IPAC2021 - List of Keywords (acceleration)

Paper	Title	Other Keywords	Page
MOPAB049	Gyroresonant Acceleration of Electrons by an Axisymmetric Transverse Electric Field	electron, resonance, cyclotron, plasma	213
	E.A. Orozco, O. Otero Olarte UIS, Bucaramanga, Colombia
	The acceleration of electrons using gyromagnetic autoresonance consist on the sustaint of the electron cyclotron resonant condition through of a magnetic field which increase on time, this scheme was propose by K. S. Golovanivsky. In this work, we considerer the gyroresonant acceleration of electrons using an axisymmetric transverse electric field and its limitations. The 2D acceleration of electrons by a TE011 cylindrical mode is studied numerically. The trajectory, energy and phase-shift between the electron transverse velocity and the electric field are determined by the numerical solution of the relativistic Newton-Lorentz equation using a finite difference scheme. The growth rate of the magnetic field obtained is such that it maintains the phase difference within the acceleration band. The study includes the evolution of the energy for electrons initially ubicated in diferents initial points. For an electron that starts from rest and located at the radial midpoint of the transverse central plane of the cavity, it is reaches an energy close to 560 keV in 625 cycles of the microwave field using an electric field amplitude of 1 kV/cm and a frequency of 2.45 GHz.
	Poster MOPAB049 [3.541 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB049
About •	paper received ※ 17 May 2021 paper accepted ※ 14 June 2021 issue date ※ 23 August 2021
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MOPAB050	Spatial Autoresonant Acceleration of Electrons by an Axysimmetric Transverse Electric Field	electron, resonance, cyclotron, cavity	217
	E.A. Orozco, O. Otero Olarte UIS, Bucaramanga, Colombia
	In this research, The autoresonance acceleration of electrons by an axisymmetric transverse electric field in presence of a stationary inhomogeneous magnetic field is studied. The dynamics of electrons is determined by the numerical solution of the relativistic Newton-Lorentz equation using a finite difference scheme. The inhomogeneous external magnetic field is generated with a three-coil system and calculated using the Biot-Savart law. The electrons move along a TE011 cylinder cavity in a stationary magnetic field whose axis coincides with the cavity axis. The magnetic field profile obtained is such that it keeps the phase difference between the electric field vector of the microwave mode and the velocity vector of the particle within the acceleration band. For an electron injected longitudinally with an energy of 1 keV and that starts at the radial midpoint of the cavity, it is accelerated up to an energy of about 185 keV using an electric field amplitude of 14 kV/cm and a frequency of 2.45 GHz at a distance of 14 cm.
	Poster MOPAB050 [3.298 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB050
About •	paper received ※ 17 May 2021 paper accepted ※ 15 June 2021 issue date ※ 30 August 2021
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MOPAB143	Simulations for MeV Energy Gain in Multi-Micron Vacuum Channel Dielectric Structures Driven by a CO₂ Laser	laser, electron, simulation, vacuum	499
	G. Yadav, O. Apsimon, Y. Wei, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom O. Apsimon, C.P. Welsch, G.X. Xia Cockcroft Institute, Warrington, Cheshire, United Kingdom G.X. Xia The University of Manchester, Manchester, United Kingdom
	Funding: This work was supported by STFC LIV. DAT under grant agreement ST/P006752/1. This research used the resources of the Supercomputing Laboratory at KAUST in Thuwal, Saudi Arabia. Dielectric Laser Accelerators (DLAs) have been demonstrated as a novel scheme for producing high acceleration gradients (~1 GV/m) within the damage threshold of the dielectric. The compactness of the DLAs and the low emittance of the output electron beam make it an attractive candidate for future endoscopic devices to be used in tumor irradiation. However, due to the small accelerating distances(sub-mm), the total energy gain is limited to sub-MeV which remains an obstacle for its realistic applications. Also, these DLAs operate under solid-state lasers with wavelengths near IR (800 nm to 2 um), where required sub-micron vacuum channel at such wavelengths imposes major aperture restrictions for the amount of charge to be accelerated. Here, we present numerical simulation results for a dielectric structure excited by a CO₂ laser with a wavelength of 10.6 um. Upon injecting a 50 MeV electron bunch through a 5.3 um diameter of vacuum channel width, our simulation suggests an energy gain beyond 1 MeV. These results are the initial steps for the realization of an mm-scale DLA capable of producing MeV energy electron beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB143
About •	paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 11 August 2021
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MOPAB144	Investigation of Optimization of Dielectric Terahertz Acceleration Structures	simulation, laser, radiation, impedance	502
	A.E. Gabriel, E.A. Nanni SLAC, Menlo Park, California, USA
	Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515 (SLAC) and by NSF Grant No. PHY-1734015. THz-frequency accelerating structures could provide the accelerating gradients needed for next generation particle accelerators with compact, GV/m-scale devices. Current THz accelerators are limited by significant losses during transport of THz radiation from the generating nonlinear crystal to the electron acceleration structure. In addition, the spectral properties of high-field THz sources make it difficult to couple THz radiation into accelerating structures. Dielectric accelerator structures reduce these losses because THz radiation can be coupled laterally into the structure, as opposed to metallic structures where THz radiation must be coupled along the beam path. In order to utilize these advantages, we are investigating the optimization of THz accelerating structures for comparison between metallic and dielectric devices. These results will help to inform future designs of improved dielectric THz acceleration structures.
	Poster MOPAB144 [6.524 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB144
About •	paper received ※ 20 May 2021 paper accepted ※ 27 May 2021 issue date ※ 22 August 2021
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MOPAB147	Efficient, High Power Terahertz Radiation Outcoupling From a Beam Driven Dielectric Wakefield Accelerator	radiation, wakefield, electron, GUI	513
	M. Yadav, G. Andonian, C.E. Hansel, W.J. Lynn, N. Majernik, B. Naranjo, J.B. Rosenzweig, O. Williams UCLA, Los Angeles, California, USA G. Andonian RadiaBeam, Santa Monica, California, USA C.P. Welsch The University of Liverpool, Liverpool, United Kingdom C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work was supported by DE-SC0009914 (UCLA) and the STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT) under grant agreement ST/P006752/1. Wakefields in dielectric structures are a useful tool for beam diagnostics and manipulation with applications including acceleration, shaping, chirping, and THz radiation generation. It is possible to use the produced THz radiation to diagnose the fields produced during the DWA interaction but, to do so, it is necessary to effectively out-couple this radiation to free space for transport to diagnostics such as a bolometer or interferometer. To this end, simulations have been conducted using CST Studio for a 10 GeV beam with FACET-II parameters in a slab-symmetric, dielectric waveguide. Various termination geometries were studied including flat cuts, metal horns, and the "Vlasov antenna". Simulations indicate that the Vlasov antenna geometry is optimal and detailed studies were conducted on a variety of dielectrics including quartz, diamond, and silicon. Multiple modes were excited and coherent Cherenkov radiation (CCR) was computationally generated for both symmetric and asymmetric beams. Finally, we include witness beams to study transport and acceleration dynamics as well as the achievable field gradients.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB147
About •	paper received ※ 24 May 2021 paper accepted ※ 29 August 2021 issue date ※ 28 August 2021
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MOPAB148	Liénard-Wiechert Numerical Radiation Modeling for Plasma Acceleration Experiments at FACET-II	radiation, plasma, betatron, experiment	517
	M. Yadav, G. Andonian, C.E. Hansel, N. Majernik, P. Manwani, B. Naranjo, J.B. Rosenzweig, O. Williams, Y. Zhuang UCLA, Los Angeles, California, USA G. Andonian RadiaBeam, Marina del Rey, California, USA O. Apsimon, A. Perera, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom O. Apsimon, A. Perera, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work was supported by DE-SC0009914 (UCLA) and the STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT) under grant agreement ST/P006752/1. Future plasma acceleration experiments at FACET-II will measure betatron radiation in order to provide single-shot non-destructive beam diagnostics. We discuss three models for betatron radiation: a new idealized particle tracking code with Liénard-Wiechert radiation, a Quasi-Static Particle-in-Cell (PIC) code with Liénard-Wiechert radiation, and a full PIC code with radiation computed via a Monte-Carlo QED Method. Predictions of the three models for the E-310 experiment are presented and compared. Finally, we discuss beam parameter reconstruction from the double differential radiation spectrum.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB148
About •	paper received ※ 24 May 2021 paper accepted ※ 01 June 2021 issue date ※ 17 August 2021
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MOPAB151	A Stable Drive Beam for High Gradient Dielectric Wakefield Acceleration	focusing, wakefield, accelerating-gradient, quadrupole	528
	T.J. Overton, Y.M. Saveliev, G.X. Xia Cockcroft Institute, Warrington, Cheshire, United Kingdom T.J. Overton, G.X. Xia The University of Manchester, Manchester, United Kingdom T.H. Pacey, Y.M. Saveliev STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Science and Technology Funding Council (STFC) student grant. A high accelerating gradient, with stable beam transport, is necessary for the next generation of particle accelerators. Dielectric wakefield accelerators are a potential solution to this problem. In these proceedings, we present simulation studies of electron bunches in the self-wake regime inside a planar dielectric structure. This is analogous to driving beams in a dielectric wakefield accelerator. The transverse and longitudinal wake fields are investigated for dielectric plate gaps, various transverse beam sizes, and longitudinal bunch profiles. The effects of these on the stability of drive bunches, and acceleration of a witness bunch, are discussed in the context of electron bunches that can be produced with conventional linac RF technology.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB151
About •	paper received ※ 13 May 2021 paper accepted ※ 07 June 2021 issue date ※ 24 August 2021
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MOPAB154	Multi-Cell Accelerating Structure Driven by a Lens-Focused Picosecond THz Pulse	laser, focusing, electron, timing	537
	S.P. Antipov, S.V. Kuzikov Euclid TechLabs, Solon, Ohio, USA A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia
	Recently, gradients on the order of 1 GV/m level have been obtained in a form of a single cycle (~1 ps) THz pulses produced by conversion of a high peak power laser radiation in nonlinear crystals (~1 mJ, 1 ps, up to 3% conversion efficiency). Such high-intensity radiation can be utilized for charged particle acceleration. However, these pulses are short in time (~1ps) and broadband, therefore a new accelerating structure type is required. In this paper, we propose a novel structure based on focusing of THz radiation in accelerating cell and stacking such cells to achieve a long-range interaction required for an efficient acceleration process. We present an example in which a 100 microJoule THz pulse produces a 600 keV energy gain in 5 mm long 10 cell accelerating structure for an ultra-relativistic electron. This design can be readily extended to non-relativistic particles. Such structure had been laser microfabricated and appropriate dimensions were achieved.
	Poster MOPAB154 [1.283 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB154
About •	paper received ※ 27 May 2021 paper accepted ※ 05 July 2021 issue date ※ 14 August 2021
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MOPAB166	Wakefield Excitation by a Sequence of Laser Pulses in Plasma	laser, wakefield, plasma, simulation	568
	D.S. Bondar KhNU, Kharkov, Ukraine V.I. Maslov, I.N. Onishchenko NSC/KIPT, Kharkov, Ukraine
	Funding: The study is supported by the National Research Fundation of Ukraine under the program "Leading and Young Scientists Research Support" (project # 2020.02/0299). PIC simulation by means of 2.5D UMKA code * of the wakefield excitation by a sequence of three Gaussian laser pulses in plasma was carried out. The dependence of excited wakefield intensity on power and width of laser pulses was investigated. It was shown the coherent addition of wakefield, excited by each laser pulse of the sequence, for linear case, while for the nonlinear case the coherency was destroyed. The profiled sequence of laser pulses was also considered. The possibility to obtain the same total wakefield excited by the profiled sequence of laser pulses with decreasing intensity, as for the uniform sequence was studied. * G. I. Dudnikova et al. Comp. Techn. 10 (2005) 37.
	Poster MOPAB166 [2.638 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB166
About •	paper received ※ 17 May 2021 paper accepted ※ 20 May 2021 issue date ※ 15 August 2021
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MOPAB167	Wakefield Excitation in Plasma of Metallic Density by a Laser Pulse	laser, plasma, wakefield, electron	571
	D.S. Bondar KhNU, Kharkov, Ukraine V.I. Maslov, I.N. Onishchenko NSC/KIPT, Kharkov, Ukraine
	Funding: The study is supported by the National Research Foundation of Ukraine under the program "Leading and Young Scientists Research Support" (project # 2020.02/0299). Recently the proposal to use X-ray Exawatt pulse for particle acceleration in a crystal has been declared . Short X-ray high-power pulse excites wakefield in electron plasma of metallic density which can be used for high gradient acceleration of charged particles. This wakefield is suited for laser wakefield acceleration. In this paper there are simulated with PIC code UMKA: excitation of the large wakefield amplitude up to several TV/m in electron plasma of metallic density by a powerful X-ray laser pulse; laser-plasma wakefield acceleration of self-injected electron bunch in such setup; combined acceleration by plasma wakefield driven by a laser pulse (LPWA) and by self-injected electron bunch (PWFA). T.Tajima. Eur. Phys. J. Special Topics 223 (2014) 1037.
	Poster MOPAB167 [2.054 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB167
About •	paper received ※ 17 May 2021 paper accepted ※ 21 May 2021 issue date ※ 22 August 2021
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MOPAB169	Generating 510 MW of X-Band Power for Structure-Based Wakefield Acceleration Using a Metamaterial-Based Power Extractor	experiment, wakefield, electron, simulation	578
	J.F. Picard, I. Mastovsky, M.A. Shapiro, R.J. Temkin MIT/PSFC, Cambridge, Massachusetts, USA M.E. Conde, D.S. Doran, J.G. Power, J.H. Shao, E.E. Wisniewski ANL, Lemont, Illinois, USA C.-J. Jing Euclid TechLabs, Solon, Ohio, USA X. Lu Northern Illinois University, DeKalb, Illinois, USA
	Funding: Research sponsored under Award No. DE-SC0015566 by U.S. Department of Energy, Office of Science, Office of High Energy Physics and Contract No. DE-AC02-06CH11357 by the Office of Science. We present our recent results generating 510 MW of power at 11.7 GHz using a metamaterial-based metallic power-extractor for application in structure-based wakefield acceleration (SWFA). SWFA is a novel acceleration scheme in which high-charge electron bunches are passed through a power extractor structure to produce a high-intensity wakefield. This wakefield can then be used to accelerate a witness bunch in the same beamline or passed to a separate acceleration beamline. MIT’s approach uses a specialized metamaterial for the power extractor design. By using a metamaterial, we can overcome some of the challenges faced by other SWFA techniques. Here, we discuss the Stage 3 experiment. The Stage 1 and Stage 2 experiments successfully demonstrated the functionality of the metamaterial approach by generating high power RF pulses using the 65 MeV electron beam at the Argonne Wakefield Accelerator (AWA) facility. The 510 MW result from Stage 3 experiment is the highest power generated to-date for SWFA at AWA, and was enable by significant design improvements, including an all-copper structure, fully-symmetric coupler design, and breakdown risk-reduction treatment.
	Poster MOPAB169 [8.882 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB169
About •	paper received ※ 08 May 2021 paper accepted ※ 16 July 2021 issue date ※ 25 August 2021
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MOPAB171	Numerical Simulation on Plasma-Based Beam Dumps Using Smilei	plasma, laser, electron, wakefield	582
	S. Kumar, C. Davut, G.X. Xia UMAN, Manchester, United Kingdom A. Bonatto, C. Davut, L. Liang The University of Manchester, Manchester, United Kingdom A. Bonatto Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil B.S. Nunes IF-UFRGS, Porto Alegre, Brazil R.P. Nunes UFRGS, Porto Alegre, Brazil
	The active plasma beam dump utilizes a laser to generate a plasma wakefield and decelerate an externally injected beam to low energy. We use the particle-in-cell code "Smi-lei" for the investigation of electron beam energy loss in plasma. In this research work, we optimize the laser and plasma parameters to investigate the active plasma beam dump scheme. In doing so, most of the beam energy will be deposited in the plasma. The optimization strategy for the beam energy loss in plasma is presented. A. Bonatto, C. B. Schroeder et al., Physics of Plasmas 22 (8) 083106 (2015). G. Xia, A. Bonatto et al., Instruments 4 (2) 10 (2020). *A Bonatto et al., J. Phys.: Conf. Ser. 1596 012058, 2020.
	Poster MOPAB171 [0.756 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB171
About •	paper received ※ 15 May 2021 paper accepted ※ 24 May 2021 issue date ※ 26 August 2021
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MOPAB236	Ion Beam Dynamics in Linac-100 Facility at Jinr	linac, cavity, emittance, rfq	767
	S.M. Polozov, V.S. Dyubkov, Y. Lozeev, T.A. Lozeeva, A.V. Samoshin MEPhI, Moscow, Russia
	The heavy-ion linac LINAC-100 is a superconducting driver-accelerator proposed as one of the prospective projects at JINR. Its goal is to accelerate primary stable isotope CW high-intensity beams to energies up to 100 MeV/u. This linac is discussed as the first stage of a new rare isotope facility DERICA (Dubna Electron-Radioactive Ion Collider fAcility), being under development at JINR since 2017. LINAC-100 is supposed to work with a wide range of beams with A/Z 3.5/7, Uranium U³⁴⁺ being the heaviest. Its concept has undergone many changes, mostly considering stripping cells to increase accelerator efficiency. During the latest investigations of various stripping cells [, *], Uranium beam stripping at the energy 10 MeV/u and utilizing three adjacent charge states 59-61+ resulted in 60% output beam intensity preservation (or 30 pA overall output current). The current layout of the LINAC-100 is the following: one or two (separately for light and heavy ions) normal conducting front-end linacs, gas stripper cell at 10 MeV/u, and the SC section. In this paper three charge state Uranium beam dynamics in the current version of SC LINAC-100 section is presented. S Polozov 2020 PhysScr 95 084006 A S Fomichev Phys Usp 62(7) 675-690 2019 Tolstikhina I 2018 Basic At Int of Acc H Ions in Matter 98 1 *** W Barth J Phys Conf Ser 1350:012096
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB236
About •	paper received ※ 20 May 2021 paper accepted ※ 17 August 2021 issue date ※ 26 August 2021
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MOPAB241	Design of the Proton and Electron Transfer Lines for AWAKE Run 2c	plasma, electron, proton, experiment	778
	R.L. Ramjiawan JAI, Oxford, United Kingdom S. Döbert, E. Gschwendtner, P. Muggli, F.M. Velotti, L. Verra CERN, Meyrin, Switzerland J.P. Farmer MPI-P, München, Germany P. Muggli MPI, Muenchen, Germany
	The AWAKE Run 1 experiment achieved electron acceleration to 2 GeV using plasma wakefield acceleration driven by 400 GeV, self-modulated proton bunches from the CERN SPS. The Run 2c phase of the experiment aims to build on these results by demonstrating acceleration to ~10 GeV while preserving the quality of the accelerated electron beam. To realize this, there will be an additional plasma cell, to separate the proton bunch self-modulation and the electron acceleration. A new 150 MeV beamline is required to transport and focus the witness electron beam to a beam size of several microns at the injection point. This specification is designed to preserve the beam emittance during acceleration, also requiring micron-level stability between the driver and witness beams. To facilitate these changes, the Run 1 proton transfer line will be reconfigured to shift the first plasma cell 40 m downstream. The Run 1 electron beamline will be adapted and used to inject electron bunches into the first plasma cell to seed the proton bunch self-modulation. Proposed adjustments to the proton transfer line and studies for the designs of the two electron transfer lines are detailed in this contribution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB241
About •	paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 17 August 2021
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MOPAB275	Study on Supports of BPM Displacement Measurement System for HLS	simulation, factory, storage-ring, feedback	870
	C.H. Wang, P. Lu, B.G. Sun, T.Y. Zhou USTC/NSRL, Hefei, Anhui, People’s Republic of China
	Funding: National Synchrotron Radiation Laboratory HLS is the second-generation light source with energy of 800 MeV and emittance of less than 40 nm-rad. In order to improve the beam orbit stability and correct the errors introduced in the orbital feedback system due to movement of the vacuum chamber and BPM, a system for measuring BPM displacement will be built. It requires a high degree of mechanical and thermal stability for its supports. The support should have a higher eigen-frequency to minimize the amplification of ground vibration. In this paper, a series of simulation, including finite element analysis (FEA), measurement and analysis have been done upon the support to make sure it can meet the requirements of the stability of the BPM displacement measurement system.
	Poster MOPAB275 [1.025 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB275
About •	paper received ※ 18 May 2021 paper accepted ※ 21 May 2021 issue date ※ 26 August 2021
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MOPAB319	Development of a Fast Betatron Tune and Chromaticity Measurement System for COSY	betatron, GUI, controls, resonance	983
	P.J. Niedermayer, C. Böhme, B. Breitkreutz, V. Kamerdzhiev, A. Lehrach FZJ, Jülich, Germany A. Lehrach RWTH, Aachen, Germany
	A fast tune measurement is developed for the Cooler Synchrotron COSY at the Institut für Kernphysik of Forschungszentrum Jülich. Betatron oscillations of the beam are excited with a band-limited RF signal via a stripline kicker. Resonant transverse oscillations are then observed using capacitive beam position monitors. Based on the bunch-by-bunch beam position data the betatron tune is determined. The usage of bunch-by-bunch data is characteristic of the new system. It allows for a discrete tune measurement within a few milliseconds, as well as continuous tune monitoring during beam acceleration. The high precision tune measurement also enables determination of the beam chromaticity. Therefore, the beam momentum is varied by means of the RF frequency and the subsequent tune change is determined. For routine use during beam operation and experiments, the developed method is integrated into the control system.
	Poster MOPAB319 [1.209 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB319
About •	paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 12 August 2021
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MOPAB325	Development of Bunch Width Monitor with High Time Resolution for Low Emittance Muon Beam in the J-PARC Muon g-2 / EDM Experiment	emittance, experiment, linac, laser	1004
	M. Yotsuzuka, T. Iijima, K. Inami, Y. Sue, K. Sumi Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan T. Iijima KMI, Nagoya, AIchi Prefecture, Japan Y. Kondo JAEA, Ibaraki-ken, Japan T. Mibe KEK, Tsukuba, Japan Y. Nakazawa Ibaraki University, Ibaraki, Japan M. Otani, N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan Y. Takeuchi Kyushu University, Fukuoka, Japan H.Y. Yasuda University of Tokyo, Tokyo, Japan
	The J-PARC muon g-2/EDM experiment plans to measure the muon anomalous magnetic moment and electric dipole moment sensitive to new physics with high precision. This experiment uses a novel method using the low-emittance muon beam achieved by cooling and re-acceleration. In the muon linac consisting of four different accelerating cavities, the main cause of the emittance growth is the beam mismatch between the different cavities. Especially for the cavity in the low-beta section (ß=0.08-0.27), the longitudinal acceptance is narrow and beam mismatch has a significant impact. In order to perform beam matching in the low-beta cavity, a new beam monitor that can measure the low-emittance muon beam with high time resolution is required. Therefore, we developed a bunch width monitor (BWM) using a microchannel plate. The time resolution of the BWM was measured to be 40 picoseconds on the test bench using a picosecond pulse laser. It means that the BWM is possible to perform diagnosis with a phase accuracy of 1% for the acceleration phase of 324 MHz. We also evaluated factors that limit the current time resolution. In this presentation, the results of an evaluation of the BWM are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB325
About •	paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 10 August 2021
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MOPAB352	High Power Test of a Dielectric Disk Loaded Accelerator for a Two Beam Wakefield Accelerator	wakefield, impedance, linear-collider, multipactoring	1096
	B.T. Freemire, C.-J. Jing, S. Poddar Euclid Beamlabs, Bolingbrook, USA M.E. Conde, D.S. Doran, G. Ha, W. Liu, J.G. Power, J.H. Shao, C. Whiteford, E.E. Wisniewski ANL, Lemont, Illinois, USA M.M. Peng TUB, Beijing, People’s Republic of China E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA Y. Zhao Euclid TechLabs, Solon, Ohio, USA
	Funding: Small Business Innovation Research Contract No. DE-SC0019864 U.S. DOE Office of Science Contract No. DE-AC02-06CH11357 As part of the Argonne 500 MeV short pulse Two Beam Wakefield Acceleration Demonstrator, a single cell X-band dielectric disk loaded accelerator (DDA) has been designed, fabricated, and tested at high power at the Argonne Wakefield Accelerator. The DDA should provide a short pulse (~20 ns) high gradient (>300 MV/m) accelerator while maintaining a reasonable r/Q and high group velocity. This will allow a significantly larger RF-to-beam efficiency than is currently possible for conventional accelerating structures. A low loss barium titantate ceramic, µ_r = 50, was selected, and a low temperature brazing alloy chosen to preserve the dielectric properties of the ceramic during brazing. High power testing produced breakdown at the triple junction, resulting from the braze joint design. No evidence of breakdown was observed on the iris of the disk, indicating that the maximum surface electric field on the dielectric was not reached. An improved braze joint has been designed and is in production, with high power testing to follow.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB352
About •	paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 21 August 2021
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MOPAB372	KARVE: A Nanoparticle Accelerator for Space Thruster Applications	ECR, radio-frequency, bunching, simulation	1151
	J.W. Lewellen, L.R. Danielson, A. Essunfeld, J.A. Hollingsworth, M.A. Holloway LANL, Los Alamos, New Mexico, USA E.K. Lewis NASA Johnson Space Center, Houston, Texas, USA
	We present a concept for using RF-based acceleration of nanoparticles (NPs) as a means of generating thrust for future space missions: the Kinetic Acceleration & Resource Vector Engine (KARVE) thruster. Acceleration of nanoparticles (NPs) via DC accelerators has been shown to be feasible in dust accelerator labs such as the Heidelberg dust accelerator and the 3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies. In contrast, KARVE uses RF-driven acceleration of nanoparticles as the basis of a thruster design lying between chemical and ion engines in performance: more efficient than chemical engines in terms of specific impulse; and higher thrust than ion engines. The properties of multi-gap RF accelerators also allow an on-the-fly tradeoff between specific impulse and thrust.
	Poster MOPAB372 [0.694 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB372
About •	paper received ※ 19 May 2021 paper accepted ※ 27 May 2021 issue date ※ 10 August 2021
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TUXB01	A 3 MeV All Optical Terahertz-Driven Electron Source at Tsinghua University	electron, laser, gun, GUI	1294
	H. Xu, Y.-C. Du, W.-H. Huang, R.K. Li, C.-X. Tang, L.X. Yan TUB, Beijing, People’s Republic of China
	Funding: Science Challenge Project No.TZ2018005 Efficient acceleration and manipulation of high-brightness electron beams using terahertz waves in a compact setup has been recently a hot research topic in acceleration community. Previous works have achieved multi-MV/m acceleration gradient and dozens of keV energy gain while leaving room for further improvements in the high-energy regime. Here, we experimentally demonstrate whole-bunch acceleration and cascaded terahertz-driven acceleration of a relativistic beam with a record energy gain of 204 keV. A terahertz-driven all-optical electron source is now under development, which hold great potential for terahertz-driven ultrafast electron diffraction and related scientific discoveries. * Xu, H., Yan, L., Du, Y. et al. Cascaded high-gradient terahertz-driven acceleration of relativistic electron beams. Nat. Photonics (2021). https://doi.org/10.1038/s41566-021-00779-x
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXB01
About •	paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 10 August 2021
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TUPAB027	Review of Accelerator Limitations and Routes to Ultimate Beams	collider, electron, luminosity, photon	1397
	F. Zimmermann CERN, Geneva, Switzerland R.W. Aßmann DESY, Hamburg, Germany M. Bai, G. Franchetti GSI, Darmstadt, Germany
	Funding: This work was supported in part by the European Commission under the HORIZON 2020 project I.FAST, no. 101004730. Various physical and technology-dependent limits are encountered for key performance parameters of accelerators such as high-gradient acceleration, high-field bending, beam size, beam brightness, beam intensity and luminosity. This paper will review these limits and the associated challenges. Possible figures-of-merit and pathways to ultimate colliders will also be explored.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB027
About •	paper received ※ 16 May 2021 paper accepted ※ 02 August 2021 issue date ※ 23 August 2021
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TUPAB079	Using ER@CEBAF to Show that a Multipass ERL Can Drive an XFEL	FEL, operation, controls, electron	1555
	G. Perez-Segurana Cockcroft Institute, Lancaster University, Lancaster, United Kingdom I.R. Bailey, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom I.R. Bailey Lancaster University, Lancaster, United Kingdom R.M. Bodenstein, S.A. Bogacz, D. Douglas, Y. Roblin, T. Satogata JLab, Newport News, Virginia, USA T. Satogata ODU, Norfolk, Virginia, USA P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	A multi-pass recirculating superconducting CW linac offers a cost effective path to a multi-user facility with unprecedented scientific and industrial reach over a wide range of disciplines. We propose such a facility as an option for a potential UK-XFEL. Energy Recovery enables multi-MHz FEL sources, for example, an X-ray FEL oscillator or regenerative amplifier FEL. Additionally, combining with external lasers and/or self-interaction would provide access to MeV and GeV gamma-rays via inverse Compton scattering at high average power for nuclear and particle physics applications. An opportunity exists to demonstrate the necessary point-to-parallel longitudinal matches to drive an XFEL and successfully energy recover at the upcoming 5-pass up, 5-pass down Energy Recovery experiment on CEBAF at JLab termed ER@CEBAF. We show candidate matches and simulations supporting the minimal necessary modifications to CEBAF this will require. This includes linearisation of the longitudinal phase space in the injector and a reduction in the dispersion of the arcs, both of which increase the energy acceptance of CEBAF. We expect to commence initial tests of these adaptations on CEBAF during 2021.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB079
About •	paper received ※ 17 May 2021 paper accepted ※ 27 July 2021 issue date ※ 17 August 2021
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TUPAB095	Arbitrary Longitudinal Pulse Shaping with a Multi-Leaf Collimator and Emittance Exchange	wakefield, plasma, laser, emittance	1600
	N. Majernik, G. Andonian, J.B. Rosenzweig UCLA, Los Angeles, California, USA D.S. Doran, G. Ha, J.G. Power, E.E. Wisniewski ANL, Lemont, Illinois, USA R.J. Roussel Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
	Funding: DOE HEP Grant DE-SC0017648, and National Science Foundation Grant No. PHY-1549132 Drive and witness beams with variable current profiles and bunch spacing can be generated using an emittance exchange beamline (EEX) in conjunction with transverse masks. Recently, this approach was used to create advanced driver profiles and demonstrate record-breaking plasma wakefield transformer ratios [Roussel, R., et al., Phys. Rev. Lett. 124, 044802 (2020)], a crucial advancement for effective witness acceleration. Presently, these transverse masks are individually laser cut, making the refinement of beam profiles a slow process. Instead, we have proposed the used of a UHV compatible multileaf collimator (MLC) to replace these masks. An MLC permits real-time adjustment of the beam masking, permitting faster optimization in a manner highly synergistic with machine learning. Beam dynamics simulations have shown that practical MLCs offer resolution that is functionally equivalent to that offered by the laser cut masks. In this work, the engineering considerations and practical implementation of such a system at the AWA facility are discussed and the results of benchtop tests are presented. * Roussel, Ryan, et al. PRL 124.4 (2020): 044802
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB095
About •	paper received ※ 19 May 2021 paper accepted ※ 20 July 2021 issue date ※ 29 August 2021
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TUPAB116	Toward THz Coherent Undulator Radiation Experiment with a Combination of Velocity Bunchings	radiation, undulator, electron, bunching	1663
	Y. Sumitomo, K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, T. Tanaka LEBRA, Funabashi, Japan
	Funding: Japan Society for the Promotion of Science (JSPS), Grant-in-Aid for Scientific Research (KAKENHI), Grant Number JP19K12631. We have launched a research program to generate the THz coherent undulator radiations, following the proposal of the combination of velocity bunchings * at Nihon University. The combination of velocity bunchings is an efficient way of bunch compression allowing a range of energy choices, in other words, a range of quasi-monochromatic radiation wavelengths generated at the undulator. In addition to the existing wideband THz light sources (0.1 - 2 THz) by the coherent edge and transition radiations currently available at Nihon Univ., the development of a high peak-power and quasi-monochromatic coherent radiation should accelerate the activities including the material science related to the THz bandwidths. In this presentation, we illustrate the program and report the current status of the experiment. * Y. Sumitomo et al., J. Phys. Conf. Ser., vol. 1067, p. 032017, 2018.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB116
About •	paper received ※ 19 May 2021 paper accepted ※ 15 June 2021 issue date ※ 15 August 2021
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TUPAB145	Methods for Numerical Noise Mitigation in Quasistatic Three-Dimensional Particle-in-Cell Code LCODE3D	plasma, simulation, wakefield, electron	1725
	I.Yu. Kargapolov, K.V. Lotov, A. Sosedkin Budker INP & NSU, Novosibirsk, Russia I.A. Shalimova ICM&MG SB RAS, Novosibirsk, Russia I.A. Shalimova, P.V. Tuev NSU, Novosibirsk, Russia P.V. Tuev BINP SB RAS, Novosibirsk, Russia
	We discuss a new quasistatic 3D particle-in-cell code LCODE3D for simulating plasma wakefield acceleration, which is a modified version of the quasistatic 2D3V code LCODE, focus on the numerical noise of the plasma solver and propose methods for reducing it. We compare different particle shape functions, as these functions affect the code stability. We also introduce the so-called dual plasma approach, which improves stability and dampens small-scale noise. After applying the proposed methods, the results of the new code closely agree with LCODE simulation results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB145
About •	paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 25 August 2021
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TUPAB155	Obtaining Accelerated Electron Bunch of High Quality in Plasma Wakefield Accelerator	plasma, wakefield, electron, accelerating-gradient	1744
	R.T. Ovsiannikov KhNU, Kharkov, Ukraine I.P. Levchuk (Yarovaya), V.I. Maslov, I.N. Onishchenko NSC/KIPT, Kharkov, Ukraine
	Funding: "This work is supported by National Research Fundation of Ukraine "Leading and Young Scientists Research Support", grant agreement # 2020.02/0299." Earlier, high-gradient accelerating electrons of a relativistic beam was demonstrated. However, due to dynamic processes in the plasma, there are problems in maintaining the small size and small energy spread of the accelerated electron bunch while maintaining sufficient values of the accelerating wakefields. Also, the question arises about the values of the limiting bunch dimensions at which the accelerating process is stable. To form a stable accelerated electron bunch, a method is usually used that involves the formation of the same accelerating fields at the location of the bunch. The same fields (plateau due to beam loading (see , )) in the region of the accelerated bunch allow all its parts to move as a whole, and ensure the preservation of the spatial distribution of electrons over time, which, in fact, means an accelerated beam of good quality. In this report, the problem of electron bunch accelerating by a short or long electron driver-bunch is considered. Romeo S., Ferrario M., Rossi A.R. Phys. Rev. Accel. Beams. 23 (2020) 071301. ** Maslov V.I. et al. Problems of Atomic Science and Technology. 6 (2020) 47.
	Poster TUPAB155 [1.723 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB155
About •	paper received ※ 18 May 2021 paper accepted ※ 16 June 2021 issue date ※ 23 August 2021
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TUPAB156	Optimal Field Shape, Accelerating Positron Bunch in Plasma Wakefield	plasma, wakefield, electron, positron	1747
	R.T. Ovsiannikov KhNU, Kharkov, Ukraine I.P. Levchuk (Yarovaya), V.I. Maslov, I.N. Onishchenko NSC/KIPT, Kharkov, Ukraine
	Funding: This work is supported by National Research Fundation of Ukraine "Leading and Young Scientists Research Support", grant agreement # 2020.02/0299. The quality of the electron or positron beam, accelerated in plasma accelerators, is still insufficient for applications. Accurate control over the properties of the electron or positron beam is a key issue for wakefield plasma accelerators. The effect of the presence of a witness-beam (the effect of the spatial charge distribution of the witness beam) (see [, ]) to compensate the energy spread of the positron beam in plasma wakefield accelerators has been studied. This paper presents the results of a numerical simulation on the optimization of the parameters of the driver-bunch and witness-bunch for the formation of a self-consistent longitudinal distribution of the accelerating plateau-type field, which leads to the same values of the wakefield for the whole bunch of accelerated particles and minimizing bunch degradation during acceleration by means of an ion-driver-bunch with external injection into the plasma wake accelerator. The dependence of the longitudinal distribution of the accelerating wakefield on the density and shape of the accelerated bunch in the blowout regime was investigated. Plateau formation and energy spread compensation were observed. Romeo S., Ferrario M., Rossi A.R. Phys. Rev. Accel. Beams. 23 (2020) 071301. ** Katsouleas T. et al. Particle Accelerators. 22 (1987) 81.
	Poster TUPAB156 [1.200 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB156
About •	paper received ※ 18 May 2021 paper accepted ※ 16 June 2021 issue date ※ 25 August 2021
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TUPAB157	Obtaining Long Accelerated Electron Bunch of Good Quality in Plasma Wakefield Accelerator at High Transformer Ratio	wakefield, plasma, electron, simulation	1750
	R.T. Ovsiannikov KhNU, Kharkov, Ukraine I.P. Levchuk (Yarovaya), V.I. Maslov, I.N. Onishchenko NSC/KIPT, Kharkov, Ukraine
	Funding: "This work is supported by National Research Fundation of Ukraine "Leading and Young Scientists Research Support", grant agreement # 2020.02/0299." The efficiency of electron acceleration by a wakefield, excited in a plasma by an electron bunch, is determined by the transformer ratio (see , ). The transformer ratio is the ratio of energy acquired by the witness to energy lost by the driver. The transformer ratio can be increased by shaping driver-bunch. In this work, using a non-linear version of the 2d3v code lcode (see *), numerical simulation of excitation of a wakefield in a plasma in blowout regime by a shaped relativistic electron bunch was performed. There is also the problem of maintaining the small dimension and small energy spread of the accelerated electron bunch while maintaining sufficient values of the accelerating gradient and the transformer ratio. Also, the question arises about the values of the limiting dimension of the witness-bunch at which the acceleration process is stable. Numerical simulation solves the problem of electron bunch acceleration of the best quality with simultaneous maximization of the transformer ratio and maximization of the witness bunch length, at which the accelerating gradient and the focusing force are constant. Maslov V.I. et al. Problems of Atomic Science and Technology. 4 (2012) 128. Baturin S.S., Zholents A. Phys. Rev. ST Accel. Beams. 20 (2017) 061302. *Lotov K.V. Phys. Plasmas. 5 (1998) 785.
	Poster TUPAB157 [1.920 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB157
About •	paper received ※ 18 May 2021 paper accepted ※ 23 June 2021 issue date ※ 30 August 2021
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TUPAB158	Electron Witness Constraints for AWAKE	emittance, plasma, wakefield, electron	1753
	J.P. Farmer, P. Muggli MPI-P, München, Germany E. Gschwendtner CERN, Meyrin, Switzerland L. Liang The University of Manchester, Manchester, United Kingdom M.S. Weidl MPI/IPP, Garching, Germany
	The AWAKE project at CERN successfully demonstrated the use of a proton driver to accelerate an electron witness in plasma. One of the key goals for AWAKE Run2 is to better control this acceleration, separating the proton-beam-modulation and electron-acceleration stages in order to achieve high energy electrons with high beam quality. Controlled acceleration additionally requires careful tuning of the witness bunch parameters at the injection point. In this work, we use particle-in-cell simulations to study the tolerances for this matching, and discuss techniques to loosen these constraints. Adli et al. (AWAKE Collaboration), Nature (2018)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB158
About •	paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 11 August 2021
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TUPAB159	Awake Run 2 at CERN	plasma, electron, experiment, proton	1757
	E. Gschwendtner CERN, Meyrin, Switzerland
	The AWAKE Run 2 experiment, starting in 2021 at CERN, aims to achieve high-charge bunches of electrons accelerated to high energy (~10 GeV) while maintaining beam quality. AWAKE Run 2 also aims to show that the process is scalable so that, by the end of the run, the AWAKE-scheme technology could be used for first particle physics applications. The first two phases of Run 2 include the investigation of the seeding of the proton bunch self-modulation with the current electron beam in the existing AWAKE facility and the test of a second new plasma source with a density step allowing to maintain strong accelerating fields. In the third phase of Run 2, electrons with an energy of 150 MeV, produced in a newly installed electron source, will be injected into a second plasma source and accelerated to high energies (several GeVs) while keeping good emittance. In the fourth phase, it is planned to replace the second plasma source with a scalable one, which eventually could be used for long-distance acceleration and first applications. In this paper, we present the program of the four phases of AWAKE Run 2, the technical challenges and the proposed schedule.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB159
About •	paper received ※ 17 May 2021 paper accepted ※ 11 June 2021 issue date ※ 19 August 2021
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TUPAB174	Basic Design Study for Disk-Loaded Structure in Muon LINAC	accelerating-gradient, linac, impedance, experiment	1801
	K. Sumi, T. Iijima, K. Inami, Y. Sue, M. Yotsuzuka Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan H. Ego, T. Mibe, M. Yoshida KEK, Ibaraki, Japan T. Iijima KMI, Nagoya, AIchi Prefecture, Japan Y. Kondo JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y. Nakazawa Ibaraki University, Hitachi, Ibaraki, Japan M. Otani, N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan Y. Takeuchi Kyushu University, Fukuoka, Japan H.Y. Yasuda University of Tokyo, Tokyo, Japan
	The world’s first disk-loaded structure (DLS) at the high-velocity part of a muon LINAC is under development for the J-PARC muon g-2/EDM experiment. We have simulated the first designed constant impedance DLS to accelerate muons from ß = 0.7 to 0.94 at an operating frequency of 1296 MHz and a phase of -10 degrees to ensure longitudinal acceptance and have shown the quality of the beam meets our requirements. Because the structure needs a high RF power of 80 MW to generate a gradient of 20 MV/m, a constant gradient DLS with the higher acceleration efficiency is being studied for lower operating RF power. In this poster, we will show the cell structure design yielding a gradient of 20 MV/m with lower RF power.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB174
About •	paper received ※ 19 May 2021 paper accepted ※ 31 August 2021 issue date ※ 18 August 2021
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TUPAB178	Recommissioning of the CRYRING@ESR Electron Cooler	electron, experiment, target, operation	1816
	C. Krantz, Z. Andelkovic, C. Dimopoulou, W. Geithner, T. Hackler, F. Herfurth, R. Hess, M. Lestinsky, E. Menz, A. Reiter, J. Roßbach, C. Schroeder, A. Täschner, G. Vorobjev GSI, Darmstadt, Germany C. Brandau, S. Schippers Justus-Liebig-University Giessen, I. Physics Institute, Atomic and Molecular Physics, Giessen, Germany V. Hannen, D. Winzen Westfälische Wilhelms-Universität Münster, Institut für Kernphysik, Münster, Germany C. Weinheimer Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany
	Funding: Parts of this work have been supported by the German Federal Ministry of Education and Research (BMBF) under contract numbers 05P19PMFA1 and 05P19RGFA1. The heavy-ion storage ring CRYRING has been recommissioned downstream of GSI’s ESR, which it complements as dedicated low-energy machine. A key element of CRYRING@ESR is its electron cooler, which features one of the coldest electron beams available. This enables efficient phase-space cooling and, in addition, provides very high energy resolution when used as internal electron target. We report on technical upgrades that have been made as part of the re-installation of the cooler at GSI/FAIR and share first results obtained after recommissioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB178
About •	paper received ※ 18 May 2021 paper accepted ※ 16 June 2021 issue date ※ 25 August 2021
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TUPAB186	Longitudinal Dynamics in the Prototype vFFA Ring for ISIS2	extraction, bunching, injection, neutron	1834
	D.J. Kelliher, J.-B. Lagrange, S. Machida, C.R. Prior, C.T. Rogers STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom A.P. Letchford, J. Pasternak STFC/RAL, Chilton, Didcot, Oxon, United Kingdom J. Pasternak Imperial College of Science and Technology, Department of Physics, London, United Kingdom E. Yamakawa JAI, Egham, Surrey, United Kingdom
	A vertical Fixed Field Accelerator (vFFA) is a candidate for a future high-power (MW-class) spallation source at ISIS. In order to assess the feasibility of this novel ring, a prototype is currently being designed. Here we consider the longitudinal dynamics in the prototype ring. A key requirement of future neutron spallation sources is flexibility of operation to best serve multiple target stations. Beam stacking allows a rapid cycling, high intensity machine to operate at lower repetition rates but with higher peak output. Here we show how beam stacking can be realised in the vFFA while minimising the peak RF voltage required.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB186
About •	paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 23 August 2021
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TUPAB188	InnovaTron: An Innovative High-Intensity Industrial Cyclotron for Production of Tc-99m and Other Frontier Medical Radioisotopes*	cyclotron, extraction, ion-source, proton	1841
	G. D’Agostino, Q. Flandroy, E. Forton, W.J.G.M. Kleeven, J. Mandrillon, V. Nuttens, E. van der Kraaij IBA, Louvain-la-Neuve, Belgium
	Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 886190. Tc-99m is the most used radioisotope in nuclear medicine. It is almost exclusively produced with a few ageing research reactors worldwide. In response to growing concerns about Tc-99m availability and its increasing demand, alternative production routes are being explored. The EU-funded InnovaTron project aims at designing an innovative compact high-intensity self-extracting cyclotron able to deliver proton beams with currents up to 5 mA or more for the direct production of Tc-99m. It could be also used for production of high quantities of other frontier medical radioisotopes. The proton beams exit without using an electrostatic deflector to overcome its current limitations. A prototype cyclotron was built by IBA in 2001. Currents up to 2 mA were extracted from it. However, at higher intensities, the extraction efficiency was not higher than 70-75% and the extracted emittance was rather large. The InnovaTron project will implement new technological solutions in the self-extracting cyclotron to be used for large-scale industrial applications. An overview on the InnovaTron project is here presented together with the first simulation results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB188
About •	paper received ※ 18 May 2021 paper accepted ※ 01 June 2021 issue date ※ 25 August 2021
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TUPAB196	Achievement of 100-kW Beam Operation in CSNS/RCS	injection, MMI, space-charge, bunching	1869
	S.Y. Xu, Y.W. An, J. Chen, L. Huang, M.Y. Huang, Y. Li, S. Wang IHEP, Beijing, People’s Republic of China H.Y. Liu, X.H. Lu IHEP CSNS, Guangdong Province, People’s Republic of China
	The China Spallation Neutron Source (CSNS) is an accelerator-based science facility. CSNS is designed to accelerate proton beam pulses to 1.6 GeV kinetic energy, striking a solid metal target to produce spallation neutrons. CSNS has two major accelerator systems, a linear accelerator (80 MeV Linac) and a 1.6 GeV rapid cycling synchrotron(RCS). The RCS accumulates and accelerates the proton beam to 1.6 GeV and then extracts the beam to the target at the repetition rate of 25 Hz. The Beam commissioning of CSNS/RCS had been started since April 2017. The most important issue in high-power beam commissioning is the beam loss control, as well as the control of induced activities, to meet the requirement of manual maintenance. A series of beam loss optimization work had been done to reduce the uncontrolled beam loss. At the end of February 2020, the CSNS reached the design beam power of 100 kW with very low uncontrolled beam loss.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB196
About •	paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 28 August 2021
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TUPAB201	Vacuum Tube Operation Tuning for a High Intensity Beam Acceleration in J-PARC RCS	vacuum, operation, electron, controls	1884
	M. Yamamoto, M. Nomura, H. Okita, T. Shimada, F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii KEK, Tokai, Ibaraki, Japan
	Tetrode vacuum tubes in the J-PARC RCS are used under a reduced filament voltage condition compared with the rating value to prolong the tube life time. One tube reached the end of life in 2020; it was the first case in the RCS after 60,000 hours operation time. This means the reduced filament voltage works well because the tube has been running beyond an expected life time suggested by the tube manufacturer. However, an electron emission from the filament is decreased by the reduced filament voltage. Although the large amplitude of the anode current is necessary for the high intensity beam acceleration to compensate an wake voltage, a solid-state amplifier to drive a control grid circuit almost reaches the output power limit because of the poor electron emission. We changed the filament voltage reduction rate from 15 % to 5 %; the required power of the solid-state amplifier was fairly reduced, whereas the accelerated beam power was same. We will describe the measurement results of the vacuum tube parameters in terms of the filament voltage tuning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB201
About •	paper received ※ 17 May 2021 paper accepted ※ 17 June 2021 issue date ※ 02 September 2021
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TUPAB209	The Particle Tracking Code Fixfield	lattice, FFAG, quadrupole, focusing	1905
	J.-B. Lagrange STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	FixField is a code developed to track particles in Fixed Field alternating gradient Accelerators (FFAs). This paper discusses the structure and features of the code.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB209
About •	paper received ※ 19 May 2021 paper accepted ※ 02 July 2021 issue date ※ 25 August 2021
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TUPAB246	Numerical Simulation and Beam-Dynamics Study of a Hollow-Core Woodpile Coupler for Dielectric Laser Accelerators	GUI, photon, laser, electron	2022
	G.S. Mauro, D. Mascali, G. Sorbello, G. Torrisi INFN/LNS, Catania, Italy A. Bacci INFN/LASA, Segrate (MI), Italy C. De Angelis, A. Locatelli University of Brescia, Brescia, Italy A.R. Rossi INFN-Milano, Milano, Italy G. Sorbello University of Catania, Catania, Italy
	Hollow core dielectric microstructures powered by lasers represent a new and promising area of accelerator research thanks to the higher damage threshold and accelerating gradients with respect to metals at optical wavelengths. In this paper we present the design of a dielectric Electromagnetic Band Gap (EBG) mode converter for high-power coupling of the accelerating mode in Dielectric Laser Accelerators (DLAs). The design is wavelength-independent, and here we propose an implementation operating at 90.505 GHz (wavelength 3.3 mm) based on a silicon woodpile structure. The coupler is composed by two perpendicularly coupled hollow-core waveguides: a TE-like mode waveguide (excited from RF/laser power) and a TM-like mode accelerating waveguide. The structure has been numerically designed and optimized, presenting Insertion Losses (IL) < 0.3 dB and an efficient mode conversion in the operating bandwidth. The properties and effectiveness of the confined accelerating mode have been optimized in order to derive the needed accelerating gradient. The simulated electric field has been used as input for Astra beam-dynamics simulations in order to compute the beam properties.
	Poster TUPAB246 [2.209 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB246
About •	paper received ※ 18 May 2021 paper accepted ※ 27 July 2021 issue date ※ 13 August 2021
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TUPAB247	Influence of the Profile of the Dielectric Structure on the Electric Fields Excited by a Laser in Dielectric Accelerators Based on Chip	electron, laser, experiment, simulation	2026
	A. Vasyliev, O.O. Bolshov, K. Galaydych, A.I. Povrozin, G.V. Sotnikov NSC/KIPT, Kharkov, Ukraine
	Funding: The National Research Foundation of Ukraine, program "Leading and Young Scientists Research Support" (project # 2020.02/0299). To provide experimental researches at the NSC KIPT theoretical studies and computations of the electron acceleration in a dielectric laser accelerator have been carried out. Laser accelerator consists of two periodic quartz structures on diffraction gratings or Chips, symmetrically located along both sides of the vacuum accelerating channel. Using PIC numerical simulations, electromagnetic fields excited by laser radiation with a wavelength of 800 nm in dielectric laser accelerators were investigated. The influence of the shape and depth of the profile of diffraction gratings or Chip structures on the distribution of the electric field in the interaction space has been studied. For modeling, different types of profiles were taken, both in serial and a unique structure. In consequence of the analysis of the obtained results, estimated efficiency of acceleration was defined for each type of profile. The rectangular profile of the diffraction grating with the maximum accelerating gradient was selected as optimal for the next experiments.
	Poster TUPAB247 [1.195 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB247
About •	paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 11 August 2021
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TUPAB249	Diffraction at the Open-Ended Dielectric-Loaded Circular Waveguide	GUI, radiation, wakefield, electron	2033
	S.N. Galyamin, A.V. Tyukhtin, V.V. Vorobev Saint Petersburg State University, Saint Petersburg, Russia
	Funding: Work supported by Russian Science Foundation (Grant No. 18-72-10137). Contemporary beam and THz technologies are tightly interlaced during last years. Strong THz fields allow realization of THz driven electron guns, THz bunch compression, streaking* and THz driven wakefield acceleration. Inversely, dielectric capillaries similar to those used for THz bunch manipulation can be in turn utilized for development of high-power narrow-band THz sources. Mentioned cases involve interaction of THz waves and particle bunches with an open end of certain dielectric loaded waveguide structure, most frequently a circular capillary. For further development of the discussed prospective topics a rigorous approach allowing analytical investigation of both radiation from open-ended capillaries and their excitation by external source would be extremely useful. We present an elegant and efficient rigorous method for solving circular open-ended dielectric-loaded waveguide diffraction problems based on Wiener-Hopf technique. We deal with the case of uniform dielectric loading and internal excitation by a waveguide mode. S-parameters, near-field and far-field distributions are presented. The obtained results can be also applied to the narrow band wakefield. L. Zhao et al., Phys. Rev. Lett., 124, 054802 (2020). M.T. Hibberd et al., Nat. Photonics, 14, 755-759 (2020). * D. Wang et al., Rev. Sci. Instr., 89(9), 093301 (2018).
	Poster TUPAB249 [2.160 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB249
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 21 August 2021
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WEPAB017	General Approach to Physics Limits of Ultimate Colliders	collider, luminosity, plasma, radiation	2624
	V.D. Shiltsev Fermilab, Batavia, Illinois, USA
	The future of the particle physics is critically dependent on feasibility of future energy frontier colliders. The concept of the feasibility is complex and includes at least three factors: feasibility of energy, feasibility of luminosity, and feasibility of cost and construction time. Here we discuss major beam physics limits of ultimate accelerators, take a look into ultimate energy reach of possible future colliders. We also foresee a looming paradigm change for the HEP research as the thrust for higher energies by necessity will mean lower luminosity.
	Poster WEPAB017 [1.720 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB017
About •	paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 17 August 2021
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WEPAB055	Development of a Linac for Injection of Ultrashort Electron Bunches Into Laser Plasma Electron Accelerators	electron, laser, plasma, linac	2725
	S. Masuda, N. Kumagai, T. Masuda, Y. Otake JASRI, Hyogo, Japan Y. Koshiba, S. Otsuka Waseda University, Tokyo, Japan T. Sakai, T. Tanaka LEBRA, Funabashi, Japan K. Sakaue The University of Tokyo, The School of Engineering, Tokyo, Japan
	Funding: This work is supported by JST-Mirai Program Grant Number JPMJMI17A1, Japan. We are developing a C-band linac that produces ultrashort electron bunches as an injector for laser plasma accelerators. A plasma wave excited by a high intense ultrashort laser pulse has a wavelength of the order of 10 to 100 fs and transverse dimensions of the order of 10 to 100 um. To inject the bunch into a proper phase of the plasma wave, a length and transverse sizes of the bunch must be much smaller than the plasma wave structure. A laser triggered photo cathode electron RF-gun and a 2pi/3 mode traveling wave buncher with 24 cells for ultrashort electron bunch production have been developed based on electron beam tracking simulations that show the bunch length is less than 10 fs with a charge of 100 fC at a focus on the plasma wave. The simulations also show that sufficiently small transverse sizes of the bunch at the focus can be obtained by a Q triplet. A highly accurate timing lower than the plasma wavelength (~10fs) is required for the synchronization between the electron bunch injection and the plasma wave excitation. An RF master oscillator with low SSB phase noise (-150dBc/Hz@10MHz) has been developed for the synchronization. We will report present development status.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB055
About •	paper received ※ 19 May 2021 paper accepted ※ 15 July 2021 issue date ※ 29 August 2021
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WEPAB143	Sub-MeV Ion Generation by Standing Wave Excitation of Ionized Gases	electron, plasma, laser, simulation	2951
	Sz. Turnár, G. Almási, J. Hebling, Cs. Korpa, M.I. Mechler, L. Pálfalvi, Z. Tibai University of Pecs, Pécs, Hungary
	Funding: Hungarian Scientific Research Fund (OTKA) (125808, 129134) ÚNKP-20-3 New National Excellence Program of the Ministry for Innovation and Technology from the source of the National Research Many ion acceleration techniques have been suggested and thoroughly studied in the last two decades. One of the promising techniques is the Coulomb explosion acceleration (CEA). Using CEA in clusters could result in symmetric acceleration if there are not any other significant mechanisms. We proposed a THz-driven accelerator scheme that is based on CEA in proton, deuterium and heavy water gas plasmas. Two counter-propagating THz pulses are focused to the ionized region of the gas jet. Following the ripping of the electrons from the gas plasmas by ultrafast standing waves, the Coulomb explosion accelerates the positive ions. According to our calculation, using 2 x 34 mJ THz pulses electrons and protons with 1.1 nC charge are accelerated up to 0.4 MeV and 0.1 MeV, respectively. The total energy of the particles is 0.7 % of the energy of the THz pulses. We examined the effect of the initial bunch charge, bunch size and shape on the final energy spectra and the directional distribution of the particles. Our presented technique is scalable from a few µm to a few thousand µm driving wavelengths and can be used for electron and heavy-ion acceleration. J. Badziak, IOP Conf. Series: J Phys: Conf. Series 959, 012001 (2018). ** M. Murakami and K. Mima, Phys. of Plasmas 16, 103108 (2009).
	Poster WEPAB143 [3.467 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB143
About •	paper received ※ 19 May 2021 paper accepted ※ 07 June 2021 issue date ※ 15 August 2021
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WEPAB158	Compact Terahertz-Powered Electron Photo-Gun	electron, gun, cathode, injection	2983
	T. Kroh, H. Çankaya, U. Demirbas, M. Fakhari, N.H. Matlis, M. Pergament, T. Rohwer CFEL, Hamburg, Germany R.W. Aßmann, H. Dinter, M.J. Kellermeier DESY, Hamburg, Germany M. Hemmer, F.X. Kärtner Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany F.X. Kärtner The Hamburg Center for Ultrafast Imaging, University of Hamburg, Hamburg, Germany
	Funding: This work is supported by the Cluster of Excellence "CUI: Advanced Imaging of Matter" of the Deutsche Forschungsgemeinschaft (DFG) - EXC 2056 - project ID 390715994. Novel accelerator concepts such as all-optical THz based compact accelerators promise to enable new science due to unique features such as reduced timing-jitter and improved space-charge broadening of the generated electron bunches. However, multi-keV electron photo-guns based on short single-cycle THz pulses for acceleration have not been demonstrated experimentally so far. Here, we present a modular THz-driven electron gun with both tunable interaction length and output orifice allowing optimization of the sub-mm interaction volume. First extraction of multi-keV electrons is demonstrated and the parameter space as well as resulting performance of the THz-driven gun by varying the timing of the two single-cycle THz pulses and the UV photo-excitation pulse are explored. Such compact gun prototypes are not only promising as injectors for compact THz-based LINACs but also as source for ultrafast electron diffraction experiments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB158
About •	paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 30 August 2021
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WEPAB175	Simulation Study of Electron Beam Acceleration with Non-Gaussian Transverse Profiles for AWAKE Run 2	emittance, plasma, electron, wakefield	3012
	L. Liang, G.X. Xia The University of Manchester, Manchester, United Kingdom J.P. Farmer MPI-P, München, Germany L. Liang, G.X. Xia Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: The authors would like to acknowledge the support from the Cockcroft Institute Core Grant and the STFC AWAKE Run 2 grant ST/T001917/1 In the physics plan for AWAKE Run 2, two known effects, beam loading the longitudinal wakefield and beam matching to the pure plasma ion channel, will be implemented for the better control of electron acceleration. It is founded in our study of beam matching that the transverse profile of the initial witness beam have a significant impact on its acceleration quality. In this paper, particle-in-cell (PIC) simulations are used to study factors that affect the acceleration quality of electron beams with different transverse profiles.
	Poster WEPAB175 [1.860 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB175
About •	paper received ※ 10 May 2021 paper accepted ※ 25 June 2021 issue date ※ 02 September 2021
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WEPAB208	Energy Sweeping Beam Extraction by the Septum Magnet Assisted with Charge Exchange for a Hadron Therapy	extraction, septum, kicker, power-supply	3109
	T.S. Dixit, A. Shaikh SAMEER, Mumbai, India T. Adachi, T. Kawakubo, K. Takayama KEK, Ibaraki, Japan
	An energy sweeping compact rapid cycling hadron therapy based on a fast cycling induction synchrotron has been proposed by KEK and SAMEER as the next generation of hadron therapy machine . For energy sweep extraction, a C+5 beam is injected, captured and trapped in the barrier bucket. A fraction of the beam is continuously released from the barrier bucket by controlling the timing of barrier pulse generation. Released C+5 ions merge into the coasting beam and moves inwards with ramping of the guiding main magnets. Ions in the coasting beam eventually hit the carbon foil placed inside the beam chamber wall. As a result, C+5 is converted to C+6 and beam orbit is largely changed as it traverses through the downstream bending magnet. This notably facilitates C+6 beam extraction, resulting in a relatively small kick angle of the septum magnet. When the septum is excited in the same way as that of the main magnets, the extracted C+6 beam always places on the center of the irradiation beam line. LISE++ simulations demonstrated the charge exchange efficiency of almost 100 % for expected beam energy. The feasibility of the switching power supply for the septum magnet has been studied. PRAB 24, 011601 (2021)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB208
About •	paper received ※ 14 May 2021 paper accepted ※ 22 June 2021 issue date ※ 16 August 2021
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WEPAB209	Review of Medical Accelerator Development at Sameer, India	linac, electron, photon, cavity	3113
	T.S. Dixit, N. Bansode, A.P. Bhagwat, S.T. Chavan, A.P. Deshpande, G. Gaikwad, S. Ghosh, R. Krishnan, C.S. Nainwad, G.D. Panchal, S.N. Pethe, K.A. Thakur, V.B. Ukey, M.M. Vidwans SAMEER, Mumbai, India
	Funding: Ministry of Electronics and Information Technology (MeitY), Government of India At the Medical Electronics Division of SAMEER, R&D for the development of a 4 MeV energy electron linac for Cancer therapy was taken up in the late ’80s. An S-band standing wave side coupled structure operating at pi/2 mode was developed for electron acceleration. The linac was integrated with other subsystems in collaboration with CSIO and PGIMER and the first machine was commissioned at PGI, Chandigarh in 1990. Thereafter, a lot of modifications like energy, dose rate, iso-center height etc. were made in the system, and later 4 more machines were commissioned in hospitals for treatment. More than 1,50,000 patients have been treated using SAMEER’s 6 MeV oncology system. Subsequently, development of dual-mode and variable energy electron and photon output machines was undertaken. Two-photon energies of 6 and 15 MV and multiple electron energies starting from 6 to 18 MeV for treatment was offered from the linac. The electron energy variation was done using plunger mechanism in the side coupling cavity. This linac was successfully baked and RF tested for various parameters. This paper describes the experimental parameters achieved for both low and high energy dual-mode linac.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB209
About •	paper received ※ 14 May 2021 paper accepted ※ 07 July 2021 issue date ※ 13 August 2021
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WEPAB378	Near-Infrared Laser System for Dielectric Laser Acceleration Experiments at SINBAD	laser, experiment, electron, timing	3596
	C. Mahnke, U. Grosse-Wortmann, I. Hartl, C.M. Heyl, Y. Hua, T. Lamb, Y. Ma, C. Mohr, J. Müller, S.H. Salman, S. Schulz, C. Vidoli DESY, Hamburg, Germany H. Çankaya CFEL, Hamburg, Germany
	The technique of dielectric laser acceleration (DLA) utilizes the strong field gradients generated by intense laser light near the surfaces of microscopic photonic structures, possibly allowing compact accelerator devices. We report on the infrared laser system at the SINBAD facility at DESY, where first DLA experiments with relativistic electrons pre-accelerated by the ARES linear accelerator started in late 2020. We constructed a low-noise Holmium fiber oscillator producing pulses at a wavelength of 2050 nm, seeding a Ho:YLF regenerative amplifier. Pulses of 2 mJ and 2 ps duration from the amplifier are transported over a distance of about 30 m to the DLA interaction point. The laser system is synchronized to the accelerator by locking the laser repetition rate to an RF master oscillator using an all-digital phase-locked loop, giving a residual timing jitter of about 45 fs. The digital locking scheme allows precise shifting of the relative timing between laser pulses and electrons without need for a dedicated optical delay line. It is planned to lock the system to the UV photocathode laser by means of an optical cross correlator further to improve the locking performance.
	Poster WEPAB378 [1.445 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB378
About •	paper received ※ 19 May 2021 paper accepted ※ 22 June 2021 issue date ※ 18 August 2021
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WEPAB397	Design of the Two-Layer Girder for Accelerating Tube	neutron, ECR, operation, simulation	3636
	X.J. Nie, H.Y. He, L. Kang IHEP, Beijing, People’s Republic of China J.X. Chen, L. Liu, R.H. Liu, C.J. Ning, A.X. Wang, G.Y. Wang, Y.J. Yu, J.S. Zhang, D.H. Zhu IHEP CSNS, Guangdong Province, People’s Republic of China J.B. Yu DNSC, Dongguan, People’s Republic of China
	An accelerating tube is one kind of important acceleration equipment of a linear accelerator. It is often made up of oxygen-free copper with a long tubular structure. It’s easy to suffer from deformation. Based on support requirements, the reasonable structure of the girder was obtained. Four supporting blocks were installed on the top surface of aluminum profile with the uniform distribution along the beam direction. The support strength with static condition and different working conditions were checked by ANSYS simulation calculation to ensure the stable operation of the girder. The two-layer girder can be used as a reference for other similar slender part for its simple structure and reliable support.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB397
About •	paper received ※ 14 May 2021 paper accepted ※ 01 September 2021 issue date ※ 22 August 2021
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THXC05	Simulation of Imaging Using Accelerated Muon Beams	simulation, linac, radio-frequency, scattering	3740
	M. Otani KEK, Tokai, Ibaraki, Japan H.M. Miyadera LANL, Los Alamos, New Mexico, USA T. Shiba Japan Atomic Energy Agency, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Muons are elementary particles with strong penetrating power and cosmic-ray muons have been utilized to see through large structures such as the pyramids. Recently, we have succeeded in accelerating muons using a radio-frequency accelerator, opening the door to new imaging techniques using accelerated muon beams. Currently, imaging with cosmic-ray muons is limited in imaging time and resolution by their intensity and energy fluctuations. The muon beams can have high intensity and monochromatic energy, allowing for better resolution imaging in less time. In this poster, imaging of spent nuclear fuel in casks using cosmic rays and muon beams, as well as imaging in other cases, will be evaluated and compared.
	Poster THXC05 [2.560 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXC05
About •	paper received ※ 16 May 2021 paper accepted ※ 19 July 2021 issue date ※ 15 August 2021
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THPAB071	Physics Goals of DWA Experiments at FACET-II	experiment, wakefield, quadrupole, focusing	3922
	J.B. Rosenzweig, H.S. Ancelin, G. Andonian, A. Fukasawa, C.E. Hansel, G.E. Lawler, W.J. Lynn, N. Majernik, J.I. Mann, P. Manwani, Y. Sakai, O. Williams, M. Yadav UCLA, Los Angeles, California, USA S.V. Baryshev Michigan State University, East Lansing, Michigan, USA S. Baturin Northern Illinois University, DeKalb, Illinois, USA M.J. Hogan, B.D. O’Shea, D.W. Storey, V. Yakimenko SLAC, Menlo Park, California, USA
	Funding: This work supported by DOE HEP Grant DE-SC0009914, The dielectric wakefield acceleration (DWA) program at FACET produced a multitude of new physics results that range from GeV/m acceleration to the discovery of high field-induced conductivity in THz waves, and beyond, to a demonstration of positron-driven wakes. Here we review the rich program now developing in the DWA experiments at FACET-II. With increases in beam quality, a key feature of this program is extended interaction lengths, near 0.5 m, permitting GeV-class acceleration. Detailed physics studies in this context include beam breakup and its control through the exploitation of DWA structure symmetry. The next step in understanding DWA limits requires the exploration of new materials with low loss tangent, large bandgap, and improved thermal characteristics. Advanced structures with photonic features for mode confinement and exclusion of the field from the dielectric, as well as quasi-optical handling of coherent Cerenkov signals is discussed. Use of DWA for laser-based injection and advanced temporal diagnostics is examined.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB071
About •	paper received ※ 25 May 2021 paper accepted ※ 28 July 2021 issue date ※ 22 August 2021
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THPAB182	DC-280 Cyclotron for Factory of Super Heavy Elements, Experimental Results	cyclotron, experiment, ECR, injection	4126
	V.A. Semin, S.L. Bogomolov, K. Gikal, G.G. Gulbekyan, I.A. Ivanenko, I.V. Kalagin, N.Yu. Kazarinov, V.I. Mironov JINR, Dubna, Moscow Region, Russia L.A. Pavlov JINR/FLNR, Moscow region, Russia
	The DC280 is the high current cyclotron with design beam intensities up to 10 pµA for ions with energy from 4 to 8 MeV/nucleon. It was developed and created at the FLNR JINR. The first was extracted from the cyclotron on January 17, 2019. Experiments on acceleration of 12C, 40Ar, 48Ca, 48Ti, 52Cr and 84Kr beams production were carried out. The following intensities of accelerated beam have been achieved: 10 pµA for 12C+2; 9,2 pµA for 40Ar+7; 7,1 pµA for 48Ca+10; 1,0 pµA for 48Ti+10; 2,4 pµA for 52Cr+10 and 1.43 pµA for 84Kr+14;. The accelerator has worked more than 9000 hours. The work of accelerator was stable and high efficiency. The total acceleration efficiency from ion source to transport channel was about 46%.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB182
About •	paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 21 August 2021
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THPAB202	Problem and Solution with the Longitudinal Tracking of the ORBIT Code	simulation, emittance, synchrotron, space-charge	4176
	L.H. Zhang, J.Y. Tang IHEP, Beijing, People’s Republic of China Y.K. Chen IHEP CSNS, Guangdong Province, People’s Republic of China L.H. Zhang University of Chinese Academy of Sciences, Beijing, People’s Republic of China
	The ORBIT code has been widely used for beam dynamics simulations including injection and acceleration in high-intensity hadron synchrotrons. When the ORBIT’s 1D longitudinal tracking was employed for the acceleration process in CSNS/RCS, the longitudinal emittance in eV-s was found decreasing substantially during acceleration, though the adiabatic condition is still met during this process. This is against the Liouville theorem that predicts the preservation of the emittance during acceleration. The recent machine study in the accelerator and the simulations with a self-made code demonstrate that the longitudinal emittance is almost invariant, which further indicates that the ORBIT longitudinal tracking might be incorrect. A detailed check-over in the ORBIT code source finds that the longitudinal finite difference equation used in the code is erroneous when applied to an acceleration process. The new code format PyORBIT has the same problem. After the small secondary factor is included in the code, ORBIT can produce results keeping the longitudinal emittance invariant. This paper presents some details about the study.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB202
About •	paper received ※ 14 May 2021 paper accepted ※ 01 July 2021 issue date ※ 21 August 2021
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THPAB207	Beam Dynamics Simulation about the Dual Harmonic System by PyORBIT	simulation, bunching, synchrotron, space-charge	4194
	H.Y. Liu, X.Y. Feng, L. Huang, M.T. Li, X.H. Lu IHEP CSNS, Guangdong Province, People’s Republic of China S. Wang, S.Y. Xu IHEP, Beijing, People’s Republic of China
	The space charge effect is a strong limitation in high-intensity accelerators, especially for low- and medium-energy proton synchrotrons. And for CSNS-II, the number of particles in the RCS is 3.9·10¹³ ppp, which is five times of CSNS. To mitigate the effects of the strong space charge effect, CSNS-II/RCS (Rapid Cycling Synchrotron) will use a dual harmonic system to increase the bunching factor during the injection and the initial acceleration phase. For studying the beam dynamics involved in a dual harmonic RF system, PyORBIT is used as the major simulation code, which is developed at SNS to simulate beam dynamics in accumulation rings and synchrotrons. We modified parts of the code to make it applicable to the beam dynamic in RCS. This paper includes the major code modification of the Dual Harmonic RF system and some benchmark results. The preliminary simulation results of the dual-harmonic system in CSNS-II/RCS simulated by the particle tracking code PyORBIT will also be discussed.
	Poster THPAB207 [0.354 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB207
About •	paper received ※ 16 May 2021 paper accepted ※ 05 July 2021 issue date ※ 11 August 2021
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THPAB310	Automatic Correction System for the TLS Booster Linac Klystron Modulator	klystron, electron, booster, linac	4396
	S.J. Huang, Y.K. Lin NSRRC, Hsinchu, Taiwan
	The aim of this article is to analyse the performance output of the klystron modulator, which is based on the observation of the output voltage and current performance of the linear-accelerator klystron modulator; we modify the operating-point parameters based on those results or assess whether the klystron needs to be replaced. For this purpose, we collect the observation data of the klystron performance; we then develop a program to adjust automatically the high-voltage setting of the klystron to ensure that the storage current maintains beam current 360 mA in the top-up mode operation.
	Poster THPAB310 [0.785 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB310
About •	paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 13 August 2021
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THPAB317	Experiment and Simulation Study on the Capture and Acceleration Process of XiPAF Synchrotron	synchrotron, experiment, cavity, proton	4409
	Y. Li, X. Guan, X.Y. Liu, M.W. Wang, X.W. Wang, Q.Z. Xing, Y. Yang, H.J. Yao, W.B. Ye, S.X. Zheng TUB, Beijing, People’s Republic of China W.L. Liu, D. Wang, Z.M. Wang, Y. Yang, M.T. Zhao NINT, Shannxi, People’s Republic of China
	The beam commissioning of the capture and acceleration process on the XiPAF (Xi’an 200MeV Proton Application Facility) synchrotron has been carried out. The efficiency of the experiment results has been compared with the simulation results. At present, the efficiency of the capture process with single-harmonic is about 73%, and the acceleration efficiency is about 82%, and the simulation results are 77% and 96% without space charge effect, respectively. In order to improve efficiency, dual-harmonic was used during the capture and acceleration process. During the experiment, the capture efficiency was increased by 5%, and the acceleration efficiency was increased by 4%. The capture efficiency decreases with the increase of the maximum RF voltages. We analyzed the reasons for the decrease in capture efficiency. In the next step, further verification will be carried out through experiments under different conditions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB317
About •	paper received ※ 19 May 2021 paper accepted ※ 08 July 2021 issue date ※ 23 August 2021
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THPAB332	Development of a Pair of 182 GHz Two-Half Power Extractor and Accelerator for Short Pulse RF Breakdown Study	GUI, electron, wakefield, alignment	4435
	J.H. Shao, J.G. Power ANL, Lemont, Illinois, USA R.B. Agustsson, S.V. Kutsaev, A.Yu. Smirnov RadiaBeam, Santa Monica, California, USA
	High-frequency structures are favorable in structure wakefield acceleration for their strong beam-structure interaction. Recent progress of advanced fabrication technologies, such as high-precision two-half milling and additive machining, has enabled experimental research of mm-wave/THz structures. In this work, we have designed a pair of 182 GHz two-half copper power extractor and accelerator for short pulse RF breakdown study. When driven by a 182 GHz 4-bunch train with 4 nC total charge and 0.3 mm rms bunch length, the power extractor will generate 0.4 ns ~8 MW RF pulses and the corresponding gradient in the single-cell accelerator will reach ~460 MV/m. RF and mechanical design of the proof-of-concept structures will be reported in this manuscript.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB332
About •	paper received ※ 26 May 2021 paper accepted ※ 19 July 2021 issue date ※ 26 August 2021
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Paper

Title

Other Keywords

Page

MOPAB049

Gyroresonant Acceleration of Electrons by an Axisymmetric Transverse Electric Field

electron, resonance, cyclotron, plasma

213

E.A. Orozco, O. Otero Olarte
UIS, Bucaramanga, Colombia

The acceleration of electrons using gyromagnetic autoresonance consist on the sustaint of the electron cyclotron resonant condition through of a magnetic field which increase on time, this scheme was propose by K. S. Golovanivsky. In this work, we considerer the gyroresonant acceleration of electrons using an axisymmetric transverse electric field and its limitations. The 2D acceleration of electrons by a TE011 cylindrical mode is studied numerically. The trajectory, energy and phase-shift between the electron transverse velocity and the electric field are determined by the numerical solution of the relativistic Newton-Lorentz equation using a finite difference scheme. The growth rate of the magnetic field obtained is such that it maintains the phase difference within the acceleration band. The study includes the evolution of the energy for electrons initially ubicated in diferents initial points. For an electron that starts from rest and located at the radial midpoint of the transverse central plane of the cavity, it is reaches an energy close to 560 keV in 625 cycles of the microwave field using an electric field amplitude of 1 kV/cm and a frequency of 2.45 GHz.

Poster MOPAB049 [3.541 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB049

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paper received ※ 17 May 2021 paper accepted ※ 14 June 2021 issue date ※ 23 August 2021

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MOPAB050

Spatial Autoresonant Acceleration of Electrons by an Axysimmetric Transverse Electric Field

electron, resonance, cyclotron, cavity

217

E.A. Orozco, O. Otero Olarte
UIS, Bucaramanga, Colombia

In this research, The autoresonance acceleration of electrons by an axisymmetric transverse electric field in presence of a stationary inhomogeneous magnetic field is studied. The dynamics of electrons is determined by the numerical solution of the relativistic Newton-Lorentz equation using a finite difference scheme. The inhomogeneous external magnetic field is generated with a three-coil system and calculated using the Biot-Savart law. The electrons move along a TE011 cylinder cavity in a stationary magnetic field whose axis coincides with the cavity axis. The magnetic field profile obtained is such that it keeps the phase difference between the electric field vector of the microwave mode and the velocity vector of the particle within the acceleration band. For an electron injected longitudinally with an energy of 1 keV and that starts at the radial midpoint of the cavity, it is accelerated up to an energy of about 185 keV using an electric field amplitude of 14 kV/cm and a frequency of 2.45 GHz at a distance of 14 cm.

Poster MOPAB050 [3.298 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB050

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paper received ※ 17 May 2021 paper accepted ※ 15 June 2021 issue date ※ 30 August 2021

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MOPAB143

Simulations for MeV Energy Gain in Multi-Micron Vacuum Channel Dielectric Structures Driven by a CO₂ Laser

laser, electron, simulation, vacuum

499

G. Yadav, O. Apsimon, Y. Wei, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
O. Apsimon, C.P. Welsch, G.X. Xia
Cockcroft Institute, Warrington, Cheshire, United Kingdom
G.X. Xia
The University of Manchester, Manchester, United Kingdom

Funding: This work was supported by STFC LIV. DAT under grant agreement ST/P006752/1. This research used the resources of the Supercomputing Laboratory at KAUST in Thuwal, Saudi Arabia.
Dielectric Laser Accelerators (DLAs) have been demonstrated as a novel scheme for producing high acceleration gradients (~1 GV/m) within the damage threshold of the dielectric. The compactness of the DLAs and the low emittance of the output electron beam make it an attractive candidate for future endoscopic devices to be used in tumor irradiation. However, due to the small accelerating distances(sub-mm), the total energy gain is limited to sub-MeV which remains an obstacle for its realistic applications. Also, these DLAs operate under solid-state lasers with wavelengths near IR (800 nm to 2 um), where required sub-micron vacuum channel at such wavelengths imposes major aperture restrictions for the amount of charge to be accelerated. Here, we present numerical simulation results for a dielectric structure excited by a CO₂ laser with a wavelength of 10.6 um. Upon injecting a 50 MeV electron bunch through a 5.3 um diameter of vacuum channel width, our simulation suggests an energy gain beyond 1 MeV. These results are the initial steps for the realization of an mm-scale DLA capable of producing MeV energy electron beams.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB143

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paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 11 August 2021

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MOPAB144

Investigation of Optimization of Dielectric Terahertz Acceleration Structures

simulation, laser, radiation, impedance

502

A.E. Gabriel, E.A. Nanni
SLAC, Menlo Park, California, USA

Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515 (SLAC) and by NSF Grant No. PHY-1734015.
THz-frequency accelerating structures could provide the accelerating gradients needed for next generation particle accelerators with compact, GV/m-scale devices. Current THz accelerators are limited by significant losses during transport of THz radiation from the generating nonlinear crystal to the electron acceleration structure. In addition, the spectral properties of high-field THz sources make it difficult to couple THz radiation into accelerating structures. Dielectric accelerator structures reduce these losses because THz radiation can be coupled laterally into the structure, as opposed to metallic structures where THz radiation must be coupled along the beam path. In order to utilize these advantages, we are investigating the optimization of THz accelerating structures for comparison between metallic and dielectric devices. These results will help to inform future designs of improved dielectric THz acceleration structures.

Poster MOPAB144 [6.524 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB144

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paper received ※ 20 May 2021 paper accepted ※ 27 May 2021 issue date ※ 22 August 2021

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MOPAB147

Efficient, High Power Terahertz Radiation Outcoupling From a Beam Driven Dielectric Wakefield Accelerator

radiation, wakefield, electron, GUI

513

M. Yadav, G. Andonian, C.E. Hansel, W.J. Lynn, N. Majernik, B. Naranjo, J.B. Rosenzweig, O. Williams
UCLA, Los Angeles, California, USA
G. Andonian
RadiaBeam, Santa Monica, California, USA
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work was supported by DE-SC0009914 (UCLA) and the STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT) under grant agreement ST/P006752/1.
Wakefields in dielectric structures are a useful tool for beam diagnostics and manipulation with applications including acceleration, shaping, chirping, and THz radiation generation. It is possible to use the produced THz radiation to diagnose the fields produced during the DWA interaction but, to do so, it is necessary to effectively out-couple this radiation to free space for transport to diagnostics such as a bolometer or interferometer. To this end, simulations have been conducted using CST Studio for a 10 GeV beam with FACET-II parameters in a slab-symmetric, dielectric waveguide. Various termination geometries were studied including flat cuts, metal horns, and the "Vlasov antenna". Simulations indicate that the Vlasov antenna geometry is optimal and detailed studies were conducted on a variety of dielectrics including quartz, diamond, and silicon. Multiple modes were excited and coherent Cherenkov radiation (CCR) was computationally generated for both symmetric and asymmetric beams. Finally, we include witness beams to study transport and acceleration dynamics as well as the achievable field gradients.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB147

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paper received ※ 24 May 2021 paper accepted ※ 29 August 2021 issue date ※ 28 August 2021

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MOPAB148

Liénard-Wiechert Numerical Radiation Modeling for Plasma Acceleration Experiments at FACET-II

radiation, plasma, betatron, experiment

517

M. Yadav, G. Andonian, C.E. Hansel, N. Majernik, P. Manwani, B. Naranjo, J.B. Rosenzweig, O. Williams, Y. Zhuang
UCLA, Los Angeles, California, USA
G. Andonian
RadiaBeam, Marina del Rey, California, USA
O. Apsimon, A. Perera, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
O. Apsimon, A. Perera, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work was supported by DE-SC0009914 (UCLA) and the STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT) under grant agreement ST/P006752/1.
Future plasma acceleration experiments at FACET-II will measure betatron radiation in order to provide single-shot non-destructive beam diagnostics. We discuss three models for betatron radiation: a new idealized particle tracking code with Liénard-Wiechert radiation, a Quasi-Static Particle-in-Cell (PIC) code with Liénard-Wiechert radiation, and a full PIC code with radiation computed via a Monte-Carlo QED Method. Predictions of the three models for the E-310 experiment are presented and compared. Finally, we discuss beam parameter reconstruction from the double differential radiation spectrum.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB148

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paper received ※ 24 May 2021 paper accepted ※ 01 June 2021 issue date ※ 17 August 2021

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MOPAB151

A Stable Drive Beam for High Gradient Dielectric Wakefield Acceleration

focusing, wakefield, accelerating-gradient, quadrupole

528

T.J. Overton, Y.M. Saveliev, G.X. Xia
Cockcroft Institute, Warrington, Cheshire, United Kingdom
T.J. Overton, G.X. Xia
The University of Manchester, Manchester, United Kingdom
T.H. Pacey, Y.M. Saveliev
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Science and Technology Funding Council (STFC) student grant.
A high accelerating gradient, with stable beam transport, is necessary for the next generation of particle accelerators. Dielectric wakefield accelerators are a potential solution to this problem. In these proceedings, we present simulation studies of electron bunches in the self-wake regime inside a planar dielectric structure. This is analogous to driving beams in a dielectric wakefield accelerator. The transverse and longitudinal wake fields are investigated for dielectric plate gaps, various transverse beam sizes, and longitudinal bunch profiles. The effects of these on the stability of drive bunches, and acceleration of a witness bunch, are discussed in the context of electron bunches that can be produced with conventional linac RF technology.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB151

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paper received ※ 13 May 2021 paper accepted ※ 07 June 2021 issue date ※ 24 August 2021

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MOPAB154

Multi-Cell Accelerating Structure Driven by a Lens-Focused Picosecond THz Pulse

laser, focusing, electron, timing

537

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

Recently, gradients on the order of 1 GV/m level have been obtained in a form of a single cycle (~1 ps) THz pulses produced by conversion of a high peak power laser radiation in nonlinear crystals (~1 mJ, 1 ps, up to 3% conversion efficiency). Such high-intensity radiation can be utilized for charged particle acceleration. However, these pulses are short in time (~1ps) and broadband, therefore a new accelerating structure type is required. In this paper, we propose a novel structure based on focusing of THz radiation in accelerating cell and stacking such cells to achieve a long-range interaction required for an efficient acceleration process. We present an example in which a 100 microJoule THz pulse produces a 600 keV energy gain in 5 mm long 10 cell accelerating structure for an ultra-relativistic electron. This design can be readily extended to non-relativistic particles. Such structure had been laser microfabricated and appropriate dimensions were achieved.

Poster MOPAB154 [1.283 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB154

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paper received ※ 27 May 2021 paper accepted ※ 05 July 2021 issue date ※ 14 August 2021

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MOPAB166

Wakefield Excitation by a Sequence of Laser Pulses in Plasma

laser, wakefield, plasma, simulation

568

D.S. Bondar
KhNU, Kharkov, Ukraine
V.I. Maslov, I.N. Onishchenko
NSC/KIPT, Kharkov, Ukraine

Funding: The study is supported by the National Research Fundation of Ukraine under the program "Leading and Young Scientists Research Support" (project # 2020.02/0299).
PIC simulation by means of 2.5D UMKA code * of the wakefield excitation by a sequence of three Gaussian laser pulses in plasma was carried out. The dependence of excited wakefield intensity on power and width of laser pulses was investigated. It was shown the coherent addition of wakefield, excited by each laser pulse of the sequence, for linear case, while for the nonlinear case the coherency was destroyed. The profiled sequence of laser pulses was also considered. The possibility to obtain the same total wakefield excited by the profiled sequence of laser pulses with decreasing intensity, as for the uniform sequence was studied.
* G. I. Dudnikova et al. Comp. Techn. 10 (2005) 37.

Poster MOPAB166 [2.638 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB166

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paper received ※ 17 May 2021 paper accepted ※ 20 May 2021 issue date ※ 15 August 2021

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MOPAB167

Wakefield Excitation in Plasma of Metallic Density by a Laser Pulse

laser, plasma, wakefield, electron

571

D.S. Bondar
KhNU, Kharkov, Ukraine
V.I. Maslov, I.N. Onishchenko
NSC/KIPT, Kharkov, Ukraine

Funding: The study is supported by the National Research Foundation of Ukraine under the program "Leading and Young Scientists Research Support" (project # 2020.02/0299).
Recently the proposal to use X-ray Exawatt pulse for particle acceleration in a crystal has been declared *. Short X-ray high-power pulse excites wakefield in electron plasma of metallic density which can be used for high gradient acceleration of charged particles. This wakefield is suited for laser wakefield acceleration. In this paper there are simulated with PIC code UMKA: excitation of the large wakefield amplitude up to several TV/m in electron plasma of metallic density by a powerful X-ray laser pulse; laser-plasma wakefield acceleration of self-injected electron bunch in such setup; combined acceleration by plasma wakefield driven by a laser pulse (LPWA) and by self-injected electron bunch (PWFA).
* T.Tajima. Eur. Phys. J. Special Topics 223 (2014) 1037.

Poster MOPAB167 [2.054 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB167

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paper received ※ 17 May 2021 paper accepted ※ 21 May 2021 issue date ※ 22 August 2021

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MOPAB169

Generating 510 MW of X-Band Power for Structure-Based Wakefield Acceleration Using a Metamaterial-Based Power Extractor

experiment, wakefield, electron, simulation

578

J.F. Picard, I. Mastovsky, M.A. Shapiro, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA
M.E. Conde, D.S. Doran, J.G. Power, J.H. Shao, E.E. Wisniewski
ANL, Lemont, Illinois, USA
C.-J. Jing
Euclid TechLabs, Solon, Ohio, USA
X. Lu
Northern Illinois University, DeKalb, Illinois, USA

Funding: Research sponsored under Award No. DE-SC0015566 by U.S. Department of Energy, Office of Science, Office of High Energy Physics and Contract No. DE-AC02-06CH11357 by the Office of Science.
We present our recent results generating 510 MW of power at 11.7 GHz using a metamaterial-based metallic power-extractor for application in structure-based wakefield acceleration (SWFA). SWFA is a novel acceleration scheme in which high-charge electron bunches are passed through a power extractor structure to produce a high-intensity wakefield. This wakefield can then be used to accelerate a witness bunch in the same beamline or passed to a separate acceleration beamline. MIT’s approach uses a specialized metamaterial for the power extractor design. By using a metamaterial, we can overcome some of the challenges faced by other SWFA techniques. Here, we discuss the Stage 3 experiment. The Stage 1 and Stage 2 experiments successfully demonstrated the functionality of the metamaterial approach by generating high power RF pulses using the 65 MeV electron beam at the Argonne Wakefield Accelerator (AWA) facility. The 510 MW result from Stage 3 experiment is the highest power generated to-date for SWFA at AWA, and was enable by significant design improvements, including an all-copper structure, fully-symmetric coupler design, and breakdown risk-reduction treatment.

Poster MOPAB169 [8.882 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB169

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paper received ※ 08 May 2021 paper accepted ※ 16 July 2021 issue date ※ 25 August 2021

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MOPAB171

Numerical Simulation on Plasma-Based Beam Dumps Using Smilei

plasma, laser, electron, wakefield

582

S. Kumar, C. Davut, G.X. Xia
UMAN, Manchester, United Kingdom
A. Bonatto, C. Davut, L. Liang
The University of Manchester, Manchester, United Kingdom
A. Bonatto
Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil
B.S. Nunes
IF-UFRGS, Porto Alegre, Brazil
R.P. Nunes
UFRGS, Porto Alegre, Brazil

The active plasma beam dump utilizes a laser to generate a plasma wakefield and decelerate an externally injected beam to low energy. We use the particle-in-cell code "Smi-lei" for the investigation of electron beam energy loss in plasma. In this research work, we optimize the laser and plasma parameters to investigate the active plasma beam dump scheme. In doing so, most of the beam energy will be deposited in the plasma. The optimization strategy for the beam energy loss in plasma is presented.
*A. Bonatto, C. B. Schroeder et al., Physics of Plasmas 22 (8) 083106 (2015).
*G. Xia, A. Bonatto et al., Instruments 4 (2) 10 (2020).
*A Bonatto et al., J. Phys.: Conf. Ser. 1596 012058, 2020.

Poster MOPAB171 [0.756 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB171

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paper received ※ 15 May 2021 paper accepted ※ 24 May 2021 issue date ※ 26 August 2021

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MOPAB236

Ion Beam Dynamics in Linac-100 Facility at Jinr

linac, cavity, emittance, rfq

767

S.M. Polozov, V.S. Dyubkov, Y. Lozeev, T.A. Lozeeva, A.V. Samoshin
MEPhI, Moscow, Russia

The heavy-ion linac LINAC-100 is a superconducting driver-accelerator proposed as one of the prospective projects at JINR. Its goal is to accelerate primary stable isotope CW high-intensity beams to energies up to 100 MeV/u*. This linac is discussed as the first stage of a new rare isotope facility DERICA (Dubna Electron-Radioactive Ion Collider fAcility), being under development at JINR since 2017**. LINAC-100 is supposed to work with a wide range of beams with A/Z 3.5/7, Uranium U³⁴⁺ being the heaviest. Its concept has undergone many changes, mostly considering stripping cells to increase accelerator efficiency. During the latest investigations of various stripping cells [***, ****], Uranium beam stripping at the energy 10 MeV/u and utilizing three adjacent charge states 59-61+ resulted in 60% output beam intensity preservation (or 30 pA overall output current). The current layout of the LINAC-100 is the following: one or two (separately for light and heavy ions) normal conducting front-end linacs, gas stripper cell at 10 MeV/u, and the SC section. In this paper three charge state Uranium beam dynamics in the current version of SC LINAC-100 section is presented.
*S Polozov 2020 PhysScr 95 084006
**A S Fomichev Phys Usp 62(7) 675-690 2019
***Tolstikhina I 2018 Basic At Int of Acc H Ions in Matter 98 1
**** W Barth J Phys Conf Ser 1350:012096

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB236

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paper received ※ 20 May 2021 paper accepted ※ 17 August 2021 issue date ※ 26 August 2021

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MOPAB241

Design of the Proton and Electron Transfer Lines for AWAKE Run 2c

plasma, electron, proton, experiment

778

R.L. Ramjiawan
JAI, Oxford, United Kingdom
S. Döbert, E. Gschwendtner, P. Muggli, F.M. Velotti, L. Verra
CERN, Meyrin, Switzerland
J.P. Farmer
MPI-P, München, Germany
P. Muggli
MPI, Muenchen, Germany

The AWAKE Run 1 experiment achieved electron acceleration to 2 GeV using plasma wakefield acceleration driven by 400 GeV, self-modulated proton bunches from the CERN SPS. The Run 2c phase of the experiment aims to build on these results by demonstrating acceleration to ~10 GeV while preserving the quality of the accelerated electron beam. To realize this, there will be an additional plasma cell, to separate the proton bunch self-modulation and the electron acceleration. A new 150 MeV beamline is required to transport and focus the witness electron beam to a beam size of several microns at the injection point. This specification is designed to preserve the beam emittance during acceleration, also requiring micron-level stability between the driver and witness beams. To facilitate these changes, the Run 1 proton transfer line will be reconfigured to shift the first plasma cell 40 m downstream. The Run 1 electron beamline will be adapted and used to inject electron bunches into the first plasma cell to seed the proton bunch self-modulation. Proposed adjustments to the proton transfer line and studies for the designs of the two electron transfer lines are detailed in this contribution.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB241

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paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 17 August 2021

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MOPAB275

Study on Supports of BPM Displacement Measurement System for HLS

simulation, factory, storage-ring, feedback

870

C.H. Wang, P. Lu, B.G. Sun, T.Y. Zhou
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: National Synchrotron Radiation Laboratory
HLS is the second-generation light source with energy of 800 MeV and emittance of less than 40 nm-rad. In order to improve the beam orbit stability and correct the errors introduced in the orbital feedback system due to movement of the vacuum chamber and BPM, a system for measuring BPM displacement will be built. It requires a high degree of mechanical and thermal stability for its supports. The support should have a higher eigen-frequency to minimize the amplification of ground vibration. In this paper, a series of simulation, including finite element analysis (FEA), measurement and analysis have been done upon the support to make sure it can meet the requirements of the stability of the BPM displacement measurement system.

Poster MOPAB275 [1.025 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB275

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paper received ※ 18 May 2021 paper accepted ※ 21 May 2021 issue date ※ 26 August 2021

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MOPAB319

Development of a Fast Betatron Tune and Chromaticity Measurement System for COSY

betatron, GUI, controls, resonance

983

P.J. Niedermayer, C. Böhme, B. Breitkreutz, V. Kamerdzhiev, A. Lehrach
FZJ, Jülich, Germany
A. Lehrach
RWTH, Aachen, Germany

A fast tune measurement is developed for the Cooler Synchrotron COSY at the Institut für Kernphysik of Forschungszentrum Jülich. Betatron oscillations of the beam are excited with a band-limited RF signal via a stripline kicker. Resonant transverse oscillations are then observed using capacitive beam position monitors. Based on the bunch-by-bunch beam position data the betatron tune is determined. The usage of bunch-by-bunch data is characteristic of the new system. It allows for a discrete tune measurement within a few milliseconds, as well as continuous tune monitoring during beam acceleration. The high precision tune measurement also enables determination of the beam chromaticity. Therefore, the beam momentum is varied by means of the RF frequency and the subsequent tune change is determined. For routine use during beam operation and experiments, the developed method is integrated into the control system.

Poster MOPAB319 [1.209 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB319

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paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 12 August 2021

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MOPAB325

Development of Bunch Width Monitor with High Time Resolution for Low Emittance Muon Beam in the J-PARC Muon g-2 / EDM Experiment

emittance, experiment, linac, laser

1004

M. Yotsuzuka, T. Iijima, K. Inami, Y. Sue, K. Sumi
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
T. Iijima
KMI, Nagoya, AIchi Prefecture, Japan
Y. Kondo
JAEA, Ibaraki-ken, Japan
T. Mibe
KEK, Tsukuba, Japan
Y. Nakazawa
Ibaraki University, Ibaraki, Japan
M. Otani, N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Takeuchi
Kyushu University, Fukuoka, Japan
H.Y. Yasuda
University of Tokyo, Tokyo, Japan

The J-PARC muon g-2/EDM experiment plans to measure the muon anomalous magnetic moment and electric dipole moment sensitive to new physics with high precision. This experiment uses a novel method using the low-emittance muon beam achieved by cooling and re-acceleration. In the muon linac consisting of four different accelerating cavities, the main cause of the emittance growth is the beam mismatch between the different cavities. Especially for the cavity in the low-beta section (ß=0.08-0.27), the longitudinal acceptance is narrow and beam mismatch has a significant impact. In order to perform beam matching in the low-beta cavity, a new beam monitor that can measure the low-emittance muon beam with high time resolution is required. Therefore, we developed a bunch width monitor (BWM) using a microchannel plate. The time resolution of the BWM was measured to be 40 picoseconds on the test bench using a picosecond pulse laser. It means that the BWM is possible to perform diagnosis with a phase accuracy of 1% for the acceleration phase of 324 MHz. We also evaluated factors that limit the current time resolution. In this presentation, the results of an evaluation of the BWM are reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB325

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paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 10 August 2021

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MOPAB352

High Power Test of a Dielectric Disk Loaded Accelerator for a Two Beam Wakefield Accelerator

wakefield, impedance, linear-collider, multipactoring

1096

B.T. Freemire, C.-J. Jing, S. Poddar
Euclid Beamlabs, Bolingbrook, USA
M.E. Conde, D.S. Doran, G. Ha, W. Liu, J.G. Power, J.H. Shao, C. Whiteford, E.E. Wisniewski
ANL, Lemont, Illinois, USA
M.M. Peng
TUB, Beijing, People’s Republic of China
E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA
Y. Zhao
Euclid TechLabs, Solon, Ohio, USA

Funding: Small Business Innovation Research Contract No. DE-SC0019864 U.S. DOE Office of Science Contract No. DE-AC02-06CH11357
As part of the Argonne 500 MeV short pulse Two Beam Wakefield Acceleration Demonstrator, a single cell X-band dielectric disk loaded accelerator (DDA) has been designed, fabricated, and tested at high power at the Argonne Wakefield Accelerator. The DDA should provide a short pulse (~20 ns) high gradient (>300 MV/m) accelerator while maintaining a reasonable r/Q and high group velocity. This will allow a significantly larger RF-to-beam efficiency than is currently possible for conventional accelerating structures. A low loss barium titantate ceramic, µ_r = 50, was selected, and a low temperature brazing alloy chosen to preserve the dielectric properties of the ceramic during brazing. High power testing produced breakdown at the triple junction, resulting from the braze joint design. No evidence of breakdown was observed on the iris of the disk, indicating that the maximum surface electric field on the dielectric was not reached. An improved braze joint has been designed and is in production, with high power testing to follow.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB352

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paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 21 August 2021

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MOPAB372

KARVE: A Nanoparticle Accelerator for Space Thruster Applications

ECR, radio-frequency, bunching, simulation

1151

J.W. Lewellen, L.R. Danielson, A. Essunfeld, J.A. Hollingsworth, M.A. Holloway
LANL, Los Alamos, New Mexico, USA
E.K. Lewis
NASA Johnson Space Center, Houston, Texas, USA

We present a concept for using RF-based acceleration of nanoparticles (NPs) as a means of generating thrust for future space missions: the Kinetic Acceleration & Resource Vector Engine (KARVE) thruster. Acceleration of nanoparticles (NPs) via DC accelerators has been shown to be feasible in dust accelerator labs such as the Heidelberg dust accelerator and the 3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies. In contrast, KARVE uses RF-driven acceleration of nanoparticles as the basis of a thruster design lying between chemical and ion engines in performance: more efficient than chemical engines in terms of specific impulse; and higher thrust than ion engines. The properties of multi-gap RF accelerators also allow an on-the-fly tradeoff between specific impulse and thrust.

Poster MOPAB372 [0.694 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB372

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paper received ※ 19 May 2021 paper accepted ※ 27 May 2021 issue date ※ 10 August 2021

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TUXB01

A 3 MeV All Optical Terahertz-Driven Electron Source at Tsinghua University

electron, laser, gun, GUI

1294

H. Xu, Y.-C. Du, W.-H. Huang, R.K. Li, C.-X. Tang, L.X. Yan
TUB, Beijing, People’s Republic of China

Funding: Science Challenge Project No.TZ2018005
Efficient acceleration and manipulation of high-brightness electron beams using terahertz waves in a compact setup has been recently a hot research topic in acceleration community. Previous works have achieved multi-MV/m acceleration gradient and dozens of keV energy gain while leaving room for further improvements in the high-energy regime. Here, we experimentally demonstrate whole-bunch acceleration and cascaded terahertz-driven acceleration of a relativistic beam with a record energy gain of 204 keV. A terahertz-driven all-optical electron source is now under development, which hold great potential for terahertz-driven ultrafast electron diffraction and related scientific discoveries.
* Xu, H., Yan, L., Du, Y. et al. Cascaded high-gradient terahertz-driven acceleration of relativistic electron beams. Nat. Photonics (2021). https://doi.org/10.1038/s41566-021-00779-x

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXB01

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paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 10 August 2021

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TUPAB027

Review of Accelerator Limitations and Routes to Ultimate Beams

collider, electron, luminosity, photon

1397

F. Zimmermann
CERN, Geneva, Switzerland
R.W. Aßmann
DESY, Hamburg, Germany
M. Bai, G. Franchetti
GSI, Darmstadt, Germany

Funding: This work was supported in part by the European Commission under the HORIZON 2020 project I.FAST, no. 101004730.
Various physical and technology-dependent limits are encountered for key performance parameters of accelerators such as high-gradient acceleration, high-field bending, beam size, beam brightness, beam intensity and luminosity. This paper will review these limits and the associated challenges. Possible figures-of-merit and pathways to ultimate colliders will also be explored.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB027

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paper received ※ 16 May 2021 paper accepted ※ 02 August 2021 issue date ※ 23 August 2021

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TUPAB079

Using ER@CEBAF to Show that a Multipass ERL Can Drive an XFEL

FEL, operation, controls, electron

1555

G. Perez-Segurana
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
I.R. Bailey, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom
I.R. Bailey
Lancaster University, Lancaster, United Kingdom
R.M. Bodenstein, S.A. Bogacz, D. Douglas, Y. Roblin, T. Satogata
JLab, Newport News, Virginia, USA
T. Satogata
ODU, Norfolk, Virginia, USA
P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

A multi-pass recirculating superconducting CW linac offers a cost effective path to a multi-user facility with unprecedented scientific and industrial reach over a wide range of disciplines. We propose such a facility as an option for a potential UK-XFEL. Energy Recovery enables multi-MHz FEL sources, for example, an X-ray FEL oscillator or regenerative amplifier FEL. Additionally, combining with external lasers and/or self-interaction would provide access to MeV and GeV gamma-rays via inverse Compton scattering at high average power for nuclear and particle physics applications. An opportunity exists to demonstrate the necessary point-to-parallel longitudinal matches to drive an XFEL and successfully energy recover at the upcoming 5-pass up, 5-pass down Energy Recovery experiment on CEBAF at JLab termed ER@CEBAF. We show candidate matches and simulations supporting the minimal necessary modifications to CEBAF this will require. This includes linearisation of the longitudinal phase space in the injector and a reduction in the dispersion of the arcs, both of which increase the energy acceptance of CEBAF. We expect to commence initial tests of these adaptations on CEBAF during 2021.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB079

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paper received ※ 17 May 2021 paper accepted ※ 27 July 2021 issue date ※ 17 August 2021

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TUPAB095

Arbitrary Longitudinal Pulse Shaping with a Multi-Leaf Collimator and Emittance Exchange

wakefield, plasma, laser, emittance

1600

N. Majernik, G. Andonian, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
D.S. Doran, G. Ha, J.G. Power, E.E. Wisniewski
ANL, Lemont, Illinois, USA
R.J. Roussel
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA

Funding: DOE HEP Grant DE-SC0017648, and National Science Foundation Grant No. PHY-1549132
Drive and witness beams with variable current profiles and bunch spacing can be generated using an emittance exchange beamline (EEX) in conjunction with transverse masks. Recently, this approach was used to create advanced driver profiles and demonstrate record-breaking plasma wakefield transformer ratios [Roussel, R., et al., Phys. Rev. Lett. 124, 044802 (2020)], a crucial advancement for effective witness acceleration. Presently, these transverse masks are individually laser cut, making the refinement of beam profiles a slow process. Instead, we have proposed the used of a UHV compatible multileaf collimator (MLC) to replace these masks. An MLC permits real-time adjustment of the beam masking, permitting faster optimization in a manner highly synergistic with machine learning. Beam dynamics simulations have shown that practical MLCs offer resolution that is functionally equivalent to that offered by the laser cut masks. In this work, the engineering considerations and practical implementation of such a system at the AWA facility are discussed and the results of benchtop tests are presented.
* Roussel, Ryan, et al. PRL 124.4 (2020): 044802

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB095

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paper received ※ 19 May 2021 paper accepted ※ 20 July 2021 issue date ※ 29 August 2021

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TUPAB116

Toward THz Coherent Undulator Radiation Experiment with a Combination of Velocity Bunchings

radiation, undulator, electron, bunching

1663

Y. Sumitomo, K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, T. Tanaka
LEBRA, Funabashi, Japan

Funding: Japan Society for the Promotion of Science (JSPS), Grant-in-Aid for Scientific Research (KAKENHI), Grant Number JP19K12631.
We have launched a research program to generate the THz coherent undulator radiations, following the proposal of the combination of velocity bunchings * at Nihon University. The combination of velocity bunchings is an efficient way of bunch compression allowing a range of energy choices, in other words, a range of quasi-monochromatic radiation wavelengths generated at the undulator. In addition to the existing wideband THz light sources (0.1 - 2 THz) by the coherent edge and transition radiations currently available at Nihon Univ., the development of a high peak-power and quasi-monochromatic coherent radiation should accelerate the activities including the material science related to the THz bandwidths. In this presentation, we illustrate the program and report the current status of the experiment.
* Y. Sumitomo et al., J. Phys. Conf. Ser., vol. 1067, p. 032017, 2018.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB116

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paper received ※ 19 May 2021 paper accepted ※ 15 June 2021 issue date ※ 15 August 2021

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TUPAB145

Methods for Numerical Noise Mitigation in Quasistatic Three-Dimensional Particle-in-Cell Code LCODE3D

plasma, simulation, wakefield, electron

1725

I.Yu. Kargapolov, K.V. Lotov, A. Sosedkin
Budker INP & NSU, Novosibirsk, Russia
I.A. Shalimova
ICM&MG SB RAS, Novosibirsk, Russia
I.A. Shalimova, P.V. Tuev
NSU, Novosibirsk, Russia
P.V. Tuev
BINP SB RAS, Novosibirsk, Russia

We discuss a new quasistatic 3D particle-in-cell code LCODE3D for simulating plasma wakefield acceleration, which is a modified version of the quasistatic 2D3V code LCODE, focus on the numerical noise of the plasma solver and propose methods for reducing it. We compare different particle shape functions, as these functions affect the code stability. We also introduce the so-called dual plasma approach, which improves stability and dampens small-scale noise. After applying the proposed methods, the results of the new code closely agree with LCODE simulation results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB145

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paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 25 August 2021

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TUPAB155

Obtaining Accelerated Electron Bunch of High Quality in Plasma Wakefield Accelerator

plasma, wakefield, electron, accelerating-gradient

1744

R.T. Ovsiannikov
KhNU, Kharkov, Ukraine
I.P. Levchuk (Yarovaya), V.I. Maslov, I.N. Onishchenko
NSC/KIPT, Kharkov, Ukraine

Funding: "This work is supported by National Research Fundation of Ukraine "Leading and Young Scientists Research Support", grant agreement # 2020.02/0299."
Earlier, high-gradient accelerating electrons of a relativistic beam was demonstrated. However, due to dynamic processes in the plasma, there are problems in maintaining the small size and small energy spread of the accelerated electron bunch while maintaining sufficient values of the accelerating wakefields. Also, the question arises about the values of the limiting bunch dimensions at which the accelerating process is stable. To form a stable accelerated electron bunch, a method is usually used that involves the formation of the same accelerating fields at the location of the bunch. The same fields (plateau due to beam loading (see *, **)) in the region of the accelerated bunch allow all its parts to move as a whole, and ensure the preservation of the spatial distribution of electrons over time, which, in fact, means an accelerated beam of good quality. In this report, the problem of electron bunch accelerating by a short or long electron driver-bunch is considered.
* Romeo S., Ferrario M., Rossi A.R. Phys. Rev. Accel. Beams. 23 (2020) 071301.
** Maslov V.I. et al. Problems of Atomic Science and Technology. 6 (2020) 47.

Poster TUPAB155 [1.723 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB155

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paper received ※ 18 May 2021 paper accepted ※ 16 June 2021 issue date ※ 23 August 2021

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TUPAB156

Optimal Field Shape, Accelerating Positron Bunch in Plasma Wakefield

plasma, wakefield, electron, positron

1747

R.T. Ovsiannikov
KhNU, Kharkov, Ukraine
I.P. Levchuk (Yarovaya), V.I. Maslov, I.N. Onishchenko
NSC/KIPT, Kharkov, Ukraine

Funding: This work is supported by National Research Fundation of Ukraine "Leading and Young Scientists Research Support", grant agreement # 2020.02/0299.
The quality of the electron or positron beam, accelerated in plasma accelerators, is still insufficient for applications. Accurate control over the properties of the electron or positron beam is a key issue for wakefield plasma accelerators. The effect of the presence of a witness-beam (the effect of the spatial charge distribution of the witness beam) (see [*, **]) to compensate the energy spread of the positron beam in plasma wakefield accelerators has been studied. This paper presents the results of a numerical simulation on the optimization of the parameters of the driver-bunch and witness-bunch for the formation of a self-consistent longitudinal distribution of the accelerating plateau-type field, which leads to the same values of the wakefield for the whole bunch of accelerated particles and minimizing bunch degradation during acceleration by means of an ion-driver-bunch with external injection into the plasma wake accelerator. The dependence of the longitudinal distribution of the accelerating wakefield on the density and shape of the accelerated bunch in the blowout regime was investigated. Plateau formation and energy spread compensation were observed.
* Romeo S., Ferrario M., Rossi A.R. Phys. Rev. Accel. Beams. 23 (2020) 071301.
** Katsouleas T. et al. Particle Accelerators. 22 (1987) 81.

Poster TUPAB156 [1.200 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB156

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paper received ※ 18 May 2021 paper accepted ※ 16 June 2021 issue date ※ 25 August 2021

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TUPAB157

Obtaining Long Accelerated Electron Bunch of Good Quality in Plasma Wakefield Accelerator at High Transformer Ratio

wakefield, plasma, electron, simulation

1750

R.T. Ovsiannikov
KhNU, Kharkov, Ukraine
I.P. Levchuk (Yarovaya), V.I. Maslov, I.N. Onishchenko
NSC/KIPT, Kharkov, Ukraine

Funding: "This work is supported by National Research Fundation of Ukraine "Leading and Young Scientists Research Support", grant agreement # 2020.02/0299."
The efficiency of electron acceleration by a wakefield, excited in a plasma by an electron bunch, is determined by the transformer ratio (see *, **). The transformer ratio is the ratio of energy acquired by the witness to energy lost by the driver. The transformer ratio can be increased by shaping driver-bunch. In this work, using a non-linear version of the 2d3v code lcode (see ***), numerical simulation of excitation of a wakefield in a plasma in blowout regime by a shaped relativistic electron bunch was performed. There is also the problem of maintaining the small dimension and small energy spread of the accelerated electron bunch while maintaining sufficient values of the accelerating gradient and the transformer ratio. Also, the question arises about the values of the limiting dimension of the witness-bunch at which the acceleration process is stable. Numerical simulation solves the problem of electron bunch acceleration of the best quality with simultaneous maximization of the transformer ratio and maximization of the witness bunch length, at which the accelerating gradient and the focusing force are constant.
*Maslov V.I. et al. Problems of Atomic Science and Technology. 4 (2012) 128.
**Baturin S.S., Zholents A. Phys. Rev. ST Accel. Beams. 20 (2017) 061302.
***Lotov K.V. Phys. Plasmas. 5 (1998) 785.

Poster TUPAB157 [1.920 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB157

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paper received ※ 18 May 2021 paper accepted ※ 23 June 2021 issue date ※ 30 August 2021

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TUPAB158

Electron Witness Constraints for AWAKE

emittance, plasma, wakefield, electron

1753

J.P. Farmer, P. Muggli
MPI-P, München, Germany
E. Gschwendtner
CERN, Meyrin, Switzerland
L. Liang
The University of Manchester, Manchester, United Kingdom
M.S. Weidl
MPI/IPP, Garching, Germany

The AWAKE project at CERN successfully demonstrated the use of a proton driver to accelerate an electron witness in plasma*. One of the key goals for AWAKE Run2 is to better control this acceleration, separating the proton-beam-modulation and electron-acceleration stages in order to achieve high energy electrons with high beam quality. Controlled acceleration additionally requires careful tuning of the witness bunch parameters at the injection point. In this work, we use particle-in-cell simulations to study the tolerances for this matching, and discuss techniques to loosen these constraints.
*Adli et al. (AWAKE Collaboration), Nature (2018)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB158

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paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 11 August 2021

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TUPAB159

Awake Run 2 at CERN

plasma, electron, experiment, proton

1757

E. Gschwendtner
CERN, Meyrin, Switzerland

The AWAKE Run 2 experiment, starting in 2021 at CERN, aims to achieve high-charge bunches of electrons accelerated to high energy (~10 GeV) while maintaining beam quality. AWAKE Run 2 also aims to show that the process is scalable so that, by the end of the run, the AWAKE-scheme technology could be used for first particle physics applications. The first two phases of Run 2 include the investigation of the seeding of the proton bunch self-modulation with the current electron beam in the existing AWAKE facility and the test of a second new plasma source with a density step allowing to maintain strong accelerating fields. In the third phase of Run 2, electrons with an energy of 150 MeV, produced in a newly installed electron source, will be injected into a second plasma source and accelerated to high energies (several GeVs) while keeping good emittance. In the fourth phase, it is planned to replace the second plasma source with a scalable one, which eventually could be used for long-distance acceleration and first applications. In this paper, we present the program of the four phases of AWAKE Run 2, the technical challenges and the proposed schedule.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB159

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paper received ※ 17 May 2021 paper accepted ※ 11 June 2021 issue date ※ 19 August 2021

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TUPAB174

Basic Design Study for Disk-Loaded Structure in Muon LINAC

accelerating-gradient, linac, impedance, experiment

1801

K. Sumi, T. Iijima, K. Inami, Y. Sue, M. Yotsuzuka
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
H. Ego, T. Mibe, M. Yoshida
KEK, Ibaraki, Japan
T. Iijima
KMI, Nagoya, AIchi Prefecture, Japan
Y. Kondo
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Nakazawa
Ibaraki University, Hitachi, Ibaraki, Japan
M. Otani, N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Takeuchi
Kyushu University, Fukuoka, Japan
H.Y. Yasuda
University of Tokyo, Tokyo, Japan

The world’s first disk-loaded structure (DLS) at the high-velocity part of a muon LINAC is under development for the J-PARC muon g-2/EDM experiment. We have simulated the first designed constant impedance DLS to accelerate muons from ß = 0.7 to 0.94 at an operating frequency of 1296 MHz and a phase of -10 degrees to ensure longitudinal acceptance and have shown the quality of the beam meets our requirements. Because the structure needs a high RF power of 80 MW to generate a gradient of 20 MV/m, a constant gradient DLS with the higher acceleration efficiency is being studied for lower operating RF power. In this poster, we will show the cell structure design yielding a gradient of 20 MV/m with lower RF power.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB174

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paper received ※ 19 May 2021 paper accepted ※ 31 August 2021 issue date ※ 18 August 2021

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TUPAB178

Recommissioning of the CRYRING@ESR Electron Cooler

electron, experiment, target, operation

1816

C. Krantz, Z. Andelkovic, C. Dimopoulou, W. Geithner, T. Hackler, F. Herfurth, R. Hess, M. Lestinsky, E. Menz, A. Reiter, J. Roßbach, C. Schroeder, A. Täschner, G. Vorobjev
GSI, Darmstadt, Germany
C. Brandau, S. Schippers
Justus-Liebig-University Giessen, I. Physics Institute, Atomic and Molecular Physics, Giessen, Germany
V. Hannen, D. Winzen
Westfälische Wilhelms-Universität Münster, Institut für Kernphysik, Münster, Germany
C. Weinheimer
Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany

Funding: Parts of this work have been supported by the German Federal Ministry of Education and Research (BMBF) under contract numbers 05P19PMFA1 and 05P19RGFA1.
The heavy-ion storage ring CRYRING has been recommissioned downstream of GSI’s ESR, which it complements as dedicated low-energy machine. A key element of CRYRING@ESR is its electron cooler, which features one of the coldest electron beams available. This enables efficient phase-space cooling and, in addition, provides very high energy resolution when used as internal electron target. We report on technical upgrades that have been made as part of the re-installation of the cooler at GSI/FAIR and share first results obtained after recommissioning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB178

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paper received ※ 18 May 2021 paper accepted ※ 16 June 2021 issue date ※ 25 August 2021

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TUPAB186

Longitudinal Dynamics in the Prototype vFFA Ring for ISIS2

extraction, bunching, injection, neutron

1834

D.J. Kelliher, J.-B. Lagrange, S. Machida, C.R. Prior, C.T. Rogers
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
A.P. Letchford, J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
E. Yamakawa
JAI, Egham, Surrey, United Kingdom

A vertical Fixed Field Accelerator (vFFA) is a candidate for a future high-power (MW-class) spallation source at ISIS. In order to assess the feasibility of this novel ring, a prototype is currently being designed. Here we consider the longitudinal dynamics in the prototype ring. A key requirement of future neutron spallation sources is flexibility of operation to best serve multiple target stations. Beam stacking allows a rapid cycling, high intensity machine to operate at lower repetition rates but with higher peak output. Here we show how beam stacking can be realised in the vFFA while minimising the peak RF voltage required.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB186

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paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 23 August 2021

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TUPAB188

InnovaTron: An Innovative High-Intensity Industrial Cyclotron for Production of Tc-99m and Other Frontier Medical Radioisotopes*

cyclotron, extraction, ion-source, proton

1841

G. D’Agostino, Q. Flandroy, E. Forton, W.J.G.M. Kleeven, J. Mandrillon, V. Nuttens, E. van der Kraaij
IBA, Louvain-la-Neuve, Belgium

Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 886190.
Tc-99m is the most used radioisotope in nuclear medicine. It is almost exclusively produced with a few ageing research reactors worldwide. In response to growing concerns about Tc-99m availability and its increasing demand, alternative production routes are being explored. The EU-funded InnovaTron project aims at designing an innovative compact high-intensity self-extracting cyclotron able to deliver proton beams with currents up to 5 mA or more for the direct production of Tc-99m. It could be also used for production of high quantities of other frontier medical radioisotopes. The proton beams exit without using an electrostatic deflector to overcome its current limitations. A prototype cyclotron was built by IBA in 2001. Currents up to 2 mA were extracted from it. However, at higher intensities, the extraction efficiency was not higher than 70-75% and the extracted emittance was rather large. The InnovaTron project will implement new technological solutions in the self-extracting cyclotron to be used for large-scale industrial applications. An overview on the InnovaTron project is here presented together with the first simulation results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB188

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paper received ※ 18 May 2021 paper accepted ※ 01 June 2021 issue date ※ 25 August 2021

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TUPAB196

Achievement of 100-kW Beam Operation in CSNS/RCS

injection, MMI, space-charge, bunching

1869

S.Y. Xu, Y.W. An, J. Chen, L. Huang, M.Y. Huang, Y. Li, S. Wang
IHEP, Beijing, People’s Republic of China
H.Y. Liu, X.H. Lu
IHEP CSNS, Guangdong Province, People’s Republic of China

The China Spallation Neutron Source (CSNS) is an accelerator-based science facility. CSNS is designed to accelerate proton beam pulses to 1.6 GeV kinetic energy, striking a solid metal target to produce spallation neutrons. CSNS has two major accelerator systems, a linear accelerator (80 MeV Linac) and a 1.6 GeV rapid cycling synchrotron(RCS). The RCS accumulates and accelerates the proton beam to 1.6 GeV and then extracts the beam to the target at the repetition rate of 25 Hz. The Beam commissioning of CSNS/RCS had been started since April 2017. The most important issue in high-power beam commissioning is the beam loss control, as well as the control of induced activities, to meet the requirement of manual maintenance. A series of beam loss optimization work had been done to reduce the uncontrolled beam loss. At the end of February 2020, the CSNS reached the design beam power of 100 kW with very low uncontrolled beam loss.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB196

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paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 28 August 2021

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TUPAB201

Vacuum Tube Operation Tuning for a High Intensity Beam Acceleration in J-PARC RCS

vacuum, operation, electron, controls

1884

M. Yamamoto, M. Nomura, H. Okita, T. Shimada, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii
KEK, Tokai, Ibaraki, Japan

Tetrode vacuum tubes in the J-PARC RCS are used under a reduced filament voltage condition compared with the rating value to prolong the tube life time. One tube reached the end of life in 2020; it was the first case in the RCS after 60,000 hours operation time. This means the reduced filament voltage works well because the tube has been running beyond an expected life time suggested by the tube manufacturer. However, an electron emission from the filament is decreased by the reduced filament voltage. Although the large amplitude of the anode current is necessary for the high intensity beam acceleration to compensate an wake voltage, a solid-state amplifier to drive a control grid circuit almost reaches the output power limit because of the poor electron emission. We changed the filament voltage reduction rate from 15 % to 5 %; the required power of the solid-state amplifier was fairly reduced, whereas the accelerated beam power was same. We will describe the measurement results of the vacuum tube parameters in terms of the filament voltage tuning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB201

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paper received ※ 17 May 2021 paper accepted ※ 17 June 2021 issue date ※ 02 September 2021

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TUPAB209

The Particle Tracking Code Fixfield

lattice, FFAG, quadrupole, focusing

1905

J.-B. Lagrange
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

FixField is a code developed to track particles in Fixed Field alternating gradient Accelerators (FFAs). This paper discusses the structure and features of the code.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB209

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paper received ※ 19 May 2021 paper accepted ※ 02 July 2021 issue date ※ 25 August 2021

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TUPAB246

Numerical Simulation and Beam-Dynamics Study of a Hollow-Core Woodpile Coupler for Dielectric Laser Accelerators

GUI, photon, laser, electron

2022

G.S. Mauro, D. Mascali, G. Sorbello, G. Torrisi
INFN/LNS, Catania, Italy
A. Bacci
INFN/LASA, Segrate (MI), Italy
C. De Angelis, A. Locatelli
University of Brescia, Brescia, Italy
A.R. Rossi
INFN-Milano, Milano, Italy
G. Sorbello
University of Catania, Catania, Italy

Hollow core dielectric microstructures powered by lasers represent a new and promising area of accelerator research thanks to the higher damage threshold and accelerating gradients with respect to metals at optical wavelengths. In this paper we present the design of a dielectric Electromagnetic Band Gap (EBG) mode converter for high-power coupling of the accelerating mode in Dielectric Laser Accelerators (DLAs). The design is wavelength-independent, and here we propose an implementation operating at 90.505 GHz (wavelength 3.3 mm) based on a silicon woodpile structure. The coupler is composed by two perpendicularly coupled hollow-core waveguides: a TE-like mode waveguide (excited from RF/laser power) and a TM-like mode accelerating waveguide. The structure has been numerically designed and optimized, presenting Insertion Losses (IL) < 0.3 dB and an efficient mode conversion in the operating bandwidth. The properties and effectiveness of the confined accelerating mode have been optimized in order to derive the needed accelerating gradient. The simulated electric field has been used as input for Astra beam-dynamics simulations in order to compute the beam properties.

Poster TUPAB246 [2.209 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB246

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paper received ※ 18 May 2021 paper accepted ※ 27 July 2021 issue date ※ 13 August 2021

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TUPAB247

Influence of the Profile of the Dielectric Structure on the Electric Fields Excited by a Laser in Dielectric Accelerators Based on Chip

electron, laser, experiment, simulation

2026

A. Vasyliev, O.O. Bolshov, K. Galaydych, A.I. Povrozin, G.V. Sotnikov
NSC/KIPT, Kharkov, Ukraine

Funding: The National Research Foundation of Ukraine, program "Leading and Young Scientists Research Support" (project # 2020.02/0299).
To provide experimental researches at the NSC KIPT theoretical studies and computations of the electron acceleration in a dielectric laser accelerator have been carried out. Laser accelerator consists of two periodic quartz structures on diffraction gratings or Chips, symmetrically located along both sides of the vacuum accelerating channel. Using PIC numerical simulations, electromagnetic fields excited by laser radiation with a wavelength of 800 nm in dielectric laser accelerators were investigated. The influence of the shape and depth of the profile of diffraction gratings or Chip structures on the distribution of the electric field in the interaction space has been studied. For modeling, different types of profiles were taken, both in serial and a unique structure. In consequence of the analysis of the obtained results, estimated efficiency of acceleration was defined for each type of profile. The rectangular profile of the diffraction grating with the maximum accelerating gradient was selected as optimal for the next experiments.

Poster TUPAB247 [1.195 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB247

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paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 11 August 2021

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TUPAB249

Diffraction at the Open-Ended Dielectric-Loaded Circular Waveguide

GUI, radiation, wakefield, electron

2033

S.N. Galyamin, A.V. Tyukhtin, V.V. Vorobev
Saint Petersburg State University, Saint Petersburg, Russia

Funding: Work supported by Russian Science Foundation (Grant No. 18-72-10137).
Contemporary beam and THz technologies are tightly interlaced during last years. Strong THz fields allow realization of THz driven electron guns, THz bunch compression, streaking* and THz driven wakefield acceleration**. Inversely, dielectric capillaries similar to those used for THz bunch manipulation can be in turn utilized for development of high-power narrow-band THz sources***. Mentioned cases involve interaction of THz waves and particle bunches with an open end of certain dielectric loaded waveguide structure, most frequently a circular capillary. For further development of the discussed prospective topics a rigorous approach allowing analytical investigation of both radiation from open-ended capillaries and their excitation by external source would be extremely useful. We present an elegant and efficient rigorous method for solving circular open-ended dielectric-loaded waveguide diffraction problems based on Wiener-Hopf technique. We deal with the case of uniform dielectric loading and internal excitation by a waveguide mode. S-parameters, near-field and far-field distributions are presented. The obtained results can be also applied to the narrow band wakefield.
* L. Zhao et al., Phys. Rev. Lett., 124, 054802 (2020).
** M.T. Hibberd et al., Nat. Photonics, 14, 755-759 (2020).
*** D. Wang et al., Rev. Sci. Instr., 89(9), 093301 (2018).

Poster TUPAB249 [2.160 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB249

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 21 August 2021

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WEPAB017

General Approach to Physics Limits of Ultimate Colliders

collider, luminosity, plasma, radiation

2624

V.D. Shiltsev
Fermilab, Batavia, Illinois, USA

The future of the particle physics is critically dependent on feasibility of future energy frontier colliders. The concept of the feasibility is complex and includes at least three factors: feasibility of energy, feasibility of luminosity, and feasibility of cost and construction time. Here we discuss major beam physics limits of ultimate accelerators, take a look into ultimate energy reach of possible future colliders. We also foresee a looming paradigm change for the HEP research as the thrust for higher energies by necessity will mean lower luminosity.

Poster WEPAB017 [1.720 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB017

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paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 17 August 2021

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WEPAB055

Development of a Linac for Injection of Ultrashort Electron Bunches Into Laser Plasma Electron Accelerators

electron, laser, plasma, linac

2725

S. Masuda, N. Kumagai, T. Masuda, Y. Otake
JASRI, Hyogo, Japan
Y. Koshiba, S. Otsuka
Waseda University, Tokyo, Japan
T. Sakai, T. Tanaka
LEBRA, Funabashi, Japan
K. Sakaue
The University of Tokyo, The School of Engineering, Tokyo, Japan

Funding: This work is supported by JST-Mirai Program Grant Number JPMJMI17A1, Japan.
We are developing a C-band linac that produces ultrashort electron bunches as an injector for laser plasma accelerators. A plasma wave excited by a high intense ultrashort laser pulse has a wavelength of the order of 10 to 100 fs and transverse dimensions of the order of 10 to 100 um. To inject the bunch into a proper phase of the plasma wave, a length and transverse sizes of the bunch must be much smaller than the plasma wave structure. A laser triggered photo cathode electron RF-gun and a 2pi/3 mode traveling wave buncher with 24 cells for ultrashort electron bunch production have been developed based on electron beam tracking simulations that show the bunch length is less than 10 fs with a charge of 100 fC at a focus on the plasma wave. The simulations also show that sufficiently small transverse sizes of the bunch at the focus can be obtained by a Q triplet. A highly accurate timing lower than the plasma wavelength (~10fs) is required for the synchronization between the electron bunch injection and the plasma wave excitation. An RF master oscillator with low SSB phase noise (-150dBc/Hz@10MHz) has been developed for the synchronization. We will report present development status.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB055

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paper received ※ 19 May 2021 paper accepted ※ 15 July 2021 issue date ※ 29 August 2021

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WEPAB143

Sub-MeV Ion Generation by Standing Wave Excitation of Ionized Gases

electron, plasma, laser, simulation

2951

Sz. Turnár, G. Almási, J. Hebling, Cs. Korpa, M.I. Mechler, L. Pálfalvi, Z. Tibai
University of Pecs, Pécs, Hungary

Funding: Hungarian Scientific Research Fund (OTKA) (125808, 129134) ÚNKP-20-3 New National Excellence Program of the Ministry for Innovation and Technology from the source of the National Research
Many ion acceleration techniques have been suggested and thoroughly studied in the last two decades*. One of the promising techniques is the Coulomb explosion acceleration (CEA)**. Using CEA in clusters could result in symmetric acceleration if there are not any other significant mechanisms. We proposed a THz-driven accelerator scheme that is based on CEA in proton, deuterium and heavy water gas plasmas. Two counter-propagating THz pulses are focused to the ionized region of the gas jet. Following the ripping of the electrons from the gas plasmas by ultrafast standing waves, the Coulomb explosion accelerates the positive ions. According to our calculation, using 2 x 34 mJ THz pulses electrons and protons with 1.1 nC charge are accelerated up to 0.4 MeV and 0.1 MeV, respectively. The total energy of the particles is 0.7 % of the energy of the THz pulses. We examined the effect of the initial bunch charge, bunch size and shape on the final energy spectra and the directional distribution of the particles. Our presented technique is scalable from a few µm to a few thousand µm driving wavelengths and can be used for electron and heavy-ion acceleration.
*J. Badziak, IOP Conf. Series: J Phys: Conf. Series 959, 012001 (2018).
** M. Murakami and K. Mima, Phys. of Plasmas 16, 103108 (2009).

Poster WEPAB143 [3.467 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB143

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paper received ※ 19 May 2021 paper accepted ※ 07 June 2021 issue date ※ 15 August 2021

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WEPAB158

Compact Terahertz-Powered Electron Photo-Gun

electron, gun, cathode, injection

2983

T. Kroh, H. Çankaya, U. Demirbas, M. Fakhari, N.H. Matlis, M. Pergament, T. Rohwer
CFEL, Hamburg, Germany
R.W. Aßmann, H. Dinter, M.J. Kellermeier
DESY, Hamburg, Germany
M. Hemmer, F.X. Kärtner
Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
F.X. Kärtner
The Hamburg Center for Ultrafast Imaging, University of Hamburg, Hamburg, Germany

Funding: This work is supported by the Cluster of Excellence "CUI: Advanced Imaging of Matter" of the Deutsche Forschungsgemeinschaft (DFG) - EXC 2056 - project ID 390715994.
Novel accelerator concepts such as all-optical THz based compact accelerators promise to enable new science due to unique features such as reduced timing-jitter and improved space-charge broadening of the generated electron bunches. However, multi-keV electron photo-guns based on short single-cycle THz pulses for acceleration have not been demonstrated experimentally so far. Here, we present a modular THz-driven electron gun with both tunable interaction length and output orifice allowing optimization of the sub-mm interaction volume. First extraction of multi-keV electrons is demonstrated and the parameter space as well as resulting performance of the THz-driven gun by varying the timing of the two single-cycle THz pulses and the UV photo-excitation pulse are explored. Such compact gun prototypes are not only promising as injectors for compact THz-based LINACs but also as source for ultrafast electron diffraction experiments.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB158

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paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 30 August 2021

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WEPAB175

Simulation Study of Electron Beam Acceleration with Non-Gaussian Transverse Profiles for AWAKE Run 2

emittance, plasma, electron, wakefield

3012

L. Liang, G.X. Xia
The University of Manchester, Manchester, United Kingdom
J.P. Farmer
MPI-P, München, Germany
L. Liang, G.X. Xia
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: The authors would like to acknowledge the support from the Cockcroft Institute Core Grant and the STFC AWAKE Run 2 grant ST/T001917/1
In the physics plan for AWAKE Run 2, two known effects, beam loading the longitudinal wakefield and beam matching to the pure plasma ion channel, will be implemented for the better control of electron acceleration. It is founded in our study of beam matching that the transverse profile of the initial witness beam have a significant impact on its acceleration quality. In this paper, particle-in-cell (PIC) simulations are used to study factors that affect the acceleration quality of electron beams with different transverse profiles.

Poster WEPAB175 [1.860 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB175

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paper received ※ 10 May 2021 paper accepted ※ 25 June 2021 issue date ※ 02 September 2021

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WEPAB208

Energy Sweeping Beam Extraction by the Septum Magnet Assisted with Charge Exchange for a Hadron Therapy

extraction, septum, kicker, power-supply

3109

T.S. Dixit, A. Shaikh
SAMEER, Mumbai, India
T. Adachi, T. Kawakubo, K. Takayama
KEK, Ibaraki, Japan

An energy sweeping compact rapid cycling hadron therapy based on a fast cycling induction synchrotron has been proposed by KEK and SAMEER as the next generation of hadron therapy machine *. For energy sweep extraction, a C+5 beam is injected, captured and trapped in the barrier bucket. A fraction of the beam is continuously released from the barrier bucket by controlling the timing of barrier pulse generation. Released C+5 ions merge into the coasting beam and moves inwards with ramping of the guiding main magnets. Ions in the coasting beam eventually hit the carbon foil placed inside the beam chamber wall. As a result, C+5 is converted to C+6 and beam orbit is largely changed as it traverses through the downstream bending magnet. This notably facilitates C+6 beam extraction, resulting in a relatively small kick angle of the septum magnet. When the septum is excited in the same way as that of the main magnets, the extracted C+6 beam always places on the center of the irradiation beam line. LISE++ simulations demonstrated the charge exchange efficiency of almost 100 % for expected beam energy. The feasibility of the switching power supply for the septum magnet has been studied.
* PRAB 24, 011601 (2021)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB208

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paper received ※ 14 May 2021 paper accepted ※ 22 June 2021 issue date ※ 16 August 2021

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WEPAB209

Review of Medical Accelerator Development at Sameer, India

linac, electron, photon, cavity

3113

T.S. Dixit, N. Bansode, A.P. Bhagwat, S.T. Chavan, A.P. Deshpande, G. Gaikwad, S. Ghosh, R. Krishnan, C.S. Nainwad, G.D. Panchal, S.N. Pethe, K.A. Thakur, V.B. Ukey, M.M. Vidwans
SAMEER, Mumbai, India

Funding: Ministry of Electronics and Information Technology (MeitY), Government of India
At the Medical Electronics Division of SAMEER, R&D for the development of a 4 MeV energy electron linac for Cancer therapy was taken up in the late ’80s. An S-band standing wave side coupled structure operating at pi/2 mode was developed for electron acceleration. The linac was integrated with other subsystems in collaboration with CSIO and PGIMER and the first machine was commissioned at PGI, Chandigarh in 1990. Thereafter, a lot of modifications like energy, dose rate, iso-center height etc. were made in the system, and later 4 more machines were commissioned in hospitals for treatment. More than 1,50,000 patients have been treated using SAMEER’s 6 MeV oncology system. Subsequently, development of dual-mode and variable energy electron and photon output machines was undertaken. Two-photon energies of 6 and 15 MV and multiple electron energies starting from 6 to 18 MeV for treatment was offered from the linac. The electron energy variation was done using plunger mechanism in the side coupling cavity. This linac was successfully baked and RF tested for various parameters. This paper describes the experimental parameters achieved for both low and high energy dual-mode linac.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB209

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paper received ※ 14 May 2021 paper accepted ※ 07 July 2021 issue date ※ 13 August 2021

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WEPAB378

Near-Infrared Laser System for Dielectric Laser Acceleration Experiments at SINBAD

laser, experiment, electron, timing

3596

C. Mahnke, U. Grosse-Wortmann, I. Hartl, C.M. Heyl, Y. Hua, T. Lamb, Y. Ma, C. Mohr, J. Müller, S.H. Salman, S. Schulz, C. Vidoli
DESY, Hamburg, Germany
H. Çankaya
CFEL, Hamburg, Germany

The technique of dielectric laser acceleration (DLA) utilizes the strong field gradients generated by intense laser light near the surfaces of microscopic photonic structures, possibly allowing compact accelerator devices. We report on the infrared laser system at the SINBAD facility at DESY, where first DLA experiments with relativistic electrons pre-accelerated by the ARES linear accelerator started in late 2020. We constructed a low-noise Holmium fiber oscillator producing pulses at a wavelength of 2050 nm, seeding a Ho:YLF regenerative amplifier. Pulses of 2 mJ and 2 ps duration from the amplifier are transported over a distance of about 30 m to the DLA interaction point. The laser system is synchronized to the accelerator by locking the laser repetition rate to an RF master oscillator using an all-digital phase-locked loop, giving a residual timing jitter of about 45 fs. The digital locking scheme allows precise shifting of the relative timing between laser pulses and electrons without need for a dedicated optical delay line. It is planned to lock the system to the UV photocathode laser by means of an optical cross correlator further to improve the locking performance.

Poster WEPAB378 [1.445 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB378

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paper received ※ 19 May 2021 paper accepted ※ 22 June 2021 issue date ※ 18 August 2021

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WEPAB397

Design of the Two-Layer Girder for Accelerating Tube

neutron, ECR, operation, simulation

3636

X.J. Nie, H.Y. He, L. Kang
IHEP, Beijing, People’s Republic of China
J.X. Chen, L. Liu, R.H. Liu, C.J. Ning, A.X. Wang, G.Y. Wang, Y.J. Yu, J.S. Zhang, D.H. Zhu
IHEP CSNS, Guangdong Province, People’s Republic of China
J.B. Yu
DNSC, Dongguan, People’s Republic of China

An accelerating tube is one kind of important acceleration equipment of a linear accelerator. It is often made up of oxygen-free copper with a long tubular structure. It’s easy to suffer from deformation. Based on support requirements, the reasonable structure of the girder was obtained. Four supporting blocks were installed on the top surface of aluminum profile with the uniform distribution along the beam direction. The support strength with static condition and different working conditions were checked by ANSYS simulation calculation to ensure the stable operation of the girder. The two-layer girder can be used as a reference for other similar slender part for its simple structure and reliable support.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB397

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paper received ※ 14 May 2021 paper accepted ※ 01 September 2021 issue date ※ 22 August 2021

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THXC05

Simulation of Imaging Using Accelerated Muon Beams

simulation, linac, radio-frequency, scattering

3740

M. Otani
KEK, Tokai, Ibaraki, Japan
H.M. Miyadera
LANL, Los Alamos, New Mexico, USA
T. Shiba
Japan Atomic Energy Agency, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Muons are elementary particles with strong penetrating power and cosmic-ray muons have been utilized to see through large structures such as the pyramids. Recently, we have succeeded in accelerating muons using a radio-frequency accelerator, opening the door to new imaging techniques using accelerated muon beams. Currently, imaging with cosmic-ray muons is limited in imaging time and resolution by their intensity and energy fluctuations. The muon beams can have high intensity and monochromatic energy, allowing for better resolution imaging in less time. In this poster, imaging of spent nuclear fuel in casks using cosmic rays and muon beams, as well as imaging in other cases, will be evaluated and compared.

Poster THXC05 [2.560 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXC05

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paper received ※ 16 May 2021 paper accepted ※ 19 July 2021 issue date ※ 15 August 2021

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THPAB071

Physics Goals of DWA Experiments at FACET-II

experiment, wakefield, quadrupole, focusing

3922

J.B. Rosenzweig, H.S. Ancelin, G. Andonian, A. Fukasawa, C.E. Hansel, G.E. Lawler, W.J. Lynn, N. Majernik, J.I. Mann, P. Manwani, Y. Sakai, O. Williams, M. Yadav
UCLA, Los Angeles, California, USA
S.V. Baryshev
Michigan State University, East Lansing, Michigan, USA
S. Baturin
Northern Illinois University, DeKalb, Illinois, USA
M.J. Hogan, B.D. O’Shea, D.W. Storey, V. Yakimenko
SLAC, Menlo Park, California, USA

Funding: This work supported by DOE HEP Grant DE-SC0009914,
The dielectric wakefield acceleration (DWA) program at FACET produced a multitude of new physics results that range from GeV/m acceleration to the discovery of high field-induced conductivity in THz waves, and beyond, to a demonstration of positron-driven wakes. Here we review the rich program now developing in the DWA experiments at FACET-II. With increases in beam quality, a key feature of this program is extended interaction lengths, near 0.5 m, permitting GeV-class acceleration. Detailed physics studies in this context include beam breakup and its control through the exploitation of DWA structure symmetry. The next step in understanding DWA limits requires the exploration of new materials with low loss tangent, large bandgap, and improved thermal characteristics. Advanced structures with photonic features for mode confinement and exclusion of the field from the dielectric, as well as quasi-optical handling of coherent Cerenkov signals is discussed. Use of DWA for laser-based injection and advanced temporal diagnostics is examined.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB071

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paper received ※ 25 May 2021 paper accepted ※ 28 July 2021 issue date ※ 22 August 2021

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THPAB182

DC-280 Cyclotron for Factory of Super Heavy Elements, Experimental Results

cyclotron, experiment, ECR, injection

4126

V.A. Semin, S.L. Bogomolov, K. Gikal, G.G. Gulbekyan, I.A. Ivanenko, I.V. Kalagin, N.Yu. Kazarinov, V.I. Mironov
JINR, Dubna, Moscow Region, Russia
L.A. Pavlov
JINR/FLNR, Moscow region, Russia

The DC280 is the high current cyclotron with design beam intensities up to 10 pµA for ions with energy from 4 to 8 MeV/nucleon. It was developed and created at the FLNR JINR. The first was extracted from the cyclotron on January 17, 2019. Experiments on acceleration of 12C, 40Ar, 48Ca, 48Ti, 52Cr and 84Kr beams production were carried out. The following intensities of accelerated beam have been achieved: 10 pµA for 12C+2; 9,2 pµA for 40Ar+7; 7,1 pµA for 48Ca+10; 1,0 pµA for 48Ti+10; 2,4 pµA for 52Cr+10 and 1.43 pµA for 84Kr+14;. The accelerator has worked more than 9000 hours. The work of accelerator was stable and high efficiency. The total acceleration efficiency from ion source to transport channel was about 46%.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB182

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paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 21 August 2021

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THPAB202

Problem and Solution with the Longitudinal Tracking of the ORBIT Code

simulation, emittance, synchrotron, space-charge

4176

L.H. Zhang, J.Y. Tang
IHEP, Beijing, People’s Republic of China
Y.K. Chen
IHEP CSNS, Guangdong Province, People’s Republic of China
L.H. Zhang
University of Chinese Academy of Sciences, Beijing, People’s Republic of China

The ORBIT code has been widely used for beam dynamics simulations including injection and acceleration in high-intensity hadron synchrotrons. When the ORBIT’s 1D longitudinal tracking was employed for the acceleration process in CSNS/RCS, the longitudinal emittance in eV-s was found decreasing substantially during acceleration, though the adiabatic condition is still met during this process. This is against the Liouville theorem that predicts the preservation of the emittance during acceleration. The recent machine study in the accelerator and the simulations with a self-made code demonstrate that the longitudinal emittance is almost invariant, which further indicates that the ORBIT longitudinal tracking might be incorrect. A detailed check-over in the ORBIT code source finds that the longitudinal finite difference equation used in the code is erroneous when applied to an acceleration process. The new code format PyORBIT has the same problem. After the small secondary factor is included in the code, ORBIT can produce results keeping the longitudinal emittance invariant. This paper presents some details about the study.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB202

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paper received ※ 14 May 2021 paper accepted ※ 01 July 2021 issue date ※ 21 August 2021

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THPAB207

Beam Dynamics Simulation about the Dual Harmonic System by PyORBIT

simulation, bunching, synchrotron, space-charge

4194

H.Y. Liu, X.Y. Feng, L. Huang, M.T. Li, X.H. Lu
IHEP CSNS, Guangdong Province, People’s Republic of China
S. Wang, S.Y. Xu
IHEP, Beijing, People’s Republic of China

The space charge effect is a strong limitation in high-intensity accelerators, especially for low- and medium-energy proton synchrotrons. And for CSNS-II, the number of particles in the RCS is 3.9·10¹³ ppp, which is five times of CSNS. To mitigate the effects of the strong space charge effect, CSNS-II/RCS (Rapid Cycling Synchrotron) will use a dual harmonic system to increase the bunching factor during the injection and the initial acceleration phase. For studying the beam dynamics involved in a dual harmonic RF system, PyORBIT is used as the major simulation code, which is developed at SNS to simulate beam dynamics in accumulation rings and synchrotrons. We modified parts of the code to make it applicable to the beam dynamic in RCS. This paper includes the major code modification of the Dual Harmonic RF system and some benchmark results. The preliminary simulation results of the dual-harmonic system in CSNS-II/RCS simulated by the particle tracking code PyORBIT will also be discussed.

Poster THPAB207 [0.354 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB207

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paper received ※ 16 May 2021 paper accepted ※ 05 July 2021 issue date ※ 11 August 2021

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THPAB310

Automatic Correction System for the TLS Booster Linac Klystron Modulator

klystron, electron, booster, linac

4396

S.J. Huang, Y.K. Lin
NSRRC, Hsinchu, Taiwan

The aim of this article is to analyse the performance output of the klystron modulator, which is based on the observation of the output voltage and current performance of the linear-accelerator klystron modulator; we modify the operating-point parameters based on those results or assess whether the klystron needs to be replaced. For this purpose, we collect the observation data of the klystron performance; we then develop a program to adjust automatically the high-voltage setting of the klystron to ensure that the storage current maintains beam current 360 mA in the top-up mode operation.

Poster THPAB310 [0.785 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB310

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paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 13 August 2021

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THPAB317

Experiment and Simulation Study on the Capture and Acceleration Process of XiPAF Synchrotron

synchrotron, experiment, cavity, proton

4409

Y. Li, X. Guan, X.Y. Liu, M.W. Wang, X.W. Wang, Q.Z. Xing, Y. Yang, H.J. Yao, W.B. Ye, S.X. Zheng
TUB, Beijing, People’s Republic of China
W.L. Liu, D. Wang, Z.M. Wang, Y. Yang, M.T. Zhao
NINT, Shannxi, People’s Republic of China

The beam commissioning of the capture and acceleration process on the XiPAF (Xi’an 200MeV Proton Application Facility) synchrotron has been carried out. The efficiency of the experiment results has been compared with the simulation results. At present, the efficiency of the capture process with single-harmonic is about 73%, and the acceleration efficiency is about 82%, and the simulation results are 77% and 96% without space charge effect, respectively. In order to improve efficiency, dual-harmonic was used during the capture and acceleration process. During the experiment, the capture efficiency was increased by 5%, and the acceleration efficiency was increased by 4%. The capture efficiency decreases with the increase of the maximum RF voltages. We analyzed the reasons for the decrease in capture efficiency. In the next step, further verification will be carried out through experiments under different conditions.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB317

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paper received ※ 19 May 2021 paper accepted ※ 08 July 2021 issue date ※ 23 August 2021

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THPAB332

Development of a Pair of 182 GHz Two-Half Power Extractor and Accelerator for Short Pulse RF Breakdown Study

GUI, electron, wakefield, alignment

4435

J.H. Shao, J.G. Power
ANL, Lemont, Illinois, USA
R.B. Agustsson, S.V. Kutsaev, A.Yu. Smirnov
RadiaBeam, Santa Monica, California, USA

High-frequency structures are favorable in structure wakefield acceleration for their strong beam-structure interaction. Recent progress of advanced fabrication technologies, such as high-precision two-half milling and additive machining, has enabled experimental research of mm-wave/THz structures. In this work, we have designed a pair of 182 GHz two-half copper power extractor and accelerator for short pulse RF breakdown study. When driven by a 182 GHz 4-bunch train with 4 nC total charge and 0.3 mm rms bunch length, the power extractor will generate 0.4 ns ~8 MW RF pulses and the corresponding gradient in the single-cell accelerator will reach ~460 MV/m. RF and mechanical design of the proof-of-concept structures will be reported in this manuscript.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB332

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paper received ※ 26 May 2021 paper accepted ※ 19 July 2021 issue date ※ 26 August 2021

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