IPAC2019 - List of Keywords (laser)

Paper	Title	Other Keywords	Page
MOXPLM2	From Dreams to Reality: Prospects for Applying Advanced Accelerator Technology to Next Generation Scientific User Facilities	plasma, electron, 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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MOPGW027	Design Considerations for Permenant Magnetic Quadrupole Triplet for Matching Into Laser Driven Wake Field Acceleration Experiment at SINBAD	plasma, electron, 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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MOPRB052	Gamma Factory at CERN: Design of a Proof-of-Principle Experiment	photon, experiment, electron, 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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MOPRB116	Laser Sculpted Cool Proton Beams	emittance, linac, proton, simulation	826
	S.M. Gibson, L.J. Nevay Royal Holloway, University of London, Surrey, United Kingdom S.E. Alden, S.M. Gibson, L.J. Nevay JAI, Egham, Surrey, United Kingdom
	Funding: We acknowledge support by STFC grant ST/P003028/1 Hydrogen ion accelerators, such as CERN’s Linac4, are increasingly used as the front end of high power proton drivers for high energy physics, spallation neutron sources and other applications. Typically, a foil strips the hydrogen ion beam to facilitate charge-exchange injection of protons into orbits of high energy accelerators, in which the resulting emittance is dominated by phase-space painting. In this paper, a new method to laser extract a narrow beam of neutralised hydrogen from the parent H⁻ ion beam is proposed. Subsequent foil stripping and capture of protons into a storage ring generates cool proton bunches with significantly reduced emittance compared to the parent beam. The properties of the extracted proton beam can be precisely controlled and sculpted by adjusting the optical parameters of the laser beam. Recirculation of the parent beam allows time for space-charge effects to repopulate the emittance phase space prior to repeated laser extraction. We present particle tracking simulations of the proposed scheme, including the laser-particle interaction with realistic optical parameters and show the resulting emittance is reduced. Developments for an experimental demonstration of a laser controlled particle beam are outlined. In principle, the proposed scheme could considerably reduce the emittance of protons bunches injected into an accelerator, such as the LHC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB116
About •	paper received ※ 16 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPTS014	The Experimental Area at the ARES LINAC	experiment, electron, 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	electron, 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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MOPTS025	Overview of the ARES Bunch Compressor at SINBAD	electron, 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, electron, 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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MOPTS030	Characterisation and First Beam Line Tests of the Elbe Stripline Kicker	kicker, septum, neutron, simulation	918
	Ch. Schneider, A. Arnold, M. Freitag, J. Hauser, P. Michel HZDR, Dresden, Germany
	The linac based CW electron accelerator ELBE operates different secondary beamlines one at a time. For the future different end stations should be served simultaneously, hence specific bunch patterns have to be kicked into different beam-lines. The variability of the bunch pattern and the frequency resp. switching time are one of the main arguments for a stripline-kicker. A design with two tapered active electrodes and two ground fenders was optimized in time and frequency domain with the software package CST. From that a design has been transferred into a construction and was manufactured. The prototype has been tested in the laboratory and installed in the ELBE beam line. The presentation summarises the recent results and the first beam line test.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS030
About •	paper received ※ 10 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, electron, 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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TUZPLM1	Adding Data Science and More Intelligence to Our Accelerator Toolbox	controls, network, electron, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZPLM1
About •	paper received ※ 20 May 2019 paper accepted ※ 16 June 2019 issue date ※ 21 June 2019
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TUPMP029	Establishing a Laser Treatment to Suppress the Secondary Electron Emission	electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP029
About •	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	electron, vacuum, experiment, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP031
About •	paper received ※ 26 April 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	electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP051
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPGW014	Characterization and Implementation of the Cryogenic Permanent Magnet Undulator CPMU17 at Bessy II	undulator, vacuum, feedback, operation	1415
	J. Bahrdt, W. Frentrup, S. Gottschlich, S. Grimmer, M. Huck, C. Kuhn, A. Meseck, C. Rethfeldt, M. Scheer, B. Schulz HZB, Berlin, Germany E.C.M. Rial DLS, Oxfordshire, United Kingdom
	In fall 2018, the cryogenic undulator CPMU17 was installed in BESSY II. Before installation, the undulator was characterized with an in-vacuum Hallprobe bench and an in-vacuum moving wire. Both systems were developed at HZB. The commissioning of the device included the orbit and tune corrections, optimization of the injection, characterization of the heat dissipation, tuning the Landau cavities for a reduction of the heat dissipation in the taper sections (temperatures below 60°C) and testing of the machine protection system. The undulator is ready to deliver light for beamline commissioning. Spectral tuning on a high undulator harmonic (longitudinal taper and alignment of e-beam orbit and undulator axis) will be done as soon as the DCM is operational.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW014
About •	paper received ※ 14 May 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	radiation, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW024
About •	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	electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW025
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPGW028	Low Energy Beam Transport System for MESA	emittance, cavity, experiment, solenoid	1461
	C. Matejcek, K. Aulenbacher, S. Friederich IKP, Mainz, Germany
	An important part of the new accelerator MESA (Mainz Energy-recovering Superconducting Accelerator) is the low energy beam transport system connecting the 100 keV electron source with the injector accelerator. The present setup includes the chopper- and bunching system. The devices are of most importance in order to achieve sufficient bunch compression particularely at higher bunch charges and currents. With the circular deflecting cavity of the chopper system it is possible to measure the longitudinal dimension of the bunches upstream of the buncher whereas downstream the longitudinal size will be measured by Smith Purcell radiation. Based on experimental results obtained from this setup we will discuss the beam parameter and compare them with simulations of the beamline.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW028
About •	paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPGW032	Mode-Locked Pulse Oscillation of a Self-Resonating Enhancement Optical Cavity	cavity, resonance, controls, feedback	1471
	Y. Hosaka QST/Takasaki, Takasaki, Japan Y. Honda, T. Omori, J. Urakawa KEK, Ibaraki, Japan A. Kosuge ISSP, Kashiwa-shi, Japan K. Sakaue The University of Tokyo, The School of Engineering, Tokyo, Japan T. Takahashi Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan Y. Uesugi Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, Sendai, Japan M. Washio Waseda University, Tokyo, Japan
	A power enhancement optical cavity is a compelling means of realizing a pulsed laser with a high peak power and high repetition frequency, which is not feasible using a simple amplifier scheme. However, a precise feedback system is necessary for maintaining the narrow resonance condition of the optical cavity; this has become a major technical issue in developing such cavities. We have developed a new approach that does not require any active feedback system, by placing the cavity in the outer loop of a laser amplifier. We report on the first demonstra-tion of a mode-locked pulse oscillation using the new system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW032
About •	paper received ※ 15 April 2019 paper accepted ※ 23 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	electron, radiation, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW051
About •	paper received ※ 30 April 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	electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW085
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPGW098	Fabrication & Cold Tests of a Millimeter-Period RF Undulator	undulator, FEL, GUI, electron	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW098
About •	paper received ※ 10 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPRB008	LUXE - a QED Experiment at the European XFEL	experiment, FEL, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB008
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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TUPRB013	Simulation Studies for a EEHG seeded FEL in the XUV	bunching, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB013
About •	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, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB018
About •	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, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB026
About •	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	electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB027
About •	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	FEL, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB031
About •	paper received ※ 17 May 2019 paper accepted ※ 22 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	FEL, radiation, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB046
About •	paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPRB053	Injector Physics Design at SHINE	electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB053
About •	paper received ※ 15 May 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	electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB057
About •	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	FEL, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB061
About •	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	electron, FEL, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB062
About •	paper received ※ 01 May 2019 paper accepted ※ 28 May 2019 issue date ※ 21 June 2019
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TUPRB070	A Peak Finding Algorithm for FEL Spectra Characterization	FEL, electron, bunching, 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
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB070
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPRB083	Status of Clara Front End Commissioning and First User Experiments	experiment, vacuum, linac, diagnostics	1851
	D. Angal-Kalinin, A.D. Brynes, R.K. Buckley, S.R. Buckley, R.J. Cash, H.M. Castaneda Cortes, J.A. Clarke, P.A. Corlett, L.S. Cowie, K.D. Dumbell, D.J. Dunning, B.D. Fell, P. Goudket, A.R. Goulden, S.A. Griffiths, J. Henderson, F. Jackson, J.K. Jones, N.Y. Joshi, S.L. Mathisen, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, T.C.Q. Noakes, T.H. Pacey, M.D. Roper, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, R.J. Smith, E.W. Snedden, M. Surman, N. Thompson, C. Tollervey, R. Valizadeh, D.A. Walsh, T.M. Weston, A.E. Wheelhouse, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A.D. Brynes, J.A. Clarke, K.D. Dumbell, D.J. Dunning, P. Goudket, F. Jackson, J.K. Jones, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, T.C.Q. Noakes, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, M. Surman, N. Thompson, R. Valizadeh, A.E. Wheelhouse, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom R.F. Clarke, G. Cox, M.D. Hancock, J.P. Hindley, C. Hodgkinson, A. Oates, W. Smith, J.T.G. Wilson STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom L.S. Cowie Cockcroft Institute, Lancaster University, Lancaster, United Kingdom N.Y. Joshi, T.H. Pacey UMAN, Manchester, United Kingdom
	CLARA (Compact Linear Accelerator for Research and Applications) is a test facility for Free Electron Laser (FEL) research and other applications at STFC’s Daresbury Laboratory. The first exploitation period using CLARA Front End (FE) provided a range of beam parameters to 12 user experiments. Beam line to Beam Area 1 (BA1) was commissioned and optimised for these experiments, some involving TW laser integration. In addition to the user exploitation programme, significant advances were made to progress on machine development. This paper summarises these developments and presents the near future plan for CLARA.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB083
About •	paper received ※ 14 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	experiment, FEL, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB086
About •	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, electron, photon, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB088
About •	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, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB092
About •	paper received ※ 14 May 2019 paper accepted ※ 19 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, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB096
About •	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, electron	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB102
About •	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, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB106
About •	paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPTS005	Advanced Beam Transport Solutions for ELIMAIA: A User Oriented Laser-Driven Ion Beamlines	proton, dipole, quadrupole, permanent-magnet	1936
	F. Schillaci, D. Margarone, V. Scuderi ELI-BEAMS, Prague, Czech Republic L. Andò, G.A.P. Cirrone, G. Cuttone, G. Milluzzo, J. Pipek, F. Romano, A.D. Russo INFN/LNS, Catania, Italy M. Maggiore INFN/LNL, Legnaro (PD), Italy
	Laser-target acceleration represents a promising alternative to standard accelerators for several potential applications, especially medical ones, but some extreme features make laser-driven ion beams not directly usable. Therefore, a large effort has been recently devoted to development of beam-transport solutions to obtain controlled and reproducible beams. In this framework, a collaboration has been established between INFN-LNS (IT) and Eli-Beamlines-IoP (CZ) to realize a complete transport beam-line, named ELIMED, dedicated to the transport, diagnostics and dosimetry of laser-driven ion beams. The transport beamline is made by three sections: a set of high field gradient permanent magnet quadrupoles with large acceptance is used to collect and inject ions in the selection section; a magnetic chicane made of C-shaped resistive dipoles is able to select beams with high resolution and to work as an active energy modulator. The final beam shaping is done by two resistive quadrupoles. In this contribution the status of the beamline is described together with the tests performed with conventional accelerators at INFN-LNS. Feasibility study of possible upgrades are also reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS005
About •	paper received ※ 15 April 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, electron, vacuum, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS011
About •	paper received ※ 29 April 2019 paper accepted ※ 28 May 2019 issue date ※ 21 June 2019
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TUPTS012	Emittance Reduction of RF Photoinjector Generated Electron Beams By Transverse Laser Beam Shaping	emittance, simulation, cathode, experiment	1958
	M. Groß, P. Boonpornprasert, Y. Chen, J.D. Good, H. Huck, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, X. Li, O. Lishilin, G. Loisch, D. Melkumyan, S.K. Mohanty, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, G. Shu, F. Stephan, G. Vashchenko DESY Zeuthen, Zeuthen, Germany I. Will MBI, Berlin, Germany
	Laser pulse shaping is one of the key elements to generate low emittance electron beams with RF photoinjectors. Ultimately high performance can be achieved with ellipsoidal laser pulses, but 3-dimensional shaping is challenging. High beam quality can also be reached by simple transverse pulse shaping, which has demonstrated improved beam emittance compared to a transversely uniform laser in the ‘pancake’ photoemission regime. In this contribution we present the truncation of a Gaussian laser at a radius of approximately one σ in the intermediate (electron bunch length directly after emission about the same as radius) photoemission regime with high acceleration gradients (up to 60 MV/m). This type of electron bunch is used e.g. at the European XFEL and FLASH free electron lasers at DESY, Hamburg site and is being investigated in detail at the Photoinjector Test facility at DESY in Zeuthen (PITZ). Here we present ray-tracing simulations and experimental data of a laser beamline upgrade enabling variable transverse truncation. Initial projected emittance measurements taken with help of this setup are shown, as well as supporting beam dynamics simulations. Additional simulations show the potential for substantial reduction of slice emittance at PITZ.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS012
About •	paper received ※ 24 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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TUPTS015	Design Steps Towards an Electron Source for Ultrafast Electron Diffraction at DELTA	electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS015
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPTS061	The Pre-Injector and Photocathode Gun Design for the MAX IV SXL	gun, cathode, emittance, linac	2064
	J. Andersson, F. Curbis, L. Isaksson, M. Kotur, D. Kumbaro, F. Lindau, E. Mansten, S. Thorin, S. Werin MAX IV Laboratory, Lund University, Lund, Sweden
	The design of the pre-injector, including the new gun, for the SXL project is being finalised for the desired modes of operation, 100 pC and 10 pC with short bunches. The photocathode gun is currently being manufactured and experiments in the MAX IV guntest facility are under preparation to verify the design. In this paper we present the design of the gun and the pre-injector and show some results from simulations using MOGA indicating an emittance below 0.3 mm mrad.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS061
About •	paper received ※ 15 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, electron, operation	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS066
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPTS069	A Plasmonic Niobium Photocathode for SRF Gun Applications	cathode, gun, cavity, photon	2079
	F.E. Hannon JLab, Newport News, Virginia, USA G. Andonian, L.H. Harris RadiaBeam, Marina del Rey, California, USA
	The typical quantum efficiency of niobium is of the order 10^-4, whilst also requiring UV lasers for emission. This paper presents the results of a plasmonic niobium surface that operates with IR laser via multiphoton emission.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS069
About •	paper received ※ 15 May 2019 paper accepted ※ 22 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	electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS089
About •	paper received ※ 14 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, electron, gun, vacuum	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS101
About •	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, electron, gun, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS102
About •	paper received ※ 14 May 2019 paper accepted ※ 19 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	electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS104
About •	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, electron, 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)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS105
About •	paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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TUPTS117	Photocathode Activities at INFN LASA	cathode, operation, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS117
About •	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	electron, undulator, FEL, controls	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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXPLM1
About •	paper received ※ 10 May 2019 paper accepted ※ 20 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, electron, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXXPLM1
About •	paper received ※ 17 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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WEXXPLS3	Is it Possible to Use Additive Manufacturing for Accelerator UHV Beam Pipes?	electron, vacuum, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXXPLS3
About •	paper received ※ 01 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEZPLM1	The LATINO Project - An Italian Perspective on Connecting SMEs with Research Infrastructures	vacuum, instrumentation, radio-frequency, operation	2277
	L. Sabbatini, D. Alesini, A. Falone, A. Gallo INFN/LNF, Frascati, Italy V. Pettinacci INFN-Roma, Roma, Italy
	Funding: The LATINO project is co-funded by the Regione Lazio within POR-FESR 2014-2020 European activities (public call ’Open Research Infrastructures’). The National Laboratories of Frascati (LNF) are the first Italian research facility for the study of nuclear and subnuclear physics with accelerators and are the largest laboratories of the Italian National Institute for Nuclear Physics (INFN), the public body whose mission is theoretical, experimental and technological research in subnuclear, nuclear and astroparticle physics. LNF have an extensive experience in designing, installation, testing and operation of particle accelerators and the related technologies. The competences range over almost all the technologies related to particle accelerators, including radio frequency, vacuum, magnets and mechanics. LNF have always had a close relationship with the regional and national industries, stimulating the development and growth of the industrial background by means of close collaboration with partners. The LATINO (a Laboratory in Advanced Technologies for INnOvation) project is an initiative that fits into this path and aims to strengthen this relationship, allowing access to the technologies, instruments and competences not otherwise available to the enterprises. A modern vision of advanced economies recommends the Technology Transfer from the research world to the productive activities through the creation of research infrastructures as the most efficient system for generating innovation and economic development [1-3]. The Regione Lazio, despite hosting centres of excellence, has a delay in the establishment of this kind of infrastructures.
	Slides WEZPLM1 [4.103 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEZPLM1
About •	paper received ※ 15 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	electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEZPLS1
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEZPLS2	High Transformer Ratio Plasma Wakefield Acceleration Driven by Photocathode Laser Shaped Electron Bunches	plasma, wakefield, acceleration, experiment	2286
	G. Loisch DESY Zeuthen, Zeuthen, Germany
	Beam driven wakefield acceleration (PWFA) schemes in plasmas are among the most promising candidates for novel, compact accelerators. Several aspects of PWFA are under investigation at the Photoinjector Test facility at DESY in Zeuthen (PITZ). One of the main characteristics of these accelerators is the ratio between field strength usable for acceleration and decelerating field strength in the driver bunch, the so called transformer ratio. To reach high transformer ratios usually shaped bunches, e.g. with ramped current profiles are employed as drivers. The so-called self-modulation instability, which causes transverse modulation of a bunch longer than the plasma wavelength, is proposed as a means of supplying short driver bunches for proton-driven PWFA. This talk will give an overview on experimental results in these two aspects of PWFA at PITZ with a focus on the production of electron bunches enabling high transformer ratio acceleration by shaping the photocathode laser pulses of a photoinjector and the demonstration of high transformer ratio PWFA. Simulations and further developments on the shaping techniques, allowing highly flexible electron bunches for future plasma wakefield accelerators are also presented.
	Slides WEZPLS2 [5.172 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEZPLS2
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WEZZPLS2	EuPRAXIA, a Step Toward a Plasma-Wakefield Based Accelerator With High Beam Quality	plasma, injection, acceleration, emittance	2291
	P.A.P. Nghiem, A. Chancé CEA-IRFU, Gif-sur-Yvette, France D. Alesini, E. Chiadroni, M. Croia, A. Del Dotto, M. Ferrario, A. Giribono, R. Pompili, S. Romeo, V. Shpakov, A. Stella, C. Vaccarezza INFN/LNF, Frascati, Italy A. Aschikhin, R.W. Aßmann, U. Dorda, A. Ferran Pousa, V. Libov, B. Marchetti, A. Martinez de la Ossa, D. Marx, P. Niknejadi, L. Schaper, E.N. Svystun, P.A. Walker, M.K. Weikum, J. Zhu DESY, Hamburg, Germany T. Audet, B. Cros, P. Lee, G. Maynard CNRS LPGP Univ Paris Sud, Orsay, France A. Beck, F. Massimo, A. Specka LLR, Palaiseau, France M. Chen, S.M. Weng Shanghai Jiao Tong University, Shanghai, People’s Republic of China A. Cianchi Università di Roma II Tor Vergata, Roma, Italy J.A. Clarke STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom M.-E. Couprie, A. Ghaith, D. Oumbarek Espinos SOLEIL, Gif-sur-Yvette, France G. Dattoli, F. Nguyen ENEA C.R. Frascati, Frascati (Roma), Italy N. Delerue LAL, Orsay, France R.A. Fonseca, L.O. Silva Instituto Superior Tecnico, Lisbon, Portugal L.A. Gizzi, G. Toci, P. Tomassini INO-CNR, Pisa, Italy A. Helm IST-UTL, Lisbon, Portugal B. Hidding Cockcroft Institute, Warrington, Cheshire, United Kingdom S.M. Hooker, R. Walczak Oxford University, Physics Department, Oxford, Oxon, United Kingdom M.G. Ibison, M. Vujanovic, C.P. Welsch, J. Wolfenden The University of Liverpool, Liverpool, United Kingdom D.A. Jaroszynski, F.Y. Li, Z.M. Sheng, S.M. Wiggins, S. Yoffe USTRAT/SUPA, Glasgow, United Kingdom K.O. Kruchinin, A.Y. Molodozhentsev ELI-BEAMS, Prague, Czech Republic L. Labate CNR/IPP, Pisa, Italy X. Li DESY Zeuthen, Zeuthen, Germany F. Mathieu LULI, Palaiseau, France Z. Mazzotta Ecole Polytechnique, Palaiseau, France T.J. Mehrling LBNL, Berkeley, USA A. Mosnier, C. Simon CEA, Gif-sur-Yvette, France A. Mostacci Rome University La Sapienza, Roma, Italy Z. Najmudin Imperial College of Science and Technology, Department of Physics, London, United Kingdom R. Pattathil, D. Symes STFC/RAL, Chilton, Didcot, Oxon, United Kingdom A.R. Rossi INFN-Milano, Milano, Italy T. Silva, J.M. Vieira IPFN, Lisbon, Portugal M.J.V. Streeter JAI, London, United Kingdom D. Terzani UniNa, Napoli, Italy
	Funding: European Union’s Horizon 2020 research and innovation programme under grant agreement No. 653782 The EuPRAXIA project aims at designing the world’s first accelerator based on plasma-wakefield advanced technique, which can deliver a 5 GeV electron beam with simultaneously high charge, low emittance and low energy spread to user’s communities. Such challenging objectives can only have a chance to be achieved when particular efforts are dedicated to identify the subsequent issues and to find the way to solve them. Many injection/acceleration schemes and techniques have been explored by means of thorough simulations in more than ten European institutes to sort out the most appropriate ones. The specific issues of high charge, high beam quality and beam extraction then transfer to the user’s applications, have been tackled with many innovative approaches. This article highlights the different advanced methods that have been employed by the EuPRAXIA collaboration and the preliminary results obtained. The needs in terms of laser and plasma parameters for such an accelerator are also summarized. - in 2017: Phys. Plasmas, 24,10,103120; Nat. Commun.8,15705; - in 2018: NIMA, 909,84-89; NIMA, 909,49-53; Phys. Rev.Acc. Beams, 21,111301; NIMA, 909,54-57; Phys. Rev.Acc. Beams, 21,052802; NIMA, 909,282-285
	Slides WEZZPLS2 [5.157 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEZZPLS2
About •	paper received ※ 12 April 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019
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WEPMP053	Operational Results of Simultaneous Four-Beam Delivery at Jefferson Lab	operation, experiment, cavity, gun	2454
	R. Kazimi, A. Freyberger, J.M. Grames, J. Hansknecht, A.S. Hofler, T.E. Plawski, M. Poelker, M.F. Spata, Y.W. Wang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. A concept for simultaneous beam delivery to all four CEBAF experimental halls from a single injector and a single main accelerator for the 12 GeV era was proposed in 2012. The original 12 GeV beam delivery plan was for a maximum of three experimental halls at a time as in the 6 GeV era. Therefore, the new concept increases the po-tential beam time for the experiments up to 33%. This change, although a major improvement in operational capabilities, required only limited modifications to the existing machine. The modifications were mainly timing and pattern changes to the beams in the injector, adding a fourth laser to the photo-cathode gun, and the addition of new RF separators to the highest pass of CEBAF. These changes are now complete and, for the first time, the full system is operating, producing four simultaneous beams through the accelerator to four different destinations. In this paper, in addition to presenting the results of the full system commissioning, we will discuss important details about the new configuration plus some of our operational challenges.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP053
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPGW010	Diagnostics and First Beam Measurements at FLUTE	electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW010
About •	paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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WEPGW042	Development of the Longitudinal Beam Monitor with High Time Resolution for a Muon LINAC in the J-PARC E34 Experiment	experiment, linac, acceleration, DTL	2571
	M. Yotsuzuka, K. Inami Nagoya University, Nagoya, Japan K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, M. Otani, K. Shimomura, T. Yamazaki KEK, Ibaraki, Japan K. Hasegawa, R. Kitamura, T. Morishita JAEA/J-PARC, Tokai-mura, Japan T. Iijima, Y. Sue Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan T. Iijima KMI, Nagoya, AIchi Prefecture, Japan H. Iinuma, Y. Nakazawa Ibaraki University, Ibaraki, Japan Y. Kondo JAEA, Ibaraki-ken, Japan N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan H.Y. Yasuda University of Tokyo, Tokyo, Japan
	Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP15H05742, JP16H03987, JP16J07784, JP18H03707 and JP18H05226. The J-PARC E34 experiment aims to measure the muon anomalous magnetic moment and the electric dipole moment with a high precision. In this experiment, ultra-slow muons generated from thermal muonium production and laser resonance ionization are accelerated in a multistage muon linac. In order to satisfy the experimental requirements, a suppression of the emittance growth between different accelerating cavities is necessary, and the transverse and longitudinal beam matching is important. Longitudinal beam monitor has to measure the bunch width with a precision of 1% corresponding to several tens of picoseconds. In addition, the beam monitor should be sensitive to a single muon, because the beam intensity during the commissioning is lower than the designed intensity. Therefore, we are developing a longitudinal beam monitor using a microchannel plate (MCP), and a measurement system using photoelectrons to estimate the performance of the beam monitor. On November 2018, the beam monitor has been successfully used in the muon RF acceleration test at the J-PARC. In this presentation, the results of the performance evaluation for this beam monitor are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW042
About •	paper received ※ 30 April 2019 paper accepted ※ 21 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, electron	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW044
About •	paper received ※ 25 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPGW052	A Rotation Method to Calibrate BPM Electric Offsets	site, radiation, instrumentation, proton	2595
	M.W. Wang, X. Guan, P.F. Ma, X.W. Wang, S.X. Zheng TUB, Beijing, People’s Republic of China M.T. Qiu, D. Wang, Z.M. Wang NINT, Shannxi, People’s Republic of China
	Beam position monitor is a key instrument for machine commissioning. To measure beam position accurately, offline calibrations to acquire the sensitivity and offsets of the BPM are essential prerequisites. A new method to calibrate the BPM electric offset is proposed in this paper. By measuring the location variation of the BPM electric center after rotatingtheBPM180degrees, theBPMoffsetcanbederived. The method is more convenient, universal and accurate than the traditional methods. The method is successfully applied to calibrate the button BPM of Xi’an Proton Application Facility. The repetitive measurement error is 20.8 um.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW052
About •	paper received ※ 16 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPGW055	Beam Longitudinal Distribution Reconstructed by GESPAR Method at CAEP THz FEL	radiation, electron, FEL, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW055
About •	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, electron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW060
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPGW073	Control System for Lasers at Hilase	controls, EPICS, software, PLC	2641
	J. Horáček, T. Mocek, M. Rehakova HiLASE Centre, Institute of Physics ASCR, v.v.i., Dolní Bře’any, Czech Republic R. Modic, J. Podlipnik, M. Pogacnik Cosy lab, Ljubljana, Slovenia
	We present the current state of the HiLASE Centre control system developed in cooperation with Cosylab. The aim of the development is to build a control system which would be in charge of the operation of kW-class in-house-developed laser beamlines. These beamlines deliver picosecond pulses with repetition rates between 1 kHz and 1 MHz and high-energy nanosecond pulses at 10 Hz. A generic control system architecture is presented, which can either support full-size development lasers or compact industrial versions. The EPICS control system work focuses on image acquisition and processing, vacuum control, provision of timing, archiving and user interfaces. HiLASE provides high-level requirements, Cosylab complements them, provides the design of the solution and implementation. Delivery is performed during on-site visits where a test plan is executed for acceptance. This approach relieves HiLASE of the need to hire and manage their own team while retaining full control over the functionality through requirements and acceptance approval. Cosylab complements HiLASE with self-managed teams that deliver to specification.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW073
About •	paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPGW078	Development and Test of a Beam Imaging System Based on Radiation Tolerant Optical Fiber Bundles	radiation, experiment, target, site	2658
	D. Celeste, E. Bravin, S. Burger, F. Roncarolo CERN, Geneva, Switzerland
	Many of the beam image systems at CERN are located in high radiation environments. In order to cope with this issue, VIDICON cameras are presently used but their production has been nowadays discontinued worldwide. The development of an alternative beam imaging system is described here, based on radiation tolerant optical fibre bundles. Such an optical line relays the image of a scintillating screen to a standard CMOS camera, located away from the high radiation zone. A prototype system based on a 10m long bundle with 10⁴ fibres has been tested in the TT2 transfer line at CERN. The light transmission is rather low, but is compensated by the sensitivity of the CMOS camera. The system had a field of view of 60 mm and a spatial resolution of ~1 mm. The radiation hardness of such a fiber bundle was tested at the IRMA-CEA facility in Saclay, France. The bundle was irradiated at a rate of 3.6 kGy/h for 8 consecutive day. The total integrated dose achieved was ~700 kGy, which corresponds to about ten years of operation at the beam imaging station with the highest radiation dose at CERN. While the light transmission was reduced by 50%, this is still adequate to provide acceptable images.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW078
About •	paper received ※ 10 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEPGW114	Interferometric Measurement of Bunch Length of a 3Mev Picocoulomb Electron Beam	electron, cathode, experiment, space-charge	2766

Paper

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

plasma, electron, 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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOXPLM2

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MOPGW027

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

plasma, electron, 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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MOPRB052

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

photon, experiment, electron, 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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MOPRB116

Laser Sculpted Cool Proton Beams

emittance, linac, proton, simulation

826

S.M. Gibson, L.J. Nevay
Royal Holloway, University of London, Surrey, United Kingdom
S.E. Alden, S.M. Gibson, L.J. Nevay
JAI, Egham, Surrey, United Kingdom

Funding: We acknowledge support by STFC grant ST/P003028/1
Hydrogen ion accelerators, such as CERN’s Linac4, are increasingly used as the front end of high power proton drivers for high energy physics, spallation neutron sources and other applications. Typically, a foil strips the hydrogen ion beam to facilitate charge-exchange injection of protons into orbits of high energy accelerators, in which the resulting emittance is dominated by phase-space painting. In this paper, a new method to laser extract a narrow beam of neutralised hydrogen from the parent H⁻ ion beam is proposed. Subsequent foil stripping and capture of protons into a storage ring generates cool proton bunches with significantly reduced emittance compared to the parent beam. The properties of the extracted proton beam can be precisely controlled and sculpted by adjusting the optical parameters of the laser beam. Recirculation of the parent beam allows time for space-charge effects to repopulate the emittance phase space prior to repeated laser extraction. We present particle tracking simulations of the proposed scheme, including the laser-particle interaction with realistic optical parameters and show the resulting emittance is reduced. Developments for an experimental demonstration of a laser controlled particle beam are outlined. In principle, the proposed scheme could considerably reduce the emittance of protons bunches injected into an accelerator, such as the LHC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB116

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paper received ※ 16 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPTS014

The Experimental Area at the ARES LINAC

experiment, electron, 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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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

electron, 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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MOPTS025

Overview of the ARES Bunch Compressor at SINBAD

electron, 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, electron, 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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MOPTS030

Characterisation and First Beam Line Tests of the Elbe Stripline Kicker

kicker, septum, neutron, simulation

918

Ch. Schneider, A. Arnold, M. Freitag, J. Hauser, P. Michel
HZDR, Dresden, Germany

The linac based CW electron accelerator ELBE operates different secondary beamlines one at a time. For the future different end stations should be served simultaneously, hence specific bunch patterns have to be kicked into different beam-lines. The variability of the bunch pattern and the frequency resp. switching time are one of the main arguments for a stripline-kicker. A design with two tapered active electrodes and two ground fenders was optimized in time and frequency domain with the software package CST. From that a design has been transferred into a construction and was manufactured. The prototype has been tested in the laboratory and installed in the ELBE beam line. The presentation summarises the recent results and the first beam line test.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS030

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paper received ※ 10 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, electron, 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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TUZPLM1

Adding Data Science and More Intelligence to Our Accelerator Toolbox

controls, network, electron, 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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TUPMP029

Establishing a Laser Treatment to Suppress the Secondary Electron Emission

electron, 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

electron, vacuum, experiment, 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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TUPMP051

MULTIPACTOR SUPPRESSION BY LASER ABLATION SURFACE ENGINEERING FOR SPACE APPLICATIONS

electron, 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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TUPGW014

Characterization and Implementation of the Cryogenic Permanent Magnet Undulator CPMU17 at Bessy II

undulator, vacuum, feedback, operation

1415

J. Bahrdt, W. Frentrup, S. Gottschlich, S. Grimmer, M. Huck, C. Kuhn, A. Meseck, C. Rethfeldt, M. Scheer, B. Schulz
HZB, Berlin, Germany
E.C.M. Rial
DLS, Oxfordshire, United Kingdom

In fall 2018, the cryogenic undulator CPMU17 was installed in BESSY II. Before installation, the undulator was characterized with an in-vacuum Hallprobe bench and an in-vacuum moving wire. Both systems were developed at HZB. The commissioning of the device included the orbit and tune corrections, optimization of the injection, characterization of the heat dissipation, tuning the Landau cavities for a reduction of the heat dissipation in the taper sections (temperatures below 60°C) and testing of the machine protection system. The undulator is ready to deliver light for beamline commissioning. Spectral tuning on a high undulator harmonic (longitudinal taper and alignment of e-beam orbit and undulator axis) will be done as soon as the DCM is operational.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW014

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paper received ※ 14 May 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

radiation, electron, 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

electron, 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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TUPGW028

Low Energy Beam Transport System for MESA

emittance, cavity, experiment, solenoid

1461

C. Matejcek, K. Aulenbacher, S. Friederich
IKP, Mainz, Germany

An important part of the new accelerator MESA (Mainz Energy-recovering Superconducting Accelerator) is the low energy beam transport system connecting the 100 keV electron source with the injector accelerator. The present setup includes the chopper- and bunching system. The devices are of most importance in order to achieve sufficient bunch compression particularely at higher bunch charges and currents. With the circular deflecting cavity of the chopper system it is possible to measure the longitudinal dimension of the bunches upstream of the buncher whereas downstream the longitudinal size will be measured by Smith Purcell radiation. Based on experimental results obtained from this setup we will discuss the beam parameter and compare them with simulations of the beamline.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW028

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

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TUPGW032

Mode-Locked Pulse Oscillation of a Self-Resonating Enhancement Optical Cavity

cavity, resonance, controls, feedback

1471

Y. Hosaka
QST/Takasaki, Takasaki, Japan
Y. Honda, T. Omori, J. Urakawa
KEK, Ibaraki, Japan
A. Kosuge
ISSP, Kashiwa-shi, Japan
K. Sakaue
The University of Tokyo, The School of Engineering, Tokyo, Japan
T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
Y. Uesugi
Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, Sendai, Japan
M. Washio
Waseda University, Tokyo, Japan

A power enhancement optical cavity is a compelling means of realizing a pulsed laser with a high peak power and high repetition frequency, which is not feasible using a simple amplifier scheme. However, a precise feedback system is necessary for maintaining the narrow resonance condition of the optical cavity; this has become a major technical issue in developing such cavities. We have developed a new approach that does not require any active feedback system, by placing the cavity in the outer loop of a laser amplifier. We report on the first demonstra-tion of a mode-locked pulse oscillation using the new system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW032

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paper received ※ 15 April 2019 paper accepted ※ 23 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

electron, radiation, 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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TUPGW085

A Hard X-Ray Compact Compton Source at CBETA

electron, 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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TUPGW098

Fabrication & Cold Tests of a Millimeter-Period RF Undulator

undulator, FEL, GUI, electron

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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TUPRB008

LUXE - a QED Experiment at the European XFEL

experiment, FEL, electron, 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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TUPRB013

Simulation Studies for a EEHG seeded FEL in the XUV

bunching, electron, 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, electron, 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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TUPRB026

Optics & Compression Schemes for a Possible FLASH Upgrade

FEL, emittance, electron, 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

electron, 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

FEL, electron, 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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TUPRB046

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

FEL, radiation, electron, 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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TUPRB053

Injector Physics Design at SHINE

electron, 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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TUPRB057

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

electron, 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

FEL, electron, 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

electron, FEL, 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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TUPRB070

A Peak Finding Algorithm for FEL Spectra Characterization

FEL, electron, bunching, 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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TUPRB083

Status of Clara Front End Commissioning and First User Experiments

experiment, vacuum, linac, diagnostics

1851

D. Angal-Kalinin, A.D. Brynes, R.K. Buckley, S.R. Buckley, R.J. Cash, H.M. Castaneda Cortes, J.A. Clarke, P.A. Corlett, L.S. Cowie, K.D. Dumbell, D.J. Dunning, B.D. Fell, P. Goudket, A.R. Goulden, S.A. Griffiths, J. Henderson, F. Jackson, J.K. Jones, N.Y. Joshi, S.L. Mathisen, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, T.C.Q. Noakes, T.H. Pacey, M.D. Roper, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, R.J. Smith, E.W. Snedden, M. Surman, N. Thompson, C. Tollervey, R. Valizadeh, D.A. Walsh, T.M. Weston, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A.D. Brynes, J.A. Clarke, K.D. Dumbell, D.J. Dunning, P. Goudket, F. Jackson, J.K. Jones, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, T.C.Q. Noakes, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, M. Surman, N. Thompson, R. Valizadeh, A.E. Wheelhouse, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R.F. Clarke, G. Cox, M.D. Hancock, J.P. Hindley, C. Hodgkinson, A. Oates, W. Smith, J.T.G. Wilson
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
L.S. Cowie
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
N.Y. Joshi, T.H. Pacey
UMAN, Manchester, United Kingdom

CLARA (Compact Linear Accelerator for Research and Applications) is a test facility for Free Electron Laser (FEL) research and other applications at STFC’s Daresbury Laboratory. The first exploitation period using CLARA Front End (FE) provided a range of beam parameters to 12 user experiments. Beam line to Beam Area 1 (BA1) was commissioned and optimised for these experiments, some involving TW laser integration. In addition to the user exploitation programme, significant advances were made to progress on machine development. This paper summarises these developments and presents the near future plan for CLARA.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB083

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paper received ※ 14 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

experiment, FEL, electron, 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, electron, photon, 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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TUPRB092

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

radiation, electron, 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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TUPRB096

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

FEL, cavity, electron, 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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TUPRB102

Numerical Study of the Delta II Polarizing Undulator for LCLS II

undulator, simulation, polarization, electron

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, electron, 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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TUPTS005

Advanced Beam Transport Solutions for ELIMAIA: A User Oriented Laser-Driven Ion Beamlines

proton, dipole, quadrupole, permanent-magnet

1936

F. Schillaci, D. Margarone, V. Scuderi
ELI-BEAMS, Prague, Czech Republic
L. Andò, G.A.P. Cirrone, G. Cuttone, G. Milluzzo, J. Pipek, F. Romano, A.D. Russo
INFN/LNS, Catania, Italy
M. Maggiore
INFN/LNL, Legnaro (PD), Italy

Laser-target acceleration represents a promising alternative to standard accelerators for several potential applications, especially medical ones, but some extreme features make laser-driven ion beams not directly usable. Therefore, a large effort has been recently devoted to development of beam-transport solutions to obtain controlled and reproducible beams. In this framework, a collaboration has been established between INFN-LNS (IT) and Eli-Beamlines-IoP (CZ) to realize a complete transport beam-line, named ELIMED, dedicated to the transport, diagnostics and dosimetry of laser-driven ion beams. The transport beamline is made by three sections: a set of high field gradient permanent magnet quadrupoles with large acceptance is used to collect and inject ions in the selection section; a magnetic chicane made of C-shaped resistive dipoles is able to select beams with high resolution and to work as an active energy modulator. The final beam shaping is done by two resistive quadrupoles. In this contribution the status of the beamline is described together with the tests performed with conventional accelerators at INFN-LNS. Feasibility study of possible upgrades are also reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS005

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paper received ※ 15 April 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, electron, vacuum, 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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TUPTS012

Emittance Reduction of RF Photoinjector Generated Electron Beams By Transverse Laser Beam Shaping

emittance, simulation, cathode, experiment

1958

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

Laser pulse shaping is one of the key elements to generate low emittance electron beams with RF photoinjectors. Ultimately high performance can be achieved with ellipsoidal laser pulses, but 3-dimensional shaping is challenging. High beam quality can also be reached by simple transverse pulse shaping, which has demonstrated improved beam emittance compared to a transversely uniform laser in the ‘pancake’ photoemission regime. In this contribution we present the truncation of a Gaussian laser at a radius of approximately one σ in the intermediate (electron bunch length directly after emission about the same as radius) photoemission regime with high acceleration gradients (up to 60 MV/m). This type of electron bunch is used e.g. at the European XFEL and FLASH free electron lasers at DESY, Hamburg site and is being investigated in detail at the Photoinjector Test facility at DESY in Zeuthen (PITZ). Here we present ray-tracing simulations and experimental data of a laser beamline upgrade enabling variable transverse truncation. Initial projected emittance measurements taken with help of this setup are shown, as well as supporting beam dynamics simulations. Additional simulations show the potential for substantial reduction of slice emittance at PITZ.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS012

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paper received ※ 24 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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TUPTS015

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

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

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TUPTS061

The Pre-Injector and Photocathode Gun Design for the MAX IV SXL

gun, cathode, emittance, linac

2064

J. Andersson, F. Curbis, L. Isaksson, M. Kotur, D. Kumbaro, F. Lindau, E. Mansten, S. Thorin, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden

The design of the pre-injector, including the new gun, for the SXL project is being finalised for the desired modes of operation, 100 pC and 10 pC with short bunches. The photocathode gun is currently being manufactured and experiments in the MAX IV guntest facility are under preparation to verify the design. In this paper we present the design of the gun and the pre-injector and show some results from simulations using MOGA indicating an emittance below 0.3 mm mrad.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS061

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paper received ※ 15 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, electron, operation

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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS066

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

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TUPTS069

A Plasmonic Niobium Photocathode for SRF Gun Applications

cathode, gun, cavity, photon

2079

F.E. Hannon
JLab, Newport News, Virginia, USA
G. Andonian, L.H. Harris
RadiaBeam, Marina del Rey, California, USA

The typical quantum efficiency of niobium is of the order 10^-4, whilst also requiring UV lasers for emission. This paper presents the results of a plasmonic niobium surface that operates with IR laser via multiphoton emission.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS069

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paper received ※ 15 May 2019 paper accepted ※ 22 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

electron, 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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TUPTS101

Bi-Alkali Antimonide Photocathodes for LEReC DC Gun

cathode, electron, gun, vacuum

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, electron, gun, 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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS102

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paper received ※ 14 May 2019 paper accepted ※ 19 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

electron, 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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS104

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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, electron, 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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TUPTS117

Photocathode Activities at INFN LASA

cathode, operation, electron, 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

electron, undulator, FEL, controls

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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WEXXPLM1

Amplified Emission of a Soft-X Ray Free-Electron Laser Based on Echo-Enabled Harmonic Generation

FEL, electron, 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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WEXXPLS3

Is it Possible to Use Additive Manufacturing for Accelerator UHV Beam Pipes?

electron, vacuum, 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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXXPLS3

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

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WEZPLM1

The LATINO Project - An Italian Perspective on Connecting SMEs with Research Infrastructures

vacuum, instrumentation, radio-frequency, operation

2277

L. Sabbatini, D. Alesini, A. Falone, A. Gallo
INFN/LNF, Frascati, Italy
V. Pettinacci
INFN-Roma, Roma, Italy

Funding: The LATINO project is co-funded by the Regione Lazio within POR-FESR 2014-2020 European activities (public call ’Open Research Infrastructures’).
The National Laboratories of Frascati (LNF) are the first Italian research facility for the study of nuclear and subnuclear physics with accelerators and are the largest laboratories of the Italian National Institute for Nuclear Physics (INFN), the public body whose mission is theoretical, experimental and technological research in subnuclear, nuclear and astroparticle physics. LNF have an extensive experience in designing, installation, testing and operation of particle accelerators and the related technologies. The competences range over almost all the technologies related to particle accelerators, including radio frequency, vacuum, magnets and mechanics. LNF have always had a close relationship with the regional and national industries, stimulating the development and growth of the industrial background by means of close collaboration with partners. The LATINO (a Laboratory in Advanced Technologies for INnOvation) project is an initiative that fits into this path and aims to strengthen this relationship, allowing access to the technologies, instruments and competences not otherwise available to the enterprises. A modern vision of advanced economies recommends the Technology Transfer from the research world to the productive activities through the creation of research infrastructures as the most efficient system for generating innovation and economic development [1-3]. The Regione Lazio, despite hosting centres of excellence, has a delay in the establishment of this kind of infrastructures.

Slides WEZPLM1 [4.103 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEZPLM1

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paper received ※ 15 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

electron, 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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEZPLS1

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

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WEZPLS2

High Transformer Ratio Plasma Wakefield Acceleration Driven by Photocathode Laser Shaped Electron Bunches

plasma, wakefield, acceleration, experiment

2286

G. Loisch
DESY Zeuthen, Zeuthen, Germany

Beam driven wakefield acceleration (PWFA) schemes in plasmas are among the most promising candidates for novel, compact accelerators. Several aspects of PWFA are under investigation at the Photoinjector Test facility at DESY in Zeuthen (PITZ). One of the main characteristics of these accelerators is the ratio between field strength usable for acceleration and decelerating field strength in the driver bunch, the so called transformer ratio. To reach high transformer ratios usually shaped bunches, e.g. with ramped current profiles are employed as drivers. The so-called self-modulation instability, which causes transverse modulation of a bunch longer than the plasma wavelength, is proposed as a means of supplying short driver bunches for proton-driven PWFA. This talk will give an overview on experimental results in these two aspects of PWFA at PITZ with a focus on the production of electron bunches enabling high transformer ratio acceleration by shaping the photocathode laser pulses of a photoinjector and the demonstration of high transformer ratio PWFA. Simulations and further developments on the shaping techniques, allowing highly flexible electron bunches for future plasma wakefield accelerators are also presented.

Slides WEZPLS2 [5.172 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEZPLS2

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

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WEZZPLS2

EuPRAXIA, a Step Toward a Plasma-Wakefield Based Accelerator With High Beam Quality

plasma, injection, acceleration, emittance

2291

P.A.P. Nghiem, A. Chancé
CEA-IRFU, Gif-sur-Yvette, France
D. Alesini, E. Chiadroni, M. Croia, A. Del Dotto, M. Ferrario, A. Giribono, R. Pompili, S. Romeo, V. Shpakov, A. Stella, C. Vaccarezza
INFN/LNF, Frascati, Italy
A. Aschikhin, R.W. Aßmann, U. Dorda, A. Ferran Pousa, V. Libov, B. Marchetti, A. Martinez de la Ossa, D. Marx, P. Niknejadi, L. Schaper, E.N. Svystun, P.A. Walker, M.K. Weikum, J. Zhu
DESY, Hamburg, Germany
T. Audet, B. Cros, P. Lee, G. Maynard
CNRS LPGP Univ Paris Sud, Orsay, France
A. Beck, F. Massimo, A. Specka
LLR, Palaiseau, France
M. Chen, S.M. Weng
Shanghai Jiao Tong University, Shanghai, People’s Republic of China
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
J.A. Clarke
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
M.-E. Couprie, A. Ghaith, D. Oumbarek Espinos
SOLEIL, Gif-sur-Yvette, France
G. Dattoli, F. Nguyen
ENEA C.R. Frascati, Frascati (Roma), Italy
N. Delerue
LAL, Orsay, France
R.A. Fonseca, L.O. Silva
Instituto Superior Tecnico, Lisbon, Portugal
L.A. Gizzi, G. Toci, P. Tomassini
INO-CNR, Pisa, Italy
A. Helm
IST-UTL, Lisbon, Portugal
B. Hidding
Cockcroft Institute, Warrington, Cheshire, United Kingdom
S.M. Hooker, R. Walczak
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
M.G. Ibison, M. Vujanovic, C.P. Welsch, J. Wolfenden
The University of Liverpool, Liverpool, United Kingdom
D.A. Jaroszynski, F.Y. Li, Z.M. Sheng, S.M. Wiggins, S. Yoffe
USTRAT/SUPA, Glasgow, United Kingdom
K.O. Kruchinin, A.Y. Molodozhentsev
ELI-BEAMS, Prague, Czech Republic
L. Labate
CNR/IPP, Pisa, Italy
X. Li
DESY Zeuthen, Zeuthen, Germany
F. Mathieu
LULI, Palaiseau, France
Z. Mazzotta
Ecole Polytechnique, Palaiseau, France
T.J. Mehrling
LBNL, Berkeley, USA
A. Mosnier, C. Simon
CEA, Gif-sur-Yvette, France
A. Mostacci
Rome University La Sapienza, Roma, Italy
Z. Najmudin
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
R. Pattathil, D. Symes
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
A.R. Rossi
INFN-Milano, Milano, Italy
T. Silva, J.M. Vieira
IPFN, Lisbon, Portugal
M.J.V. Streeter
JAI, London, United Kingdom
D. Terzani
UniNa, Napoli, Italy

Funding: European Union’s Horizon 2020 research and innovation programme under grant agreement No. 653782
The EuPRAXIA project aims at designing the world’s first accelerator based on plasma-wakefield advanced technique, which can deliver a 5 GeV electron beam with simultaneously high charge, low emittance and low energy spread to user’s communities. Such challenging objectives can only have a chance to be achieved when particular efforts are dedicated to identify the subsequent issues and to find the way to solve them. Many injection/acceleration schemes and techniques have been explored by means of thorough simulations in more than ten European institutes to sort out the most appropriate ones. The specific issues of high charge, high beam quality and beam extraction then transfer to the user’s applications, have been tackled with many innovative approaches*. This article highlights the different advanced methods that have been employed by the EuPRAXIA collaboration and the preliminary results obtained. The needs in terms of laser and plasma parameters for such an accelerator are also summarized.
*- in 2017: Phys. Plasmas, 24,10,103120; Nat. Commun.8,15705; - in 2018: NIMA, 909,84-89; NIMA, 909,49-53; Phys. Rev.Acc. Beams, 21,111301; NIMA, 909,54-57; Phys. Rev.Acc. Beams, 21,052802; NIMA, 909,282-285

Slides WEZZPLS2 [5.157 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEZZPLS2

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paper received ※ 12 April 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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WEPMP053

Operational Results of Simultaneous Four-Beam Delivery at Jefferson Lab

operation, experiment, cavity, gun

2454

R. Kazimi, A. Freyberger, J.M. Grames, J. Hansknecht, A.S. Hofler, T.E. Plawski, M. Poelker, M.F. Spata, Y.W. Wang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A concept for simultaneous beam delivery to all four CEBAF experimental halls from a single injector and a single main accelerator for the 12 GeV era was proposed in 2012. The original 12 GeV beam delivery plan was for a maximum of three experimental halls at a time as in the 6 GeV era. Therefore, the new concept increases the po-tential beam time for the experiments up to 33%. This change, although a major improvement in operational capabilities, required only limited modifications to the existing machine. The modifications were mainly timing and pattern changes to the beams in the injector, adding a fourth laser to the photo-cathode gun, and the addition of new RF separators to the highest pass of CEBAF. These changes are now complete and, for the first time, the full system is operating, producing four simultaneous beams through the accelerator to four different destinations. In this paper, in addition to presenting the results of the full system commissioning, we will discuss important details about the new configuration plus some of our operational challenges.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP053

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

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WEPGW010

Diagnostics and First Beam Measurements at FLUTE

electron, 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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WEPGW042

Development of the Longitudinal Beam Monitor with High Time Resolution for a Muon LINAC in the J-PARC E34 Experiment

experiment, linac, acceleration, DTL

2571

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

Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP15H05742, JP16H03987, JP16J07784, JP18H03707 and JP18H05226.
The J-PARC E34 experiment aims to measure the muon anomalous magnetic moment and the electric dipole moment with a high precision. In this experiment, ultra-slow muons generated from thermal muonium production and laser resonance ionization are accelerated in a multistage muon linac. In order to satisfy the experimental requirements, a suppression of the emittance growth between different accelerating cavities is necessary, and the transverse and longitudinal beam matching is important. Longitudinal beam monitor has to measure the bunch width with a precision of 1% corresponding to several tens of picoseconds. In addition, the beam monitor should be sensitive to a single muon, because the beam intensity during the commissioning is lower than the designed intensity. Therefore, we are developing a longitudinal beam monitor using a microchannel plate (MCP), and a measurement system using photoelectrons to estimate the performance of the beam monitor. On November 2018, the beam monitor has been successfully used in the muon RF acceleration test at the J-PARC. In this presentation, the results of the performance evaluation for this beam monitor are reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW042

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paper received ※ 30 April 2019 paper accepted ※ 21 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, electron

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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WEPGW052

A Rotation Method to Calibrate BPM Electric Offsets

site, radiation, instrumentation, proton

2595

M.W. Wang, X. Guan, P.F. Ma, X.W. Wang, S.X. Zheng
TUB, Beijing, People’s Republic of China
M.T. Qiu, D. Wang, Z.M. Wang
NINT, Shannxi, People’s Republic of China

Beam position monitor is a key instrument for machine commissioning. To measure beam position accurately, offline calibrations to acquire the sensitivity and offsets of the BPM are essential prerequisites. A new method to calibrate the BPM electric offset is proposed in this paper. By measuring the location variation of the BPM electric center after rotatingtheBPM180degrees, theBPMoffsetcanbederived. The method is more convenient, universal and accurate than the traditional methods. The method is successfully applied to calibrate the button BPM of Xi’an Proton Application Facility. The repetitive measurement error is 20.8 um.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW052

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

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WEPGW055

Beam Longitudinal Distribution Reconstructed by GESPAR Method at CAEP THz FEL

radiation, electron, FEL, 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, electron, 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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WEPGW073

Control System for Lasers at Hilase

controls, EPICS, software, PLC

2641

J. Horáček, T. Mocek, M. Rehakova
HiLASE Centre, Institute of Physics ASCR, v.v.i., Dolní Bře’any, Czech Republic
R. Modic, J. Podlipnik, M. Pogacnik
Cosy lab, Ljubljana, Slovenia

We present the current state of the HiLASE Centre control system developed in cooperation with Cosylab. The aim of the development is to build a control system which would be in charge of the operation of kW-class in-house-developed laser beamlines. These beamlines deliver picosecond pulses with repetition rates between 1 kHz and 1 MHz and high-energy nanosecond pulses at 10 Hz. A generic control system architecture is presented, which can either support full-size development lasers or compact industrial versions. The EPICS control system work focuses on image acquisition and processing, vacuum control, provision of timing, archiving and user interfaces. HiLASE provides high-level requirements, Cosylab complements them, provides the design of the solution and implementation. Delivery is performed during on-site visits where a test plan is executed for acceptance. This approach relieves HiLASE of the need to hire and manage their own team while retaining full control over the functionality through requirements and acceptance approval. Cosylab complements HiLASE with self-managed teams that deliver to specification.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW073

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

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WEPGW078

Development and Test of a Beam Imaging System Based on Radiation Tolerant Optical Fiber Bundles

radiation, experiment, target, site

2658

D. Celeste, E. Bravin, S. Burger, F. Roncarolo
CERN, Geneva, Switzerland

Many of the beam image systems at CERN are located in high radiation environments. In order to cope with this issue, VIDICON cameras are presently used but their production has been nowadays discontinued worldwide. The development of an alternative beam imaging system is described here, based on radiation tolerant optical fibre bundles. Such an optical line relays the image of a scintillating screen to a standard CMOS camera, located away from the high radiation zone. A prototype system based on a 10m long bundle with 10⁴ fibres has been tested in the TT2 transfer line at CERN. The light transmission is rather low, but is compensated by the sensitivity of the CMOS camera. The system had a field of view of 60 mm and a spatial resolution of ~1 mm. The radiation hardness of such a fiber bundle was tested at the IRMA-CEA facility in Saclay, France. The bundle was irradiated at a rate of 3.6 kGy/h for 8 consecutive day. The total integrated dose achieved was ~700 kGy, which corresponds to about ten years of operation at the beam imaging station with the highest radiation dose at CERN. While the light transmission was reduced by 50%, this is still adequate to provide acceptable images.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW078

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

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WEPGW114

Interferometric Measurement of Bunch Length of a 3Mev Picocoulomb Electron Beam

electron, 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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WEPRB054

Design of the Multiplexing Optical Measurement System for a Pre-bunched THz Free Electron Laser

radiation, detector, FEL, electron

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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WEPTS007

Short Bunch Experiment at EXALT Facility

cathode, experiment, electron, 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, electron, 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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WEPTS019

Accumulating Laser-Coolable Ions in a Linear Paul Trap for Ultrahigh-Density Beam Dynamics Experiment

experiment, plasma, accumulation, quadrupole

3134

K. Ito, H. Higaki, T. Masuda, H. Okamoto
HU/AdSM, Higashi-Hiroshima, Japan

An ion plasma confined in a linear Paul trap (LPT) exhibits the dynamic behavior physically equivalent to that of a charged-particle beam in an alternating-gradient transport channel. The Simulator of Particle Orbit Dynamics (S-POD) is a compact apparatus designed on the basis of this fact for diverse beam-physics experiments. We have so far employed Ar+ ions that can readily be produced from neutral Ar gas atoms through the electron bombardment process. A space-charge-induced tune shift of up to about 20% of the bare tune can be achieved in Ar+ plasmas [*]. We are now preparing for future S-POD experiment to explore even higher beam-density regions. For this purpose, a large number of Ca+ ions need to be stored in the LPT. Since S-POD is equipped with a powerful laser cooler for Ca+, the use of this ion species vastly expands the density range we can survey. The production of an intense bunch of Ca+ ions is, however, not so easy because of some technical reasons. By optimizing the operating condition of a multi-sectioned LPT, we succeeded in increasing the number of accumulated Ca+ ions to the level comparable to Ar+ ion plasmas. This paper reports on updated results of the experiment.
* K. Ito et al., Phys. Rev. Accel. Beams Vol. 20, 064201 (2017).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS019

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

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WEPTS061

Experimental Test of Longitudinal Space-Charge Amplifier in Optical Range

electron, undulator, 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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WEPTS089

Microbunching Instability Mitigation via Multi-Stage Cancellation

bunching, electron, linac, 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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS089

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paper received ※ 07 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS093

Emittance Preservation for LCLS-II-HE Project

emittance, electron, lattice, 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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THYYPLS3

A Remote-Controlled Robot-Car in the TPS Tunnel

photon, controls, radiation, operation

3435

T.Y. Lee, B.Y. Chen, T.W. Hsu, B.Y. Huang, C.H. Kuo, W.Y. Lin
NSRRC, Hsinchu, Taiwan

A remote-controlled robot-car named ’PhotonBot’ was put into the TPS accelerator tunnel and is equipped with a 360 degrees LiDAR for SLAM and navigation, two cameras for perception and first-person view, and a thermal imaging system. The robot can be remotely controlled and can send data to a remote PC through Wi-Fi. With SLAM, it can go more freely without being restricted to a designated path. In order to ensure it can work continuously, there is a wireless charging station in case of a low battery.

Slides THYYPLS3 [18.013 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THYYPLS3

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paper received ※ 09 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPMP009

LATINO: A Laboratory in Advanced Technologies for Innovation

vacuum, controls, radio-frequency, operation

3466

L. Sabbatini, D. Alesini, A. Falone, A. Gallo
INFN/LNF, Frascati (Roma), Italy
V. Pettinacci
INFN-Roma, Roma, Italy

Funding: The LATINO project is co-funded by the Regione Lazio within POR-FESR 2014-2020 European activities (public call ’Open Research Infrastructures’).
LATINO (a Laboratory in Advanced Technologies for INnOvation) is an open Research Infrastructure that will be hosted at the Frascati National Laboratories (LNF) of the Italian National Institute for Nuclear Physics (INFN). LATINO will allow the scientific community and the SMEs to get access to the technologies and competences developed for particle accelerators. The Infrastructure will be organized in four Laboratories: Radio Frequency, Vacuum and Thermal Treatments, Magnetic Measurements, Mechanical Integration. The list of the available instruments will include, besides others, a high power X-Band station to test cavities up to 50 Hz repetition rate and 200 MW input power, a network analyser to characterize microwave devices up to 100 GHz, a ultra high vacuum oven for thermal treatments and brazing, an outgassing measurement system to characterize vacuum materials, a stretched wire bench and a rotating coil for the magnetic field measurements of multipoles, environment and laser scanners. The regional and national industrial background comprises a remarkable number of highly qualified small and medium enterprises that could take advantage of the technologies offered by LATINO infrastructure to develop novel products within the Key Enabling Technologies and to get the access to new market segments. The Infrastructure will be fully operational at the beginning of 2020. For further information please visit www.latino.lnf.infn.it.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP009

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

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THPMP044

Radiation Hard Sensor for Reactor Applications

GUI, radiation, timing, detector

3545

R.J. Abrams, M.A. Cummings, R.P. Johnson, T.J. Roberts
Muons, Inc, Illinois, USA
D.M. Kaplan
Illinois Institute of Technology, Chicago, Illinois, USA

A novel method of measuring temperature of the coolant inside a reactor core is presented. The method, which is both standoff and non-invasive, is based on the interaction between an ultrasonic pulse and a delayed light pulse in the coolant. In the interaction, the light pulse, which is scattered backward by Brillouin scattering, is frequency-shifted. The frequency shift is dependent on the temperature and other parameters of the coolant. The light pulses and the ultrasound pulses are generated and detected outside of the core.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP044

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paper received ※ 14 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

photon, electron, 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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THPGW001

Design of LhARA - Laser Hybrid Accelerator for Radiobiological Applications

proton, focusing, target, experiment

3578

J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
O. Ettlinger, C. Hunt, A. Kurup, K.R. Long, Z. Najmudin, J.K. Pozimski
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
H.T. Lau
EBG MedAustron, Wr. Neustadt, Austria

Recent developments of using lasers interacting with targets for the creation of ion beams offer a possibility to provide beams for radiobiology research. This research aims to precisely study the radiobiological effectiveness of charged particles on various cultures of cells, which is essential to inform next generation hadron therapy treat-ment plans. The Laser hybrid Accelerator for Radiobio-logical Applications (LhARA) has been proposed to use a laser driven beam, which will be captured and focused using Gabor Lenses. The beam will be then energy and momentum selected to create a beam for in-vitro cells studies or sent to a post-accelerator ring to create beam for in-vivo studies. The optical design of LhARA is pre-sented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW001

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paper received ※ 15 May 2019 paper accepted ※ 23 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, electron

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, electron, simulation

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

electron, MMI, 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, electron

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

acceleration, photon, simulation, electron

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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THPGW016

Overview and Prospects of Plasma Wakefield Acceleration Experiments at PITZ

plasma, electron, wakefield, 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, electron

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, electron

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, electron, 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, electron, 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, electron, 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, electron, 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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THPGW035

Development of Yb-Based Laser System for Crab Crossing Laser-Compton Scattering

electron, 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*

radiation, experiment, electronics, electron

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

electron, 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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THPGW042

Applications of Compact Laser Plasma Accelerator (CLAPA) Beamline in Peking University

proton, radiation, acceleration, plasma

3676

D.Y. Li, J.E. Chen, Y.X. Geng, X.Y. Hu, C.C. Li, Q. Liao, C. Lin, H.Y. Lu, W.J. Ma, M.J. Wu, X.H. Xu, X.Q. Yan, T. Yang, Y.Y. Zhao, J.G. Zhu, K. Zhu
PKU, Beijing, People’s Republic of China

Proton beam with energies less than 10 MeV, <1% energy spread, several to tens of pC charge can be stably produced and transported in Compact LAser Plasma Accelerator (CLAPA) at Peking University. The CLAPA beam line is an object-image point analysing system, which ensures the transmission efficiency and energy selection accuracy for proton beams with initial large divergence angle and energy spread. A spread-out Bragg peak (SOBP) is produced with high precision beam control, which is essential for cancer therapy. Other primary application experiments based on laser-accelerated proton beam have also been carried out, such as proton radiograph, stress testing for tungsten, irradiation of semi-conductor sensor to simulate the space irradiation environment and so on.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW042

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paper received ※ 15 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

electron, gun, cathode, emittance

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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THPGW044

Highly Stable Linearly Polarized Arbitrary Temporal Shaping of Picosecond Laser Pulses

controls, polarization, experiment, flattop

3682

F. Liu, S. Huang, K.X. Liu
PKU, Beijing, People’s Republic of China
S. Zhang
JLab, Newport News, Virginia, USA

This paper reports the study and demonstration of a new variable temporal shaping method capable of generating linearly polarized picosecond laser pulses with arbitrary predefined shapes, which are highly desired by various applications including low emittance high brightness electron bunch generation in photocathode guns. It is found that both high transmittance and high stability of the shaped pulses can be achieved simultaneously when crystals are set at specific phase delay through the fine control of the crystal temperature. Such variable temporal shaping technique may lead to new opportunities for many potential applications over a wide range of laser wavelengths, pulse repetition rates, time structures and power levels, etc. In addition, a new double-pass variable shaping method is also proposed and could significantly simplify the shaper structure and reduce the cost.
*liu_fangming@pku.edu.cn

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW044

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

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THPGW045

A Simple Way to Introduce an Ajustable Femtosecond Pre-Pulse to Enhance Laser-Driven Proton Acceleration

target, proton, plasma, acceleration

3686

P.J. Wang, Z.X. Cao, Y.X. Geng, D.F. Kong, C. Lin, JB. Liu, H.Y. Lu, W.J. Ma, Z.S. Mei, Z.P. Pan, Y.R. Shou, D.H. Wang, S.R. Xu, X.Q. Yan, Y.Y. Zhao
PKU, Beijing, People’s Republic of China
G.Y. Gao
LMU, Garching, Germany

We demonstrate a simple way to introduce a femtosecond pre-pulse with adjustable intensity and delay without using an additional compressor to enhance laser-driven proton acceleration. Targets with different thicknesses were shoot at normal incidence by varying the pre-pulses. Experimental results show that significant enhancement on the proton energy can be achieved when the intensity of pre-pulse is optimized. Density profile of preplasma was obtained by bydrodynamic simulations. PIC simulations reveal that the preplasma generated by a femtosecond pre-pulse can increase the intensity of main pulse.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW045

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paper received ※ 30 April 2019 paper accepted ※ 19 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, electron, 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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THPGW054

Generation and Delivery of an Ultraviolet Laser Beam for the RF-Photoinjector of the Awake Electron Beam

electron, 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, electron, 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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THPGW070

Design of the Cockcroft Beamline: Adjustable Transport of Laser Wakefield Electrons to an Undulator

undulator, electron, 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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW070

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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, electron

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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THPGW080

Initial Results of High-Gradient Breakdown Tests for W-Band Accelerating Structures

cavity, experiment, electron, 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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW080

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

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THPRB018

Large-Scale Optical Synchronization System of the European XFEL with Femtosecond Precision

FEL, electron, 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

plasma, electron, 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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THPRB023

An MTCA.4 Based Position Feedback Application Using Laserinterferometers

experiment, controls, feedback, interface

3853

K.P. Przygoda, L. Butkowski, S. Pfeiffer, H. Schlarb, P. Wiljes
DESY, Hamburg, Germany

To perform experiments on the nanometer scale at high brilliant x-ray light sources, it is highly recommended to have the mechanical components of the experiment, like lenses, mirrors and samples, as stable as possible. Since these components need to move from nanometer up to millimeter range they cannot be stabilized by only using rigid structures. For that reason an active stabilization system with fast and precise sensors needs to be developed. Here a Laserinterferometer is used, which provides picometer resolution at several MHz sample rate. In this paper we will present a laboratory setup which consists of a 6-slot Micro Telecommunication Computing Architecture generation 4 (MTCA.4) crate with standard components such MicroTCA carrier hub (MCH), central processing unit (CPU), power supply (PS) and cooling unit (CU). The Interferometer application has been setup with Deutsches Elektronen-Synchrotron (DESY) advanced mezzanine card (DAMC-FMC20) data processing unit, DESY Field Programmable Gate Array (FPGA) mezzanine card (DFMC-UNIO) universal input and output extension and DESY rear transition module (DRTM-PZT4) piezo driver. The encoder signals given by the interferometer controller are processed within the FPGA and then forwarded to the piezo amplifier RTM-board. The signal processing application includes decoding the digital feedback signal, calculating the coordinate transform for specific experimental setups and closed-loop operation based on a proportional integral derivative (PID) controller. The first results of the laboratory setup are demonstrated and briefly discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB023

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

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THPRB034

Timing Synchronization System for Beam Injection from the SACLA Linac to the SPring-8 Storage Ring

timing, linac, injection, storage-ring

3882

T. Ohshima, N. Hosoda, S. Matsubara
JASRI, Hyogo, Japan
N. Hosoda, H. Maesaka, T. Ohshima
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

We developed a timing synchronization system for beam injections from the linac of the X-ray free-electron laser (XFEL), SACLA, to the current SPring-8 storage ring. This injection scheme is beneficial for the next upgraded ring, SPring-8-II, where low emittance injection beams is required. The developed timing system aims at synchronizing the timing between the RF frequencies of the two accelerators which do not have a common subharmonic frequency. An important point is to keep the high performance of the current timing system which provides stable XFEL operation at SACLA. For this purpose, we designed and constructed a MicroTCA.4 system comprised of a high-speed ADC and an RF front-end for the synchronization. The RF signal of SACLA is digitized by the ADC whose clock is synchronized to SPring-8. A digital down-converter in the FPGA on the ADC module gives the phase difference instantaneously and a feedback logic applies a frequency modulation (FM) to the master oscillator of SACLA so as to synchronize SACLA with SPring-8. A bench test result showed that the timing jitter between the two frequency at injection timing was 1.2 ps rms, which was sufficient for the required value of 3 ps rms for the beam injection to the ring. In this presentation, we report an overview of the synchronization system, details of the developed electronics and the system performance obtained by a beam injection experiment from SACLA to SPring-8.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB034

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

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THPRB095

A Simulation Framework for Photon-Particle Interactions for Laserwires and Further Applications

photon, electron, 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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THPRB107

A Novel Design of a Laser Phase Monitor for AWA RF Photocathode Electron Gun

LLRF, electron, 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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THPTS002

Sirius Pre-alignment Results

alignment, booster, storage-ring, network

4106

R. Junqueira Leão, H. Geraissate Paranhos de Oliveira, F. Rodrigues, G.R. Rovigatti de Oliveira, U.R. Sposito
LNLS, Campinas, Brazil

Sirius is a 4th generation synchrotron light source under final installation and beginning of commissioning phase in Brazil, with a bare emittance of 250 picometer rad. In order to fulfil stability requirements (magnets displacement caused by vibration of 6 nm) imposed to achieve expected performance, the mechanical assembly of supporting structures and magnets were designed without adjustment mechanisms. Yet, the misalignment errors of the magnets are the dominating source of dynamical aperture reduction, leading to a maximum permissible deviation of 40 micrometers between adjacent magnets. To this end, dimensional engineering was applied to conceive an alignment concept for magnets on a same girder based solely on the geometric characteristics of the parts. For the large volume positioning of girders in the storage ring tunnel, the applied methodology followed a strategy optimized to reduce measurement uncertainty, as described in the literature. This paper will present the complete measurement process that led to the alignment of Sirius, from the deployment and survey of reference networks to the final alignment of the machine. To express a consistent and unequivocal alignment result and assess the alignment quality considering the measurement uncertainty, an innovative metric described previously was employed. This work will show that the positioning of supports satisfies the requirement of 80 micrometer between girders. Also, the devices and mechanisms used for assembling will be detailed. Inspection of full girder set performed on a Coordinate measuring machine shows a maximum deviation of 30 micrometers for any pair of magnets on a common support.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS002

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

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THPTS043

PRELIMINARY MAGNETIC FIELD CALCULATION OF A 30-DEGREE DIPOLE MAGNET

dipole, simulation, proton, operation

4204

H. Liang, J. Huang, C. Jiang, T. Liu, B. Qin, K. Tang, J. Yang, J.Q. Ye
HUST, Wuhan, People’s Republic of China
Y. Xie, T. Yu
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China

Preliminary design and field calculation of a 30-degree H-type dipole which can be applied to the beamline is introduced in this paper. According to the phys-ical requirements, 2D and 3D models are built and ana-lysed using OPERA. For achieving the magnetic field specifications, air slots are adopted, and trapezoidal shim on pole surface is used to improve the magnetic field error. Rogowski curve and harmonic shim at the pole end is used to reduce the integral magnetic field error and the higher order harmonic field error.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS043

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

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THPTS086

Design of a CCD-based Laser Alignment Detection System

alignment, detector, controls, vacuum

4311

J.X. Chen
IHEP CSNS, Guangdong Province, People’s Republic of China
X.Y. He, W. Wang, H.T. Zhang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Work supported by National Natural Science Foundation of China (11705199)
Accelerator online alignment technology is an important means for accelerator stability detecting. A CCD-based laser alignment detection system is designed for the linear accelerator, and the detection distance of the system could reach 100m. The reference comparison method is used to detect the laser imaging position acquired by the reference detector at different times, and to obtain the relative positional deviation of the measurement reference or the tested objects. Through the measurement error analysis, the precision of the system is expected to reach ±10μm.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS086

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

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FRYPLM2

Lasers for Novel Accelerators

plasma, electron, 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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