IPAC2022 - List of Keywords (wakefield)

Paper	Title	Other Keywords	Page
MOPLXGD2	Progress Towards Demonstration of a Plasma-Based FEL	plasma, FEL, laser, electron	6
	E. Chiadroni LNF-INFN, Frascati, Italy
	Plasma-based technology promises a revolution in the field of particle accelerators by pushing beams to gigaelectronvolt energies within centimeter distances. Several experiments are ongoing world-wide towards demonstration of a plasma based FEL enabling the realization of ultra-compact facilities for user applications like Free-Electron Lasers (FEL). The progress towards a plasma based FEL user facility is here reported, with particular focus on the recent results about the first experimental evidence of FEL lasing by a compact (3 cm) particle beam-driven plasma accelerator at the SPARC_LAB test facility. The status and prospects are discussed.
	Slides MOPLXGD2 [17.683 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPLXGD2
About •	Received ※ 12 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 30 June 2022
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MOOYGD2	The AWAKE Experiment in 2021: Performance and Preliminary Results on Electron-Seeding of Self-Modulation	proton, electron, plasma, experiment	21
	E. Gschwendtner, L. Verra, G. Zevi Della Porta CERN, Meyrin, Switzerland P. Muggli, L. Verra MPI, Muenchen, Germany P. Muggli MPI-P, München, Germany L. Verra TUM, Munich, Germany
	The future programme of the Advanced Wakefield (AWAKE) experiment at CERN relies on the seeded self-modulation of an entire proton bunch, resulting in phase-reproducible micro-bunches. This important milestone was achieved during the 2021 proton run by injecting a short electron bunch ahead of the proton bunch, demonstrating for the first time the electron-seeding of proton bunch self-modulation. This talk describes the programme, performance and preliminary results of the AWAKE experiment in the 2021 proton run, and introduces the program of the 2022 proton run. The observation of electron-seeded self-modulation opens new avenues of exploration which will be studied in 2022, including the effect of a phase difference between the front and the back of a proton bunch and the possibility of reproducibly seeding the hosing instability using the electron beam.
	Slides MOOYGD2 [7.040 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOOYGD2
About •	Received ※ 07 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 16 June 2022
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MOPOPT019	Wakefield Studies for a Bunch Arrival-Time Monitor Concept with Rod-Shaped Pickups on a Printed Circuit Board for X-Ray Free-Electron Lasers	pick-up, FEL, electron, simulation	271
	B.E.J. Scheible, A. Penirschke THM, Friedberg, Germany W. Ackermann, H. De Gersem TEMF, TU Darmstadt, Darmstadt, Germany M.K. Czwalinna, H. Schlarb DESY, Hamburg, Germany
	Funding: This work is supported by the German Federal Ministry of Education and Research (BMBF) under contract No. 05K19RO1. The European XFEL (EuXFEL) and other notable X-ray Free-Electron Laser facilities rely on an all-optical synchronization system with electro-optical bunch arrival-time monitors (BAM). The current BAMs were benchmarked with a resolution of 3.5 fs for nominal 250 pC bunches at the EuXFEL, including jitter of the optical reference system. The arrival-time jitter could be reduced to about 10 fs with a beam-based feedback system. For future experiments at the EuXFEL the bunch charge will be decreased to a level where the existing system’s accuracy will no longer be sufficient. In simulations a concept based on rod-shaped pickups mounted on a printed circuit board indicated its potential for such low charge applications. For the feasibility of the proposed design, its contribution to the total impedance is essential. In this work the design and an intermediate version are compared to state-of-the-art BAM regarding their wake potential. Furthermore, measures to mitigate wakefields are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT019
About •	Received ※ 08 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 05 July 2022
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MOPOTK043	Wakefield Effects Evaluation on Nanometer Small Beam at KEK-ATF	simulation, vacuum, alignment, cavity	556
	Y. Abe, K. Kubo, T. Okugi, N. Terunuma Sokendai, Ibaraki, Japan K. Kubo, T. Okugi, N. Terunuma KEK, Ibaraki, Japan
	Funding: This work was supported by JST, the establishment of university fellowships towards the creation of science technology innovation, Grant Number JPMJFS2136. This work was also supported by JST SPRING, Grant Number SDP221102. Accelerator Test Facility (ATF) is R&D facility to evaluate final focus technology for small beam required by ILC. The final focus beamline(ATF2) sets the goal to achieve 37 nm vertical beam size and 41 nm beam size had been demonstrated. Moreover, a significant intensity dependence on a nanometer beam size was observed and several studies of the wakefield had been conducted [,,*]. ATF2 is a proper beamline for wakefield studies with low emittance beam and nanometer resolution cavity BPMs and a nanometer beam size monitor. The simulation results were qualitatively cross-checked with experimental results and showed that the effects of some vacuum components and BPMs were significant. Further analysis of the wakefield will be done for flexible components (e.g. bellows). An upgrade of the ATF2 beamline is proposed by including minimization of the wakefield sources, to establish technologies for stable nanometer beam. J.Snuverink et al., PHYS. REV.ACCEL. BEAMS19, 091002. T.Okugi et al., PASJ16, FRPI023, 2019. *P.Korysko et al., PHYS. REV.ACCEL. BEAMS23, 121004.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK043
About •	Received ※ 20 May 2022 — Revised ※ 16 June 2022 — Accepted ※ 01 July 2022 — Issue date ※ 05 July 2022
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MOPOTK067	High-Charge Transmission Diagnostics for Beam-Driven RF Structures	experiment, diagnostics, acceleration, monitoring	618
	E.E. Wisniewski, G. Chen, D.S. Doran, S.Y. Kim, W. Liu, X. Lu, J.G. Power, C. Whiteford ANL, Lemont, Illinois, USA X. Lu, D.C. Merenich Northern Illinois University, DeKalb, Illinois, USA F. Stulle BERGOZ Instrumentation, Saint Genis Pouilly, France E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: U.S. Department of Energy Office of Science Contract No. DE-AC02-06CH11357. The Argonne Wakefield Accelerator group (AWA) has been using high Charge bunch-trains (>450 nC) for structure wakefield RF power generation and high power testing (100 s of MW) for many years. These experiments involve fast beam-tuning for high charge transmission through small aperture wakefield structures over a large range of charge levels. The success of these experiments depends on real-time, non-destructive, fast charge measurements with devices that are robust in the high-charge and high-powered RF environment. AWA uses Bergoz Integrating Charge Transformers (ICT) which are ideal for these critical charge measurements. The devices used, the method developed and its application are detailed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK067
About •	Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 27 June 2022
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MOPOMS010	Beam Dynamics and Drive Beam Losses Within a Planar Dielectric Wakefield Accelerator	acceleration, emittance, quadrupole, focusing	641
	T.J. Overton, Y.M. Saveliev Cockcroft Institute, Warrington, Cheshire, United Kingdom T.H. Pacey, Y.M. Saveliev STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G.X. Xia UMAN, Manchester, United Kingdom
	Funding: Science and Technology Funding Council (STFC) Student Grant Beam-driven dielectric wakefield accelerators (DWA) have the potential to provide accelerating gradients in the GV/m range. The transverse dynamics in such devices need to be understood to avoid instabilities over long transport distances and facilitate beam matching to specific applications (e.g. FELs). This presentation details simulation studies of the magnitude of beam-breakup instability (BBU) in planar dielectric lined waveguides (DLWs). These are for DWA drive beams, with high charge and momentum that can be produced at current facilities. Using a series of perpendicular DLW segments has been proposed to control instabilities over larger distances. Using self-developed software, the beam dynamics of a drive beam within a DLW are simulated and the magnitude of beam losses along a DLW of varying lengths calculated and beam quality preservation investigated. Methods to reduce transverse instabilities have been explored, and the impact of these on the length of a possible DWA acceleration stage are investigated. An acceleration stage with m-scale length, consisting of multiple alternating planar DLWs, is suggested and preservation of beam quality along this distance is shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS010
About •	Received ※ 07 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 17 June 2022
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MOPOMS012	Simulation Studies of Drive Beam Instability in a Dielectric Wakefield Accelerator	simulation, GUI, focusing, quadrupole	645
	W.H. Tan, P. Piot Northern Illinois University, DeKalb, Illinois, USA A. Huebl, R. Jambunathan, R. Lehé, A. Myers, T. Rheaume, J.-L. Vay, W. Zhang LBNL, Berkeley, USA P. Piot ANL, Lemont, Illinois, USA
	Funding: This work is supported by the US DOE award DE-SC0018656 with NIU and DE-AC02-06CH11357 with ANL. This work used resources from NERSC, supported by DOE contract DE-AC02-05CH11231. This research used WarpX, which is supported by the US DOE Exascale Computing Project. Primary WarpX contributors are with LBNL, LLNL, CEA-LIDYL, SLAC, DESY, CERN, and Modern Electron. Beam-driven collinear wakefield acceleration using structure wakefield accelerators promises a high gradient acceleration within a smaller physical footprint. Sustainable extraction of energy from the drive beam relies on precise understanding of its long term dynamics and the possible onset or mitigation of the beam instability. The advance of computational power and tools makes it possible to model the full physics of beam-driven wakefield acceleration. Here we report on the long-term beam dynamics studies of a drive beam considering the example of a dielectric waveguide using high fidelity particle-in-cell simulations performed with WarpX.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS012
About •	Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 16 June 2022
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MOPOMS016	Application of Nanostructures and Metamaterials in Accelerator Physics	electron, acceleration, plasma, laser	659
	J. Resta-López ICMUV, Paterna, Spain Ö. Apsimon, C. Bonțoiu, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom A. Bonatto Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil B. Galante CERN, Meyrin, Switzerland C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom G.X. Xia UMAN, Manchester, United Kingdom
	Funding: This work is supported by the Generalitat Valenciana under Grant agreement No. CIDEGENT/2019/058. Carbon-based nanostructures and metamaterials offer extraordinary mechanical and opto-electrical properties, which make them suitable for applications in diverse fields, including, for example, bioscience, energy technology and quantum computing. In the latest years, important R&D efforts have been made to investigate the potential use of graphene and carbon-nanotube (CNT) based structures to manipulate and accelerate particle beams. In the same way, the special interaction of graphene and CNTs with charged particles and electromagnetic radiation might open interesting possibilities for the design of compact coherent radiation sources, and novel beam diagnostics techniques as well. This paper gives an overview of novel concepts based on nanostructures and metamaterials with potential application in the field of accelerator physics. Several examples are shown and future prospects discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS016
About •	Received ※ 08 June 2022 — Accepted ※ 12 June 2022 — Issue date ※ 13 June 2022
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MOPOMS050	Rigorous Approach for Calculation of Radiation of a Charged Particle Bunch Exiting an Open-Ended Dielectrically Loaded Waveguide	GUI, radiation, electron, acceleration	757
	S.N. Galyamin Saint Petersburg State University, Saint Petersburg, Russia S. Baturin ITMO University, Saint Petersburg, Russia
	Funding: Work supported by Russian Science Foundation (Grant No. 18-72-10137). Beam-driven radiation sources based on open-ended waveguide structures with dielectric filling are of essential interest due to their attractive possibilities to generate high-power narrow-band Cherenkov radiation. An important problem here is to effectively extract the radiation from the waveguide to the open space. Therefore, further development of this scheme requires rigorous mathematical approach describing the interaction of both charged particle bunch and produced radiation with the open end of a waveguide. In this report, we present the corresponding analytical approach based on our recent paper* where diffraction of a waveguide mode at the open end of a dielectrically loaded waveguide has been rigorously investigated. * D. Wang et al., Rev. Sci. Instruments, Vol. 89, 093301 (2018). ** S.N. Galyamin et al., IEEE Trans. Microwave Theory Techn., Vol. 69, 2429-2438 (2021).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS050
About •	Received ※ 09 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 03 July 2022
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WEOZSP1	Longitudinal Bunch Shaping Using an X-Band Transverse Deflecting Cavity Powered by Wakefield Power Extractor at Argonne Wakefield Accelerator Facility	electron, quadrupole, simulation, acceleration	1655
	S.Y. Kim, G. Chen, D.S. Doran, W. Liu, J.G. Power, E.E. Wisniewski ANL, Lemont, Illinois, USA A. Bibian, C.-J. Jing, E.W. Knight, S.V. Kuzikov Euclid TechLabs, Solon, Ohio, USA P. Piot Northern Illinois University, DeKalb, Illinois, USA
	Funding: This project is supported under DoE SBIR Phase I Grant No. DE-SC0021733. This work is also supported by Department of Energy, Office of Science, under contract No. DEAC02-06CH11357. Longitudinal bunch shaping using transverse deflecting cavities (TDC) was recently proposed. This configuration is well suited for shaping the current profile of high-charge bunches since it does not use dipole magnets, and therefore, is not prone to deleterious effects arising from coherent synchrotron radiation. An intercepting mask located downstream of the first TDC, which introduce a spatiotemporal correlation, transversely shape the beam. Downstream of the second TDC, upon removal of the cross-plane correlation, the bunch is temporally shaped. In this paper, we investigate longitudinal bunch shaping with an X-band TDC powered by an X-band, short-pulse wakefield Power Extraction and Transfer Structure (PETS), where the wakefield from the drive beam propagating through the PETS is the power source. We describe the RF designs of the X-band TDC and the configuration of the overall shaping system. Finally, we explore via beam-dynamics simulations the performances of the proposed shaper and its possible application to various bunch shapes relevant to beam-driven acceleration and coherent radiation generation. Gwanghui Ha et al., Phys. Rev. Accel. Beams 23, 072803, 2020
	Slides WEOZSP1 [6.235 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEOZSP1
About •	Received ※ 14 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 17 June 2022
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WEPOST030	Multitask Optimization of Laser-Plasma Accelerators Using Simulation Codes with Different Fidelities	simulation, plasma, laser, acceleration	1761
	Á. Ferran Pousa, M. Kirchen, A. Martinez de la Ossa, M. Thévenet DESY, Hamburg, Germany S.T.P. Hudson, J.M. Larson ANL, Lemont, Illinois, USA A. Huebl, R. Lehé, J.-L. Vay LBNL, Berkeley, USA S. Jalas University of Hamburg, Hamburg, Germany
	When designing a laser-plasma acceleration experiment, one commonly explores the parameter space (plasma density, laser intensity, focal position, etc.) with simulations in order to find an optimal configuration that, for example, minimizes the energy spread or emittance of the accelerated beam. However, laser-plasma acceleration is typically modeled with full particle-in-cell (PIC) codes, which can be computationally expensive. Various reduced models can approximate beam behavior at a much lower computational cost. Although such models do not capture the full physics, they could still suggest promising sets of parameters to be simulated with a full PIC code and thereby speed up the overall design optimization. In this work we automate such a workflow with a Bayesian multitask algorithm, where each task has a different fidelity. This algorithm learns from past simulation results from both full PIC codes and reduced PIC codes and dynamically chooses the next parameters to be simulated. We illustrate this workflow with a proof-of-concept optimization using the Wake-T and FBPIC codes. The libEnsemble library is used to orchestrate this workflow on a modern GPU-accelerated high-performance computing system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST030
About •	Received ※ 08 June 2022 — Accepted ※ 11 June 2022 — Issue date ※ 14 June 2022
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WEPOST034	Magnetic Characterization of a Superconducting Transverse Gradient Undulator for Compact Laser Wakefield Accelerator-Driven FELs	undulator, laser, FEL, electron	1772
	K. Damminsek, A. Bernhard, H.J. Cha, A.W. Grau, A.-S. Müller, M.S. Ning, Y. Tong KIT, Karlsruhe, Germany S.C. Richter CERN, Meyrin, Switzerland R. Rossmanith DESY, Hamburg, Germany
	Funding: Federal Ministry of Education and Research of Germany and the Development and Promotion of Science and Technology Talents Project (DPST) A transverse gradient undulator (TGU) is a key component compensating for the relatively large energy spread of Laser Wakefield Accelerator (LWFA)-generated electron beams for realizing a compact Free Electron Laser (FEL). A superconducting TGU with 40 periods has been fabricated at the Karlsruhe Institute of Technology (KIT). In this contribution, we report that the superconducting TGU has been commissioned with nominal operational parameters at an off-line test bench. An experimental set-up for mapping the magnetic field on a two-dimensional grid in the TGU gap has been employed for the magnetic characterization. We show the first preliminary results of these measurements showing the longitudinal quality, the transverse gradient and the transient behaviour of the superconducting TGU field.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST034
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 20 June 2022
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WEPOST039	Mapping Charge Capture and Acceleration in a Plasma Wakefield of a Proton Bunch Using Variable Emittance Electron Beam Injection	electron, plasma, experiment, emittance	1780
	E. Granados, A.-M. Bachmann, E. Chevallay, S. Döbert, V.N. Fedosseev, F. Friebel, S.J. Gessner, E. Gschwendtner, S.Y. Kim, S. Mazzoni, M. Turner, L. Verra CERN, Meyrin, Switzerland A.-M. Bachmann, L. Verra MPI, Muenchen, Germany S.Y. Kim UNIST, Ulsan, Republic of Korea S.Y. Kim ANL, Lemont, Illinois, USA J.T. Moody MPI-P, München, Germany
	In the Phase 2 of the AWAKE first experimental run (from May to November 2018), an electron beam was used to probe and test proton-driven wakefield accelera-tion in a rubidium plasma column. The witness electron bunches were produced using an RF-gun equipped with a Cs₂Te photocathode illuminated by a tailorable ultrafast ultraviolet (UV) laser pulse. The construction of the UV beam optical system enabled appropriate transverse beam shaping and control of its pulse duration, size, and position on the photocathode, as well as time delay with respect to the ionizing laser pulse that seeds the plasma wakefields in the proton bunches. Variable photocathode illumination provided the required flexibility to produce electron bunches with variable charge, emittance, and injection trajectory into the plasma column. In this work, we analyze the overall charge capture and shot-to-shot reproducibility of the proton-driven plasma wakefield accelerator with various UV illumination and electron bunch injection parameters.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST039
About •	Received ※ 23 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 29 June 2022
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WEPOST046	Beam Matching in an Elliptical Plasma Blowout Driven by Highly Asymmetric Flat Beams	plasma, emittance, simulation, focusing	1802
	P. Manwani, H.S. Ancelin, G. Andonian, N. Majernik, J.B. Rosenzweig, M. Yadav UCLA, Los Angeles, California, USA G. Andonian RadiaBeam, Marina del Rey, California, USA G. Ha, J.G. Power ANL, Lemont, Illinois, USA M. Yadav The University of Liverpool, Liverpool, United Kingdom M. Yadav Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work was performed with the support of the US Department of Energy under Contract No. DE-SC0017648 and DESC0009914. Particle beams with highly asymmetric emittance ratios, or flat beams, are employed at accelerator facilities such as the AWA and foreseen at FACET-II. Flat beams have been used to drive wakefields in dielectric structures and are an ideal candidate for high-gradient wakefields in plasmas. The high aspect ratio produces a blowout region that is elliptical in cross section and this asymmetry in the ion column structure creates asymmetric focusing in the two transverse planes. The ellipticity of the plasma blowout decreases as the normalized peak current increases, and gradually approaches an axisymmetric column. An appropriate matching condition for the beam envelope inside the elliptical blowout is introduced. Simulations are performed to investigate the ellipticity of the resultant wakefield based on the initial drive beam parameters, and are compared to analytical calculations. The parameter space for two cases at the AWA and FACET facilities, with requirements for plasma profile and achievable fields, is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST046
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 29 June 2022
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WEPOST048	Excitation of Very High Gradient Plasma Wakefields From Nanometer Scale Beams	plasma, focusing, simulation, quadrupole	1806
	P. Manwani, H.S. Ancelin, G. Andonian, D.R. Chow, N. Majernik, J.B. Rosenzweig, M. Yadav UCLA, Los Angeles, California, USA G. Andonian RadiaBeam, Marina del Rey, California, USA R. Robles SLAC, Menlo Park, California, USA M. Yadav The University of Liverpool, Liverpool, United Kingdom M. Yadav Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work was performed with the support of the US Department of Energy under Contract No. DESC0009914. The plasma based terawatt attosecond project at SLAC, termed PAX, offers near mega-Ampere beams that could be used to demonstrate plasma wakefield acceleration at very high gradients (TV/m). The beam has a large aspect ratio which allows it to be used at high densities since the longitudinal beam size is lower than the plasma skin depth. This beam can be focused using a permanent magnitude quadrupole (PMQ) triplet to further reduce its transverse size. Since the beam is extremely short compared to the plasma skin depth, it behaves like a delta-function perturbation to the plasma. This reduces the expected focusing effect of the ion column and simulations show that only the tail of the beam is notably focused and decelerated. This scenario is investigated with attendant experimental considerations discussed. The creation of the witness beam by the deceleration of the tail of the beam is also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST048
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 29 June 2022
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WEPOTK030	Modelling Growth and Asymmetry in Seeded Self-Modulation of Elliptical Beams in Plasma	plasma, simulation, proton, acceleration	2122
	A. Perera, O. Apsimon, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom Ö. Apsimon, A. Perera, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work was supported by STFC UK grant ST/P006752/1. The Authors are grateful for computing time provided by the STFC Scientific Computing Department’s SCARF cluster. The seeded self-modulation (SSM) of long particle bunches for the generation of gigavolts-per-meter wakefields that can accelerate witness electron beams was first shown using the Super Proton Synchrotron beam as a driver by the AWAKE experiment. The stability of the produced microbunch trains over tens or hundreds of meters is crucial for extrapolating this scheme as proposed for use in several high energy plasma-based linear colliders. However, aside from the competing hosing instability, which has been shown to be suppressible by SSM when that process saturates, few works have examined other effects of transverse asymmetry in this process. Here, we use analytical modelling and 3D particle-in-cell simulations with QuickPIC to characterise the impact on the SSM growth process due to transverse asymmetry in the beam. A metric is constructed for asymmetry in simulation results, showing that the initial azimuthal complexity changes only slightly during SSM growth. Further, we show quantitative agreement between simulations and analytical predictions for the scaling of the reduction SSM growth rate with unequal aspect ratio of the initial beam profile. These results serve to inform planning and tolerances for both AWAKE and other SSM-based novel acceleration methods in the future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK030
About •	Received ※ 09 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 23 June 2022
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WEPOTK052	Beam Coupling Impedance Study and Its Database of Siam Photon Source Storage Ring	impedance, storage-ring, vacuum, simulation	2177
	N. Juntong, T. Chanwattana, S. Jummunt, K. Kittimanapun, T. Phimsen, W. Promdee, T. Pulampong SLRI, Nakhon Ratchasima, Thailand
	Since the Siam Photon Source (SPS) had an electron beam energy upgraded from 1.0 GeV to 1.2 GeV in 2005, the storage ring impedance measurements were done once in 2007. Two insertion magnet devices have been installed in the SPS storage ring during June to August 2013. There are several vacuum components added to the storage ring; these affect the ring impedance. Quantitative understanding of instabilities requires detailed knowledge of the impedance of the ring. For this purpose, the development of an impedance database is a necessity, where the wake potentials of each vacuum component are kept and maintained in a standard format. The self-describing data sets (SDDS) file format will be utilized to record components wake potentials. The wake potentials of each vacuum component can be obtained from a particle tracking simulation; a CST particle studio program will be used in the simulation process. The wake potentials can also be included in a beam dynamic tracking program such as ELEGANT to observe beam behaviors with these instabilities and find a curing means. The study results will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK052
About •	Received ※ 19 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 25 June 2022
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WEPOTK064	Generating Sub-Femtosecond Electron Beams at Plasma Wakefield Accelerators	plasma, emittance, electron, simulation	2217
	R. Robles, C. Emma, R.M. Hessami, K. Larsen, A. Marinelli SLAC, Menlo Park, California, USA
	Funding: This work was supported by US Department of Energy Contracts No. DE-AC02-76SF00515 and by the DOE, Laboratory Directed Research and Development program at SLAC, under contract DE-AC02-76SF00515. The Plasma-driven Attosecond X-ray source (PAX) project at FACET-II aims to produce attosecond EUV/soft x-ray pulses with milijoule-scale pulse energy via nearly coherent emission from pre-bunched electron beams. In the baseline approach, a beam is generated using the density downramp injection scheme with a percent-per-micron chirp and 1e-4 scale slice energy spread. Subsequent compression yields a current spike of just 100 as duration which can emit 10 nm light nearly coherently due to its strong pre-bunching. In this work, we report simulation studies of a scheme to generate similarly short beams without relying on plasma injection. Instead, we utilize a high-charge beam generated at an RF photocathode, with its tail acting as the witness bunch for the wake. The witness develops a percent-per-micron chirp in the plasma which is then compressible downstream. The final bunch length demonstrated here is as short as 100 nm, and is limited primarily by emittance effects. The configurations studied in this work are available for experimental testing at existing PWFA facilities such as FACET-II. APL Photonics 6, 076107 (2021)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK064
About •	Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022
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WEPOMS013	Neural Network Solver for Coherent Synchrotron Radiation Wakefield Calculations in Accelerator-Based Charged Particle Beams	simulation, radiation, synchrotron, synchrotron-radiation	2261
	A.L. Edelen, C. Emma, C.E. Mayes, R.J. Roussel SLAC, Menlo Park, California, USA
	Particle accelerators support a wide array of scientific, industrial, and medical applications. To meet the needs of these applications, accelerator physicists rely heavily on detailed simulations of the complicated particle beam dynamics through the accelerator. One of the most computationally expensive and difficult-to-model effects is the impact of Coherent Synchrotron Radiation (CSR). CSR is one of the major drivers of growth in the beam emittance, which is a key metric of beam quality that is critical in many applications. The CSR wakefield is very computationally intensive to compute with traditional electromagnetic solvers, and this is a major limitation in accurately simulating accelerators. Here, we demonstrate a new approach for the CSR wakefield computation using a neural network solver structured in a way that is readily generalizable to new setups. We validate its performance by adding it to a standard beam tracking test problem and show a ten-fold speedup along with high accuracy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS013
About •	Received ※ 10 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 03 July 2022
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WEPOMS015	Basic Relations of Laser-Plasma Interaction in the 3D Relativistic, Non-Linear Regime	laser, plasma, electron, acceleration	2265
	D.F.G. Minenna, E. Bargel, L. Batista, P.A.P. Nghiem CEA-IRFU, Gif-sur-Yvette, France
	In the approximation where the plasma is considered as a fluid, basic relations are derived to describe the plasma wave driven by an ultra-intense laser pulse. A set of partial differential equations is obtained. It is then numerically solved to calculate the resulting 3D electric field structure that can be used as accelerating cavities for electrons. The laser strength parameter is varied to investigate regimes from weakly nonlinear up to total cavitation where all the initial electrons of the plasma are expelled.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS015
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 10 July 2022
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WEPOMS045	Modeling and Mitigation of Long-Range Wakefields for Advanced Linear Colliders	linac, HOM, collider, dipole	2350
	F. Bosco, M. Carillo, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo Sapienza University of Rome, Rome, Italy O. Camacho, A. Fukasawa, N. Majernik, J.B. Rosenzweig UCLA, Los Angeles, USA E. Chiadroni, B. Spataro, C. Vaccarezza LNF-INFN, Frascati, Italy L. Faillace, A. Giribono INFN/LNF, Frascati, Italy
	Funding: This work is supported by DARPA under Contract N.HR001120C0072, by DOE Contract DE-SC0009914 and DE-SC0020409, by the National Science Foundation Grant N.PHY-1549132 and by INFN. The luminosity requirements of TeV-class linear colliders demand use of intense charged beams at high repetition rates. Such features imply multi-bunch operation with long current trains accelerated over the km length scale. Consequently, particle beams are exposed to the mutual parasitic interaction due to the long-range wakefields excited by the leading bunches in the accelerating structures. Such perturbations to the motion induce transverse oscillations of the bunches, potentially leading to instabilities such as transverse beam break-up. Here we present a dedicated tracking code that studies the effects of long-range transverse wakefield interaction among different bunches in linear accelerators. Being described by means of an efficient matrix formalism, such effects can be included while preserving short computational times. As a reference case, we use our code to investigate the performance of a state-of-the-art linear collider currently under design and, in addition, we discuss possible mitigation techniques based on frequency detuning and damping.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS045
About •	Received ※ 20 May 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 10 July 2022
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FROXGD1	A Method for Obtaining 3D Charge Density Distribution of a Self-Modulated Proton Bunch	proton, plasma, experiment, electron	3118
	T. Nechaeva, P. Muggli MPI-P, München, Germany L. Verra, G. Zevi Della Porta CERN, Meyrin, Switzerland L. Verra TUM, Munich, Germany L. Verra MPI, Muenchen, Germany
	The Advanced Wakefield Experiment (AWAKE) at CERN is the first plasma wakefield accelerator experiment to use a proton bunch as driver. The long bunch undergoes seeded self-modulation (SSM) in a 10 m-long plasma. SSM transforms the bunch into a train of short micro-bunches that resonantly drive high-amplitude wakefields. We use optical transition radiation (OTR) and a streak camera to obtain time-resolved images of the bunch transverse charge density distribution in a given plane. In this paper we present a method to obtain 3D images of the bunch by scanning the OTR across the entrance slit of the streak camera. Reconstruction of the 3D distribution is possible because with seeding self-modulation is reproducible. The 3D images allow for checking the axi-symmetry of SSM and for detecting the possible presence of the non-axi-symmetric hosing instability (HI). F. Batsch et al., Phys. Rev. Lett. 126, 164802 (2021).
	Slides FROXGD1 [4.026 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-FROXGD1
About •	Received ※ 20 May 2022 — Revised ※ 15 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 30 June 2022
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FROXSP2	Demonstration of Gradient Above 300 MV/m in Short Pulse Regime Using an X-Band Single-Cell Structure	acceleration, experiment, accelerating-gradient, electron	3134
	J.H. Shao, D.S. Doran, G. Ha, C.-J. Jing, W. Liu, J.G. Power, C. Whiteford, E.E. Wisniewski ANL, Lemont, Illinois, USA H.B. Chen, X. Lin, M.M. Peng, J. Shi, H. Zha TUB, Beijing, People’s Republic of China C. Jing Euclid Beamlabs, Bolingbrook, USA
	High gradient acceleration is one of the critical technologies required by future linear colliders, free-electron lasers, and compact linac-based applications. Among decade long effort to break state-of-the-art gradient limitation of ~100 MV/m in normal conducting structures, using RF pulses shorter than 20 ns is a promising approach based on theoretic analysis and experimental observation. In this study, we demonstrated high gradient above 300 MV/m using an X-band 11.7 GHz single-cell travelling-wave structure with 6 ns FWHM RF pulses generated by a power extractor. In comparison, a scaled 11.424 GHz structure only reached below 150 MV/m driven by 30-100 ns RF pulses from a klystron with pulse compression. The experimental results and the suggested new mechanism of beam acceleration in the Breakdown Insensitive Acceleration Regime (BIAR) are presented in this manuscript.
	Slides FROXSP2 [8.998 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-FROXSP2
About •	Received ※ 11 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 20 June 2022
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Paper

Title

Other Keywords

Page

MOPLXGD2

Progress Towards Demonstration of a Plasma-Based FEL

plasma, FEL, laser, electron

6

E. Chiadroni
LNF-INFN, Frascati, Italy

Plasma-based technology promises a revolution in the field of particle accelerators by pushing beams to gigaelectronvolt energies within centimeter distances. Several experiments are ongoing world-wide towards demonstration of a plasma based FEL enabling the realization of ultra-compact facilities for user applications like Free-Electron Lasers (FEL). The progress towards a plasma based FEL user facility is here reported, with particular focus on the recent results about the first experimental evidence of FEL lasing by a compact (3 cm) particle beam-driven plasma accelerator at the SPARC_LAB test facility. The status and prospects are discussed.

Slides MOPLXGD2 [17.683 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPLXGD2

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Received ※ 12 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 30 June 2022

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MOOYGD2

The AWAKE Experiment in 2021: Performance and Preliminary Results on Electron-Seeding of Self-Modulation

proton, electron, plasma, experiment

21

E. Gschwendtner, L. Verra, G. Zevi Della Porta
CERN, Meyrin, Switzerland
P. Muggli, L. Verra
MPI, Muenchen, Germany
P. Muggli
MPI-P, München, Germany
L. Verra
TUM, Munich, Germany

The future programme of the Advanced Wakefield (AWAKE) experiment at CERN relies on the seeded self-modulation of an entire proton bunch, resulting in phase-reproducible micro-bunches. This important milestone was achieved during the 2021 proton run by injecting a short electron bunch ahead of the proton bunch, demonstrating for the first time the electron-seeding of proton bunch self-modulation. This talk describes the programme, performance and preliminary results of the AWAKE experiment in the 2021 proton run, and introduces the program of the 2022 proton run. The observation of electron-seeded self-modulation opens new avenues of exploration which will be studied in 2022, including the effect of a phase difference between the front and the back of a proton bunch and the possibility of reproducibly seeding the hosing instability using the electron beam.

Slides MOOYGD2 [7.040 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOOYGD2

About •

Received ※ 07 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 16 June 2022

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MOPOPT019

Wakefield Studies for a Bunch Arrival-Time Monitor Concept with Rod-Shaped Pickups on a Printed Circuit Board for X-Ray Free-Electron Lasers

pick-up, FEL, electron, simulation

271

B.E.J. Scheible, A. Penirschke
THM, Friedberg, Germany
W. Ackermann, H. De Gersem
TEMF, TU Darmstadt, Darmstadt, Germany
M.K. Czwalinna, H. Schlarb
DESY, Hamburg, Germany

Funding: This work is supported by the German Federal Ministry of Education and Research (BMBF) under contract No. 05K19RO1.
The European XFEL (EuXFEL) and other notable X-ray Free-Electron Laser facilities rely on an all-optical synchronization system with electro-optical bunch arrival-time monitors (BAM). The current BAMs were benchmarked with a resolution of 3.5 fs for nominal 250 pC bunches at the EuXFEL, including jitter of the optical reference system. The arrival-time jitter could be reduced to about 10 fs with a beam-based feedback system. For future experiments at the EuXFEL the bunch charge will be decreased to a level where the existing system’s accuracy will no longer be sufficient. In simulations a concept based on rod-shaped pickups mounted on a printed circuit board indicated its potential for such low charge applications. For the feasibility of the proposed design, its contribution to the total impedance is essential. In this work the design and an intermediate version are compared to state-of-the-art BAM regarding their wake potential. Furthermore, measures to mitigate wakefields are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT019

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Received ※ 08 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 05 July 2022

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MOPOTK043

Wakefield Effects Evaluation on Nanometer Small Beam at KEK-ATF

simulation, vacuum, alignment, cavity

556

Y. Abe, K. Kubo, T. Okugi, N. Terunuma
Sokendai, Ibaraki, Japan
K. Kubo, T. Okugi, N. Terunuma
KEK, Ibaraki, Japan

Funding: This work was supported by JST, the establishment of university fellowships towards the creation of science technology innovation, Grant Number JPMJFS2136. This work was also supported by JST SPRING, Grant Number SDP221102.
Accelerator Test Facility (ATF) is R&D facility to evaluate final focus technology for small beam required by ILC. The final focus beamline(ATF2) sets the goal to achieve 37 nm vertical beam size and 41 nm beam size had been demonstrated. Moreover, a significant intensity dependence on a nanometer beam size was observed and several studies of the wakefield had been conducted [*,**,***]. ATF2 is a proper beamline for wakefield studies with low emittance beam and nanometer resolution cavity BPMs and a nanometer beam size monitor. The simulation results were qualitatively cross-checked with experimental results and showed that the effects of some vacuum components and BPMs were significant. Further analysis of the wakefield will be done for flexible components (e.g. bellows). An upgrade of the ATF2 beamline is proposed by including minimization of the wakefield sources, to establish technologies for stable nanometer beam.
*J.Snuverink et al., PHYS. REV.ACCEL. BEAMS19, 091002.
**T.Okugi et al., PASJ16, FRPI023, 2019.
***P.Korysko et al., PHYS. REV.ACCEL. BEAMS23, 121004.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK043

About •

Received ※ 20 May 2022 — Revised ※ 16 June 2022 — Accepted ※ 01 July 2022 — Issue date ※ 05 July 2022

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MOPOTK067

High-Charge Transmission Diagnostics for Beam-Driven RF Structures

experiment, diagnostics, acceleration, monitoring

618

E.E. Wisniewski, G. Chen, D.S. Doran, S.Y. Kim, W. Liu, X. Lu, J.G. Power, C. Whiteford
ANL, Lemont, Illinois, USA
X. Lu, D.C. Merenich
Northern Illinois University, DeKalb, Illinois, USA
F. Stulle
BERGOZ Instrumentation, Saint Genis Pouilly, France
E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: U.S. Department of Energy Office of Science Contract No. DE-AC02-06CH11357.
The Argonne Wakefield Accelerator group (AWA) has been using high Charge bunch-trains (>450 nC) for structure wakefield RF power generation and high power testing (100 s of MW) for many years. These experiments involve fast beam-tuning for high charge transmission through small aperture wakefield structures over a large range of charge levels. The success of these experiments depends on real-time, non-destructive, fast charge measurements with devices that are robust in the high-charge and high-powered RF environment. AWA uses Bergoz Integrating Charge Transformers (ICT) which are ideal for these critical charge measurements. The devices used, the method developed and its application are detailed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK067

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Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 27 June 2022

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MOPOMS010

Beam Dynamics and Drive Beam Losses Within a Planar Dielectric Wakefield Accelerator

acceleration, emittance, quadrupole, focusing

641

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

Funding: Science and Technology Funding Council (STFC) Student Grant
Beam-driven dielectric wakefield accelerators (DWA) have the potential to provide accelerating gradients in the GV/m range. The transverse dynamics in such devices need to be understood to avoid instabilities over long transport distances and facilitate beam matching to specific applications (e.g. FELs). This presentation details simulation studies of the magnitude of beam-breakup instability (BBU) in planar dielectric lined waveguides (DLWs). These are for DWA drive beams, with high charge and momentum that can be produced at current facilities. Using a series of perpendicular DLW segments has been proposed to control instabilities over larger distances. Using self-developed software, the beam dynamics of a drive beam within a DLW are simulated and the magnitude of beam losses along a DLW of varying lengths calculated and beam quality preservation investigated. Methods to reduce transverse instabilities have been explored, and the impact of these on the length of a possible DWA acceleration stage are investigated. An acceleration stage with m-scale length, consisting of multiple alternating planar DLWs, is suggested and preservation of beam quality along this distance is shown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS010

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Received ※ 07 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 17 June 2022

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MOPOMS012

Simulation Studies of Drive Beam Instability in a Dielectric Wakefield Accelerator

simulation, GUI, focusing, quadrupole

645

W.H. Tan, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
A. Huebl, R. Jambunathan, R. Lehé, A. Myers, T. Rheaume, J.-L. Vay, W. Zhang
LBNL, Berkeley, USA
P. Piot
ANL, Lemont, Illinois, USA

Funding: This work is supported by the US DOE award DE-SC0018656 with NIU and DE-AC02-06CH11357 with ANL. This work used resources from NERSC, supported by DOE contract DE-AC02-05CH11231. This research used WarpX, which is supported by the US DOE Exascale Computing Project. Primary WarpX contributors are with LBNL, LLNL, CEA-LIDYL, SLAC, DESY, CERN, and Modern Electron.
Beam-driven collinear wakefield acceleration using structure wakefield accelerators promises a high gradient acceleration within a smaller physical footprint. Sustainable extraction of energy from the drive beam relies on precise understanding of its long term dynamics and the possible onset or mitigation of the beam instability. The advance of computational power and tools makes it possible to model the full physics of beam-driven wakefield acceleration. Here we report on the long-term beam dynamics studies of a drive beam considering the example of a dielectric waveguide using high fidelity particle-in-cell simulations performed with WarpX.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS012

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Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 16 June 2022

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MOPOMS016

Application of Nanostructures and Metamaterials in Accelerator Physics

electron, acceleration, plasma, laser

659

J. Resta-López
ICMUV, Paterna, Spain
Ö. Apsimon, C. Bonțoiu, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
A. Bonatto
Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil
B. Galante
CERN, Meyrin, Switzerland
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
G.X. Xia
UMAN, Manchester, United Kingdom

Funding: This work is supported by the Generalitat Valenciana under Grant agreement No. CIDEGENT/2019/058.
Carbon-based nanostructures and metamaterials offer extraordinary mechanical and opto-electrical properties, which make them suitable for applications in diverse fields, including, for example, bioscience, energy technology and quantum computing. In the latest years, important R&D efforts have been made to investigate the potential use of graphene and carbon-nanotube (CNT) based structures to manipulate and accelerate particle beams. In the same way, the special interaction of graphene and CNTs with charged particles and electromagnetic radiation might open interesting possibilities for the design of compact coherent radiation sources, and novel beam diagnostics techniques as well. This paper gives an overview of novel concepts based on nanostructures and metamaterials with potential application in the field of accelerator physics. Several examples are shown and future prospects discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS016

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Received ※ 08 June 2022 — Accepted ※ 12 June 2022 — Issue date ※ 13 June 2022

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MOPOMS050

Rigorous Approach for Calculation of Radiation of a Charged Particle Bunch Exiting an Open-Ended Dielectrically Loaded Waveguide

GUI, radiation, electron, acceleration

757

S.N. Galyamin
Saint Petersburg State University, Saint Petersburg, Russia
S. Baturin
ITMO University, Saint Petersburg, Russia

Funding: Work supported by Russian Science Foundation (Grant No. 18-72-10137).
Beam-driven radiation sources based on open-ended waveguide structures with dielectric filling are of essential interest due to their attractive possibilities to generate high-power narrow-band Cherenkov radiation*. An important problem here is to effectively extract the radiation from the waveguide to the open space. Therefore, further development of this scheme requires rigorous mathematical approach describing the interaction of both charged particle bunch and produced radiation with the open end of a waveguide. In this report, we present the corresponding analytical approach based on our recent paper** where diffraction of a waveguide mode at the open end of a dielectrically loaded waveguide has been rigorously investigated.
* D. Wang et al., Rev. Sci. Instruments, Vol. 89, 093301 (2018).
** S.N. Galyamin et al., IEEE Trans. Microwave Theory Techn., Vol. 69, 2429-2438 (2021).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS050

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Received ※ 09 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 03 July 2022

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WEOZSP1

Longitudinal Bunch Shaping Using an X-Band Transverse Deflecting Cavity Powered by Wakefield Power Extractor at Argonne Wakefield Accelerator Facility

electron, quadrupole, simulation, acceleration

1655

S.Y. Kim, G. Chen, D.S. Doran, W. Liu, J.G. Power, E.E. Wisniewski
ANL, Lemont, Illinois, USA
A. Bibian, C.-J. Jing, E.W. Knight, S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Funding: This project is supported under DoE SBIR Phase I Grant No. DE-SC0021733. This work is also supported by Department of Energy, Office of Science, under contract No. DEAC02-06CH11357.
Longitudinal bunch shaping using transverse deflecting cavities (TDC) was recently proposed*. This configuration is well suited for shaping the current profile of high-charge bunches since it does not use dipole magnets, and therefore, is not prone to deleterious effects arising from coherent synchrotron radiation. An intercepting mask located downstream of the first TDC, which introduce a spatiotemporal correlation, transversely shape the beam. Downstream of the second TDC, upon removal of the cross-plane correlation, the bunch is temporally shaped. In this paper, we investigate longitudinal bunch shaping with an X-band TDC powered by an X-band, short-pulse wakefield Power Extraction and Transfer Structure (PETS), where the wakefield from the drive beam propagating through the PETS is the power source. We describe the RF designs of the X-band TDC and the configuration of the overall shaping system. Finally, we explore via beam-dynamics simulations the performances of the proposed shaper and its possible application to various bunch shapes relevant to beam-driven acceleration and coherent radiation generation.
*Gwanghui Ha et al., Phys. Rev. Accel. Beams 23, 072803, 2020

Slides WEOZSP1 [6.235 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEOZSP1

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Received ※ 14 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 17 June 2022

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WEPOST030

Multitask Optimization of Laser-Plasma Accelerators Using Simulation Codes with Different Fidelities

simulation, plasma, laser, acceleration

1761

Á. Ferran Pousa, M. Kirchen, A. Martinez de la Ossa, M. Thévenet
DESY, Hamburg, Germany
S.T.P. Hudson, J.M. Larson
ANL, Lemont, Illinois, USA
A. Huebl, R. Lehé, J.-L. Vay
LBNL, Berkeley, USA
S. Jalas
University of Hamburg, Hamburg, Germany

When designing a laser-plasma acceleration experiment, one commonly explores the parameter space (plasma density, laser intensity, focal position, etc.) with simulations in order to find an optimal configuration that, for example, minimizes the energy spread or emittance of the accelerated beam. However, laser-plasma acceleration is typically modeled with full particle-in-cell (PIC) codes, which can be computationally expensive. Various reduced models can approximate beam behavior at a much lower computational cost. Although such models do not capture the full physics, they could still suggest promising sets of parameters to be simulated with a full PIC code and thereby speed up the overall design optimization. In this work we automate such a workflow with a Bayesian multitask algorithm, where each task has a different fidelity. This algorithm learns from past simulation results from both full PIC codes and reduced PIC codes and dynamically chooses the next parameters to be simulated. We illustrate this workflow with a proof-of-concept optimization using the Wake-T and FBPIC codes. The libEnsemble library is used to orchestrate this workflow on a modern GPU-accelerated high-performance computing system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST030

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Received ※ 08 June 2022 — Accepted ※ 11 June 2022 — Issue date ※ 14 June 2022

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WEPOST034

Magnetic Characterization of a Superconducting Transverse Gradient Undulator for Compact Laser Wakefield Accelerator-Driven FELs

undulator, laser, FEL, electron

1772

K. Damminsek, A. Bernhard, H.J. Cha, A.W. Grau, A.-S. Müller, M.S. Ning, Y. Tong
KIT, Karlsruhe, Germany
S.C. Richter
CERN, Meyrin, Switzerland
R. Rossmanith
DESY, Hamburg, Germany

Funding: Federal Ministry of Education and Research of Germany and the Development and Promotion of Science and Technology Talents Project (DPST)
A transverse gradient undulator (TGU) is a key component compensating for the relatively large energy spread of Laser Wakefield Accelerator (LWFA)-generated electron beams for realizing a compact Free Electron Laser (FEL). A superconducting TGU with 40 periods has been fabricated at the Karlsruhe Institute of Technology (KIT). In this contribution, we report that the superconducting TGU has been commissioned with nominal operational parameters at an off-line test bench. An experimental set-up for mapping the magnetic field on a two-dimensional grid in the TGU gap has been employed for the magnetic characterization. We show the first preliminary results of these measurements showing the longitudinal quality, the transverse gradient and the transient behaviour of the superconducting TGU field.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST034

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 20 June 2022

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WEPOST039

Mapping Charge Capture and Acceleration in a Plasma Wakefield of a Proton Bunch Using Variable Emittance Electron Beam Injection

electron, plasma, experiment, emittance

1780

E. Granados, A.-M. Bachmann, E. Chevallay, S. Döbert, V.N. Fedosseev, F. Friebel, S.J. Gessner, E. Gschwendtner, S.Y. Kim, S. Mazzoni, M. Turner, L. Verra
CERN, Meyrin, Switzerland
A.-M. Bachmann, L. Verra
MPI, Muenchen, Germany
S.Y. Kim
UNIST, Ulsan, Republic of Korea
S.Y. Kim
ANL, Lemont, Illinois, USA
J.T. Moody
MPI-P, München, Germany

In the Phase 2 of the AWAKE first experimental run (from May to November 2018), an electron beam was used to probe and test proton-driven wakefield accelera-tion in a rubidium plasma column. The witness electron bunches were produced using an RF-gun equipped with a Cs₂Te photocathode illuminated by a tailorable ultrafast ultraviolet (UV) laser pulse. The construction of the UV beam optical system enabled appropriate transverse beam shaping and control of its pulse duration, size, and position on the photocathode, as well as time delay with respect to the ionizing laser pulse that seeds the plasma wakefields in the proton bunches. Variable photocathode illumination provided the required flexibility to produce electron bunches with variable charge, emittance, and injection trajectory into the plasma column. In this work, we analyze the overall charge capture and shot-to-shot reproducibility of the proton-driven plasma wakefield accelerator with various UV illumination and electron bunch injection parameters.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST039

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Received ※ 23 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 29 June 2022

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WEPOST046

Beam Matching in an Elliptical Plasma Blowout Driven by Highly Asymmetric Flat Beams

plasma, emittance, simulation, focusing

1802

P. Manwani, H.S. Ancelin, G. Andonian, N. Majernik, J.B. Rosenzweig, M. Yadav
UCLA, Los Angeles, California, USA
G. Andonian
RadiaBeam, Marina del Rey, California, USA
G. Ha, J.G. Power
ANL, Lemont, Illinois, USA
M. Yadav
The University of Liverpool, Liverpool, United Kingdom
M. Yadav
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work was performed with the support of the US Department of Energy under Contract No. DE-SC0017648 and DESC0009914.
Particle beams with highly asymmetric emittance ratios, or flat beams, are employed at accelerator facilities such as the AWA and foreseen at FACET-II. Flat beams have been used to drive wakefields in dielectric structures and are an ideal candidate for high-gradient wakefields in plasmas. The high aspect ratio produces a blowout region that is elliptical in cross section and this asymmetry in the ion column structure creates asymmetric focusing in the two transverse planes. The ellipticity of the plasma blowout decreases as the normalized peak current increases, and gradually approaches an axisymmetric column. An appropriate matching condition for the beam envelope inside the elliptical blowout is introduced. Simulations are performed to investigate the ellipticity of the resultant wakefield based on the initial drive beam parameters, and are compared to analytical calculations. The parameter space for two cases at the AWA and FACET facilities, with requirements for plasma profile and achievable fields, is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST046

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 29 June 2022

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WEPOST048

Excitation of Very High Gradient Plasma Wakefields From Nanometer Scale Beams

plasma, focusing, simulation, quadrupole

1806

P. Manwani, H.S. Ancelin, G. Andonian, D.R. Chow, N. Majernik, J.B. Rosenzweig, M. Yadav
UCLA, Los Angeles, California, USA
G. Andonian
RadiaBeam, Marina del Rey, California, USA
R. Robles
SLAC, Menlo Park, California, USA
M. Yadav
The University of Liverpool, Liverpool, United Kingdom
M. Yadav
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work was performed with the support of the US Department of Energy under Contract No. DESC0009914.
The plasma based terawatt attosecond project at SLAC, termed PAX, offers near mega-Ampere beams that could be used to demonstrate plasma wakefield acceleration at very high gradients (TV/m). The beam has a large aspect ratio which allows it to be used at high densities since the longitudinal beam size is lower than the plasma skin depth. This beam can be focused using a permanent magnitude quadrupole (PMQ) triplet to further reduce its transverse size. Since the beam is extremely short compared to the plasma skin depth, it behaves like a delta-function perturbation to the plasma. This reduces the expected focusing effect of the ion column and simulations show that only the tail of the beam is notably focused and decelerated. This scenario is investigated with attendant experimental considerations discussed. The creation of the witness beam by the deceleration of the tail of the beam is also discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST048

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 29 June 2022

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WEPOTK030

Modelling Growth and Asymmetry in Seeded Self-Modulation of Elliptical Beams in Plasma

plasma, simulation, proton, acceleration

2122

A. Perera, O. Apsimon, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
Ö. Apsimon, A. Perera, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work was supported by STFC UK grant ST/P006752/1. The Authors are grateful for computing time provided by the STFC Scientific Computing Department’s SCARF cluster.
The seeded self-modulation (SSM) of long particle bunches for the generation of gigavolts-per-meter wakefields that can accelerate witness electron beams was first shown using the Super Proton Synchrotron beam as a driver by the AWAKE experiment. The stability of the produced microbunch trains over tens or hundreds of meters is crucial for extrapolating this scheme as proposed for use in several high energy plasma-based linear colliders. However, aside from the competing hosing instability, which has been shown to be suppressible by SSM when that process saturates, few works have examined other effects of transverse asymmetry in this process. Here, we use analytical modelling and 3D particle-in-cell simulations with QuickPIC to characterise the impact on the SSM growth process due to transverse asymmetry in the beam. A metric is constructed for asymmetry in simulation results, showing that the initial azimuthal complexity changes only slightly during SSM growth. Further, we show quantitative agreement between simulations and analytical predictions for the scaling of the reduction SSM growth rate with unequal aspect ratio of the initial beam profile. These results serve to inform planning and tolerances for both AWAKE and other SSM-based novel acceleration methods in the future.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK030

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Received ※ 09 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 23 June 2022

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WEPOTK052

Beam Coupling Impedance Study and Its Database of Siam Photon Source Storage Ring

impedance, storage-ring, vacuum, simulation

2177

N. Juntong, T. Chanwattana, S. Jummunt, K. Kittimanapun, T. Phimsen, W. Promdee, T. Pulampong
SLRI, Nakhon Ratchasima, Thailand

Since the Siam Photon Source (SPS) had an electron beam energy upgraded from 1.0 GeV to 1.2 GeV in 2005, the storage ring impedance measurements were done once in 2007. Two insertion magnet devices have been installed in the SPS storage ring during June to August 2013. There are several vacuum components added to the storage ring; these affect the ring impedance. Quantitative understanding of instabilities requires detailed knowledge of the impedance of the ring. For this purpose, the development of an impedance database is a necessity, where the wake potentials of each vacuum component are kept and maintained in a standard format. The self-describing data sets (SDDS) file format will be utilized to record components wake potentials. The wake potentials of each vacuum component can be obtained from a particle tracking simulation; a CST particle studio program will be used in the simulation process. The wake potentials can also be included in a beam dynamic tracking program such as ELEGANT to observe beam behaviors with these instabilities and find a curing means. The study results will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK052

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Received ※ 19 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 25 June 2022

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WEPOTK064

Generating Sub-Femtosecond Electron Beams at Plasma Wakefield Accelerators

plasma, emittance, electron, simulation

2217

R. Robles, C. Emma, R.M. Hessami, K. Larsen, A. Marinelli
SLAC, Menlo Park, California, USA

Funding: This work was supported by US Department of Energy Contracts No. DE-AC02-76SF00515 and by the DOE, Laboratory Directed Research and Development program at SLAC, under contract DE-AC02-76SF00515.
The Plasma-driven Attosecond X-ray source (PAX) project at FACET-II aims to produce attosecond EUV/soft x-ray pulses with milijoule-scale pulse energy via nearly coherent emission from pre-bunched electron beams. In the baseline approach*, a beam is generated using the density downramp injection scheme with a percent-per-micron chirp and 1e-4 scale slice energy spread. Subsequent compression yields a current spike of just 100 as duration which can emit 10 nm light nearly coherently due to its strong pre-bunching. In this work, we report simulation studies of a scheme to generate similarly short beams without relying on plasma injection. Instead, we utilize a high-charge beam generated at an RF photocathode, with its tail acting as the witness bunch for the wake. The witness develops a percent-per-micron chirp in the plasma which is then compressible downstream. The final bunch length demonstrated here is as short as 100 nm, and is limited primarily by emittance effects. The configurations studied in this work are available for experimental testing at existing PWFA facilities such as FACET-II.
*APL Photonics 6, 076107 (2021)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK064

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Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022

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WEPOMS013

Neural Network Solver for Coherent Synchrotron Radiation Wakefield Calculations in Accelerator-Based Charged Particle Beams

simulation, radiation, synchrotron, synchrotron-radiation

2261

A.L. Edelen, C. Emma, C.E. Mayes, R.J. Roussel
SLAC, Menlo Park, California, USA

Particle accelerators support a wide array of scientific, industrial, and medical applications. To meet the needs of these applications, accelerator physicists rely heavily on detailed simulations of the complicated particle beam dynamics through the accelerator. One of the most computationally expensive and difficult-to-model effects is the impact of Coherent Synchrotron Radiation (CSR). CSR is one of the major drivers of growth in the beam emittance, which is a key metric of beam quality that is critical in many applications. The CSR wakefield is very computationally intensive to compute with traditional electromagnetic solvers, and this is a major limitation in accurately simulating accelerators. Here, we demonstrate a new approach for the CSR wakefield computation using a neural network solver structured in a way that is readily generalizable to new setups. We validate its performance by adding it to a standard beam tracking test problem and show a ten-fold speedup along with high accuracy.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS013

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Received ※ 10 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 03 July 2022

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WEPOMS015

Basic Relations of Laser-Plasma Interaction in the 3D Relativistic, Non-Linear Regime

laser, plasma, electron, acceleration

2265

D.F.G. Minenna, E. Bargel, L. Batista, P.A.P. Nghiem
CEA-IRFU, Gif-sur-Yvette, France

In the approximation where the plasma is considered as a fluid, basic relations are derived to describe the plasma wave driven by an ultra-intense laser pulse. A set of partial differential equations is obtained. It is then numerically solved to calculate the resulting 3D electric field structure that can be used as accelerating cavities for electrons. The laser strength parameter is varied to investigate regimes from weakly nonlinear up to total cavitation where all the initial electrons of the plasma are expelled.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS015

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Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 10 July 2022

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WEPOMS045

Modeling and Mitigation of Long-Range Wakefields for Advanced Linear Colliders

linac, HOM, collider, dipole

2350

F. Bosco, M. Carillo, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
O. Camacho, A. Fukasawa, N. Majernik, J.B. Rosenzweig
UCLA, Los Angeles, USA
E. Chiadroni, B. Spataro, C. Vaccarezza
LNF-INFN, Frascati, Italy
L. Faillace, A. Giribono
INFN/LNF, Frascati, Italy

Funding: This work is supported by DARPA under Contract N.HR001120C0072, by DOE Contract DE-SC0009914 and DE-SC0020409, by the National Science Foundation Grant N.PHY-1549132 and by INFN.
The luminosity requirements of TeV-class linear colliders demand use of intense charged beams at high repetition rates. Such features imply multi-bunch operation with long current trains accelerated over the km length scale. Consequently, particle beams are exposed to the mutual parasitic interaction due to the long-range wakefields excited by the leading bunches in the accelerating structures. Such perturbations to the motion induce transverse oscillations of the bunches, potentially leading to instabilities such as transverse beam break-up. Here we present a dedicated tracking code that studies the effects of long-range transverse wakefield interaction among different bunches in linear accelerators. Being described by means of an efficient matrix formalism, such effects can be included while preserving short computational times. As a reference case, we use our code to investigate the performance of a state-of-the-art linear collider currently under design and, in addition, we discuss possible mitigation techniques based on frequency detuning and damping.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS045

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Received ※ 20 May 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 10 July 2022

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FROXGD1

A Method for Obtaining 3D Charge Density Distribution of a Self-Modulated Proton Bunch

proton, plasma, experiment, electron

3118

T. Nechaeva, P. Muggli
MPI-P, München, Germany
L. Verra, G. Zevi Della Porta
CERN, Meyrin, Switzerland
L. Verra
TUM, Munich, Germany
L. Verra
MPI, Muenchen, Germany

The Advanced Wakefield Experiment (AWAKE) at CERN is the first plasma wakefield accelerator experiment to use a proton bunch as driver. The long bunch undergoes seeded self-modulation (SSM) in a 10 m-long plasma. SSM transforms the bunch into a train of short micro-bunches that resonantly drive high-amplitude wakefields. We use optical transition radiation (OTR) and a streak camera to obtain time-resolved images of the bunch transverse charge density distribution in a given plane. In this paper we present a method to obtain 3D images of the bunch by scanning the OTR across the entrance slit of the streak camera. Reconstruction of the 3D distribution is possible because with seeding self-modulation is reproducible*. The 3D images allow for checking the axi-symmetry of SSM and for detecting the possible presence of the non-axi-symmetric hosing instability (HI).
* F. Batsch et al., Phys. Rev. Lett. 126, 164802 (2021).

Slides FROXGD1 [4.026 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-FROXGD1

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Received ※ 20 May 2022 — Revised ※ 15 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 30 June 2022

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FROXSP2

Demonstration of Gradient Above 300 MV/m in Short Pulse Regime Using an X-Band Single-Cell Structure

acceleration, experiment, accelerating-gradient, electron

3134

J.H. Shao, D.S. Doran, G. Ha, C.-J. Jing, W. Liu, J.G. Power, C. Whiteford, E.E. Wisniewski
ANL, Lemont, Illinois, USA
H.B. Chen, X. Lin, M.M. Peng, J. Shi, H. Zha
TUB, Beijing, People’s Republic of China
C. Jing
Euclid Beamlabs, Bolingbrook, USA

High gradient acceleration is one of the critical technologies required by future linear colliders, free-electron lasers, and compact linac-based applications. Among decade long effort to break state-of-the-art gradient limitation of ~100 MV/m in normal conducting structures, using RF pulses shorter than 20 ns is a promising approach based on theoretic analysis and experimental observation. In this study, we demonstrated high gradient above 300 MV/m using an X-band 11.7 GHz single-cell travelling-wave structure with 6 ns FWHM RF pulses generated by a power extractor. In comparison, a scaled 11.424 GHz structure only reached below 150 MV/m driven by 30-100 ns RF pulses from a klystron with pulse compression. The experimental results and the suggested new mechanism of beam acceleration in the Breakdown Insensitive Acceleration Regime (BIAR) are presented in this manuscript.

Slides FROXSP2 [8.998 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-FROXSP2

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Received ※ 11 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 20 June 2022

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