IPAC2021 - List of Authors (Grames, J.M.)

Paper	Title	Page
MOPAB324	High Voltage Design and Evaluation of Wien Filters for the CEBAF 200 keV Injector Upgrade	1000
	G.G. Palacios Serrano, P.A. Adderley, J.F. Benesch, D.B. Bullard, J.M. Grames, C. Hernandez-Garcia, A.S. Hofler, D. Machie, M. Poelker, M.L. Stutzman, R. Suleiman JLab, Newport News, Virginia, USA H. Baumgart, G.G. Palacios Serrano ODU, Norfolk, Virginia, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. High-energy nuclear physics experiments at the Jefferson Lab Continuous Electron Beam Accelerator Facility (CEBAF) require highly spin-polarization electron beams, produced from strained super-lattice GaAs photocathodes, activated to negative electron affinity in a photogun operating at 130 kV dc. A pair of Wien filter spin rotators in the injector defines the orientation of the electron beam polarization at the end station target. An upgrade of the CEBAF injector to better support the upcoming MOLLER experiment requires increasing the electron beam energy to 200 keV, to reduce unwanted helicity correlated intensity and position systematics and provide precise control of the polarization orientation. Our contribution describes design, fabrication and testing of the high voltage system to upgrade the Wien spin rotator to be compatible with the 200 keV beam. This required Solidworks modeling, CST and Opera electro- and magnetostatic simulations, upgrading HV vacuum feedthroughs, and assembly techniques for improving electrode alignment. The electric and magnetic fields required by the Wien condition and the successful HV characterization under vacuum conditions are also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB324
About •	paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 18 August 2021
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TUPAB037	The Design of a High Charge Polarized Preinjector for the Electron-Ion Collider	1428
	E. Wang, W. Liu, V.H. Ranjbar, J. Skaritka, N. Tsoupas BNL, Upton, New York, USA J.M. Grames, J. Guo JLab, Newport News, Virginia, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy The design of the electron pre-injector of the Electron-Ion Collider (EIC) project to generate 4 x 7 nC bunch has been advancing to meet the requirements for injection into the Rapid Cycling Synchrotron (RCS). The major challenges are high charge transport and achieving small energy spread from 3 GHz traveling-wave plate(TWP). The designed preinjector includes the polarized electron source, bunching section, TWP Linac, zigzag phase space manipulation and spin rotator. In this report, we will discuss the RF frequency selection and the way to reduce energy spread down to 0.2% by longitudinal phase space manipulate. We will also report the results of beamline simulation using space charge code and the conceptual design of spin rotator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB037
About •	paper received ※ 16 May 2021 paper accepted ※ 15 June 2021 issue date ※ 31 August 2021
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WEXA04	The RCS Design Status for the Electron Ion Collider	2521
	V.H. Ranjbar, M. Blaskiewicz, Z.A. Conway, D.M. Gassner, C. Hetzel, B. Lepore, H. Lovelace III, I. Marneris, F. Méot, C. Montag, J. Skaritka, N. Tsoupas, E. Wang, F.J. Willeke BNL, Upton, New York, USA J.M. Grames, J. Guo, F. Lin, V.S. Morozov, T. Satogata JLab, Newport News, Virginia, USA D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The design of the Electron-Ion Collider Rapid Cycling Synchrotron (RCS) to be constructed at Brookhaven National Laboratory is advancing to meet the injection requirements for the Electron Storage Ring (ESR). Over the past year activities are focused on developing the approach to inject two 28 nC bunches every second, up from the original design of one 10nC bunch every second. The solution requires several key changes concerning the injection and extraction kickers, charge accumulation via bunch merging and a carefully calibrated RF acceleration profile to match the longitudinal emittance required by the ESR.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXA04
About •	paper received ※ 19 May 2021 paper accepted ※ 26 August 2021 issue date ※ 31 August 2021
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WEPAB005	Design Status Update of the Electron-Ion Collider	2585
	C. Montag, E.C. Aschenauer, G. Bassi, J. Beebe-Wang, J.S. Berg, M. Blaskiewicz, A. Blednykh, J.M. Brennan, S.J. Brooks, K.A. Brown, Z.A. Conway, K.A. Drees, A.V. Fedotov, W. Fischer, C. Folz, D.M. Gassner, X. Gu, R.C. Gupta, Y. Hao, A. Hershcovitch, C. Hetzel, D. Holmes, H. Huang, W.A. Jackson, J. Kewisch, Y. Li, C. Liu, H. Lovelace III, Y. Luo, M. Mapes, D. Marx, G.T. McIntyre, F. Méot, M.G. Minty, S.K. Nayak, R.B. Palmer, B. Parker, S. Peggs, B. Podobedov, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, S. Seletskiy, V.V. Smaluk, K.S. Smith, S. Tepikian, R. Than, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, S. Verdú-Andrés, E. Wang, D. Weiss, F.J. Willeke, H. Witte, Q. Wu, W. Xu, A. Zaltsman, W. Zhang BNL, Upton, New York, USA S.V. Benson, J.M. Grames, F. Lin, T.J. Michalski, V.S. Morozov, E.A. Nissen, J.P. Preble, R.A. Rimmer, T. Satogata, A. Seryi, M. Wiseman, W. Wittmer, Y. Zhang JLab, Newport News, Virginia, USA Y. Cai, Y.M. Nosochkov, G. Stupakov, M.K. Sullivan SLAC, Menlo Park, California, USA K.E. Deitrick, C.M. Gulliford, G.H. Hoffstaetter, J.E. Unger Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA E. Gianfelice-Wendt Fermilab, Batavia, Illinois, USA T. Satogata ODU, Norfolk, Virginia, USA D. Xu FRIB, East Lansing, Michigan, USA
	Funding: Work supported by BSA, LLC under Contract No. DE-SC0012704, by JSA, LLC under Contract No. DE-AC05-06OR23177, and by SLAC under Contract No. DE-AC02-76SF00515 with the U.S. Department of Energy. The design of the electron-ion collider EIC to be constructed at Brookhaven National Laboratory has been continuously evolving towards a realistic and robust design that meets all the requirements set forth by the nuclear physics community in the White Paper. Over the past year activities have been focused on maturing the design, and on developing alternatives to mitigate risk. These include improvements of the interaction region design as well as modifications of the hadron ring vacuum system to accommodate the high average and peak beam currents. Beam dynamics studies have been performed to determine and optimize the dynamic aperture in the two collider rings and the beam-beam performance. We will present the EIC design with a focus on recent developments.
	Poster WEPAB005 [2.095 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB005
About •	paper received ※ 14 May 2021 paper accepted ※ 22 June 2021 issue date ※ 17 August 2021
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WEPAB019	RF Harmonic Kicker R&D Demonstration and Its Application to the RCS Injection of the EIC	2632
	G.-T. Park, M.W. Bruker, J.M. Grames, J. Guo, R.A. Rimmer, S.O. Solomon, H. Wang JLab, Newport News, Virginia, USA
	The Rapid Cycling Synchrotron (RCS) of the Electron-Ion Collider (EIC) at Brookhaven National Laboratory (BNL) * is an accelerating component of the electron injection complex, which provides polarized electrons in electron-ion collisions in the main Electron Storage Ring (ESR). We present the injection scheme into the RCS based on an ultra-fast harmonic kicker, whose "five odd-harmonic modes" prototype was developed in the context of the Jefferson Lab EIC (JLEIC) conceptual design . In its early stage of R&D, the sharp (~3 ns width) waveform construction, beam dynamics, and pulsed power operation with short ramping time (~10 us) will be discussed together with the fabrication work of the JLEIC prototype . BNL, "Electron Ion Collider Conceptual Design Report", 2020 G. Park et. al, JLAB-TN-044 * G. Park et. al., JLAB-TN-046
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB019
About •	paper received ※ 17 May 2021 paper accepted ※ 22 June 2021 issue date ※ 27 August 2021
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WEPAB104	Improving the Operational Lifetime of the CEBAF Photo-Gun by Anode Biasing	2840
	J.T. Yoskowitz, G.A. Krafft, G.G. Palacios Serrano, S.A.K. Wijethunga ODU, Norfolk, Virginia, USA J.M. Grames, J. Hansknecht, C. Hernandez-Garcia, M. Poelker, M.L. Stutzman, R. Suleiman JLab, Newport News, Virginia, USA S.B. van der Geer Pulsar Physics, Eindhoven, The Netherlands
	Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. The operating lifetime of GaAs-based photocathodes in DC high voltage electron photo-guns is dominated by the ionization rate of residual beamline gas molecules. In this work, experiments were performed to quantify the improvement in photocathode charge lifetime by biasing the photo-gun anode with a positive voltage, which repels ions generated downstream of the anode. The photo-cathode charge lifetime improved by almost a factor of two when the anode was biased compared to the usual grounded configuration. Simulations were performed using the particle tracking code General Particle Tracer (GPT) with a new custom element. The simulation results showed that both the number and energy of ions play a role in the pattern of QE degradation. The experiment results and conclusions supported by GPT simulations will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB104
About •	paper received ※ 20 May 2021 paper accepted ※ 02 June 2021 issue date ※ 24 August 2021
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WEPAB105	Simulating Electron Impact Ionization Using a General Particle Tracer (GPT) Custom Element	2843
	J.T. Yoskowitz, G.A. Krafft ODU, Norfolk, Virginia, USA J.M. Grames JLab, Newport News, Virginia, USA G.R. Montoya Soto Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico C.A. Valerio ECFM-UAS, Culiacan, Sinaloa, Mexico S.B. van der Geer Pulsar Physics, Eindhoven, The Netherlands
	Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177, Consejo Nacional de Ciencia y Tecnología (CONACYT). A new C++ custom element has been developed with the framework of General Particle Tracer (GPT) to simulate electron impact ionization of residual gas molecules. The custom element uses Monte-Carlo routines to determine both the ion production rate and the secondary electron kinetic energy based on user-defined gas densities and theoretical values for the ionization cross section and the secondary electron differential cross section. It then uses relativistic kinematics to track the secondary electron, the scattered electron, and the newly formed ion after ionization. The ion production rate and the secondary electron energy distribution determined by the custom element have been benchmarked against theoretical calculations and against simulations made using the simulation package IBSimu. While the custom element was originally built for particle accelerator simulations, it is readily extensible to other applications. The custom element will be described in detail and examples of applications at the Thomas Jefferson National Accelerator Facility will be presented for ion production in a DC high voltage photo-gun.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB105
About •	paper received ※ 20 May 2021 paper accepted ※ 25 June 2021 issue date ※ 02 September 2021
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WEPAB138	Superconducting RF Gun with High Current and the Capability to Generate Polarized Electron Beams	2936
	I. Petrushina SUNY SB, Stony Brook, New York, USA S.A. Belomestnykh, S. Kazakov, T.N. Khabiboulline, M. Martinello, Y.M. Pischalnikov, V.P. Yakovlev Fermilab, Batavia, Illinois, USA J.C. Brutus, P. Inacker, Y.C. Jing, V. Litvinenko, J. Skaritka, E. Wang BNL, Upton, New York, USA J.M. Grames, M. Poelker, R. Suleiman, E.J-M. Voutier JLab, Newport News, Virginia, USA
	High-current low-emittance CW electron beams are indispensable for nuclear and high-energy physics fixed target and collider experiments, cooling high energy hadron beams, generating CW beams of monoenergetic X-rays (in FELs) and gamma-rays (in Compton sources). Polarization of electrons in these beams provides extra value by opening a new set of observables and frequently improving the data quality. We report on the upgrade of the unique and fully functional CW SRF 1.25 MeV SRF gun, built as part of the Coherent electron Cooling (CeC) project, which has demonstrated sustained CW operation with CsK2Sb photocathodes generating electron bunches with record-low transverse emittances and record-high bunch charge exceeding 10 nC. We propose to extend the capabilities of this system to high average current of 100 milliampere in two steps: increasing the current 30-fold at each step with the goal to demonstrate reliable long-term operation of the high-current low-emittance CW SRF guns. We also propose to test polarized GaAs photocathodes in the ultra-high vacuum (UHV) environment of the SRF gun, which has never been successfully demonstrated in RF accelerators.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB138
About •	paper received ※ 25 May 2021 paper accepted ※ 29 July 2021 issue date ※ 23 August 2021
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Paper

Title

Page

High Voltage Design and Evaluation of Wien Filters for the CEBAF 200 keV Injector Upgrade

1000

G.G. Palacios Serrano, P.A. Adderley, J.F. Benesch, D.B. Bullard, J.M. Grames, C. Hernandez-Garcia, A.S. Hofler, D. Machie, M. Poelker, M.L. Stutzman, R. Suleiman
JLab, Newport News, Virginia, USA
H. Baumgart, G.G. Palacios Serrano
ODU, Norfolk, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
High-energy nuclear physics experiments at the Jefferson Lab Continuous Electron Beam Accelerator Facility (CEBAF) require highly spin-polarization electron beams, produced from strained super-lattice GaAs photocathodes, activated to negative electron affinity in a photogun operating at 130 kV dc. A pair of Wien filter spin rotators in the injector defines the orientation of the electron beam polarization at the end station target. An upgrade of the CEBAF injector to better support the upcoming MOLLER experiment requires increasing the electron beam energy to 200 keV, to reduce unwanted helicity correlated intensity and position systematics and provide precise control of the polarization orientation. Our contribution describes design, fabrication and testing of the high voltage system to upgrade the Wien spin rotator to be compatible with the 200 keV beam. This required Solidworks modeling, CST and Opera electro- and magnetostatic simulations, upgrading HV vacuum feedthroughs, and assembly techniques for improving electrode alignment. The electric and magnetic fields required by the Wien condition and the successful HV characterization under vacuum conditions are also presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB324

About •

paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 18 August 2021

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TUPAB037

The Design of a High Charge Polarized Preinjector for the Electron-Ion Collider

1428

E. Wang, W. Liu, V.H. Ranjbar, J. Skaritka, N. Tsoupas
BNL, Upton, New York, USA
J.M. Grames, J. Guo
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy
The design of the electron pre-injector of the Electron-Ion Collider (EIC) project to generate 4 x 7 nC bunch has been advancing to meet the requirements for injection into the Rapid Cycling Synchrotron (RCS). The major challenges are high charge transport and achieving small energy spread from 3 GHz traveling-wave plate(TWP). The designed preinjector includes the polarized electron source, bunching section, TWP Linac, zigzag phase space manipulation and spin rotator. In this report, we will discuss the RF frequency selection and the way to reduce energy spread down to 0.2% by longitudinal phase space manipulate. We will also report the results of beamline simulation using space charge code and the conceptual design of spin rotator.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB037

About •

paper received ※ 16 May 2021 paper accepted ※ 15 June 2021 issue date ※ 31 August 2021

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WEXA04

The RCS Design Status for the Electron Ion Collider

2521

V.H. Ranjbar, M. Blaskiewicz, Z.A. Conway, D.M. Gassner, C. Hetzel, B. Lepore, H. Lovelace III, I. Marneris, F. Méot, C. Montag, J. Skaritka, N. Tsoupas, E. Wang, F.J. Willeke
BNL, Upton, New York, USA
J.M. Grames, J. Guo, F. Lin, V.S. Morozov, T. Satogata
JLab, Newport News, Virginia, USA
D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The design of the Electron-Ion Collider Rapid Cycling Synchrotron (RCS) to be constructed at Brookhaven National Laboratory is advancing to meet the injection requirements for the Electron Storage Ring (ESR). Over the past year activities are focused on developing the approach to inject two 28 nC bunches every second, up from the original design of one 10nC bunch every second. The solution requires several key changes concerning the injection and extraction kickers, charge accumulation via bunch merging and a carefully calibrated RF acceleration profile to match the longitudinal emittance required by the ESR.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXA04

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paper received ※ 19 May 2021 paper accepted ※ 26 August 2021 issue date ※ 31 August 2021

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WEPAB005

Design Status Update of the Electron-Ion Collider

2585

C. Montag, E.C. Aschenauer, G. Bassi, J. Beebe-Wang, J.S. Berg, M. Blaskiewicz, A. Blednykh, J.M. Brennan, S.J. Brooks, K.A. Brown, Z.A. Conway, K.A. Drees, A.V. Fedotov, W. Fischer, C. Folz, D.M. Gassner, X. Gu, R.C. Gupta, Y. Hao, A. Hershcovitch, C. Hetzel, D. Holmes, H. Huang, W.A. Jackson, J. Kewisch, Y. Li, C. Liu, H. Lovelace III, Y. Luo, M. Mapes, D. Marx, G.T. McIntyre, F. Méot, M.G. Minty, S.K. Nayak, R.B. Palmer, B. Parker, S. Peggs, B. Podobedov, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, S. Seletskiy, V.V. Smaluk, K.S. Smith, S. Tepikian, R. Than, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, S. Verdú-Andrés, E. Wang, D. Weiss, F.J. Willeke, H. Witte, Q. Wu, W. Xu, A. Zaltsman, W. Zhang
BNL, Upton, New York, USA
S.V. Benson, J.M. Grames, F. Lin, T.J. Michalski, V.S. Morozov, E.A. Nissen, J.P. Preble, R.A. Rimmer, T. Satogata, A. Seryi, M. Wiseman, W. Wittmer, Y. Zhang
JLab, Newport News, Virginia, USA
Y. Cai, Y.M. Nosochkov, G. Stupakov, M.K. Sullivan
SLAC, Menlo Park, California, USA
K.E. Deitrick, C.M. Gulliford, G.H. Hoffstaetter, J.E. Unger
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA
T. Satogata
ODU, Norfolk, Virginia, USA
D. Xu
FRIB, East Lansing, Michigan, USA

Funding: Work supported by BSA, LLC under Contract No. DE-SC0012704, by JSA, LLC under Contract No. DE-AC05-06OR23177, and by SLAC under Contract No. DE-AC02-76SF00515 with the U.S. Department of Energy.
The design of the electron-ion collider EIC to be constructed at Brookhaven National Laboratory has been continuously evolving towards a realistic and robust design that meets all the requirements set forth by the nuclear physics community in the White Paper. Over the past year activities have been focused on maturing the design, and on developing alternatives to mitigate risk. These include improvements of the interaction region design as well as modifications of the hadron ring vacuum system to accommodate the high average and peak beam currents. Beam dynamics studies have been performed to determine and optimize the dynamic aperture in the two collider rings and the beam-beam performance. We will present the EIC design with a focus on recent developments.

Poster WEPAB005 [2.095 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB005

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paper received ※ 14 May 2021 paper accepted ※ 22 June 2021 issue date ※ 17 August 2021

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WEPAB019

RF Harmonic Kicker R&D Demonstration and Its Application to the RCS Injection of the EIC

2632

G.-T. Park, M.W. Bruker, J.M. Grames, J. Guo, R.A. Rimmer, S.O. Solomon, H. Wang
JLab, Newport News, Virginia, USA

The Rapid Cycling Synchrotron (RCS) of the Electron-Ion Collider (EIC) at Brookhaven National Laboratory (BNL) * is an accelerating component of the electron injection complex, which provides polarized electrons in electron-ion collisions in the main Electron Storage Ring (ESR). We present the injection scheme into the RCS based on an ultra-fast harmonic kicker, whose "five odd-harmonic modes" prototype was developed in the context of the Jefferson Lab EIC (JLEIC) conceptual design **. In its early stage of R&D, the sharp (~3 ns width) waveform construction, beam dynamics, and pulsed power operation with short ramping time (~10 us) will be discussed together with the fabrication work of the JLEIC prototype ***.
* BNL, "Electron Ion Collider Conceptual Design Report", 2020
** G. Park et. al, JLAB-TN-044
*** G. Park et. al., JLAB-TN-046

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB019

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paper received ※ 17 May 2021 paper accepted ※ 22 June 2021 issue date ※ 27 August 2021

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WEPAB104

Improving the Operational Lifetime of the CEBAF Photo-Gun by Anode Biasing

2840

J.T. Yoskowitz, G.A. Krafft, G.G. Palacios Serrano, S.A.K. Wijethunga
ODU, Norfolk, Virginia, USA
J.M. Grames, J. Hansknecht, C. Hernandez-Garcia, M. Poelker, M.L. Stutzman, R. Suleiman
JLab, Newport News, Virginia, USA
S.B. van der Geer
Pulsar Physics, Eindhoven, The Netherlands

Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
The operating lifetime of GaAs-based photocathodes in DC high voltage electron photo-guns is dominated by the ionization rate of residual beamline gas molecules. In this work, experiments were performed to quantify the improvement in photocathode charge lifetime by biasing the photo-gun anode with a positive voltage, which repels ions generated downstream of the anode. The photo-cathode charge lifetime improved by almost a factor of two when the anode was biased compared to the usual grounded configuration. Simulations were performed using the particle tracking code General Particle Tracer (GPT) with a new custom element. The simulation results showed that both the number and energy of ions play a role in the pattern of QE degradation. The experiment results and conclusions supported by GPT simulations will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB104

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paper received ※ 20 May 2021 paper accepted ※ 02 June 2021 issue date ※ 24 August 2021

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WEPAB105

Simulating Electron Impact Ionization Using a General Particle Tracer (GPT) Custom Element

2843

J.T. Yoskowitz, G.A. Krafft
ODU, Norfolk, Virginia, USA
J.M. Grames
JLab, Newport News, Virginia, USA
G.R. Montoya Soto
Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
C.A. Valerio
ECFM-UAS, Culiacan, Sinaloa, Mexico
S.B. van der Geer
Pulsar Physics, Eindhoven, The Netherlands

Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177, Consejo Nacional de Ciencia y Tecnología (CONACYT).
A new C++ custom element has been developed with the framework of General Particle Tracer (GPT) to simulate electron impact ionization of residual gas molecules. The custom element uses Monte-Carlo routines to determine both the ion production rate and the secondary electron kinetic energy based on user-defined gas densities and theoretical values for the ionization cross section and the secondary electron differential cross section. It then uses relativistic kinematics to track the secondary electron, the scattered electron, and the newly formed ion after ionization. The ion production rate and the secondary electron energy distribution determined by the custom element have been benchmarked against theoretical calculations and against simulations made using the simulation package IBSimu. While the custom element was originally built for particle accelerator simulations, it is readily extensible to other applications. The custom element will be described in detail and examples of applications at the Thomas Jefferson National Accelerator Facility will be presented for ion production in a DC high voltage photo-gun.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB105

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paper received ※ 20 May 2021 paper accepted ※ 25 June 2021 issue date ※ 02 September 2021

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WEPAB138

Superconducting RF Gun with High Current and the Capability to Generate Polarized Electron Beams

2936

I. Petrushina
SUNY SB, Stony Brook, New York, USA
S.A. Belomestnykh, S. Kazakov, T.N. Khabiboulline, M. Martinello, Y.M. Pischalnikov, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA
J.C. Brutus, P. Inacker, Y.C. Jing, V. Litvinenko, J. Skaritka, E. Wang
BNL, Upton, New York, USA
J.M. Grames, M. Poelker, R. Suleiman, E.J-M. Voutier
JLab, Newport News, Virginia, USA

High-current low-emittance CW electron beams are indispensable for nuclear and high-energy physics fixed target and collider experiments, cooling high energy hadron beams, generating CW beams of monoenergetic X-rays (in FELs) and gamma-rays (in Compton sources). Polarization of electrons in these beams provides extra value by opening a new set of observables and frequently improving the data quality. We report on the upgrade of the unique and fully functional CW SRF 1.25 MeV SRF gun, built as part of the Coherent electron Cooling (CeC) project, which has demonstrated sustained CW operation with CsK2Sb photocathodes generating electron bunches with record-low transverse emittances and record-high bunch charge exceeding 10 nC. We propose to extend the capabilities of this system to high average current of 100 milliampere in two steps: increasing the current 30-fold at each step with the goal to demonstrate reliable long-term operation of the high-current low-emittance CW SRF guns. We also propose to test polarized GaAs photocathodes in the ultra-high vacuum (UHV) environment of the SRF gun, which has never been successfully demonstrated in RF accelerators.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB138

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paper received ※ 25 May 2021 paper accepted ※ 29 July 2021 issue date ※ 23 August 2021

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