics, which was observed experimentally and confirmed by simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB094

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPRB095

Microbunching Plasma-Cascade Instability

plasma, simulation, bunching, focusing

3035

V. Litvinenko
Stony Brook University, Stony Brook, USA
T. Hayes, Y.C. Jing, D. Kayran, J. Ma, T.A. Miller, G. Narayan, I. Pinayev, F. Severino, G. Wang
BNL, Upton, Long Island, New York, USA
I. Petrushina
SUNY SB, Stony Brook, New York, USA
K. Shih
SBU, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and NSF Grant No. PHY-141525
We present a new type of longitudinal microbunching instability entitled ’Plasma-Cascade Instability’. This instability could occur in beams propagating along a straight section with external focusing elements. We present a theoretical description of this instability as well as self-consistent 3D simulations. Finally, we present results of experimental observation of Plasma-Cascade Instability at frequencies up to 10 THz using SRF linear accelerator built for Coherent electron Cooling experiment *.
* Commissioning of FEL-based Coherent electron Cooling system, V.N. Litvinenko et al., In proc. of 38th Int. Free Electron Laser Conf.(FEL’17), Santa Fe, NM, USA, August 20-25, 2017, p. 132

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB095

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paper received ※ 18 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPRB102

Correction of Crosstalk Effect in the LEReC Booster Cavity

cavity, booster, resonance, HOM

3051

B.P. Xiao, K. Mernick, F. Severino, K.S. Smith, T. Xin, W. Xu
BNL, Upton, Long Island, New York, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
The Linac of Low Energy RHIC electron Cooler (LEReC) is designed to deliver a 1.6 MeV to 2.6 MeV electron beam, with peak-to-peak dp/p less than 7·10^-4. The booster cavity is the major accelerating component in LEReC, which is a 0.4 cell cavity operating at 2 K, with a maximum energy gain of 2.2 MeV. It is modified from the Energy Recovery Linac (ERL) photocathode gun, with fundamental power coupler (FPC), pickup coupler (PU) and higher order mode (HOM) coupler close to each other. The direct coupling between FPC and PU induced crosstalk effect in this cavity. This effect is simulated and measured, and is further corrected using low level RF (LLRF) to meet the energy spread requirement.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB102

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPRB106

Simulation of the Transition Radiation Transport Through an Optic System

radiation, simulation, optics, diagnostics

3059

M. Marongiu, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
F.G. Bisesto, E. Chiadroni, G. Di Pirro, G. Franzini, A. Giribono, V. Shpakov, A. Stella, A. Variola
INFN/LNF, Frascati, Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
A. Mostacci, L. Palumbo
INFN-Roma, Roma, Italy

Optical Transition Radiation (OTR) screens are widely used for beam profile measurements. The radiation is emitted when a charged particle beam crosses the boundary between two media with different optical properties. The main advantages of OTR are the instantaneous emission process allowing fast single shot measurements (i.e. bunch by bunch measurements in a multi bunch machine), and the good linearity with the beam charge (if coherent effects can be neglected). Furthermore, OTR angular distribution strongly depends on beam energy. Since OTR screens are typically placed in several positions along the Linac to monitor beam envelope, one may perform a distributed energy measurement along the machine: this will be useful, for instance, during the commissioning phase of a machine. This paper deals with the studies of an algorithm to optimize the generation and the transport of the transition radiation through an optic system using the simulation tool Zemax. The algorithm, in combination with a particle tracking code (i.e. Elegant), will allow to simulate the radiation generated by a beam and, so, to take into account beam divergence and energy spread or chromatic effects in the optic system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB106

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paper received ※ 08 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPRB107

The New 1-18 MHz Wideband RF System for the CERN PS Booster

cavity, vacuum, electronics, impedance

3063

M.M. Paoluzzi, L. Arnaudon, V. Bretin, Y. Cuvet, J. Daricou, S. Energico, M. Haase, A.J. Jones, D. Landré, C. Rossi
CERN, Meyrin, Switzerland
C. Ohmori
KEK/JAEA, Ibaraki-Ken, Japan

The LHC Injector Upgrade (LIU) project at CERN prepares the injectors to meet the requirements of the High Luminosity LHC. For protons, it includes the new Linac4, PS Booster (PSB), PS and SPS. Among the major changes concerning the PSB, the extraction energy increase from 1.4 GeV to 2 GeV and the higher beam intensity, made possible by the Linac4 together with the new charge exchange injection system into the PSB (2·10¹³ protons) strongly affect the RF system requirements. To deal with this more demanding beam operation, a new RF system was designed. It is based on modern magnetic alloy loaded cavities driven by solid-state amplifiers. Its wideband frequency response (1 MHz to 18 MHz) covers all the required frequency schemes. This new RF system has been produced in 2017 and 2018; installation is planned during 2019, the first year of Long Shutdown 2 (LS2) and commissioning foreseen in 2020. Most of the production and testing was outsourced to industry; parts acceptance, cavities assembly and pre-testing was done in-house. A quality assurance plan was established to achieve the required high reliability. This paper describes the procurement, production and testing strategies and methodologies. It also reports the achieved results, system performances and relevant statistics.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB107

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paper received ※ 26 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS007

Short Bunch Experiment at EXALT Facility

laser, cathode, experiment, gun

3100

C. Bruni, J-N. Cayla, S. Chancé, V. Chaumat, N. Delerue, N. ElKamchi, P. Lepercq, H. Purwar
LAL, Orsay, France
E. Baynard, M. Pittman
CLUPS, Orsay, France
B. Lucas, O. Neveu
CNRS LPGP Univ Paris Sud, Orsay, France
T. Vinatier
DESY, Hamburg, Germany

Nowdays, different applications required short bunches, with low energy spread and low emittances. On EXALT facility, we perform an experiment with a short (few100 femtosecond) laser pulse on a photocathode in a 3 GHz RF gun. We perform the measurement of the single photon emission process with a copper cathode. We show that the longitudinal photoinjector model via transfer matrix is suitable for the reconstruction of the bunch duration even in short pulse mode with an increased accurracy charge below 20 pC. We clearly measure the parabolic profile in the energy spectrum resulting from blow out phenomena at the cathode due to strong space charge forces. Measurements are also compared with the Astra simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS007

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paper received ※ 21 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS013

The Cooling Effect of Beam Self-Fields on the Photocathode Surface in High Gradient RF Injectors

cathode, emittance, laser, space-charge

3112

Y. Chen, M. Krasilnikov, F. Stephan
DESY Zeuthen, Zeuthen, Germany

The intrinsic slice emittance of the emitted electrons on the photocathode surface at each moment during the transient photoemission process depends on the transverse size of the slice and the mean kinetic energy of the electrons within the slice. The latter relies on the surface barrier potentials of the cathode material at a fixed wavelength of the incident light, and is thus significantly influenced by the presence of strong rf and beam self-fields at / close to the cathode surface. This is, in particular, the case in high brightness injectors for modern free electron lasers. In this article, the beam self-fields are determined in a self-consistent approach, based on which improved transverse and temporal emission distributions are obtained. The nonlinear correlations of the intrinsic surface slice emittance within the bunch are shown for multiple bunch charges. A peak to peak variation of the intrinsic surface emittance is estimated as 30\% for the highest charge-density case considered in this paper. An overall reduction of the average intrinsic emittance is computed as 10\% accordingly. The cooling effect on the cathode surface is enhanced as the local space-charge density rises. Furthermore, the impacts of the cooling effect on downstream beam qualities are demonstrated through particle tracking simulations based on the injector setup at the Photo Injector Test Facility at DESY in Zeuthen (PITZ).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS013

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paper received ※ 27 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPTS017

Synchrotron Radiation Module in OCELOT Toolkit

undulator, radiation, simulation, FEL

3127

S. Tomin, G. Geloni
EuXFEL, Hamburg, Germany

Synchrotron radiation (SR) sources based on single-pass accelerators (e.g. linacs, plasma accelerators) have to cope with electron beams with a rather complicated phase space distribution. In this case, the convolution method usually employed to calculate radiation properties can give poor accuracy or be not applicable at all. Moreover, dynamical effects can also play a role in the emission mechanism. This happens when the beam parameters (e.g. beam current) significantly change during the passage through the undulator. In this work, we present a dedicated SR module of the OCELOT toolkit, which is well suited to deal with these situations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS017

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS034

Generation of Sub-Femtosecond Electron Beams and Electron Bunch Trains With High Form Factor Using Wake Field Structures

wakefield, bunching, space-charge, simulation

3174

Z. Dong, H. Chen, X.J. Deng, Y.C. Du, Z. Zhou
TUB, Beijing, People’s Republic of China

In this paper, we propose two beam manipulation methods with wakefield structures in a photo-injector. First, we propose a simple scheme to compensate non-linear effects during ballistic bunching by using a wakefield structure. Simulations have shown beams of 1 pC charge can be compressed to 1.56 fs rms, and even shorter beams (a few hundred attoseconds) can be obtained with bunch charge well below 1 pC. In the second part, a method of producing bunch trains with high form factor is proposed by using multiple wake-field structures. Simulation results have shown the production of a train with a form factor of 0.5 using a 1 nC beam at few-MeV energy.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS034

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paper received ※ 11 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS043

SixTrack Version 5: Status and New Developments

simulation, scattering, collimation, HOM

3200

R. De Maria, J. Andersson, L. Field, M. Giovannozzi, P.D. Hermes, N. Hoimyr, G. Iadarola, S. Kostoglou, E.H. Maclean, E. McIntosh, A. Mereghetti, J. Molson, V.K.B. Olsen, D. Pellegrini, T. Persson, M. Schwinzerl
CERN, Geneva, Switzerland
B. Dalena, T. Pugnat
CEA-IRFU, Gif-sur-Yvette, France
K.N. Sjobak
University of Oslo, Oslo, Norway
I. Zacharov
EPFL, Lausanne, Switzerland

SixTrack Version 5 is a major SixTrack release that introduces new features, with improved integration of the existing ones, and extensive code restructuring. New features include dynamic-memory management, scattering-routine integration, a new initial-condition module, and reviewed post-processing methods. Existing features like on-line aperture checking and Fluka-coupling are now enabled by default. Extensive performance regression tests have been developed and deployed as part of the new-release generation. The new features of the tracking environment developed for the massive numerical simulations will be discussed as well.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS043

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paper received ※ 17 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS048

Electron Beam Dynamics Simulation for Electron Lenses

gun, simulation, cathode, experiment

3220

S. Sadovich, A. Rossi
CERN, Meyrin, Switzerland
G. Stancari
Fermilab, Batavia, Illinois, USA

A test stand is under construction at CERN to study high perveance electron guns, electron beam dynamics, and electron beam diagnostics for electron lenses. It will be used to test electron guns for the Hollow Electron Lenses under consideration for beam halo control for High Luminosity LHC (CERN), and for the Space Charge Compensation at SIS18 (GSI) in the frame of the EU funded ARIES project. In order to prepare for this test stand, simulations will be presented and compared with experiments undertaken at the Fermilab (FNAL) electron lens test stand. These were conducted using a hollow electron gun, with the magnetic field configuration and beam current varied to study their effect. The impact of imperfections on the beam dynamics and overall quality of the electron beam will be discussed. A method for comparing experimental data with simulation is also presented to allow bench-marking of the computer models and simulation tools that will later be applied to the analysis of measurements performed at CERN.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS048

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS050

Multi-Species Electron-Ion Simulations and their Application to the LHC

simulation, operation, beam-losses, space-charge

3228

L. Mether, G. Iadarola, K.L. Poland, G. Rumolo, G. Skripka
CERN, Meyrin, Switzerland

During operation in 2017 and 2018, the LHC suffered from recurrent beam aborts associated with beam losses in one of its arc cells in correlation with quickly developing transverse coherent oscillations. The events are thought to have been caused by a localised high gas density resulting from the phase transition of a macro-particle that has entered the beam. In order to model the observed coherent effects through the interaction of the beam with the induced pressure bump, novel modelling capabilities have been implemented that allow for the simulation of multiple clouds of different particle species and their interaction with the beam. In this contribution the simulation model and its application are described.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS050

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paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPTS051

Comparison of Electron Cloud Build-Up Simulations Against Heat Load Measurements for the LHC Arcs With Different Beam Configurations

simulation, operation, synchrotron-radiation, radiation

3232

G. Skripka, G. Iadarola, L. Mether, G. Rumolo, E.G.T. Wulff
CERN, Meyrin, Switzerland
P. Dijkstal
PSI, Villigen PSI, Switzerland

Electron cloud effects are among the main performance limitations for the operation of the Large Hadron Collider (LHC) with 25 ns bunch spacing. A large number of electrons impacting on the beam screens of the cold magnets induces significant heat load, reaching values close to the full cooling capacity available from the cryogenic system. Interestingly, it is observed that parts of the machine that are by design identical show very different heat loads. We used numerical simulations to investigate the possibility that these differences are induced by different surface properties, in particular maximum Secondary Electron Yield (SEY) for the different cryomagnets. Using the PyECLOUD code, the electron cloud build-up was simulated assuming different values of SEY in the LHC cold magnets. Comparing the measured heat loads to the simulation results for the 25 ns beams at 450 GeV we have identified the SEY values that match the observations in these conditions. These SEY values were found to be in good agreement with the heat loads measured with different beam configurations (changing the bunch pattern, the bunch intensity and the beam energy).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS051

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS052

Electron Cloud Build-Up Simulations in the Two-Beam Common Chamber of the HL-LHC TDIS With Nonuniform Surface Properties

simulation, injection, vacuum, operation

3236

G. Skripka, C. Bracco, G. Iadarola, A. Perillo-Marcone
CERN, Meyrin, Switzerland

The segmented injection protection absorber (TDIS) foreseen for the High-Luminosity Large Hadron Collider (HL-LHC) project is designed to protect the machine in case of injection kicker malfunctioning. Since the current LHC injection protection absorber has suffered from vacuum issues possibly induced by electron multipacting, numerical studies were done to estimate the electron flux expected on the internal surfaces of the TDIS. This device will consist of three pairs of movable absorbing blocks above and below one beam and a beam screen surrounding the second circulating beam. The build-up of electron cloud in the TDIS was simulated accounting for the presence of two counter-rotating beams, for the configuration of the jaws and for the different materials used for the different surfaces in the device. The simulation studies have also investigated the possibility of coating the most critical surfaces with amorphous carbon in order to mitigate the multipacting.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS052

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paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPTS055

Energy Modulation of Electron Beam in Corrugated Dielectric Waveguide

experiment, simulation, wakefield, acceleration

3248

A. Lyapin, S.T. Boogert, S.M. Gibson, K. Lekomtsev
JAI, Egham, Surrey, United Kingdom
A. Aryshev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
A.A. Tishchenko
MEPhI, Moscow, Russia
A.A. Tishchenko
NRC, Moscow, Russia

Energy modulated electron beams have a wide range of applications in accelerator physics, for example they can serve as drivers in resonant wakefield acceleration schemes. A strong wakefield induced energy modulation can be produced using a dielectric lined waveguide, the resultant micro-bunched beam is capable of producing coherent terahertz radiation *. We report on observation of energy modulation due to self-wakefields in a few picosecond duration and ~1 nC charge electron bunches of LUCX facility at KEK. To produce the modulation, we used a corrugated dielectric waveguide with an inner radius of 2 mm and a period of corrugation of 10 mm. In this case, the period of corrugation is longer than the wavelength of the main accelerating mode. We show electromagnetic simulations of on-axis electric fields leading to an optimisation of the corrugation period allowing to enhance the accelerating/decelerating fields compared to dielectric lined waveguides with a constant inner radius.
* S. Antipov et al., Experimental observation of energy modulation in electron beams passing though terahertz dielectric wakefield structures, PRL 108, 144801 (2012).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS055

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS061

Experimental Test of Longitudinal Space-Charge Amplifier in Optical Range

undulator, laser, FEL, experiment

3267

C. Lechner, M. Dohlus, B. Faatz, V. Grattoni, G. Paraskaki, J. Rönsch-Schulenburg, E. Schneidmiller, M.V. Yurkov, J. Zemella
DESY, Hamburg, Germany
V. Miltchev
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Longitudinal space-charge effects can act as a driver for short wavelength radiation production in a longitudinal space-charge amplifier (LSCA) *. A single cascade of an LSCA was tested using the hardware of the sFLASH experiment installed at the FEL user facility FLASH (at DESY, Hamburg). Scans of the longitudinal dispersion of the chicane were performed with the tightly focused electron beam for different compression settings, while recording the intensity of the emission from a few-period undulator. We present experimental results and estimates on electron beam properties.
* E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST Accel Beam 13, 110701 (2010)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS061

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPTS066

Suppression of Correlated Energy Spread Using Emittance Exchange

cavity, linac, controls, simulation

3275

J. Seok, M. Chung
UNIST, Ulsan, Republic of Korea
M.E. Conde, G. Ha, J.G. Power
ANL, Argonne, Illinois, USA

An emittance exchange (EEX) provides a precise longitudinal phase space manipulation of electron bunch. It has been studied for an easy and precise control of temporal distribution, but controls of energy distribution have not been explored. Since the energy control using EEX is under the identical principle to the temporal control, the EEX beamline can control a correlated energy spread of the electron bunch. This would benefit accelerator facilities requiring a low energy spread such as X-ray Free Electron Laser Oscil-lator (XFELO). In this paper, we present principle and preliminary simulation work on the suppression of correlated energy spread using the EEX beamline. ing the EEX beamline.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS066

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paper received ※ 21 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS069

The Effects of Stochastic Space Charge in High Brightness Photolectron Beamlines for Ultrafast Electron Diffraction

space-charge, simulation, emittance, cathode

3283

M.A. Gordon, Y.K. Kim
University of Chicago, Chicago, Illinois, USA
J.M. Maxson
Cornell University, Ithaca, New York, USA
J.M. Maxson
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was supported by the U.S. National Science Foundation under award PHY-1549132, the Center for Bright Beams.
As we move to ultra-high brightness photocathodes and ultra-cold beams, we may become more sensitive to stochastic, point-to point effects such as disorder induced heating and the Boersch effect, given the failure of Debye screening. In this study, we explore the effects of stochastic scattering. Modern beam dynamics codes often approximate point to point interactions with a potential created by smoothing the charge over space, removing sensitivity to stochastic effects. This approximation is often used in beamline optimization, because it is much faster. We study the limits of validity of this approximation. In particular, we will simulate effects of stochastic space charge on a high brightness photoemission beamline, an ultrafast electron diffraction beamline with a photocathode temperature of 5 meV with a final beam energy of 225 keV. Emittance dilution in the transverse plane and transverse beam size relative to smooth space charge simulations will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS069

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS073

Beam-Beam Effect: Crab Dynamics Calculation in JLEIC

simulation, luminosity, collider, cavity

3293

H. Huang, F. Lin, V.S. Morozov, Y. Roblin, A.V. Sy, Y. Zhang
JLab, Newport News, Virgina, USA
I. Neththikumara, S. Sosa, B. Terzić
ODU, Norfolk, Virginia, USA

The electron and ion beams of a future Electron Ion Collider (EIC) must collide at an angle for detection, machine and engineering design reasons. To avoid associated luminosity reduction, a local crabbing scheme is used where each beam is crabbed before collision and de-crabbed after collision. The crab crossing scheme then provides a head-on collision for beams with a non-zero crossing angle. We develop a framework for accurate simulation of crabbing dynamics with beam-beam effects by combining symplectic particle tracking codes with a beam-beam model based on the Bassetti-Erskine analytic solution. We present simulation results using our implementation of such a framework where the beam dynamics around the ring is tracked using Elegant and the beam-beam kick is modeled in Python.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS073

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paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS075

Effect of Beam-Beam Kick on Electron Beam Quality in First Bunched Electron Cooler

solenoid, alignment, focusing, simulation

3297

S. Seletskiy, M. Blaskiewicz, A.V. Fedotov, D. Kayran, J. Kewisch
BNL, Upton, Long Island, New York, USA

The low energy RHIC electron cooler (LEReC) currently under commissioning at BNL is going to be the first non-magnetized bunched electron cooler (EC). For successful cooling LEReC requires that the electrons in the cooling section (CS) have small angles with respect to co-propagating ions. Since there is no strong magnetic field in the CS, the effects of ions on both the trajectory and focusing of the e-bunches is critical. In this paper we consider the ion beam kick on the electron bunches and derive requirements to the respective alignment of electron and ion beams in non-magnetized coolers.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS075

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paper received ※ 08 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS081

An Analytic Approach to Emittance Growth from the Beam-Beam Effect with Applications to the LHeC

proton, emittance, GUI, collider

3307

E.A. Nissen
JLab, Newport News, Virginia, USA
D. Schulte
CERN, Meyrin, Switzerland

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, world-wide license to publish or reproduce this manuscript.
In colliders with asymmetric rigidity such as the proposed Large Hadron electron Collider, jitter in the weaker beam can cause emittance growth via coherent beam-beam interactions. The LHeC in this case would collide 7 TeV protons on 60 GeV electrons, which can be modeled using a weak-strong model. In this work we estimate the proton beam emittance growth by separating out the longitudinal angular kicks from an off-center bunch interaction and produce an analytic expression for the emittance growth per turn in systems like the LHeC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS081

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paper received ※ 01 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS082

Luminosity Studies of Asymmetric Crab Crossing in JLEIC

luminosity, ECR, collider, cavity

3311

E.A. Nissen
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, world-wide license to publish or reproduce this manuscript.
The proposed Jefferson Lab Electron Ion Collider (JLE-IC) currently plans to use a crab crossing scheme to max-imize the available luminosity. It had been suggested that space and cost savings, as well as hadron beam quality improvements, could be realized by leaving the ion beam un-crabbed and increasing the crabbing angle of the elec-tron beam. This and variations in-between equal and totally one-sided crabbing are examined for both JLEIC and LHC parameters, with various changes in crabbing angle and frequency studied to maximize luminosity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS082

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paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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WEPTS083

Multipass Simulations of Space Charge Compensation using Electron Columns at IOTA

space-charge, simulation, cavity, proton

3313

C.S. Park, E.G. Stern
Fermilab, Batavia, Illinois, USA
S. Chattopadhyay, B.T. Freemire
Northern Illinois University, DeKalb, Illinois, USA
C.E. Mitchell, R.D. Ryne
LBNL, Berkeley, California, USA

Defocusing repulsive forces due to self space charge fields lead to degradation of high-intensity particle beams. Being of particular concern for low- and medium-energy proton beams, they result in emittance growth, beam halo formation, and beam loss. They set stringent limits on the intensity of frontier accelerators; therefore, the mitigation of space charge effects is a crucial challenge to improve proton beam intensity. The space charge effects in a positively charged proton beam can be effectively compensated using negatively charged electron columns. In this paper, we present the results of simulations using Synergia of the Electron Column lattice for IOTA. Beam loss due to space charge effects and aperture restrictions have been studied, as well as bunch formation and matching using an adiabatic ramp of the RF cavity. The results show the need for space charge compensation, and provide the basis for integration of the Synergia and Warp codes in order to form a complete simulation of space charge compensation using an Electron Column in IOTA.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS083

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paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS088

Integration of Cavity Design and Beam Dynamics Simulation Using the Parallel IMPACT and the ACE3P Codes

cavity, simulation, emittance, gun

3317

J. Qiang, D.A. Bizzozero
LBNL, Berkeley, California, USA
L. Ge, Z. Li, C.-K. Ng, L. Xiao
SLAC, Menlo Park, California, USA

Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and DE-AC02-76SF00515,
The 3D parallel code suite IMPACT has been extensively used in the beam dynamics study of photoinjectors while the 3D parallel code ACE3P has been extensively used in the RF cavity design. In this paper, we propose integrating the ACE3P cavity design and the IMPACT beam dynamics simulation into a single work flow. Such a workflow enables efficient simulation of 3D effects(e.g. RF coupler) on high performance computers.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS088

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paper received ※ 07 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS089

Microbunching Instability Mitigation via Multi-Stage Cancellation

bunching, linac, laser, impedance

3321

J. Qiang, B. Li
LBNL, Berkeley, California, USA

Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and used computer resources at the National Energy Research Scientific Computing Center.
The microbunching instability driven by beam collective effects in the linear accelerator of a free electron laser (FEL) facility can significantly degrade electron beam quality and FEL performance. Understanding and control of the instability is a priority for the design of modern high-brightness electron accelerators. In this paper, we study an instability cancellation phenomenon due to 180 degree phase slippage of the current modulations between different amplification stages. A case study of using a nonisochronous dogleg section in a double compression scheme to cancel the current modulation is illustrated.

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paper received ※ 07 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS090

Suppression of Microbunching Instability Through Dispersive Lattice

bunching, linac, quadrupole, simulation

3325

J. Qiang, B. Li
LBNL, Berkeley, California, USA

Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and used computer resources at the National Energy Research Scientific Computing Center.
The microbunching instability from the initial small modulation such as shot-noise can be amplified by longitudinal space-charge force and causes significant electron beam quality degradation at the exit of accelerator for the next generation x-ray free electron laser. In the paper, we present analytical and numerical simulation studies of a novel method using dispersion leakage from some quadrupoles inside a chicane.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS090

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paper received ※ 26 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS092

3d Start-to-End Simulations of the Coherent Electron Cooling

simulation, FEL, plasma, kicker

3329

J. Ma, V. Litvinenko, G. Wang
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Coherent electron cooling (CeC) is a novel technique for rapidly cooling high-energy, high-intensity hadron beam. Two designs of coherent electron cooler, with a free electron laser (FEL) amplifier and a plasma-cascade micro-bunching amplifier, are cost effective and don’t require separation of hadrons and electrons. These schemes are used for the demonstration experiment in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). SPACE, a parallel, relativistic 3D electromagnetic Particle-in-Cell (PIC) code, has been used for simulation studies of these two coherent electron cooler systems.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS092

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paper received ※ 15 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS093

Emittance Preservation for LCLS-II-HE Project

emittance, lattice, laser, space-charge

3333

J. Wu, T.O. Raubenheimer, M.D. Woodley
SLAC, Menlo Park, California, USA
J. Qiang
LBNL, Berkeley, California, USA

Funding: The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
A small transverse slice emittance at the undulator entrance is essential for high performance of the free electron laser. To achieve this, preservation of the phase space density of the electron bunch during acceleration and compression is absolutely necessary. The LCLS-II-HE is designed to transport a 100 pC bunch with an emittance of ~0.3 mm-mrad with minimal emittance dilution. However, in simulations starting from a normalized emittance on the order of 0.1 mm-mrad, the emittance growth is significant. In this paper, the sources of emittance growth are studied along the accelerator, in particular, around the laser-heater, the two bunch compressors. We have investigated mechanisms of emittance growth such as space charge, coherent synchrotron radiation, chromatic aberration, and spurious dispersion. Due to the extremely small emittance from the injector, 3-D space charge effect is important to determine the space charge dominated region and emittance dominated region. With this understanding, emittance preservation schemes are proposed. Studies are carried out with IMPACT simulation code, as well as ASTRA and ELEGANT.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS093

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paper received ※ 23 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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WEPTS094

Generation High-Charge of Flat Beams at the Argonne Wakefield Accelerator

emittance, solenoid, quadrupole, experiment

3337

T. Xu, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
M.E. Conde, G. Ha, J.G. Power, E.E. Wisniewski
ANL, Argonne, Illinois, USA
M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan
P. Piot
Fermilab, Batavia, Illinois, USA

Funding: This work is supported by the U.S. DOE contracts No. DESC0017750, DE-SC0018656 with NIU, and No. DE-AC02-06CH11357 with ANL.
Beams with large transverse emittance ratios (flat beams)have received renewed interest for their possible applications in future linear colliders and advanced accelerators. A flat beam can be produced by generating a magnetized beam and then repartitioning its emittance using three skew quadrupoles. In this paper, we report on the experimental generation of∼1nC flat beams at the Argonne WakefieldAccelerator (AWA). The emittance ratio of the flat beam is demonstrated to be continuously variable by adjusting the magnetic field on the cathode.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS094

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS100

The ESR Closed Orbit Calculation and Simulation

controls, simulation, experiment, MMI

3349

S. Dastan, S. Dastan, R. Saffari
University of Guilan, Rasht, Iran
S. Dastan, J. Rahighi
ILSF, Tehran, Iran
S. Livinov, M. Steck
GSI, Darmstadt, Germany

The commissioning of the ESR with a new control system based on the LSA (LHC System Architecture) has started recently. This new control system is under development and considers all aspects of the expected functionality to operate the GSI/FAIR accelerators and incorporates the present GSI controls infrastructure*. Two years ago, the old control system which was based on outdated computers and operating system, was discontinued. So, both the heavy ion synchrotron SIS-18 and the Experimental Storage Ring (ESR) operation from now on have to be performed with the new FAIR control system. In order to introduce an improved model to the control system change, new calculations and simulations for SIS and ESR are necessary. In this paper we summarize the results of closed orbit calculations for the ESR which are done with three different codes, namely: ELEGANT*, MAD-X and MIRKO. Also, because the results of ELEGANT and MAD-X in this issue are similar to each other, we present ELEGANT results in the report.
* R. Bär, DEVELOPMENT OF A NEW CONTROL SYSTEM FOR THE FAIR ACCELERATOR COMPLEX AT GSI. Kobe.
** Borland, M., elegant: A Flexible SDDS-Compliant Code for Accelerator Simulation.

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paper received ※ 29 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS102

Helical Wiggler Model for Fast Tracking

wiggler, radiation, optics, undulator

3356

W.F. Bergan, V. Khachatryan, D.L. Rubin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: NSF-1734189 DGE-1650441
In order to test the process of Optical Stochastic Cooling (OSC) at the Cornell Electron Storage Ring (CESR), we plan to use helical wigglers as both the pickup and kicker, since the required radiation wavelength of 800nm can be achieved with lower magnetic field strength in helical as compared to planar wigglers. In order to simulate the lattice with such wigglers, it is useful to be able to model the effect of the wiggler on the optics without resorting to direct tracking, which is time-consuming and so ill-suited for the repeated evaluations necessary in running an optimizer. We generate a Taylor map to third order for this element using analytic field expressions, enabling easy determination of the effects of such an element on linear and nonlinear optics. This model is compared with the results of direct tracking and shows good agreement.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS102

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS106

Accelerator Optimization using Big Data Science Techniques

plasma, experiment, radiation, proton

3370

C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: This project has received funding from STFC under grant reference ST/P006752/1.
Managing, analyzing and interpreting large, complex datasets and high rates of data flow is a growing challenge for many areas of science and industry. At particle accelerators and light sources, this data flow occurs both, in the experiments as well as the machine itself. The Liverpool Big Data Science Center for Doctoral Training (LIV. DAT) was established in 2017 to tackle the challenges in Monte Carlo modelling, high performance computing, machine learning and data analysis across particle, nuclear and astrophysics, as well as accelerator science. LIV. DAT is currently training 24 PHD students, making it one of the largest initiatives of this type in the world. This contribution presents research results obtained to date in projects that focus on the application of big data techniques within accelerator R&D.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS106

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THYPLM1

Development of the Vertically Polarizing Hard X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project

undulator, photon, operation, free-electron-laser

3408

M. Leitner, D. Arbelaez, J.N. Corlett, A.J. DeMello, L. Garcia Fajardo, D. Leitner, S. Marks, K.A. McCombs, T. Miller, D.V. Munson, J. Niu, K.L. Ray, D.A. Sadlier, D. Schlueter, E.J. Wallén
LBNL, Berkeley, California, USA
H. Bassan, D.E. Bruch, D.S. Martinez-Galarce, H.-D. Nuhn, M. Rowen, Z.R. Wolf
SLAC, Menlo Park, California, USA
C.W. Chen
NSRRC, Hsinchu, Taiwan

Funding: Work supported by the Director, Oﬃce of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The Linear Coherent Light Source II (LCLS-II) is a free electron laser facility currently in its final construction stage at Stanford Linear Accelerator Center. The project includes two variable-gap, hybrid-permanent-magnet undulator lines: A soft x-ray undulator line with 21 undulator segments optimized for a photon energy range from 0.2 keV to 1.3 keV and a hard x-ray undulator line with 32 undulator segments designed for a photon energy range from 1.0 keV to 25.0 keV. This paper focuses on the design, development, and performance of the hard x-ray undulator line which utilizes uniquely-developed, vertically-polarizing undulators. To fully compensate the magnetic force throughout the entire gap range these devices incorporate non-linear spring systems which permit the construction of relatively compact undulators. However, significant magnetic field repeatability challenges have been encountered during prototyping of this novel design. The paper describes the innovative design improvements that were implemented which lead to reaching the LCLS-II required performance. These final design solutions can also be advantageous improving the operation of any future undulator design.

Slides THYPLM1 [28.498 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THYPLM1

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THYYPLM2

Two Orbit Operation at Bessy II - During a User Test Week

injection, resonance, experiment, operation

3419

P. Goslawski, F. Andreas, F. Armborst, T. Atkinson, J. Feikes, A. Jankowiak, J. Li, T. Mertens, M. Ries, A. Schälicke, G. Schiwietz, G. Wüstefeld
HZB, Berlin, Germany

Operating a storage ring close to a horizontal resonance and manipulating the transverse non-linear beam dynamics can generate stable Transverse Resonance Island Buckets (TRIBs), which give a 2nd stable orbit in the ring. Both orbits can be populated with different electron bunch filling patterns and provide two different radiation sources to the user community. Such a machine setting has been established at BESSY II and was tested under realistic user conditions in a first ’TRIBs/Two Orbit User Test Week’ in February 2018. Results and user feedback will be discussed in this contribution.

Slides THYYPLM2 [64.754 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THYYPLM2

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paper received ※ 14 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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THYYPLS1

On-Demand Beam Route and RF Parameter Switching System for Time-Sharing of a Linac for X-ray Free-Electron Laser as an Injector to a 4th-Generation Synchrotron Radiation Source

linac, FEL, injection, controls

3427

H. Maesaka, T. Fukui, T. Hara, T. Inagaki, H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
T. Hasegawa, O. Morimoto, Y. Tajiri, S. Tanaka, M. Yoshioka
SES, Hyogo-pref., Japan
N. Hosoda, S. Matsubara, T. Ohshima
JASRI/SPring-8, Hyogo-ken, Japan
C. Kondo, K. Okada, M. Yamaga
JASRI, Hyogo, Japan

We have an upgrade plan of the SPring-8 storage ring to provide much more brilliant X-rays with a low-emittance electron beam. Since the upgraded ring requires a low-emittance injection beam, we are planning to timeshare the linac of the X-ray free electron laser (XFEL) facility, SACLA, as an injector for the upgraded ring. The SACLA linac delivers low-emittance and short-bunch electron beams to two XFEL beamlines with a 60 Hz repetition rate. The beam route is right now equally changed by a kicker magnet at a switchyard. The beam parameter is also optimized for each XFEL beamline by changing RF parameters pulse-by-pulse with simple software at this moment*. Since the number of beam injection shots to the storage ring is much less frequent than XFEL shots, one of the XFEL shots must be overridden by an injection with on-demand basis. In addition, the beam quality, such as 1 mm mrad normalized emittance, 10 fs bunch length and 10 kA peak current, must be maintained not to deteriorate the XFEL performance. Therefore, we have developed an on-demand beam route and RF parameter switching system with sufficient speed, precision and reliability. A beam route data is transmitted to each accelerator unit by a reflective memory network, and special software changes the parameters of each accelerator unit pulse-by-pulse according to the received data. We tested the on-demand switching system at a test bench and the SACLA linac. The beam parameters were appropriately controlled with a negligible failure rate. The user service of the beam injection from SACLA to SPring-8 is scheduled in 2020 and the on-demand switching system is almost ready for the time-sharing operation of multiple XFEL beamlines and a SPring-8 injection.
* T. Hara et al., Phys. Rev. Accel. Beams 21, 040701 (2018).

Slides THYYPLS1 [8.519 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THYYPLS1

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paper received ※ 16 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THAPLM3

2019 Nishikawa Tetsuji Prize Talk

collider, proton, operation, experiment

3439

V.D. Shiltsev
Fermilab, Batavia, Illinois, USA

For his original work on electron lenses in synchrotron colliders, his outstanding contribution to the construction and operation of high-energy, high-luminosity hadron colliders and for his tireless leadership in the accelerator community.

Slides THAPLM3 [17.631 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THAPLM3

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paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPMP002

Optics Design and Beam Dynamics Simulation for a VHEE Radiobiology Beam Line at PRAE Accelerator

linac, gun, radiation, optics

3444

A. Faus-Golfe, B. Bai, Y. Han, C. Vallerand
LAL, Orsay, France
R. Delorme, Y. Prezado
IMNC, Orsay, France
M. Dosanjh
CERN, Meyrin, Switzerland
P. Duchesne
IPN, Orsay, France
V. Favaudon, C. Fouillade, P.M. Poortmans, F. Pouzoulet
Institut Curie - Centre de Protonthérapie d’Orsay, Orsay, France

The Platform for Research and Applications with Electrons (PRAE) is a multidisciplinary R&D facility gathering subatomic physics, instrumentation, radiobiology and clinical research around a high-performance electron accelerator with beam energies up to 70 MeV. In this paper we report the complete optics design and performance evaluation of a Very High Energy Electron (VHEE) innovative radiobiology study, in particular by using Grid mini-beam and FLASH methodologies, which could represent a major breakthrough in Radiation Therapy (RT) treatment modality.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP002

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paper received ※ 27 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPMP003

The PRORAD Beam Line Design for PRAE

alignment, linac, gun, dipole

3448

A. Faus-Golfe, B. Bai, Y. Han, C. Vallerand
LAL, Orsay, France
P. Duchesne, D. Marchand, E.J-M. Voutier
IPN, Orsay, France

The PRAE (Platform for Research and Applications with Electrons) accelerator is being built at Orsay campus with the main objective of creating a multidisciplinary R&D platform, involving subatomic physics, instrumentation, radiobiology and clinical research around a high-performance electron accelerator with beam energies up to 70 MeV (planned 140 MeV). In this paper we will report the optics design and beam dynamics simulations for the beam line dedicated to subatomic physics, more specifically for the measurement of the proton radius. This measurement requires extremely low energy spread (5×10−4) and small beam sizes with low divergence at three beam energies: 30, 50 and 70 MeV. The beam line includes a D-type chicane coupled to a dechirping passive structure, which generates inductive wakeﬁelds in order to get the performances required for such measurement.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP003

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPMP006

Study on the Theta Pinch Plasmas for Applied as Ion Stripper

plasma, experiment, target, heavy-ion

3456

K. Cistakov, Ph. Christ, M. Fröhlich, M. Iberler, J. Jacoby, L. Manganelli, G. Xu
IAP, Frankfurt am Main, Germany
R. Gavrilin, A. Khurchiev, S.M. Savin
ITEP, Moscow, Russia

Funding: Work supported by BMBF contr. No. 05P18RFRB1
With regard to the development of new accelerator technologies for high-intensity ion beams and more efficient acceleration, the transfer of radiation ions to higher charged states is a prerequisite for many experiments. However, the recent stripping technologies such as film and gas stripper for heavy ion beams with the desired intensities required great effort or are not suitable. The contribution presents the current state of plasma strippers with fully ionized hydrogen with simultaneously high particle densities in the range of some 10¹⁷ cm^-3 for FAIR. To achieve this high particle density, an inductive discharge plasma is ignited within a stripper cell parallel to the axis of the ion beam and compressed towards the beam axis. The advantage over conventional ion strippers is about 1000 times smaller recombination rate for electrons*. This significantly increases the equilibrium charge state of ions. At the same time, the relative fraction of ions on the maximum of charge state distribution increases up to 25%**. This should create good conditions for the use of plasma strippers at FAIR.
*Th.Peter, "Energy loss of heavy ions in dense plasma"
**O.Haas, "Simulation Studies of plasma-based charge strippers",Proceedings of IPAC 2015, Richmond, VA, USA

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP006

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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THPMP007

MICROTCA TECHNOLOGY LAB AT DESY: CURRENT CASES IN TECHNOLOGY TRANSFER

controls, operation, LLRF, hardware

3459

T. Walter, I. Mahns, H. Schlarb
DESY, Hamburg, Germany

Funding: The MicroTCA Technology Lab (A Helmholtz Innovation Lab) is supported by the Helmholtz Association under grant HIL-002.
MicroTCA-based LLRF systems for beam control and beam diagnostics are gaining traction in many facilities around the world. Over the past decade, a comprehensive portfolio of hardware solutions (boards, crates, backplanes) has become available to cater for demanding signal processing applications in state-of-the-art facilities like the European XFEL. Gradually, industrial applications of MicroTCA also have become more common. In response various requests, DESY has opened the MicroTCA Technology Lab (A Helmholtz Innovation Lab) in April 2018 as a service unit for research and industry with a focus on: - Customer-specific developments in MicroTCA (hardware, firmware, software), - High-end test and measurement services, - Consulting and system integration. We report on intermediate results and emerging projects after one year of operation, with transfer examples from the industrial automation and medical technology sectors as well as overlapping developments for the physics research community.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP007

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPMP008

Feasibility Study on Mo-99 Production Using Hybrid Method Based on High Power Electron Accelerator

target, neutron, radiation, photon

3462

A. Taghibi Khotbeh-Sara, F. Rahmani
KNTU, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran
H. Khalafi
AEOI, Tehran, Iran
M. Mohseni Kejani
Shahid Beheshti University, Tehran, Iran

In this study, the idea 99Mo production using hybrid method based on electron accelerator has been pre-sented. Two different main production channels of 100Mo(γ,n)99Mo and 98Mo(n,γ)99Mo can be used for 99Mo production in this system. By considering high power Linac (30 MeV, 1 mA in average beam current) and one-stage approach, the calculation of 100Mo(γ,n)99Mo reactions in the optimized 100Mo target in two different designs (strip and disc) has been simu-lated. It is predicted that about 61 and 53 Ci of 99Mo activity per 24-hour irradiation on the strip target and the disc plates can be achieved, respectively. The threshold energy of photoneutron at 100Mo is about 9 MeV, so a large part of bremsstrahlung photons cannot participate in photoneutron reaction. For feasibility study, new hybrid approach has been tested by 10 MeV Rhodotron. Due to the low threshold of photo-neutron in deuteron (about 2.2 MeV) and significant low energy photons in 100Mo, photoneutron flux is available. So, Molybdenum target in heavy water Tank increases the production yield of 99Mo using neutron absorption reaction in 98Mo. The total activity of 99Mo has been predicted about 0.23 Ci per 24 hours e-beam irradiation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP008

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPMP012

New Industrial Application Beamline for the cERL in KEK

target, radiation, linac, vacuum

3475

Y. Morikawa, K. Haga, M. Hagiwara, K. Harada, N. Higashi, T. Honda, Y. Honda, M. Hosumi, Y. Kamiya, R. Kato, H. Kawata, Y. Kobayashi, H. Matsumura, C. Mitsuda, T. Miura, T. Miyajima, S. Nagahashi, N. Nakamura, K.N. Nigorikawa, T. Nogami, T. Obina, H. Sagehashi, H. Sakai, M. Shimada, M. Tadano, R. Takai, H. Takaki, O.A. Tanaka, Y. Tanimoto, A. Toyoda, T. Uchiyama, A. Ueda, K. Umemori, M. Yamamoto
KEK, Ibaraki, Japan

The new beam line for the industrial applications is constructed at the cERL (compact Energy Recovery LINAC) in KEK. In these applications, only north straight sections of cERL consisting of injector and main LINAC will be used. The test for the radio isotope production and electron beam irradiation for the materials are firstly planned with very small beam current without energy recovery.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP012

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paper received ※ 11 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPMP016

Design of the Condenser System and Imaging System for a UEM

gun, experiment, cathode, cavity

3485

T. Chen, W. Li, Y.J. Pei
USTC/NSRL, Hefei, Anhui, People’s Republic of China

The ultrafast electron microscope provides a useful tool for exploring fine structure and observing dynamic process at nanometer and picosecond scale, which has been extensively applied in chemistry and biological field. After emitting from the electron gun, electron beams are focused on the stage sample by the condenser system and then be projected by the imaging system on the screen. In the present study, a two-lens condenser system is simulated by Parmela and a three-lens imaging system is designed using thin-lens approximation. Besides, the shape factor of metallic spheres which have different radius for perturbation method is measured, which is conductive to measuring the Z/Q parameter and the electric field along the axis of the C-band 3MeV photocathode gun for the UEM.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP016

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPMP020

Single-Shot Cascade High Energy Electron Radiography based on Strong Permanent Magnet Quadrupole Composed Imaging Lens

experiment, simulation, quadrupole, optics

3491

Z. Zhou, Y.-C. Du, W.-H. Huang
TUB, Beijing, People’s Republic of China

High energy electron imaging, an extension of conventional transmission electron microscopy, is suitable for imaging of thicker objects and expected to be a promising tool for diagnostics of high energy density physics (HEDP). A cascade high energy electron imaging system using two-stage imaging lenses based on strong permanent magnet quadrupoles is designed, optimized and finally installed at Tsinghua university. Encouraging result of 1.6-μm space resolution is obtained in our primary experiments, along with the clear imaging of a spherical capsule as a substitute of the targets used in inertial confinement fusion. Successful implement of cascade high energy electron imaging system is necessary for reaching better resolving power of the imaging system, and well matching of design, simulation with experimental results paves the way to high energy electron microscopy to provide full capacities for diagnostics of HEDP with sub-um and picosecond spatiotemporal resolutions.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP020

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paper received ※ 07 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPMP021

X-ray Dose Rate of 6/4 MeV European S-band Linac Structure for Industrial Application at RTX

target, linac, simulation, operation

3494

P. Buaphad, I.G. Jeong, Y. Joo, H.R. Lee
University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
I.G. Jeong, J.Y. Lee
Korea Atomic Energy Research Institute (KAERI), Daejeon, Republic of Korea
Y. Joo, Y. Kim, H.R. Lee
KAERI, Daejon, Republic of Korea
H.D. Park, S. Song
RTX, Daejeon, Republic of Korea

Recently, RTX has been developing a 6/4 MeV European S-band (= 2998 MHz) industrial linac by using a magnetron with a low RF power of about 3 MW for container inspection system (CIS). Its accelerating structure is designed to operate in π/2 mode by coupling 6 accelerating cells together through 5 side-coupled cells. In CIS, high dose rate X-rays from MeV-energy electron beam has been used to detect the possible presence of contrabands in cargoes or truck containers. To determine a dose rate output, the X-ray dose rate can be simulated by using FLUKA Monte Carlo simulation. The aim of this work was to study the effects of thickness of X-ray target on dose rate as well as X-ray dose map at 1.0 m away from the X-ray target. This study gives the thickness of target in which the dose rate can be highest and electron beam current can be lowest.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP021

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paper received ※ 24 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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THPMP025

Modern Heavy Ion Based Test Facilities For Spacecrafts Electronics Qualification

radiation, detector, heavy-ion, monitoring

3497

P.A. Chubunov
ISDE, Moscow, Russia
V.S. Anashin
United Rocket and Space Corporation, Institute of Space Device Engineering, Moscow, Russia
I.V. Kalagin, S.V. Mitrofanov, V.A. Skuratov
JINR, Dubna, Moscow Region, Russia

All spacecraft electronics should be subject to radiation hardness qualifications. For modern semiconductor technologies, individual high-energy particles of outer space are the greatest danger, causing upsets and failures in satellite equipment. For ground tests at single event effects, heavy ion-based modeling facilities are used. The report describes the test benches used for testing space-based electronics, created on the basis of the U-400, U-400M ion accelerators in the FLNR JINR (Dubna, Russia) at the request of ISDE (Moscow, Russia).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP025

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paper received ※ 18 May 2019 paper accepted ※ 26 May 2019 issue date ※ 21 June 2019

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THPMP026

Mobile Accelerator Based on Ironless Pulsed Betatron for Dynamic Objects Radiographing

betatron, radiation, ion-source, target

3500

V.A. Fomichev, A.A. Chinin, S.G. Kozlov, Yu.P. Kuropatkin, V.I. Nizhegorodtsev, I.N. Romanov, K.V. Savchenko, V.D. Selemir, O.A. Shamro, E.V. Urlin
RFNC-VNIIEF, Sarov, Nizhniy Novgorod region, Russia

The paper concerns a mobile accelerator based on the ironless pulsed betatron. The accelerator has a possibility to obtain up to three frames in a single pulse and is aimed to radiograph dynamic objects with a large optical thickness. The block diagram of the accelerator, the temporal diagram of its separate systems operation and oscillograms of the betatron output parameters are provided. The testing powering in a single frame mode was carried out in 2018. The capacitance of the storage of the betatron electromagnet pulsed powering system that defines the electron beam energy was equal to 1800 μF. The following test results have been obtained. The thickness of the lead test object examined with X-rays reached 140 mm at 4 m from the tantalum target of the betatron. The full width of the output gamma pulse at half maximum in a single frame mode was equal to 120 ns; the dimension of the radiation source was 6 mm x 3 mm; the dimension of the tantalum target was 6 mm x 6 mm. The application of these accelerators within the radiographic complex* enables the optimization of the hydrodynamic experiments geometry resulting in the increase of the test efficiency.
* Pat. 2548585 C1 RU MPK G03B 42/02. D.I. Zenkov and others. «Mobile radiographic complex and radiation source of betatron type for radiographic complex» (in Russian), 2015.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP026

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paper received ※ 25 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPMP034

Simulating Matter Interactions of Partially Stripped Ions in BDSIM

target, simulation, hadron, dipole

3514

A. Abramov, S.T. Boogert, L.J. Nevay
JAI, Egham, Surrey, United Kingdom

Acceleration and storage of beams of relativistic partially stripped ions is more challenging than in the case of fully stripped ions because the interactions with matter, such as those with residual gas and collimators can strip electrons via ionisation. BDSIM is a code for the simulation of energy deposition and charged particle backgrounds in accelerators that uses the Geant4 physics library. Geant4 includes a broad range of ion elastic and inelastic interactions and allows the definition of partially stripped ion beams. However, no models are currently available to handle in-flight interactions involving the bound electrons. In this paper we present a semi-empirical model of beam ion stripping by material atoms that is implemented in BDSIM as an extension of Geant4’s existing physics processes and is fully integrated into a comprehensive set of matter interactions for partially stripped ions. The stripping cross-section for select cases and results from comprehensive simulations are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP034

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPMP038

Collaborative Strategies for Meeting the Global Need for Cancer Radiation Therapy Treatment Systems

linac, radiation, vacuum, permanent-magnet

3526

M. Dosanjh, P. Collier, I. Syratchev, W. Wuensch
CERN, Meyrin, Switzerland
A. Aggarwal
KCL, London, United Kingdom
D. Angal-Kalinin, P.A. McIntosh, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Apsimon
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
S.T. Boogert
Royal Holloway, University of London, Surrey, United Kingdom
G. Burt
Lancaster University, Lancaster, United Kingdom
N. Coleman, D.A. Pistenmaa
ICEC, Washington, DC, USA
A.W. Cross
USTRAT/SUPA, Glasgow, United Kingdom
I.V. Konoplev, S.L. Sheehy
JAI, Oxford, United Kingdom

The idea of designing affordable equipment and developing sustainable infrastructures for delivering radiation treatment for patients with cancer in countries that lack resources and expertise stimulated a first International Cancer Expert Corps (ICEC) championed, CERN-hosted workshop in Geneva in November 2016. Which has since been followed by three additional workshops involving the sponsorship and support from UK Science and Technology Facilities Council (STFC). One of the major challenges in meeting this need to deliver radiotherapy in low- and middle-income countries (LMIC) is to design a linear accelerator and associated instrumentation system which can be operated in locations where general infrastructures and qualified human resources are poor or lacking, power outages and water supply fluctuations can occur frequently and where climatic conditions might be harsh and challenging. In parallel it is essential to address education, training and mentoring requirements for current, as well as future novel radiation therapy treatment (RTT) systems.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP038

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paper received ※ 11 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPMP039

How Robust Are Existing Medical Linacs in Challenging Environments? A Study of Down Time and Failure Causes.

linac, controls, vacuum, gun

3530

S.L. Sheehy, L. Wroe
JAI, Oxford, United Kingdom
A.J. Egerton
Egerton Consulting Ltd, Minety, Malmesbury, Wiltshire, United Kingdom
A. Steinberg
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

There is a severe lack of radiotherapy linear accelerators (LINACs) in Low- and Middle-Income countries (LMICs), limiting capacity for cancer care in these regions. Anecdotally, operating high tech accelerators in environments with power fluctuations, harsh climatic conditions and geographic isolation leads to large failure rates and downtime. To guide future developments, this study presents a data-driven approach to collect statistical data on LINAC downtime and failure modes, comparing to a simple availability model.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP039

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPMP041

A Comparative Study of Biological Effects of Electrons and Co-60 Gamma Rays on pBR322 Plasmid DNA

radiation, experiment, controls, proton

3533

K.L. Small, R.M. Jones
UMAN, Manchester, United Kingdom
D. Angal-Kalinin, M. Surman
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A. Chadwick, N.T. Henthorn, K. Kirkby, M.J. Merchant, R. Morris, E. Santina
The Christie NHS Foundation Trust, Manchester, United Kingdom
R. Edge
Dalton Cumbrian Facility, University of Manchester, Cumbria, United Kingdom
R.J. Smith
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Very High-Energy Electron (VHEE) therapy is a rapidly developing field motivated by developments in high-gradient linacs. Advantages include sufficient penetration (>30 cm) for treatment of deep-seated tumours, measured insensitivity to inhomogeneities and rapid delivery time, making VHEE viable for treatment of heterogeneous regions, e.g. lung or bowel. Researchers at the University of Manchester and CERN have routinely produced accelerating gradients of ~100 MeV/m for the CLIC project. Suitable modification can result in a high gradient medical linac producing 250 MeV electrons within a treatment room. Radiobiological research for VHEE is vital to understand its use in radiotherapy and how it compares with conventional modalities. The goal of radiotherapy is to destroy tumour cells while sparing healthy cells, primarily by damaging DNA within the cancer cell. The study aim is to understand the fundamental interactions between VHEE and biological structures through plasmid irradiation studies - both computational, using the Monte Carlo GEANT4-DNA code, and experimental. Plasmid irradiation experiments have been carried out at using Co-60 gammas at the Dalton Cumbrian Facility and using 6-15 MeV electrons at the Christie NHS Foundation Trust to determine the type and quantity of damage caused to DNA by electron irradiation. These experiments are a world first in VHEE radiobiology, with further studies planned at higher energies using the CLARA and CLEAR facilities at Daresbury and CERN. These studies will also consider the effective dose range of VHEE with energy, as well as implications of damage on DNA. Research into this area of radiotherapy can provide a valuable addition to tools currently available to physicians in the fight against cancer.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP041

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPMP046

Knowledge Exchange Within the Particle Accelerator Community via Cloud Computing

simulation, GUI, software, HOM

3548

D.L. Bruhwiler, D.T. Abell, N.M. Cook, C.C. Hall, M.V. Keilman, P. Moeller, R. Nagler, B. Nash
RadiaSoft LLC, Boulder, Colorado, USA

Funding: Work supported by US Department of Energy under Award Nos. DE-SC0011237, DE-SC0011340, DE-SC0018719, DE-SC0015212, DE-SC0017181 and DE-SC0017162.
The development, testing and use of particle accelerator modeling codes is a core competency of accelerator research laboratories around the world, and likewise for synchrotron radiation and X-ray optics codes at lightsource facilities. Such codes require time and training to learn a command-line workflow involving multiple input and configuration files, execution on a high-performance server or cluster, post-processing with specialized software and finally visualization. Such workflows are error prone an difficult to reproduce. Cloud computing and UI design are core competencies of RadiaSoft LLC, where the Sirepo* framework is being developed to make state of the art codes available in the browser of any desktop, laptop or tablet. We present our initial successes as real world examples of knowledge exchange (KE) between industry and the research community. This work is leading to broader knowledge exchange throughout the community by facilitating education of students and enabling instantaneous sharing of simulation details between colleagues. Sirepo design objectives include: seamless integration with legacy codes, low barrier to entry for new users, configuration transfer to command line mode, catalog of provenance to aid reproducibility, and simplified collaboration through multimodal sharing. The Sirepo Scientific Gateway** allows users to directly test the software. The combination of intuitive browser-based GUIs and Sirepo’s server-side application container technology enables simplified computational archiving and reproducibility. If embraced by the community, this could become an important asset for the design, commissioning and future upgrade of particle accelerator and X-ray beamline facilities.
* Sirepo cloud computing framework, https://github.com/radiasoft/sirepo
** Sirepo Scientific Gateway, https://sirepo.com

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP046

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paper received ※ 21 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPMP049

Sequential Excitation Scheme for Laser Stripping of Hydrogen Ion Beams

laser, photon, cavity, proton

3558

Y. Liu, A.V. Aleksandrov, S.M. Cousineau, T.V. Gorlov, A. Rakhman
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
Resonant laser excitation of the electron in a hydrogen atom is essential to achieve high-efficiency laser stripping of hydrogen ion (H⁻) beam. In the laser stripping experiments recently carried out at SNS, an ultra-violet (UV) laser was used to excite the electrons in 1-GeV hydrogen atoms from the n=1 state to the n=3 state. In this talk, we propose a sequential resonant excitation scheme by using two laser beams to excite electrons in a sequence of two steps: from the n=1 state to the n=2 state and from the n=2 state to any higher state. The advantages of the sequential resonant excitation scheme include (1) lower laser power requirement due to higher transition probability in the first excitation step and (2) possibility of shifting the stripping laser wavelength from UV regime to longer wavelengths. An application of the sequential resonant excitation scheme in combination with the double-resonance optical cavity technology to the laser stripping of 1.3-GeV H⁻ beam (envisioned in the SNS proton power upgrade project) will be described.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP049

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPMP053

Tuning Quadrupoles for Brighter and Sharper Ultra-fast Electron Diffraction Imaging

quadrupole, focusing, experiment, solenoid

3571

X. Yang, L. Doom, M.G. Fedurin, Y. Hidaka, J.J. Li, D. Padrazo Jr, T.V. Shaftan, V.V. Smaluk, G.M. Wang, L.-H. Yu, Y. Zhu
BNL, Upton, Long Island, New York, USA
W. Wan
ShanghaiTech University, Shanghai, People’s Republic of China

Funding: BNL LDRD
We report our proof-of-principle design and experi-mental commissioning of broadly tunable and low-cost transverse focusing lens system for MeV-energy electron beams at the ultra-fast electron diffraction (UED) beam-line of the Accelerator Test Facility II of BNL. We exper-imentally demonstrate the independent control over the size and divergence of the electron beam at the sample via tunable quadrupoles. By applying online optimiza-tion, we achieve minimum beam sizes 75 µm from 1 to 13 pC, two orders of magnitude higher charge density than previously achieved using conventional solenoid tech-nique. Finally, we experimentally demonstrate Bragg-diffraction image (BDI) with significant improvement up to 3 times brighter and 2 times sharper BDI peaks via the optimized quadrupoles, improvement larger with higher charge. The result could be crucial for the future single-shot ultra-fast electron microscope development.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP053

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPGW002

A Passive Plasma Beam Dump Study with Application to EuPRAXIA

plasma, wakefield, simulation, laser

3581

R.P. Nunes
UFRGS, Porto Alegre, Brazil
A. Bonatto
University of Manchester, Manchester, United Kingdom
G.X. Xia
UMAN, Manchester, United Kingdom

Funding: The author R. P. Nunes acknowledges the financial support provided by FAPERGS.
This work presents a study about a passive dumping scheme applied to the beam generated by the accelerator stage of the EuPraxia experiment. Particle-in-cell simulations have been carried out and its results are compared with analytical estimates, showing a reasonable agreement.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW002

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paper received ※ 05 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPGW003

Energy Loss of an Electron Beam with Gaussian Density Profile Propagating in a Passive Plasma Beam Dump

plasma, wakefield, simulation, laser

3584

A. Bonatto
University of Manchester, Manchester, United Kingdom
R.P. Nunes
UFRGS, Porto Alegre, Brazil
G.X. Xia
UMAN, Manchester, United Kingdom

Funding: CNPq, and FAPERGS, from Brazil.
A semi-analytical 1D model is derived for the total energy loss of an electron beam with Gaussian density profile undergoing a passive plasma beam dump. The model is compared to a previous one, obtained for a half-sine longitudinal density profile. It is shown that both models agree if the beam density profiles are properly matched, and if their sizes are small in comparison to the length of wakefield decelerating length. The beam energy obtained from both models is compared to 1D PIC simulation results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW003

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paper received ※ 09 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPGW011

Commissioning-Stages and Radio-Protection Concept for the THz-Linac Based Accelerator "AXSIS" at DESY

MMI, laser, operation, linac

3598

F. Burkart, R.W. Aßmann, U. Dorda, B. Marchetti
DESY, Hamburg, Germany
F.X. Kärtner, N.H. Matlis, T. Rohwer
CFEL, Hamburg, Germany

The dedicated accelerator R&D facility SINBAD at DESY hosts the AXSIS accelerator. This project is funded by the European Research Council to develop a compact source for attosecond serial X-ray crystallography and spectroscopy. For that purpose, in one of the arcs of the SINBAD facility and the neighboring laser labs, an accelerator research site is being constructed where a fully THz-driven accelerator (electron gun and linac, < 30MeV) will be installed. The current status of the hardware installation of the electron beam accelerator is presented. Furthermore, the required radio-protection measures and maximum beam parameters are presented. In this contribution the commissioning plans and the staging of the beam operation for the accelerator complex will be shown and discussed in detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW011

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPGW012

Wake-T: A Fast Particle Tracking Code for Plasma-Based Accelerators

plasma, simulation, emittance, laser

3601

A. Ferran Pousa, R.W. Aßmann, A. Martinez de la Ossa
DESY, Hamburg, Germany
A. Ferran Pousa
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

The design and study of plasma-based accelerators relies typically on costly 3D Particle-In-Cell (PIC) simulations due to the complexity of the laser-plasma and beam-plasma interactions. However, under certain assumptions, more efficient and simple models can be implemented to describe the dynamics of the accelerated beams. Wake-T (Wakefield particle Tracker) is a new code for analytical and numerical particle tracking in plasma-based accelerators which is orders of magnitude faster than conventional PIC codes. This allows for fast parameter scans and is well suited for the initial design and optimization of these novel accelerators.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW012

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paper received ※ 24 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPGW014

Tolerance Studies and Limitations for Photonic Bandgap Fiber Accelerators

laser, acceleration, photon, simulation

3605

L. Genovese, R.W. Aßmann, U. Dorda, M. Kellermeier, W. Kuropka, F. Lemery, F. Mayet
DESY, Hamburg, Germany
W. Kuropka, F. Mayet
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Laser-driven hollow core photonic bandgap (PBG) fibers were proposed by Lin in 2001 as high-gradient accelerators. The central defect in the transversely periodic lattice supports an accelerating mode for synchronous acceleration in the ultra-relativistic regime. The optical frequencies in such dielectric laser accelerators motivate a sensitivity and tolerance study to overcome manufacturing imperfections. Finally we discuss the propagation characteristics of Lin-fibers and find that small-bandwidth (~ns) pulses would be needed for efficient acceleration over longer distances.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW014

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paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPGW015

Proposed Beam Test of a Transverse Gradient Undulator at the SINBAD Facility at DESY

undulator, linac, experiment, radiation

3609

R. Rossmanith, A. Bernhard, K. Damminsek, J. Gethmann, S. Richter
KIT, Karlsruhe, Germany
R.W. Aßmann, F. Burkart, U. Dorda, F. Jafarinia, B. Marchetti
DESY, Hamburg, Germany
M. Kaluza
IOQ, Jena, Germany

While Laser Plasma Accelerators produce beams with the high output energy required for FELs, up to now the relatively high energy spread has prohibited FEL lasing. Therefore it was proposed to replace the normal FEL undulators by Transverse Gradient Undulators (TGUs). For a first, small scale test of the TGU concept, a 40 period prototype high gradient superconductive TGU was built at KIT and will be tested with beam at the ARES-linac in the new accelerator test facility SINBAD (Short Innovative Bunches and Accelerators at Desy) at DESY. The proposed tests are summarized in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW015

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paper received ※ 07 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPGW016

Overview and Prospects of Plasma Wakefield Acceleration Experiments at PITZ

plasma, wakefield, laser, experiment

3612

O. Lishilin, Y. Chen, J.D. Good, M. Groß, I.I. Isaev, C. Koschitzki, M. Krasilnikov, G. Loisch, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, F. Stephan
DESY Zeuthen, Zeuthen, Germany
R. Brinkmann, A. Martinez de la Ossa, J. Osterhoff
DESY, Hamburg, Germany
F.J. Grüner
Center for Free-Electron Laser Science, Universität Hamburg, Hamburg, Germany
T.J. Mehrling, C.B. Schroeder
LBNL, Berkeley, USA

The Photo Injector Test Facility at DESY in Zeuthen (PITZ) carries out studies of beam-driven plasma wakefield acceleration (PWFA). The facility possesses a flexible photocathode laser beam shaping system and a variety of diagnostics including a high-resolution dipole spectrometer and an rf deflector which enables the observation of the longitudinal phase space of electron beams after their passage through a plasma. Two plasma sources are available: a gas discharge plasma cell and a photoionized lithium vapor plasma cell. Studies at PITZ include investigations of the self-modulation instability of long electron beams and the high transformer ratio, i.e., the ratio between the maximum accelerating field behind the drive beam and the decelerating field within the beam. This overview includes the experimental results and plans for future experiments.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW016

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paper received ※ 30 April 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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THPGW017

Self-Modulation Instability of Electron Beams in Plasma Channels of Variable Length

plasma, wakefield, simulation, laser

3616

O. Lishilin, Y. Chen, J.D. Good, M. Groß, I.I. Isaev, C. Koschitzki, M. Krasilnikov, G. Loisch, A. Oppelt, H.J. Qian, F. Stephan
DESY Zeuthen, Zeuthen, Germany
R. Brinkmann, A. Martinez de la Ossa, J. Osterhoff
DESY, Hamburg, Germany
F.J. Grüner
Center for Free-Electron Laser Science, Universität Hamburg, Hamburg, Germany
T.J. Mehrling, C.B. Schroeder
LBNL, Berkeley, USA

The self-modulation instability (SMI) of long (in respect to the plasma wavelength) charged particle beams passing through plasma enables the use of currently existing high energy charged particle beams as drivers for plasma wakefield accelerators. At the Photo Injector Test facility at DESY in Zeuthen (PITZ) the SMI of electron beams is studied *, **. An enhanced experimental setup includes a plasma channel of variable length which allows to investigate in details the development stages of the SMI by measuring the instability growth rate and phase velocity as a function of propagation distance in the plasma. In this contribution we present the experimental setup improvements, first measurement results and supporting beam dynamics simulations.
* M. Gross, et al., Phys. Rev. Lett., vol. 120, p. 144802, 2018.
** G. Loisch, et al., Plasma Physics and Controlled Fusion, vol. 61(4), p. 045012, 2019

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW017

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paper received ※ 11 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPGW019

FLASHforward Findings for the EuPRAXIA Design Study and the Next-Generation of Compact Accelerator Facilities

plasma, wakefield, focusing, laser

3619

P. Niknejadi, R.T.P. D’Arcy, J.M. Garland, J. Osterhoff, L. Schaper, B. Schmidt, G.E. Tauscher
DESY, Hamburg, Germany
M. Ferrario, S. Romeo
INFN/LNF, Frascati, Italy
C.A. Lindstrøm
University of Oslo, Oslo, Norway
T.J. Mehrling
LBNL, Berkeley, USA

FLASHForward, the exploratory FLASH beamline for Future-ORiented Wakefield Accelerator Research and Development, is a European pilot test bed facility for accelerating electron beams to GeV-levels in a few centimeters of ionized gas. The main focus is on the advancement of plasma-based particle acceleration technology through investigation of injection schemes, novel concepts and diagnostics, as well as benchmarking theoretical studies and simulations. Since the plasma wakefield will be driven by the optimal high-current-density electron beams extracted from the FLASH L-band Superconducting RF accelerator, FLASHForward has been in a unique position for studying and providing insight for the design study of next-generation light source and high energy physics facilities such as EuPRAXIA*. Summary of these findings and their broader impact is discussed here.
*P. A. Walker, et. al., "Horizon 2020 EuPRAXIA design study," Journal of Physics Conference Series 874(1):012029, July 2017.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW019

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paper received ※ 15 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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THPGW022

The Effect of the Transverse Beam Jitter on the Accelerated Electron Beam Quality in a Laser-Driven Plasma Accelerator with External Injection at SINBAD for ATHENAe

plasma, laser, injection, acceleration

3624

E.N. Svystun, R.W. Aßmann, U. Dorda, B. Marchetti
DESY, Hamburg, Germany

Laser plasma accelerators with external injection of an RF-generated electron beam, providing high accelerating field gradients and increased control over the electron beam injection process, are promising candidates for production electron beams matching the requirements of modern user-applications. The experiments are planned at the SINBAD (Short INnovative Bunches and Accelerators at DESY) facility to test this acceleration technique in the context of the ATHENAe (Accelerator Technology HElmholtz iNfrAstructure) project. In this paper we present numerical studies on the effect of the transverse electron beam jitter on the final quality of a sub-femtosecond, 0.75 pC, 100 MeV electron beam accelerated to 1 GeV energy in the plasma wakefield driven by a 196 TW, 5 J laser pulse.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW022

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paper received ※ 07 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPGW023

Numerical Studies on Electron Beam Quality Optimization in a Laser-Driven Plasma Accelerator with External Injection at SINBAD for ATHENAe

plasma, laser, acceleration, injection

3628

E.N. Svystun, R.W. Aßmann, U. Dorda, B. Marchetti, A. Martinez de la Ossa
DESY, Hamburg, Germany

Nowadays the electron beams produced in plasma-based accelerators (PBAs) are of sufficient energy for multi-GeV applications. However, to allow PBAs to be usable for demanding applications such as Free-Electron Lasers, the quality and stability of plasma-accelerated beams have to be improved. We present numerical studies on accelera-tion of an RF-generated electron beam with a charge of 0.8 pC and initial mean energy of 100 MeV to GeV energies by a laser-plasma accelerator. This acceleration scheme is planned to be tested experimentally within the framework of the ATHENAe (Accelerator Technology HElmholtz iNfrAstructure) project at the SINBAD (Short INnovative Bunches and Accelerators at DESY) facility at DESY, Hamburg. Electron beam injection, acceleration and extraction from the plasma are investigated through start-to-end 3D simulations. The effect of the injection phase on the accelerated beam quality is investigated through tolerance studies on the arrival-time jitter between the electron beam and the external laser.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW023

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paper received ※ 01 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPGW025

Facility Considerations for a European Plasma Accelerator Infrastructure (EuPRAXIA)

plasma, laser, site, positron

3635

P.A. Walker, R.W. Aßmann, U. Dorda, B. Marchetti, M.K. Weikum
DESY, Hamburg, Germany
E. Chiadroni, M. Ferrario
INFN/LNF, Frascati, Italy
A. Specka
LLR, Palaiseau, France
R. Walczak
JAI, Oxford, United Kingdom

Funding: This work was supported by the European Union‘s Horizon 2020 research and innovation programme under grant agreement No. 653782.
EuPRAXIA (European Plasma Research Accelerator with eXcellence In Applications) is a conceptual design study for a compact European infrastructure with multi-GeV electron beams based on plasma accelerators. The concept foresees two main experimental sites, one at INFN in Frascati and one at DESY in Hamburg. In Frascati, an RF injector based on S-band and X-band technology (electron energy up to 1 GeV) will be constructed and used as a drive beam for beam driven plasma acceleration (PWFA) with final electron beam energies up to 5 GeV. At DESY, the focus will be on laser driven plasma acceleration (LWFA) and an RF injector based on S-band technology (electron energy up to 240 MeV) or alternatively a plasma injector (electron energy up to 150 MeV) can be used before the beam is injected into the plasma accelerator for external LWFA and acceleration up to 5 GeV. A single stage approach based on LWFA with internal injection will also be pursued in a second beamline. User areas at both sites will provide access to FEL pilot experiments, positron generation, compact radiation sources, and test beams for HEP detector development. This contribution discusses facility space considerations for the future plasma accelerator research infrastructure of EuPRAXIA.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW025

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paper received ※ 13 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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THPGW026

Status of the Horizon 2020 EuPRAXIA Conceptual Design Study

plasma, laser, acceleration, site

3638

M.K. Weikum, A. Aschikhin, R.W. Aßmann, R. Brinkmann, U. Dorda, A. Ferran Pousa, T. Heinemann, F. Jafarinia, A. Knetsch, C. Lechner, W. Leemans, B. Marchetti, A. Martinez de la Ossa, P. Niknejadi, J. Osterhoff, K. Poder, R. Rossmanith, L. Schaper, E.N. Svystun, G.E. Tauscher, P.A. Walker, J. Zhu
DESY, Hamburg, Germany
T. Akhter, S. De Nicola
INFN-Napoli, Napoli, Italy
D. Alesini, M.P. Anania, F.G. Bisesto, E. Chiadroni, M. Croia, A. Del Dotto, M. Ferrario, F. Filippi, A. Gallo, A. Giribono, R. Pompili, S. Romeo, J. Scifo, C. Vaccarezza, F. Villa
INFN/LNF, Frascati, Italy
A.S. Alexandrova, R. Torres, C.P. Welsch, J. Wolfenden
The University of Liverpool, Liverpool, United Kingdom
A.S. Alexandrova, A. Beaton, J.A. Clarke, A.F. Habib, T. Heinemann, B. Hidding, P. Scherkl, N. Thompson, R. Torres, D. Ullmann, C.P. Welsch, S.M. Wiggins, J. Wolfenden, G.X. Xia
Cockcroft Institute, Warrington, Cheshire, United Kingdom
N.E. Andreev, D. Pugacheva
JIHT RAS, Moscow, Russia
N.E. Andreev, D. Pugacheva
MIPT, Dolgoprudniy, Moscow Region, Russia
I.A. Andriyash, M.-E. Couprie, A. Ghaith, D. Oumbarek Espinos
SOLEIL, Gif-sur-Yvette, France
T. Audet, B. Cros, G. Maynard
CNRS LPGP Univ Paris Sud, Orsay, France
A. Bacci, D. Giove, V. Petrillo, A.R. Rossi, L. Serafini
INFN-Milano, Milano, Italy
I.F. Barna, M.A. Pocsai
Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary
A. Beaton, A.F. Habib, T. Heinemann, B. Hidding, D.A. Jaroszynski, G.G. Manahan, P. Scherkl, Z.M. Sheng, D. Ullmann, S.M. Wiggins
USTRAT/SUPA, Glasgow, United Kingdom
A. Beck, F. Massimo, A. Specka
LLR, Palaiseau, France
A. Beluze, F. Mathieu, D.N. Papadopoulos
LULI, Palaiseau, France
A. Bernhard, E. Bründermann, A.-S. Müller
KIT, Karlsruhe, Germany
S. Bielawski, E. Roussel, C. Szwaj
PhLAM/CERLA, Villeneuve d’Ascq, France
F. Brandi, G. Bussolino, L.A. Gizzi, P. Koester, L. Labate, B. Patrizi, G. Toci, P. Tomassini, M. Vannini
INO-CNR, Pisa, Italy
M.H. Bussmann, A. Irman, U. Schramm
HZDR, Dresden, Germany
M. Büscher, A. Lehrach
FZJ, Jülich, Germany
A. Chancé, P.A.P. Nghiem, C. Simon
CEA-IRFU, Gif-sur-Yvette, France
M. Chen, Z.M. Sheng
Shanghai Jiao Tong University, Shanghai, People’s Republic of China
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
A. Cianchi
INFN-Roma II, Roma, Italy
J.A. Clarke, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J. Cole, S.M. Hooker, M.J.V. Streeter, R. Walczak
JAI, London, United Kingdom
P.A. Crump, M. Huebner
FBH, Berlin, Germany
G. Dattoli, F. Nguyen
ENEA C.R. Frascati, Frascati (Roma), Italy
N. Delerue, K. Wang
LAL, Orsay, France
J.M. Dias, R.A. Fonseca, J.L. Martins, L.O. Silva, T. Silva, U. Sinha, J.M. Vieira
IPFN, Lisbon, Portugal
R. Fedele, G. Fiore, D. Terzani
UniNa, Napoli, Italy
A. Ferran Pousa, T. Heinemann, V. Libov
University of Hamburg, Hamburg, Germany
M. Galimberti, P.D. Mason, R. Pattathil, D. Symes
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
L.A. Gizzi, L. Labate
INFN-Pisa, Pisa, Italy
F.J. Grüner, A.R. Maier
CFEL, Hamburg, Germany
F.J. Grüner, O.S. Karger, A.R. Maier
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
C. Haefner, C. Siders
LLNL, Livermore, California, USA
B.J. Holzer
CERN, Geneva, Switzerland
S.M. Hooker
University of Oxford, Oxford, United Kingdom
T. Hosokai
ISIR, Osaka, Japan
C. Joshi
UCLA, Los Angeles, California, USA
M. Kaluza
IOQ, Jena, Germany
M. Kaluza
HIJ, Jena, Germany
M. Kando
JAEA/Kansai, Kyoto, Japan
S. Karsch
LMU, Garching, Germany
E. Khazanov, I. Kostyukov
IAP/RAS, Nizhny Novgorod, Russia
D. Khikhlukha, D. Kocon, G. Korn, K.O. Kruchinin, A.Y. Molodozhentsev, L. Pribyl
ELI-BEAMS, Prague, Czech Republic
O.S. Kononenko, A. Lifschitz
LOA, Palaiseau, France
C. Le Blanc, Z. Mazzotta
Ecole Polytechnique, Palaiseau, France
X. Li
DESY Zeuthen, Zeuthen, Germany
V. Litvinenko
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
W. Lu
TUB, Beijing, People’s Republic of China
O. Lundh
Lund University, Lund, Sweden
V. Malka
Weizmann Institute of Science, Physics, Rehovot, Israel
S.P.D. Mangles, Z. Najmudin, A.A. Sahai
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
A. Mostacci
INFN-Roma, Roma, Italy
A. Mostacci
Sapienza University of Rome, Rome, Italy
C.D. Murphy
York University, Heslington, York, United Kingdom
V. Petrillo
Universita’ degli Studi di Milano, Milano, Italy
M. Rossetti Conti
Universita’ degli Studi di Milano & INFN, Milano, Italy
G. Sarri
Queen’s University of Belfast, Belfast, Northern Ireland, United Kingdom
C.B. Schroeder
LBNL, Berkeley, California, USA
C.-G. Wahlstrom
Lund Institute of Technology (LTH), Lund University, Lund, Sweden
R. Walczak
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
G.X. Xia
UMAN, Manchester, United Kingdom
M. Yabashi
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
A. Zigler
The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem, Israel

Funding: This work was supported by the European Union’s Horizon 2020 Research and Innovation programme under grant agreement No. 653782.
The Horizon 2020 Project EuPRAXIA (European Plasma Research Accelerator with eXcellence In Applications) is producing a conceptual design report for a highly compact and cost-effective European facility with multi-GeV electron beams accelerated using plasmas. EuPRAXIA will be set up as a distributed Open Innovation platform with two construction sites, one with a focus on beam-driven plasma acceleration (PWFA) and another site with a focus on laser-driven plasma acceleration (LWFA). User areas at both sites will provide access to FEL pilot experiments, positron generation and acceleration, compact radiation sources, and test beams for HEP detector development. Support centres in four different countries will complement the pan-European implementation of this infrastructure.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW026

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paper received ※ 26 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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THPGW033

Numerical Study of Photonic-Crystal-Based Dielectric Accelerators

GUI, photon, acceleration, impedance

3653

G. Torrisi, L. Celona, S. Gammino, D. Mascali, G. Sorbello
INFN/LNS, Catania, Italy
C. De Angelis, A. Locatelli
University of Brescia, Brescia, Italy
G.S. Mauro
INFN/LNL, Legnaro (PD), Italy
G. Sorbello
University of Catania, Catania, Italy

All-dielectric electromagnetic band gap (EBG) waveguides structures promise significant improvement of accelerating gradient of laser-driven acceleration with the potential to miniaturize the accelerator itself. In this work we study photonic crystal structures designed for acceleration of relativistic electrons. We explore the performance of the all-dielectric EBG accelerating waveguide structures thanks to full wave electromagnetic simulations of couplers and accelerating waveguides. The characteristic interaction impedance, accelerating gradient and all the key parameters that are typically used to characterize linear accelerators are evaluated and used to compare the properties of the accelerating mode field distribution in different geometries.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW033

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paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPGW035

Development of Yb-Based Laser System for Crab Crossing Laser-Compton Scattering

laser, luminosity, experiment, scattering

3657

R. Morita, Y. Koshiba, S. Ota, M. Washio
Waseda University, Tokyo, Japan
T. Higashiguchi
Center for Optical Research and Education, Utsunomiya University, Utsunomiya, Japan
K. Sakaue
The University of Tokyo, The School of Engineering, Tokyo, Japan
J. Urakawa
KEK, Ibaraki, Japan

Funding: This work was supported by JSPS KAKENHI 18H0123.
We are going to demonstrate the principle of crab crossing in laser-Compton scattering which creates head-on collision in a pseudo manner to enhance the intensity of laser-Compton X-ray. When the electron beam is tilted by half of the collision angle, the scat-tered X-rays becomes the largest. Calculation shows that more than threefold luminosity will be achieved in our system and could be larger luminosity depending on the beam parameters. The intensity of scattered light can be efficiently enhanced by using a collision laser with high intensity, high quality and ultrashort pulse duration. Thus, we have introduced a regenera-tive amplifier using ceramics thin-disk as a collision laser and developed a dedicated laser system. In this conference, we will report on our laser system and results of crab crossing laser-Compton scattering.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW035

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPGW036

Development of Supercontinuum Light Production System Using Er Fiber Laser for Pulse Radiolysis*

laser, radiation, experiment, electronics

3660

T. Uchida, S. Hanai, K. Sakaue, M. Washio
Waseda University, Tokyo, Japan

Pulse radiolysis is one of the methods to elucidate radiation chemical reactions. In order to elucidate that, not only high temporal resolution, but also a light source with a broad spectrum band is required. A Xe flash lamp is mentioned as a light source having a broad spectrum band. However, in measurement using a Xe flash lamp, the time resolution is limited to the nanosecond order. In this research, we have developed supercontinuum light as a light source that enables picosecond time resolution and has a broader spectrum band. In this paper, we developed a light source using an Er doped fiber laser for pulse radiolysis measurement, and report the results and future prospects here.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW036

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paper received ※ 15 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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THPGW037

Hybrid Yb/Nd Laser System for RF Gun in SuperKEKB Phase II and Phase III Commissioning

laser, gun, MMI, injection

3663

R. Zhang, Y. Honda, M. Yoshida, X. Zhou
KEK, Ibaraki, Japan
H.K. Kumano, N. Toyotomi
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan

SuperEKKB phase II commissioning has been finished in the summer of 2018. By use of Ytterbium doped fiber and Nd:YAG hybrid laser system, 2.3 nC electron beam with low emittance has been achieved at the end of linac, which is generated by RF gun. The electron beam is injected and stored in High Energy Ring successfully. Basing on these operation experiences, the Nd:YAG laser system will be used for the early stages of SuperKEKB phase III commissioning. After the update of laser system during 2018 summer maintenance, about 5.3 nC electron charge is generated by RF gun. Beside this, the laser spatial and temporal reshaping experiment has been being done in order to realize the electron beam with low emittance and low energy spread. Meanwhile, a perspective towards the next step Yb:YAG laser system is also introduced in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW037

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paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPGW043

Conceptual design of a MeV Ultrafast Electron Diffraction Based on 1.4 Cell RF Gun

gun, cathode, emittance, laser

3679

J.J. Li, H.M. Chen, K. Fan, Y. Song, P. Yang, Y.T. Yang
HUST, Wuhan, People’s Republic of China

Ultrafast Electron Diffraction (UED) is a powerful tool to investigate the dynamic structure with temporal scale of 100 femtoseconds and spatial scale of atomic length. To achieve high quality diffraction patterns, the transverse emittance and the longitudinal length of electron bunches should be reduced. MeV UED, using photocath-ode RF gun instead of traditional DC gun, is being developed to produce high quality electron bunches with lower emittance and shorter length. We are developing a MeV UED facility based on a 1.4 cell photocathode RF gun that can provide higher acceleration gradient at Huazhong University of Science and Technology. In this paper, the conceptual design of the MeV UED is pro-posed with typical parameters of the system, as well as the ASTRA simulation results of optimization.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW043

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paper received ※ 11 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPGW047

Cylindrical Cavity Design and Particle-Tracking Simulation in Cyclotron Auto-Resonance Accelerator

cavity, cyclotron, resonance, acceleration

3689

Y.T. Yuan
HUST, Wuhan, People’s Republic of China
K. Fan
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China
Y. Jiang
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA

The Cyclotron Auto-Resonance Accelerator (CARA) is a novel concept of accelerating continuous-wave (CW) charged-particle beams. This type of accelerator has ap-plications in environment improvement area and genera-tion of high-power microwaves. In CARA, the CW elec-tron beam follows a gyrating trajectory while undergoing the interaction with a rotating TE11-mode RF field and tapered static magnetic field. The cylindrical cavity oper-ating at TE11p-mode is adapted to accelerate electron beam. The cavity size is optimized to obtain a beam with designed energy, then a design method of the TE11p-mode acceleration cavity is described here. Moreover, regard-less of space charge effect, several particle-tracking simu-lations of CARAs are showed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW047

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paper received ※ 16 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPGW048

Temporal Characterization of Electron Bunches From Self-Injection and Ionization Injection in a Laser Wakefield Accelerator

injection, laser, plasma, radiation

3693

J. Zhang, Y.X. He, J.F. Hua, D.X. Liu, W. Lu, Y. Ma, C.H. Pai, Y.P. Wu
TUB, Beijing, People’s Republic of China
Z. Nie, Q. Su
UCLA, Los Angeles, California, USA

Plasma based accelerators (PBAs) have a proven capability to generate high energy electron beams with ultrashort duration (~ 10 fs) and high peak current (~ 10 kA), which opens the opportunity for compact free electron lasers. To meet the requirements of such challenging applications, controllable injection is highly needed to produce high-quality and highly stable electron beams. As we know, the beam parameters，including the current profile, strongly depend on the injection process. To explore the underlying physics and optimize beam parameters in PBAs, a temporal characterization is highly required for different injection schemes. Based on coherent transition radiation(CTR) method, the preliminary experiment to measure beam temporal profiles from both self-injection and ionization injection schemes in a single-shot mode has been performed at Tsinghua University. And the simulations using the similar experimental parameters have been performed to interpret the different injection processes, which show some agreement with the experimental results, especially for the features of bunch durations

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW048

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPGW051

MCP Based Detectors of European XFEL

FEL, detector, photon, radiation

3703

E. Syresin, O.I. Brovko, A.Yu. Grebentsov
JINR, Dubna, Moscow Region, Russia
W. Freund, J. Grünert
EuXFEL, Schenefeld, Germany
M.V. Yurkov
DESY, Hamburg, Germany

Radiation detectors based on microchannel plates (MCP) are used for measurements of the SASE process of the European XFEL. Detectors operate in a wide dynamic range from the level of spontaneous emission to the saturation level (between a few nJ and 25 mJ) and in a wide wavelength range from 0.05 nm to 0.4 nm for SASE1 and SASE2 and from 0.4 nm to 4.43 nm for SASE3. Photon pulse energies are measured by the MCPs with an anode and by a photodiode. The MCP imager measures the photon beam image with a phosphor screen. Three MCP detectors are installed, one behind each SASE undulator (SASE1, SASE2, and SASE3). Calibration and first experiments with the MCP detectors are under discussion.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW051

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paper received ※ 29 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPGW054

Generation and Delivery of an Ultraviolet Laser Beam for the RF-Photoinjector of the Awake Electron Beam

laser, cathode, plasma, proton

3709

V. Fedosseev, F. Batsch, C. Capelli, E. Chevallay, N. Chritin, S. Döbert, T. Feniet, F. Friebel, P. Gander, E. Granados, E. Gschwendtner, J. Hansen, C. Heßler, H. Panuganti, K.A. Szczurek
CERN, Meyrin, Switzerland
M. Hüther, M. Martyanov, J.T. Moody, P. Muggli
MPI-P, München, Germany

In the AWAKE experiment, the electron beam is used to probe the proton-driven wakefield acceleration in a 10 m long rubidium vapor source. Electron bunches are produced using an RF-gun equipped with a Cs2Te photocathode illuminated by an ultraviolet (UV) laser pulse. To generate the UV laser beam a fraction of the infrared (IR) laser beam used for ionization of rubidium is extracted from the laser system, time-compressed to a picosecond scale and frequency tripled using nonlinear crystals. The transport line of the laser beam over the 20 m distance was built using rigid supports for mirrors and air-evacuated tube to prevent any possible beam pointing instabilities due to vibrations and air convection. Construction of the UV beam optical system enables appropriate beam shaping and control of its size and position on the cathode, as well as time delay with respect to the IR pulse, i.e. with respect to the plasma wakefield seeder. In this paper, we present the design of the UV beam line and results of its commissioning regarding IR/UV conversion, beam pointing stability, and means of beam control and monitoring.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW054

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paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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THPGW059

Laser-Plasma Acceleration Modeling Approach in the Case of ESCULAP Project.

plasma, laser, acceleration, GPU

3723

V. Kubytskyi, C. Bruni, K. Cassou, V. Chaumat, N. Delerue, D. Douillet, S. Jenzer, H. Purwar, K. Wang
LAL, Orsay, France
E. Baynar, M. Pittman
CLUPS, Orsay, France
J. Demailly, O. Guilbaud, S. Kazamias, B. Lucas, G. Maynard, O. Neveu, D. Ros
CNRS LPGP Univ Paris Sud, Orsay, France
D. Garzella
CEA-IRFU, Gif-sur-Yvette, France
R. Prazeres
CLIO/ELISE/LCP, Orsay, France

Objective of ESCULAP project is the experimental study of Laser-Plasma Acceleration (LPA) of relativistic electron bunch from photo-injector in 10 cm length plasma cell *. In parallel, numerical tools have been developed in order to optimize the setup configuration and the analysis of the expected results. The most important issue when dealing with numerical simulation over such large interaction distances is to obtain a good accuracy at a limited computing cost in order to be able to perform parametric studies. Reduction of the computational cost can be obtained either by using state-of-the-art numerical technics and/or by introducing adapted approximation in the physical model. Concerning LPA, the relevant Maxwell-Vlasov equations can be numerically solved by Particle-In-Cell (PIC) methods without any additional approximation, but can be very computationally expensive. On the other hand, the quasi-static approximation ***, which yields a drastic reduction of the computational cost, appears to be well adapted to the LPA regime. In this paper we present a detailed comparison of the performance, in terms of CPU, of LPA calculations and of the accuracies of their results obtained either with a highly optimized PIC code (FBPIC **) or with the well known quasi-static code WAKE ***. We first show that, when considering a sufficiently low charge bunch for which the beam loading effect can be neglected, the quasi-static approximation is fully validated in the LPA regime. The case of a higher bunch charge, with significant beam loading effects, has also been investigated using an enhanced version of WAKE, named WAKE-EP. Additionally, a cost evaluation, in terms of used energy per calculation, has also been done using the multi-CPU and multi-GPU versions of FBPIC.
* E. Baynard et al, Nucl. Instrum. Meth. Phys. Res. A 909, 46 (2018)
** R.Lehe et al., Comp. Phys. Com. 203, 66 (2016)
*** P. Mora & A, Jr Th. Antonsen, Phys. of Plasmas 4, 217 (1997)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW059

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPGW067

Progress Towards a Single-Shot Emittance Measurement Technique at AWAKE

emittance, quadrupole, plasma, dipole

3742

J. Chappell, D.A. Cooke, L.C. Deacon, S. Jolly, F. Keeble, M. Wing
UCL, London, United Kingdom

Externally injected electrons are captured and accelerated in the plasma wake of a self-modulated proton beam at the Advanced Wakefield Experiment (AWAKE) at CERN. The energy distribution of the accelerated electron beam is measured using a dipole spectrometer in combination with a scintillator screen, with two upstream quadrupoles providing energy-dependent focusing. Measuring the vertical beam size variation with horizontal position along the scintillator screen, and therefore energy, results in an effective quadrupole scan permitting single shot vertical geometric emittance measurements. Limitations of the method due to effects such as imperfect beam focusing and finite resolution are explored via simulations using the beam tracking code BDSIM.
james.chappell.17@ucl.ac.uk

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPGW070

Design of the Cockcroft Beamline: Adjustable Transport of Laser Wakefield Electrons to an Undulator

undulator, laser, plasma, radiation

3749

K.A. Dewhurst, H.L. Owen
UMAN, Manchester, United Kingdom
E. Brunetti, D.A. Jaroszynski, S.M. Wiggins
USTRAT/SUPA, Glasgow, United Kingdom
B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
M.J. de Loos, S.B. van der Geer
Pulsar Physics, Eindhoven, The Netherlands

Funding: Work supported by U.K. STFC (Grant No. ST/G008248/1), EuPRAXIA (Grant No. 653782), ECs LASERLAB-EUROPE (Grant No. 654148), U.K. EPSRC (Grant No. EP/J018171/1, EP/J500094/1 and EP/N028694/1).
The Cockcroft Beamline is being designed to transport 1 GeV electrons from a laser wakefield accelerator (LWFA) to an undulator at the Scottish Centre for the Application of Plasma-based Accelerators (SCAPA) in Glasgow, UK. To demonstrate undulator radiation in the X-ray spectral region and potentially free electron laser (FEL) gain, electrons should be transported between the LWFA and the undulators with high fidelity. In this paper we present the design of an adjustable beam line to transport LWFA electrons to the undulator for a range of energies, from 0.5 GeV to 1 GeV, while preserving the electron beam properties and matching the undulator-beam coupling.

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPGW073

Status on a Laser Injection in Beam Driven Dielectric Wakefield Accelerator Experiment

wakefield, experiment, plasma, laser

3761

G. Andonian, T.J. Campese, F.H. O’Shea
RadiaBeam, Santa Monica, California, USA
D.L. Bruhwiler, N.M. Cook
RadiaSoft LLC, Boulder, Colorado, USA
M.E. Conde, D.S. Doran, G. Ha, J.G. Power, J.H. Shao, E.E. Wisniewski
ANL, Argonne, Illinois, USA
J.B. Rosenzweig
UCLA, Los Angeles, California, USA
T. Xu
Northern Illinois University, DeKalb, Illinois, USA

The generation of high-brightness beams with ultra-low emittance using the plasma photocathode technique has gained significant traction in recent years. The practical execution of a combined plasma wakefield acceleration section and a laser injected typically requires a dual gas medium for precision ionization of low and high ionization thresholds. The concept can be partially simplified in experiment by replacing the plasma wakefield acceleration component with a dielectric wakefield acceleration scheme, sacrificing field gradient but maintaining low emittance beam generation. In this paper, we describe the progress on the design of a hybrid scheme, using laser injection in a gas medium within a dielectric wakefield accelerator structure. The proof-of-concept experiment is planned to take place at the Argonne Wakefield Accelerator.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW073

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPGW079

THz-Based Femtosecond MeV Electron Bunch Compression

FEM, GUI, experiment, focusing

3766

M.A.K. Othman, M.C. Hoffmann, M.E. Kozina, R.K. Li, E.A. Nanni, X. Shen, E.J. Snively, X.J. Wang
SLAC, Menlo Park, California, USA

Funding: This work was supported by Department of Energy contract DE-AC02-76SF00515.
Probing structural dynamics at atomic spatial and ultrashort temporal scales reveals unprecedented details of fundamental behavior of nature, allowing for better understanding of intricate energy-matter interaction occurring at such scales. Developing state-of-the-art technology to access these details entails utilizing X-ray free-electron lasers (XFELs), ultrafast electron diffraction (UED), and advanced electron microscopes. In particular, ultrafast diffraction science received growing attention thanks to innovation in sources, detectors and instrumentation in general. Within this context, interest in laser-generated THz wave-matter interaction has recently emerged as a new regime for controlling electrons with high temporal precision. Previously, the SLAC UED team has demonstrated attosecond electron metrology using laser-generated single-cycle THz radiation, which is intrinsically phase locked to the optical drive pulses, to manipulate multi-MeV relativistic electron beams. Here we demonstrate further steps towards achieving ultrafast timing resolution that utilizes femtosecond electron bunches. The proposed setup allows for compressing electron beam bunches down to a femtosecond using interaction with high field single-cycle THz pulses. We demonstrate a novel design of a dispersion-free parallel-plate tapered waveguide that provides focusing of THz pulses achieving >100 MV/m field strength at the interaction point as measured by electro-optical sampling for ~7 μJ of incoming THz pulse energy. The structure is being designed and built for bunch compression experiments using the SLAC UED facility.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW079

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPGW080

Initial Results of High-Gradient Breakdown Tests for W-Band Accelerating Structures

cavity, experiment, laser, vacuum

3769

M.A.K. Othman, V.A. Dolgashev, A.A. Haase, E.A. Nanni, J. Neilson, S.G. Tantawi
SLAC, Menlo Park, California, USA
S. Jawla, J.F. Picard, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA
S.C. Schaub
MIT, Cambridge, Massachusetts, USA
B. Spataro
INFN/LNF, Frascati, Italy

Funding: This work was supported by Department of Energy contract DE-AC02-76SF00515 (SLAC) and grant DE-SC0015566 (MIT). This work was also supported by NSF grants PHY-1734015.
Emerging accelerator technology at mm-wave and THz frequencies has recently shown notable progress. Indeed, metallic and dielectric accelerating structures at THz frequencies are plausible candidates toward miniaturization of accelerators. RF breakdown in such structures is a major factor limiting their performance. Therefore, comprehensive analysis of RF breakdown physics in mm-wave accelerating structures is needed, which includes understanding of dependencies of the breakdown rate on geometric, electromagnetic and material properties. In this work we report on high power tests of a 110 GHz single-cell standing wave accelerating structure powered by a 1 MW gyrotron. The RF power is coupled from the gyrotron into the accelerating structure with a Gaussian to TM01 mode converter through a quasi-optical setup. We demonstrate coupling of 10 ns, 100s of kilowatt pulses into the structure using a fast switch and achieving ~150 MV/m accelerating gradients. Measurements of RF signals and field-emitted currents allow for complete comprehensive of the high-gradient behavior of W-band structures, including breakdown probability.

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPGW087

Transverse Jitter Tolerance Issues for Beam-Driven Plasma Accelerators

plasma, emittance, acceleration, FEL

3774

G.R. White, T.O. Raubenheimer
SLAC, Menlo Park, California, USA

Funding: Work supported by the Department of Energy under Contract Number: DE-AC02-76SF00515.
Transverse jitter tolerances are considered for beam-driven plasma accelerators. A simple model for jitter transfer from the drive to witness beam is developed and concrete examples are studied for: high-brightness witness bunch injectors; high-energy boosters for FEL’s; and future Linear Colliders. Compared with an existing PWFA driver facility ([*,**]), the calculated tolerances are 18X ’ 170X tighter than achievable, even considering any upgrades with existing technology.
* Nature 445 741 Feb 2007, Nature 515, Nov. 2014
** FACET-II Technical Design Report, SLAC-R-1072, "The FLASHForward facility at DESY", NIMA Oct., 2015

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW087

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPGW089

Mechanical Design of a Diamond Crystal Hard X-Ray Self-Seeding Monochromator for PAL-XFEL

FEL, vacuum, controls, alignment

3782

D. Shu, J.W.J. Anton, S.P. Kearney, K. Kim, Yu. Shvyd’ko
ANL, Argonne, Illinois, USA
H.-S. Kang, C.-K. Min, B.G. Oh, S.Y. Rah
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357
As a part of the Argonne Strategic Partnership Project (SPP) 85H21, a collaboration between Advanced Photon Source (APS), Argonne National Laboratory (ANL) and Pohang Accelerator Laboratory (PAL), we have designed, constructed, and tested a thin-film-diamond monochromator for the PAL X-ray Free-Electron-Laser (PAL-XFEL) hard x-ray self-seeding project*. The mechanical design of the PAL-XFEL diamond crystal hard x-ray self-seeding monochromator is based on the APS design of a diamond-crystal monochromator for the LCLS hard x-ray self-seeding project** with enhanced diamond crystal holder for two thin-film-diamond crystals with thicknesses of 30 microns and 100 microns***. The customized high quality thin-film-diamonds and special graphite holder were provided by the Technological Institute for Super-hard and Novel Carbon Materials of Russia (TISNCM)****, and tested at the APS***. An in-vacuum multi-axis precision positioning mechanism is designed to manipulate the duo-thin-film diamonds holder with resolutions and stabilities required by the hard x-ray self-seeding physics. Mechanical specifications, designs, and preliminary test results of the diamond monochromator are presented in this paper.
*Chang-Ki Min, et al, sub. J. Sync. Rad., 2018
**D. Shu, et al, J. Phys.: Conf. Ser. 425 (2013) 052004
***Y. Shvyd’ko, et al, FEL2017, Santa Fe
****Polyakov S, et. al, 2011 Diam. Rel. Mat. 20 726

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW089

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPRB013

The ESSnuSB Target Station

target, proton, hadron, linac

3831

E. Bouquerel, E. Baussan, L. D’Alessi, M. Dracos
IPHC, Strasbourg Cedex 2, France
P. Cupial, M. Koziol
AGH University of Science and Technology, Kraków, Poland
N. Vassilopoulos
IHEP, Beijing, People’s Republic of China

Funding: This project is supported by the COST Action CA15139 EuroNuNet. It has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 777419.
The ESSνSB project, recently granted by the EU H₂020 programme for a 4-year design study, proposes to use the protons produced by the linac (2 GeV, 5 MW) of the European Spallation Source (ESS) currently in construction in Lund (Sweden) to deliver a neutrino super beam. It follows the studies made by the FP7 Design Study EUROν[1] (2008-2012), regarding future neutrino facilities. The primary proton beam line completing the linear accelerator will consist of one or several accumulator rings and a proton beam switchyard. The secondary beam line producing neutrinos will consist of a four-horn/target station, a decay tunnel and a beam dump. A challenging component of this project is the enormous target heat-load generated by the 5 MW proton beam. In order to reduce this heat-load there will be four targets, which will be hit in sequence by the compressed proton pulses, thereby reducing the beam power on each target to 1.25 MW. Following the EUROν studies, a packed bed of titanium spheres cooled with helium gas has become the baseline design for a Super Beam based on a 2-5 GeV proton beam with a power of up to 1 MW per target, with other targets being considered for comparison. The hadron collection will be performed by four hadron collectors (magnetic horns), one for each target. Each of these target/hadron-collector assemblies will receive proton pulses three times more frequently than in present projects, and by an average beam power of 1.25 MW, which is twice as high as in present neutrino projects. The feasibility of the target/horn station for the ESSνSB project is discussed here.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB013

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPRB018

Large-Scale Optical Synchronization System of the European XFEL with Femtosecond Precision

laser, FEL, FEM, controls

3835

T. Lamb, M.K. Czwalinna, M. Felber, C. Gerth, T. Kozak, J.M. Müller, H. Schlarb, S. Schulz, C. Sydlo, M. Titberidze, F. Zummack
DESY, Hamburg, Germany

Femtosecond pulsed optical synchronization systems have evolved over the last few years and are now a mature technique to synchronize FELs. A large-scale femtosecond-precision synchronization system with up to 44 end-stations has been constructed at the European XFEL to meet the FEL synchronization stability requirements. The synchronization system is used to phase-lock various laser systems with femtosecond accuracy, to precisely measure the electron bunch arrival time along the accelerator for fast arrival time feedbacks and to locally phase stabilize the phase of the RF reference signals for the accelerator RF controls on a femtosecond level. The architecture of the large-scale synchronization system and design choices made to achieve the reliability, maintainability and performance requirements are presented together with measurement results from the past year of operation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB018

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB020

A Feedback System to Minimize the Electron Bunch Arrival-Time Jitter Between Femtosecond Laser Pulses and Electron Bunches for Laser-Driven Plasma Wakefield Accelerators

laser, plasma, feedback, optics

3843

S. Mattiello, A. Penirschke
THM, Friedberg, Germany
H. Schlarb
DESY, Hamburg, Germany

Funding: The work of S. Mattiello is supported by the German Federal Ministry of Education and Research (BMBF) within the Project MAKE-PWA.
In a laser driven plasma based particle accelerator a stable synchronization of the electron bunch and of the plasma wake field in the range of less than 2 fs is necessary in order to optimize the acceleration. For this purpose we are developing a new shot to shot feedback system with a time resolution of less than 1 fs*. We plane to generate stable THz pulses by optical rectification of a fraction of the plasma generating high energy laser pulses in a nonlinear lithium niobate crystal. With these pulses we will energy modulate the electron bunches shot to shot before the plasma to achieve the time resolution. In this contribution we will focus on realization aspects of the shot to shot feedback system and the lithium niobate crystal itself. Here we compare different approximations for the modeling of the generation dynamics (second order or first order calculation) and of the dielectric function (influence of the dispersion relation, of the free carries generated by the pump adsorption and their saturation, depletion of the pump) in order to investigate the importance of a detailed description of the optical properties for the THz generation.
*The feedback system will be tested at the Accelerator R&D facility SINBAD (Short Innovative Bunches and Accelerators at DESY).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB020

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB021

Automatic Loop for Carrier Suppression in Attosecond RF Receivers

controls, operation, FPGA, electronics

3847

U. Mavrič, M. Hoffmann, F. Ludwig, H. Schlarb, L. Springer
DESY, Hamburg, Germany

The carrier suppression interferometer method can be used as a radio receiver architecture which allows for detection of RF signals in the attosecond range. The carrier suppression scheme requires an automatic carrier suppression circuit which provides stable operation of the RF receiver in the best operating point. In the poster we investigate the requirements for such an algorithm, evaluate the achievable closed loop bandwidth and the side effects on the overall-performance. In addition we apply the carrier tracking to simplify and automate the characterization of various electronic phase shifters and attenuators in the as-range

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB021

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPRB049

MODELING AND SIMULATION FOR MULTI-FEEDING CAVITY WITHOUT BEAM LOADING

cavity, impedance, simulation, beam-loading

3921

K. Liu, Q. Gu, L. Li, Ch. Wang, M.H. Zhao
SINAP, Shanghai, People’s Republic of China
Q. Gu
SSRF, Shanghai, People’s Republic of China

The Multi-feeding cavity usually be applied in super-conducting and normal-conducting RF cavity. The differences between multiple input couplers in coupler coefficient, incident power and phase will cause the cavity field stabilities can not meet the requirements. For explore the influences of these differences and develop equations for measurement, a multi-feeding LCR transient model was developed. As two-feeding cavity, the VHF photocathode electron gun was model and simulated in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB049

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paper received ※ 06 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB050

LLRF System Modelling and Controller Design in UED

LLRF, cavity, controls, cathode

3924

Y.Q. Li, K. Fan, Y. Song
HUST, Wuhan, People’s Republic of China

In the Ultrafast Electron Diffraction (UED) facility for investigating material structure, drifts of amplitude and phase in cavity have different effects on beam quality. So it is critical for pump-probe experiments in the UED to keep accurate synchronization between the laser and electron. To achieve the desired 50fs resolution, the Low Level Radio Frequency (LLRF) controller in S-band normal conducting cavity needs to satisfy the stability: ±0.01% (rms) for the amplitude and ±0.01° (rms) for the phase, respectively. Then we can study the performance of the RF control system by simulating the LLRF system. In the simulation program, feedback, feed-forward algorithms, and beam current variations can be simulated in a Matlab/Simulink environment. This paper shows that a model-based controller design can meet the necessary requirements of the field regulation and implement the algorithms.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB050

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paper received ※ 20 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB055

DAMAGE BEHAVIOR OF TUNGSTEN TARGETS FOR 6 MEV LINEAR ACCELERATORS

target, experiment, ECR, controls

3934

Z.H. Wang, Z.N. Liu, J. Shi, H. Zha
TUB, Beijing, People’s Republic of China

The target in electron linear accelerator is subjected to high-frequency and intense thermal shocks. Elevated temperatures in the target may lead to target recrystallization, fatigue cracking, creep and vaporization. In this study, experiments were carried out to investigate the damage behaviour of tungsten targets in 6 MeV linear accelerators under pulsed electron beam. The results show that recrystallization occurs after loading 6 MeV electron beam with repetition frequency of 220 Hz, pulse width of 4μs and mean current of 151μA for 248 s. Deformation and cracking caused by recrystallization are observed on the surface of the target.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB055

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPRB056

Dose Measurement Experiments for Single and Composite Targets in 6 Mev Linear Accelerators

target, site, experiment, simulation

3937

Z.H. Wang, J.Y. Liu, J. Shi, H. Zha
TUB, Beijing, People’s Republic of China

The target in electron linear accelerator plays an im-portant role in the production of photon. Targets of different materials and thicknesses have different X-ray yields. In this study, experiments were carried out to measure the dose rates of single targets and composite targets of different thicknesses for 6 MeV linear accel-erators utilizing ionization chamber. The electron ener-gy spectrum at the outlet of accelerating tube was de-tected with magnetic analyser. The experimental results show consistent rules with Monte Carlo simulations. Composite material target of 1.2 mm tungsten and 2 mm copper can deliver 1242 rad/min/100uA dose rate at 1 meter in front of the target. Dose rates of tungsten- rhenium alloy(74%W-26%rhenium) targets were exam-ined too.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB056

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPRB059

Radiation Safety at SOLARIS 1.5 GeV Storage Ring

radiation, storage-ring, injection, MMI

3940

M.B. Jaglarz
SOLARIS, Kraków, Poland
A.I. Wawrzyniak, J. Wikłacz
Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland

Radiation measurements at Solaris are continuously performed by using 9 radiation monitor stations (RMS) located around the storage ring and the beamlines area. 4 of RMS are connected to the Personal Safety System and in case of exceeding alarm level dump the beam or close safety shutters. Moreover thermoluminescence dosimeters (TLDs) are used to registered doses in the classified areas according to the Polish regulation. Measurements are performed since 2015 when the commissioning of the storage ring has started. Since that time several improvements to the radiation shielding was done to fulfill the ALARA principle. Moreover the electron beam optimizations during the injection, ramping and operation were performed to decrease the electrons losses and the radiation level. This presentation will report on radiation measurements results obtained before and after the chopper installation. Additionally problems with radiation level while the beam current is increasing to the designed 500mA value will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB059

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paper received ※ 26 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB063

Field Control Challenges for Different LINAC Types

cavity, controls, linac, FEL

3946

O. Troeng, A.J. Johansson
Lund University, Lund, Sweden
M. Eshraqi
ESS, Lund, Sweden
S. Pfeiffer
DESY, Hamburg, Germany

Linacs for free-electron lasers typically require cavity field stabilities of 0.01\% and 0.01 degree, while the requirements for high-intensity proton linacs are on the order of 0.1–1\% and 0.1–1 degrees. From these numbers it is easy to believe that the field control problem for proton linacs is many times easier than for free-electron lasers linacs. In this contribution we explain why this is not necessarily the case, and discuss the factors that make field control challenging. We also discuss the drivers for field stability, and how high-level decisions on the linac design affect the difficulty of the field control problem.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB063

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB072

Operational Experience of a Prototype LHC Injection Kicker Magnet with a Low SEY Coating and Redistributed Power Deposition

kicker, injection, operation, vacuum

3974

M.J. Barnes, C. Bracco, G. Bregliozzi, A. Chmielinska, L. Ducimetière, B. Goddard, G. Iadarola, T. Kramer, V. Vlachodimitropoulos, W.J.M. Weterings
CERN, Geneva, Switzerland
A. Chmielinska
EPFL, Lausanne, Switzerland
L. Vega Cid
ETSII UPM, Madrid, Spain

Funding: This research was supported by the HL-LHC project
In the event that it is necessary to exchange an LHC injection kicker magnet (MKI), the newly installed kicker magnet would limit HL-LHC operation for a few hundred hours due to dynamic vacuum activity. A surface coating with a low secondary electron yield, applied to the inner surface of an alumina tube to reduce dynamic vacuum activity without increasing the probability of UFOs, and which is compatible with the high voltage environment, was included in a prototype MKI installed in the LHC during the 2017-18 Year End Technical Stop. In addition, this MKI included an upgrade to relocate a significant portion of beam induced power from the yoke to a ’damping element’: this element is not at pulsed high voltage. The effectiveness of the upgrades has been demonstrated during LHC operation, hence a future version will include water cooling of this ’damping element’. This paper reviews dynamic vacuum around the MKIs and summarizes operational experience of the upgraded MKI.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB072

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paper received ※ 08 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPRB091

APPLICATION PROGRAMS FOR TPS BEAM TRIP ANALYSIS

power-supply, kicker, photon, operation

4032

B.Y. Chen, T.W. Hsu, B.Y. Huang, C.S. Huang, C.H. Kuo, T.Y. Lee, W.Y. Lin
NSRRC, Hsinchu, Taiwan

For the Taiwan Photon Source (TPS), the orbit inter-lock system is one of the most important machine pro-tection systems. It is the fastest and the most preferred system to detect abnormalities to prevent possible dam-ages caused by magnet power supply failures or subsys-tems failures. In order to monitor electron orbit changes during a beam trip, we developed the ’orbit monitoring and recording tool’, the ’TBT BPM analysis tool’ and the ’magnet power supply recording and analysis tool’ to assist us in the failure analysis as will be discussed in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB091

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB095

A Simulation Framework for Photon-Particle Interactions for Laserwires and Further Applications

laser, photon, scattering, simulation

4045

S.E. Alden, S.M. Gibson, L.J. Nevay
JAI, Egham, Surrey, United Kingdom

A model has been developed for simulating photon-particle interactions with Beam Delivery Simulation (BDSIM). BDSIM is a high energy physics program that utilises the Geant4, CLHEP, and ROOT libraries to seamlessly track particles through an accelerator. The photon-particle interactions introduce the capability for modelling a range of applications in accelerator physics. One such application is a laserwire which is a minimally invasive diagnostic technique to measure beam profiles and emittance. In this paper we describe the recent implementation of inverse Compton scattering and electron stripping of Hydrogen ions. This is demonstrated on an example beamline.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB095

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB096

Real-Time Beam Orbit Stabilisation to 200 Nanometres in Single-Pass Mode Using a High-Precision Dual-Phase Feedback System

feedback, extraction, collider, real-time

4049

D.R. Bett, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan
JAI, Oxford, United Kingdom

A high-resolution, low-latency, stripline beam position monitor (BPM) system has been developed for use at particle accelerators and beamlines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system consists of fast analogue stripline BPM signal processors input to a custom FPGA-based digital feedback board which drives a pair of kickers local to the BPMs and nominally orthogonal in phase in closed-loop feedback mode, thus achieving both beam position and angle stabilisation. The feedback system was tested with the electron beam in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan. Recent upgrades to the BPMs have increased the single-shot, real-time position resolution of the system to ~150 nm for a beam charge of 1.3 nC. We report the latest results which demonstrate the feedback system operating at this resolution limit and a beam stabilisation performance of 200 nm.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB096

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPRB102

Monte Carlo Optimization of Fast Beam Loss Monitors for LCLS-II

detector, target, photon, simulation

4066

M. Santana-Leitner, C.I. Clarke, A.S. Fisher, A.M. Harris, C. Hast, T.T. Liang
SLAC, Menlo Park, California, USA
E. Griesmayer
CIVIDEC Instrumentation, Wien, Austria

Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515
Commissioning of the LCLS-II hard X-ray FEL is starting at SLAC National Accelerator Laboratory. This facility will ultimately accelerate electrons to 8 GeV, with beams of 375 kW at 1 MHz. At such high-powers, errant beams will need to be detected very fast -200 μs- to limit exposure and to protect beam-line and safety components. Currently, LCLS-I uses ion chambers both as Point Beam Loss Monitors (PBLM) by collimators, dumps, septa, etc., and also as Long Beam Loss Monitors (LBML) that provide detection coverage in extended areas where the accelerator enclosure is not sufficiently thick to shield full beam losses. But due to the finite ion mobility and related screening effects, ion chambers are not fast enough, and their response would not be linear at high charge rates. LCLS-II will use synthetic mono-crystalline diamond chips as PBLMs, as those offer nanosecond time resolution due to the high mobility of holes generated in the valence band by charged particles. LBLMs will be 200 m-long optical fibers, with photomultipliers to detect Cerenkov photons produced by charged particles in the fibers. Use of these technologies requires tests and models to correlate their response to different beam losses. Response functions for these detectors have been developed for the FLUKA Monte Carlo code. After benchmarking the models, these have been applied to place PBLMs at locations where signal is relatively insensitive to beam-strike uncertainties and sufficiently above electronic noise, while keeping lifetime to radiation-damage long. Also, topologies where found were one PBLM can protect several components, resulting in cost reductions. As for LBLMs, the existing model helps scale signals for different beam loss configurations as a function of the fiber position.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB102

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB107

A Novel Design of a Laser Phase Monitor for AWA RF Photocathode Electron Gun

laser, LLRF, feedback, controls

4076

W. Liu, M.E. Conde, D.S. Doran, G. Ha, J.G. Power, J.H. Shao, C. Whiteford, E.E. Wisniewski
ANL, Argonne, Illinois, USA

It is critical to maintain a stable laser phase for RF photocathode electron gun to achieve high beam stability. In order to achieve a higher beam stability for AWA(Argonne Wakefield Accelerator) beamline, a novel laser phase monitor has been designed to allow us to monitor and feedback on. Both the design and its applications at AWA are presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB107

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPRB115

MicroTCA Based LLRF Control Systems for TARLA and NICA

LLRF, cavity, controls, operation

4089

P. Nonn, C. Gümüş, C.K. Kampmeyer, H. Schlarb, Ch. Schmidt, T. Walter
DESY, Hamburg, Germany

The MicroTCA Technology Lab (A Helmholtz Innovation Lab) is preparing two turn-key Low Level RF control systems for facilities outside of DESY. The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is a 40 MeV electron accelerator with continuous wave (CW) RF operation. The MicroTCA based LLRF control system is responsible for two normal conducting and four superconducting cavities, controlling the RF as well as cavity tuning via motors and piezos. The Light Ion Linac (LILAC) is one of the injectors for the Nuclotron-based Ion Collider Facility (NICA) in Dubna, Russia. It will provide a 7 MeV/u pulsed, polarized proton or deuteron beam. The MicroTCA based LLRF control system will control five normal conducting cavities, consisting of one RFQ, one buncher, one debuncher and two IH-cavities. MicroTCA Technology Lab is cooperating with BEVATECH GmbH, Frankfurt, Germany, who designed the cavities. This paper gives a brief overview of the design of both LLRF systems as well as the status of their assembly.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB115

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPRB117

Stability and Reliability Issues of PAL-XFEL Modulator

FEL, klystron, operation, power-supply

4096

S.H. Kim, H.-S. Kang, K.H. Kim, H.-S. Lee, C.-K. Min, S.S. Park, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This work is supported by Ministry of Science, ICT(Information/Communication Technology) and Future Planning.
The Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL) employs 51 units of the pulse modulator in order to obtain the 10 GeV electron beam, which drive one X-band to linearize and 50 S-band klystrons. The PAL-XFEL requires very tight control of the klystron RF phase jitter 0.03-degree for S-band RF, 0.1-degree for X-band RF and the beam voltage stability of below 50 ppm. The RF phase jitter is directly related to the amplitude stability of modulator output pulses. There are several factors to satisfy the stability and reliability for the PAL-XFEL modulator. The largest sources of pulse-to-pulse instability are a current charging power supply (CCPS) for PFN charging, a thyratron switch, and a klystron focusing magnet power supply (MPS). In this paper, the operation and debugging results of those devices are described.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB117

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paper received ※ 16 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS007

MYRRHA 80 kW CW RF Coupler Design

cavity, multipactoring, vacuum, simulation

4115

Y. Gómez Martínez, M.A. Baylac, D. Bondoux, F. Bouly, P.-O. Dumont
LPSC, Grenoble Cedex, France
S. Blivet, C. Joly, J. Lesrel, H. Saugnac
IPN, Orsay, France
W. Kaabi
LAL, Orsay, France

MYRRHA [1] (Multi Purpose Hybrid Reactor for High Tech Applications) is an Accelerator Driven System (ADS) project. Its superconducting linac will provide a 600 MeV - 4 mA proton beam. The first project phase based on a 100 MeV linac is launched. The Radio-Frequency (RF) couplers have been designed to handle 80 kW CW at 352.2 MHz. This paper describes the thermal, mechanical and RF studies leading to the final design of the RF coupler.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS007

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paper received ※ 10 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS009

High-Current Emittance Measurements at MAMI

emittance, quadrupole, experiment, simulation

4121

S. Heidrich, K. Aulenbacher, M. Dehn, P. Heil
IKP, Mainz, Germany
M.W. Bruker
HIM, Mainz, Germany

Funding: Work supported by BMBF-Verbundforschung Verbundprojekt 05H2015UMRB1, R&D Beschleuniger (Positronenquellen)
The effects of high beam currents and different types of electron sources on the emittance of the beam at the 3.5 MeV beamline of the Mainzer Microtron MAMI were observed. A thermionic BaO source and a GaAs-based photo-source that allows spin polarization were used. In order to measure the beam size, a new type of wire scanner was utilized. The results show maximum normalized emittance values in the order of a few hundred nmrad for both sources, which lies distinctly within the acceptance of the higher energy stages of the accelerator.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS009

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS019

Design of Beam Position Monitoring System for IPM Low Energy Electron LINAC

cavity, simulation, software, linac

4394

N. Messbah, F. Abbasi Davani
Shahid Beheshti University, Tehran, Iran
S. Ahmadiannamin
ILSF, Tehran, Iran
H. Shaker, M. Shirshekan
IPM, Tehran, Iran

A beam position monitor (BPM) is a common device used in particle accelerators to measure the position of a beam of charged-particles. The goal of this project is to simulate and build prototype of different parts to be used for IPM low energy electron Linac being developed at Institute for Research in Fundamental Sciences. The IPM low energy electron Linac will initially be operated at a 7𝜇sec pulse duration and 250 Hz repetition rate with 2.998 GHz bunching frequency. A 4.5-MeV electron beam will be available in the second phase of commissioning. The device is composed of two pickup S-band cavities and a detection circuit to read out the electron beam’s position. The electrode pickup sensors will sense the mode strength generated by the passing beam of electrons. The working modes are TM110 (dipole) for the so called position cavity and TM010 (monopole) for the reference cavity. When the beam crosses the two cavity gaps it induces signals proportional to the product of charge and position offset in the position cavity, and to the charge only in the reference cavity. the position cavity has four rectangular waveguides that couple to the dipole mode while rejecting the monopole mode that would otherwise limit the resolution of the electronics. This signal will be input to a detection circuit that will be used to calculate the signals detected by four antennas arranged. A 180 degree hybrid at the first stage reduce the monopole and a heterodyne receiver principle was used to down-convert the signal frequency in about MHz IF frequency. These signals can then be used to determine the beam’s displacement from the center.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS019

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paper received ※ 15 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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THPTS026

Effect of Nitric Hydrofluoric Acid Treatment on Brazing of Alumina Ceramics and Pure Titanium

vacuum, controls, experiment, gun

4161

M. Kinsho, J. Kamiya
JAEA/J-PARC, Tokai-mura, Japan
K. Abe
Hitachi Power Semiconductor Device, Ltd., Hitachishi, Ibaraki, Japan
T. Nakamura
Asahi Kinzoku Co., Ltd., Gifu, Japan

Alumina ceramics vacuum chamber which is used for the 3GeV rapid-cycling synchrotron (RCS) in J-PARC is composed of alumina duct, titanium (Ti) flanges and Ti sleeves. Before brazing the alumina duct and the Ti sleeves, the Ti sleeves were treated with nitric hydrofluoric acid. The purpose of this study is to clear the effect of this treatment for titanium material. It was cleared by SEM observation that the roughness of the titanium material after the nitric hydrofluoric acid treatment becomes big. It was also measured that the thickness of oxide film on surface of the titanium material was 12.7 nm before treatment and 6.0 nm after treatment. As a result of measuring the wettability of the brazing material which was silver brazing filler metal (Ag: 72%, Cu: 28%) on the Ti surface and the diffusion of the Ti material into the brazing material, it became clear that both the clearing of oxide layer on the alumina ceramics and the vacuum condition of the vacuum heating furnace were important for brazing between alumina ceramics and pure titanium.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS026

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS029

Optimization of Staggered Array Undulator

undulator, solenoid, cryogenics, site

4171

L.J. Chen, Q.K. Jia
USTC/NSRL, Hefei, Anhui, People’s Republic of China
M. Li, P. Li, J. Wang, D. Wu, D.X. Xiao, L.G. Yan, X. Yang
CAEP/IAE, Mianyang, Sichuan, People’s Republic of China

Funding: the National Key Research and Development Program of China under Grant No. 2016YFA0402003 the National Nature Science Foundation of China under Grant No. 11611140102.
The staggered array undulator consists of staggered poles and solenoid coils that form a periodically aligned transverse magnetic field in the pole gap. The addition of magnets in the longitudinal gap between the poles further enhances the peak field strength of the undulator. A method of enhancing the peak field strength of the undulator using cryogenic temperature permanent magnets and adding side magnets has been studied. The remanence of the magnet will increase at low temperatures and the peak field strength of the undulator will increase. The side magnets do not increase the maximum peak field strength of the undulator, but can reduce the solenoid magnetic field requirements and reduce the solenoid volume and cost. The influence of the special magnetic pole and magnet shape on the peak field strength of the undulator has also been studied.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS029

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPTS037

The Deformation-Stress Simulation and Measurement of Titanium Foil Strip for Hadron Monitor

simulation, experiment, hadron, ECR

4187

A.X. Wang, J.X. Chen, H.Y. He, L. Liu, X.J. Nie, C.J. Ning, J.L. Sun, G.Y. Wang, J.B. Yu, Y.J. Yu, J.S. Zhang, D.H. Zhu
IHEP CSNS, Guangdong Province, People’s Republic of China
L. Kang
IHEP, Beijing, People’s Republic of China

The measurement of beam profile by hadron monitor is in fact the measurement of the positive current after the secondary electrons escaped. According to the situation that the number of beam particles is small and the current signal is weak, the material titanium with high secondary electron generation rate is select by material comparison, and the foil strip type is used to increase the cross section area to obtain lager current level. On account of dead weight itself, as well as thermal expansion and contraction, the foil strip shall be loose. The loosen strip will deviate from its theoretical position, and cause the measuring error. Therefore, the deformation-stress of Ti foil strip (1000*50*0.1) was simulated under the pretension (10~90N) with the finite element software ANSYS. A set of experiment device with pretension adjustment and heating for the foil strip was designed, and then the deformation-stress was tested by a high precision 3-D imaging measurement system. Compared with the simulation results, the pretension would better set at about 50N.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS037

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paper received ※ 12 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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THPTS038

There-Dimensional Simulation of a C-Band 32-Beam Klystron

klystron, cavity, simulation, bunching

4190

Z.N. Liu, H.B. Chen, J. Shi, H. Zha
TUB, Beijing, People’s Republic of China

A 32-beam klystron working at 5.712 GHz has been designed with efficiency of 70% and output power of 3.4 MW. Core oscillations method (COM) is chosen to bunch electrons. The code KlyC is used for 1-D and 1.5-D calculation and a series of parameters are given after optimizing, including the position, frequency, R/Q, Q₀ and Qe of cavities. CST/PIC is used to make the final design and coaxial cavities are used. This paper describes 1-D, 1.5-D and 3-D beam dynamics of the klystron, compares their differences, and analyses effect of these differences on efficiency.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS038

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPTS039

DESIGN OF A COMPACT VARIABLE X-BAND RF POWER SPLITTER

GUI, impedance, klystron, network

4194

F. Liu, H.B. Chen, J.Y. Liu, Z.N. Liu, J. Shi, H. Zha
TUB, Beijing, People’s Republic of China

This paper presents a design of a compact variable X-band RF power splitter. The RF power splitter includes one input port and two output ports, and the power divi-sion ratio can be adjusted by changing the position of a short circuit piston. This system keeps a good match (less than -40 dB) at any power division ratio. An E-bend waveguide structure is selected to make the geometry more compact (11cm in length, 3.5cm in width and 5 cm in height). Special studies was conducted to sustain a low surface electrical field (maximum 65 MV/m at 100 MW input), and large bandwidth (250MHz). This power split-ter is designed for high-power test stand at Tsinghua Uni-versity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS039

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS045

Preparation of Titanum-Zirconium-Vanadium Films by Quantitative Deposition

vacuum, experiment, ECR, operation

4210

J.Q. Shao, C. Chen, X.Q. Ge, W. Li, S. Wang, Y. Wang, W. Wei, B. Zhang, Y.X. Zhang, B.L. Zhu
USTC/NSRL, Hefei, Anhui, People’s Republic of China

TiZrV has been used in vacuum technology and electric vacuum devices due to its high pumping speed and low activation temperature in recent years. At the same time, many preparation methods have been developed. Different from the current coating method of magnetron sputtering, this paper discusses the preparation of thin film coating from the viewpoint of vacuum sintering, which is flexible in design and more suitable for operation. Based on the analysis of the surface morphology of the sintered film, the feasibility and operability of the experimental method were explored from the surface compactness of the getter.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS045

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paper received ※ 25 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPTS063

Development of a W-Band Power Extraction Structure

cavity, undulator, GUI, extraction

4252

F. Toufexis, B.J. Angier, D. Gamzina, A. McGuire, M. Shumail, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
We are modifying the X-Band Test Accelerator at SLAC to operate as an Extreme Ultra Violet (EUV) light source*. The existing photo electron gun will be replaced by a thermionic X-Band injector which utilizes RF bunch compression. The beam is accelerated up to 129 MeV using an X-Band traveling wave structure followed by a novel high shunt impedance standing wave structure. The beam then goes through a mm-wave undulator with a period of 1.75 mm, producing EUV radiation around 13.5 nm. The undulator is powered by a W-Band decelerator structure, which extracts the RF power from the electron beam. In this work we present the mechanical design and fabrication of the 91.392 GHz decelerator structure, as well as structural characterization of its cavities using SEM and 3D microscopy.
* F. Toufexis, et al, "A Compact EUV Light Source using a mm-wave Undulator", Proceedings of IPAC17.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS063

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paper received ※ 10 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPTS064

Sub-Picosecond X-Ray Streak Camera using High-Gradient RF Cavities

cathode, photon, gun, simulation

4256

F. Toufexis, V.A. Dolgashev
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
We are developing an ultrafast diagnostic system for X-ray beams from Synchrotron Light Sources and Free-Electron Lasers. In this system, the X-ray beam is focused on the photocathode of a high-gradient radio-frequency cavity that accelerates the photo-emitted electrons to a few MeV while preserving their time structure. The accelerated electron beam is streaked by radio-frequency deflectors and then imaged on a screen. This approach will allow orders of magnitude improvement in time resolution over traditional streak cameras and could potentially enable time-resolved diagnostics of sub-100 fs X-ray pulses. We present preliminary beam dynamics simulations of this system and discuss the implementation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS064

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paper received ※ 11 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPTS073

Radiation Damage to Undulator Electronics at an Electron Accelerator

radiation, electronics, photon, neutron

4285

T.Y. Chung, C.-H. Chang, A.Y. Chen, Y.W. Chen, J.C. Huang, J.C. Jan
NSRRC, Hsinchu, Taiwan

Experience gained from commissioning and operation of three elliptical polarization undulators (EPU) at the TPS taught us that undulator driving systems can behave erratically following a beam dump or loss. In this work, we discuss possible harmful radiation sources in a storage ring and analyse the effect of lack of electronic component radiation resistance in the system. According to measurements of spatial radiation distribution at the TPS, we propose solutions and an improved design for Phase-II EPUs.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS073

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paper received ※ 19 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS077

Beam Instability Induced by RF System of an FEL-THZ Source

FEL, linac, target, radiation

4298

X.D. Tu, G. Feng, S.J. He, T. Hu, J. Jiang, S.Y. Lu, Y.Q. Xiong
HUST, Wuhan, People’s Republic of China

An SLAC-like Compact Linac installed on the HUST FEL-THz has been used as an injector to produce high power THz radiation. To meet the requirements of monochromaticity and repeatability for FEL, performance of electron beam and stability of RF system are notable. According to the existing facility, based on measurement results of RF jitter, instability of beam has been calculated, and it has been verified in relevant experiments. Furthermore, stability targets in RF system has been pro-posed in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS077

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS087

Micro-aligned Solenoid for Magnetized Bunched-beam Electron Cooling of 100 GeV/u Ions

solenoid, alignment, GUI, collider

4314

P.M. McIntyre, J. Breitschopf, J. Gerity, J.N. Kellams
Texas A&M University, College Station, USA
J. Breitschopf, J. Gerity, J.N. Kellams, A. Sattarov
ATC, College Station, Texas, USA

Funding: This work is supported by grant DE-SC0018468 from the US Dept. of Energy.
Magnetized electron cooling of ion beams requires pre-cise alignment of the electron beam with the equilibrium trajectory of the ion bunch. For the parameters required for JLEIC, a solenoid with bore field ~1 T, length ~30 m, and rms alignment of ~μrad is required. Such precise alignment has never been accomplished in a 1 T solenoid. The design of a micro-aligned solenoid is presented. A gap-separated stack of thin steel washers is located inside the solenoid. The washer stack shields transverse magnet-ic fields from its interior by a factor of ~10. A 30-washer module of the structure was built and measured using ultra-sensitive capacitive probes using a coordinate meas-uring machine. The r.m.s. coplanarity of the washer gaps was measured to be <5 μm, consistent with the required micro-alignment.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS087

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paper received ※ 17 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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FRXXPLM3

Development of a Pulsed Power Supply Utilizing 13 kV Class SiC-MOSFET

pulsed-power, high-voltage, power-supply, operation

4364

K. Okamura, F. Naito, K. Takayama
KEK, Ibaraki, Japan
K. Fukuda, H. Kitai, K. Sakamoto
AIST, Tsukuba, Ibaraki, Japan
T. Kaito
Chiba Institute of Technology, Narashino, Chiba, Japan
D. Kumamoto
Nagaoka University of Technology, Nagaoka, Niigata, Japan
S. Lim, A. Tokuchi
Pulsed Power Japan Laboratory Ltd., Kusatsu-shi Shiga, Japan

Funding: A part of this work has been implemented under a joint research project of Tsukuba Power Electronics Constellation (TPEC).
To resolve the drawback of conventional thyratron switches, development of a semiconductor high voltage switch utilizing a 13 kV class SiC-MOSFET developed by Tsukuba Power Electronics Constellations (TPEC) is proceeding. At first, the device evaluation test was carried out with a resistive load circuit. With the conditions of drain voltage of 10 kV and load resistance of 1 kΩ, turn on loss Eon, turn off loss Eoff, rise time Tr and fall time Tf were 1.7 mJ, 1.1 mJ, 64 ns, and 75 ns, respectively. As to gate charge characteristics, required electric charge to increase gate source voltage from 0 V to 20 V was about 80 nC. Thereafter, the 2s-12p switch array was designed and assembled, where 12 MOSFETs are equally aligned on a circle shaped circuit board and two circuit boards are stacked in series. A 14 kV-490 A-5 us pulse with a rise time of 430 ns in the long pulse mode and a 18 kV-318 A-1 us pulse with a rise time of 289 ns in the short pulse mode were successfully demonstrated. This switch will be installed as a turn-off switch for the injec-tion ES kicker in the KEK-DA.

Slides FRXXPLM3 [5.088 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-FRXXPLM3

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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FRXXPLS1

Tests of a 3D Printed BPM with a Stretched Wire and with a Particle Beam

vacuum, pick-up, experiment, instrumentation

4368

N. Delerue, D. Auguste, J. Bonis, F. Gauthier, S. Jenzer, A.M. Moutardier
LAL, Orsay, France

Funding: CNRS/IN2P3
We have successfully printed a beam position monitor using 3D printing. After ultra-high vacuum testing and initial measurements with a network analyser we now reports on tests of this BPM using the stretched wire method. The BPM has been installed on a test stand with a wire going through it and electrical pulses have been sent. The signal measured on the pick-ups was compared to that of two conventional BPMs and shows no anomaly specific to the 3D printed BPMs. Following the success of these tests we have also installed this BPM in a beam line at the PhotoInjector at LAL (PHIL). We show that it can give position measurements with an accuracy comparable to that of other BPMs.

Slides FRXXPLS1 [29.118 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-FRXXPLS1

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paper received ※ 19 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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FRXXPLS3

Application of a Phase Space Beam Position and Size Monitor for Synchrotron Radiation

synchrotron, detector, synchrotron-radiation, radiation

4376

N. Samadi
University of Saskatchewan, Saskatoon, Canada
L.D. Chapman, L.O. Dallin
CLS, Saskatoon, Saskatchewan, Canada
X. Shi
ANL, Argonne, Illinois, USA

We will report on a system (ps-BPM) that can measure the electron source vertical position and angular motion along with the vertical source size and angular size at a single location in a synchrotron bend magnet beamline*. This system uses a combination of a monochromator and a filter with a K-edge to which the monochromator was tuned in energy. The vertical distribution of the beam with and without the filter was simultaneously visualized with an imaging detector. The small range of angles from the source onto the monochromator crystals creates an energy range that allows part of the beam to be below the K-edge and the other part above. Measurement of the beam vertical location without the absorber and edge vertical location with the absorber allowes measurement of the source position and angle. The beam width and edge width give information about the vertical electron source size and angular distribution. The ps-BPM measurements have been made where the electron beam size and angular distribution was adjusted using skew quads. The ps-BPM measurements correlate well with modeling of the ps-BPM system as well as conventional beam size measurements using a pinhole.
* A phase-space beam position monitor for synchrotron radiation. J Synchrotron Radiat, 2015. 22(4): p. 946-55.

Slides FRXXPLS3 [4.593 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-FRXXPLS3

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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FRYPLM2

Lasers for Novel Accelerators

laser, plasma, operation, photon

4385

L.A. Gizzi, P. Koester, L. Labate, G. Toci, M. Vannini
INO-CNR, Pisa, Italy
F. Mathieu
LULI, Palaiseau, France
Z. Mazzotta
ARCNL, Amsterdam, The Netherlands
Z. Mazzotta
Ecole Polytechnique, Palaiseau, France

Significant progress has been made over the last decade in optical laser performance including repetition rate, average and peak power, and laser-system footprint making these systems attractive for many applications including novel accelerators. Most novel acceleration schemes require high-power lasers. The talk will present drive laser requirements for current novel accelerator schemes, industry plans to meet these requirements, and the future for high-power lasers.

Slides FRYPLM2 [32.406 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-FRYPLM2

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paper received ※ 08 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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