SRF2023 - List of Authors (Saito, K.)

Paper	Title	Page
THTUT00	Welcome to SRF2023 Tutorials
	K. Saito FRIB, East Lansing, Michigan, USA
	Welcome to SRF2023 Tutorial by K. Saito, SRF2023 Chair. # Welcome to MSU Campus # Emergency evacuation # Lunch/ Dinner place # Internet connection # Purpose of SRF23 Tutorial # Very Brief Overview of SRF2023 # Tutorial Theme of SRF2023 Conference
	Slides THTUT00 [3.527 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOIAA01	FRIB Transition to User Operations, Power Ramp Up, and Upgrade Perspectives	1
	J. Wei, H. Ao, B. Arend, S. Beher, G. Bollen, N.K. Bultman, F. Casagrande, W. Chang, Y. Choi, S. Cogan, C. Compton, M. Cortesi, J.C. Curtin, K.D. Davidson, X.J. Du, K. Elliott, B. Ewert, A. Facco, A. Fila, K. Fukushima, V. Ganni, A. Ganshyn, T.N. Ginter, T. Glasmacher, J.-W. Guo, Y. Hao, W. Hartung, N.M. Hasan, M. Hausmann, K. Holland, H.-C. Hseuh, M. Ikegami, D.D. Jager, S. Jones, N. Joseph, T. Kanemura, S.H. Kim, C. Knowles, T. Konomi, B.R. Kortum, E. Kwan, T. Lange, M. Larmann, T.L. Larter, K. Laturkar, R.E. Laxdal, J. LeTourneau, Z. Li, S.M. Lidia, G. Machicoane, C. Magsig, P.E. Manwiller, F. Marti, T. Maruta, E.S. Metzgar, S.J. Miller, Y. Momozaki, D.G. Morris, M. Mugerian, I.N. Nesterenko, C. Nguyen, P.N. Ostroumov, M.S. Patil, A.S. Plastun, L. Popielarski, M. Portillo, J. Priller, X. Rao, M.A. Reaume, K. Saito, B.M. Sherrill, M.K. Smith, J. Song, M. Steiner, A. Stolz, O. Tarasov, B.P. Tousignant, R. Walker, X. Wang, J.D. Wenstrom, G. West, K. Witgen, M. Wright, T. Xu, Y. Yamazaki, T. Zhang, Q. Zhao, S. Zhao FRIB, East Lansing, Michigan, USA K. Hosoyama KEK, Ibaraki, Japan P. Hurh Fermilab, Batavia, Illinois, USA M.P. Kelly, Y. Momozaki ANL, Lemont, Illinois, USA R.E. Laxdal TRIUMF, Vancouver, Canada S.O. Prestemon LBNL, Berkeley, California, USA M. Wiseman JLab, Newport News, Virginia, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. After project completion on scope, on cost, and ahead of schedule, the Facility for Rare Isotope Beams began operations for scientific users in May of 2022. During the first 12 months of user operations, the FRIB accelerator complex delivered 5250 beam hours, including 1528 hours to nine science experiments conducted with primary beams of 36Ar, 48Ca, 70Zn, 82Se, 124Xe, and 198Pt at beam energies >200 MeV/u; 2724 hours for beam developments, studies, and tuning; and 998 hours to industrial users and non-scientific programs using the FRIB Single Event Effect (FSEE) beam line. The ramp-up to a beam power of 400 kW is planned over a six-year period; 1 kW was delivered for initial user runs from in 2022, and 5 kW was delivered as of February 2023. Upgrade plans include doubling the primary-beam energy to 400 MeV/nucleon for enhanced discovery potential (¿FRIB 400¿). This talk reports on FRIB status and progress since SRF2021, emphasizing lessons learned during the transition from beam commissioning to machine operations, challenges and resolutions for the power ramp-up, progress with accelerator improvements, and R&D for the energy upgrade.
	Slides MOIAA01 [7.037 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOIAA01
About •	Received ※ 20 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 03 July 2023 — Issue date ※ 19 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB026	Development of Transformative Cavity Processing - Superiority of Electropolishing on High Gradient Performance over Buffered Chemical Polishing at Low Frequency (322 MHz)	145
	K. Saito, C. Compton, K. Elliott, W. Hartung, S.H. Kim, T.K. Konomi, E.S. Metzgar, S.J. Miller, L. Popielarski, A.T. Taylor, T. Xu FRIB, East Lansing, Michigan, USA
	Funding: The work is supported by DOE Awards DE-SC0022994. A DOE grant R&D titled ¿Development of Transformative Preparation Technology to Push up High Q/G Performance of FRIB Spare HWR Cryomodule Cavities¿ is ongoing at FRIB. This R&D is for 2 years since September 2022. This project proposes four objectives: 1) Superiority on high gradient performance of electropolishing (EP) over buffered chemical polishing at low frequency (322 MHz), 2) High Qo performance by the local magnetic shield, 3) Development of HFQS-free BCP and, 4) Wet N-doping method. This paper will report the result of first object, and a local magnetic shield design and simulation to reduce the residual magnetic field < 0.1 mG in the vertical test Dewar, for the object 2.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB026
About •	Received ※ 14 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 08 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB027	Successful Superheating Field Formulas from an Intuitive Model	151
	K. Saito, T. Konomi FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science DE-S0000661 and the National Science Foundation under Cooperative Agreement PHY-1102511 To date, many theoretical formulas for superheating field on SRF cavity are already proposed based rather complicated calculations. This paper proposes the formulas by a very intuitive simple model: energy balance between RF magnetic energy and superconducting condensed one, and a condition of vanishing the mirror vortex line image. The penetration of a single vortex determines the superheating field for a type II superconductor. On the other hand, for type I superconductors, the surface flux penetration determines it. The formula fits very well quantitatively the results of niobium cavity and Nb₃Sn one. In addition, it gives a nice guideline for new material beyond niobium. male, senior
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB027
About •	Received ※ 23 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 15 July 2023
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MOPMB067	Design of a Cathode Insertion and Transfer System for LCLS-II-HE SRF Gun	267
	R. Xiang, A. Arnold, S. Gatzmaga, A. Hoffmann, P. Murcek, R. Steinbrück, J. Teichert HZDR, Dresden, Germany C. Adolphsen, J. Smedley SLAC, Menlo Park, California, USA W. Hartung, S.H. Kim, T.K. Konomi, S.J. Miller, L. Popielarski, K. Saito, T. Xu FRIB, East Lansing, Michigan, USA M.P. Kelly, T.B. Petersen ANL, Lemont, Illinois, USA J.W. Lewellen LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by cooperation project between MSU and HZDR RC113062 from the U.S. Department of Energy Office of Science under Cooperative Agreement DE-AC02-76SF00515. Superconducting radio frequency photo injectors (SRF gun) offer advantages for operating in continuous wave (CW) mode and generating high-brightness and high-current beams. A new SRF gun is designed as a low emittance photo injector for LCLS-II-HE and a prototype gun is currently being developed under collaboration between SLAC, FRIB, HZDR and ANL. The aim is to demonstrate stable CW operation at a cathode gradient of 30 MV/m. One of the crucial component for successful SRF gun operation is the photocathode system. The new SRF gun will adopt the HZDR-type cathode, which includes a cathode holder fixture (cathode stalk) developed by FRIB and a sophisticated cathode exchange system designed by HZDR. This innovative cathode insertion system ensures accurate, particle-free and warm cathode exchanges. A novel alignment process targets the cathode to the stalk axis without touching cathode plug itself. To commission the prototype gun, metallic cathodes will be used. A specifically designed vacuum system ensures vacuum pressure of 10^-9 mbar for transport of a single cathode from the cleanroom to the gun. Thus maintaining cathode quality.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB067
About •	Received ※ 18 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTB063	Fabrication Efforts Toward a Superconducting Rf Photo-Infector Quarter-Wave Cavity for Use in Low Emittance Injector Applications	568
	C. Compton NSCL, East Lansing, Michigan, USA K. Elliott, W. Hartung, J.D. Hulbert, S.H. Kim, T. Konomi, S.J. Miller, M.S. Patil, J.T. Popielarski, L. Popielarski, K. Saito, K. Witgen, T. Xu FRIB, East Lansing, Michigan, USA M. Kedzie, M.P. Kelly, T.B. Petersen ANL, Lemont, Illinois, USA J.W. Lewellen, J. Smedley SLAC, Menlo Park, California, USA
	Funding: * Work supported by the Department of Energy Contract DE-AC02- 76SF00515 The Facility for Rare Isotope Beams (FRIB), in collaboration with Argonne National Laboratory (ANL) and Helmholtz-Zentrum Dresden-Rossendorf (HDZR), is working on the design and fabrication of a photo-injector cryomodule; suitable for operation as part of accelerator systems at SLAC National Accelerator Laboratory. Project scope requires the fabrication of two 185.7 MHz superconducting, quarter-wave resonators (QWR) based, injector cavities. Cavity fabrication will be completed at FRIB with contracted vendors supporting subcomponent fabrication and electron-beam welding. Fabrication will use poly-crystalline and large grain RRR niobium materials. The current status of cavity fabrication will be presented including material procurement, prototype forming, and electron-beam welding development.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB063
About •	Received ※ 17 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 21 August 2023 — Issue date ※ 21 August 2023
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TUPTB069	Design and Tests of a Cathode Stalk for the LCLS-II-HE Low Emittance Injector SRF Gun	589
	T.K. Konomi, W. Hartung, S.H. Kim, S.J. Miller, D.G. Morris, K. Saito, A.T. Taylor, T. Xu, Z.Y. Yin FRIB, East Lansing, Michigan, USA C. Adolphsen, J. Smedley, L. Xiao SLAC, Menlo Park, California, USA S. Gatzmaga, P. Murcek, R. Xiang HZDR, Dresden, Germany M.P. Kelly, T.B. Petersen ANL, Lemont, Illinois, USA J.W. Lewellen LANL, Los Alamos, New Mexico, USA
	A SRF gun can operate CW with a high gradient and ultra-low vacuum for high-quantum efficiency, low MTE photocathodes, useful features for delivery of high-brightness, high-repetition-rate beams. For these reasons, an SRF gun based photoinjector was chosen for a proposed Low Emittance Injector addition to the LCLS-II-HE facility, which will operate CW with bunch rates up to 1 MHz. For this injector, a prototype 185.7 MHz QWR gun is being developed in a collaborative effort among FRIB, HZDR, ANL and SLAC, with the goal of achieving a photocathode gradient of at least 30 MV/m. The photocathode is held by a coaxial fixture (cathode stalk) for thermal isolation from the cavity body. The system must allow for precise alignment of the photocathode, particle-free photocathode exchange, cryogenic (55-70 K) or warm (273-300 K) photocathode operating temperatures, and DC biasing to inhibit multipacting. A prototype cathode stalk has been built and bench tests are underway to validate the design. Measurements include RF power dissipation, DC bias hold-off, multipacting suppression and heat transfer effectiveness. This paper describes the cathode stalk design and the test results.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB069
About •	Received ※ 03 July 2023 — Revised ※ 27 July 2023 — Accepted ※ 19 August 2023 — Issue date ※ 20 August 2023
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THIXA01	Investigation of Plasma Processing for Coaxial Resonators	960
	W. Hartung, W. Chang, K. Elliott, S.H. Kim, T. Konomi, K. Saito, P.R. Tutt, T. Xu FRIB, East Lansing, Michigan, USA
	Plasma processing has been investigated by several facilities as a method to mitigate degradation of SRF cavity performance. It provides an alternative to removal and disassembly of cryomodules for refurbishment of each cavity via repeat etching and rinsing. Promising results have been obtained by several groups. Studies of plasma processing for quarter-wave resonators (QWRs) and half-wave resonators (HWRs) were undertaken at FRIB, where a total of 324 such resonators are presently in operation. Plasma ignition and optimization measurements were done with room-temperature-matched input couplers. Plasma cleaning tests were done on several QWRs using the fundamental power coupler (FPC) to drive the plasma. We investigated the usefulness of higher-order modes (HOMs) to drive the plasma. HOMs allow for less mismatch at the FPC and hence lower field in the coupler relative to the cavity. Before-and-after cold tests showed a significant reduction in field emission X-rays with judicious application of plasma processing.
	Slides THIXA01 [2.060 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-THIXA01
About •	Received ※ 01 September 2023 — Accepted ※ 02 September 2023 — Issue date ※ 02 September 2023
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FRIBA05	Automation of FRIB SRF Cavities and SC Solenoids Turn-on/off	999
	W. Chang, Y. Choi, X.J. Du, W. Hartung, S.H. Kim, T. Konomi, S.R. Kunjir, H. Nguyen, K. Saito, T. Xu, S. Zhao FRIB, East Lansing, Michigan, USA A. Facco INFN/LNL, Legnaro (PD), Italy
	The superconducting driver Linac for the Facility for Rare Isotope Beams (FRIB) is a heavy ion accelerator that accelerate ions to 200 MeV per nucleon. The Linac has 46 cryomodules that contain 324 superconducting radio frequency (SRF) cavities and 69 superconducting (SC) solenoid packages. For operation of all cryomodules with high efficiency and reliability, automation for SRF cavity and SC solenoid fast turn-on/off is essentially. Based on cryomodule commissioning results and expert experience, all manual cavity and solenoid turn-on/off procedures and steps have been replaced by automatic programs for FRIB linac operation. This allows the operators to turn the systems on and off without expert-level training. Automation reduces the risk of human error, speeds up beam recovery after user access to experimental areas, and increases beam availability. The cavity turn-on procedure makes sure that the cavity can operate at low field with expected read backs, ramps up the field, and makes sure that the RF amplitude and phase are stable. The design, implementation, and operating experience with automation will be presented.
	Slides FRIBA05 [3.503 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-FRIBA05
About •	Received ※ 29 June 2023 — Revised ※ 16 August 2023 — Accepted ※ 21 August 2023 — Issue date ※ 21 August 2023
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FRIBA07	Status of the SLAC/MSU SRF Gun Development Project	1003
	S.J. Miller, Y. Al-Mahmoud, W. Chang, Y. Choi, C. Compton, X.J. Du, K. Elliott, W. Hartung, J.D. Hulbert, S.H. Kim, T. Konomi, D.G. Morris, M.S. Patil, L. Popielarski, K. Saito, A. Taylor, B.P. Tousignant, J. Wei, J.D. Wenstrom, K. Witgen, T. Xu FRIB, East Lansing, Michigan, USA C. Adolphsen, R. Coy, F. Ji, M.J. Murphy, J. Smedley, L. Xiao SLAC, Menlo Park, California, USA A. Arnold, S. Gatzmaga, P. Murcek, J. Teichert, R. Xiang HZDR, Dresden, Germany M.P. Kelly, T.B. Petersen, P. Piot ANL, Lemont, Illinois, USA J.W. Lewellen LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the Department of Energy under Contract DE-AC02-76SF00515 The Linac Coherent Light Source II High Energy (LCLS-II-HE) Project at SLAC includes the construction of a low-emittance injector (LEI) and a superconducting quarter-wave resonator (QWR) at 185.7 MHz. Several alternatives to a superconducting radio frequency (SRF) QWR gun were considered for the LEI, including nor-mal-conducting RF guns evolved from the LCLS-II gun design. Compared to normal-conducting designs, the combination of an intrinsically outstanding vacuum environment (for cathode lifetime), and the potential for a larger ultimate performance envelope, led to the deci-sion to pursue development of the QWR-SRF gun. A prototype gun is currently being designed and fabricated at the Facility for Rare Isotope Beams (FRIB) at Michi-gan State University (MSU). This paper presents perfor-mance goals for the new gun design, an overview of the prototype development effort, status, and future plans including fabrication.
	Slides FRIBA07 [9.655 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-FRIBA07
About •	Received ※ 15 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 11 July 2023
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Paper

Title

Page

THTUT00

Welcome to SRF2023 Tutorials

K. Saito
FRIB, East Lansing, Michigan, USA

Welcome to SRF2023 Tutorial by K. Saito, SRF2023 Chair. # Welcome to MSU Campus # Emergency evacuation # Lunch/ Dinner place # Internet connection # Purpose of SRF23 Tutorial # Very Brief Overview of SRF2023 # Tutorial Theme of SRF2023 Conference

Slides THTUT00 [3.527 MB]

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOIAA01

FRIB Transition to User Operations, Power Ramp Up, and Upgrade Perspectives

1

J. Wei, H. Ao, B. Arend, S. Beher, G. Bollen, N.K. Bultman, F. Casagrande, W. Chang, Y. Choi, S. Cogan, C. Compton, M. Cortesi, J.C. Curtin, K.D. Davidson, X.J. Du, K. Elliott, B. Ewert, A. Facco, A. Fila, K. Fukushima, V. Ganni, A. Ganshyn, T.N. Ginter, T. Glasmacher, J.-W. Guo, Y. Hao, W. Hartung, N.M. Hasan, M. Hausmann, K. Holland, H.-C. Hseuh, M. Ikegami, D.D. Jager, S. Jones, N. Joseph, T. Kanemura, S.H. Kim, C. Knowles, T. Konomi, B.R. Kortum, E. Kwan, T. Lange, M. Larmann, T.L. Larter, K. Laturkar, R.E. Laxdal, J. LeTourneau, Z. Li, S.M. Lidia, G. Machicoane, C. Magsig, P.E. Manwiller, F. Marti, T. Maruta, E.S. Metzgar, S.J. Miller, Y. Momozaki, D.G. Morris, M. Mugerian, I.N. Nesterenko, C. Nguyen, P.N. Ostroumov, M.S. Patil, A.S. Plastun, L. Popielarski, M. Portillo, J. Priller, X. Rao, M.A. Reaume, K. Saito, B.M. Sherrill, M.K. Smith, J. Song, M. Steiner, A. Stolz, O. Tarasov, B.P. Tousignant, R. Walker, X. Wang, J.D. Wenstrom, G. West, K. Witgen, M. Wright, T. Xu, Y. Yamazaki, T. Zhang, Q. Zhao, S. Zhao
FRIB, East Lansing, Michigan, USA
K. Hosoyama
KEK, Ibaraki, Japan
P. Hurh
Fermilab, Batavia, Illinois, USA
M.P. Kelly, Y. Momozaki
ANL, Lemont, Illinois, USA
R.E. Laxdal
TRIUMF, Vancouver, Canada
S.O. Prestemon
LBNL, Berkeley, California, USA
M. Wiseman
JLab, Newport News, Virginia, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
After project completion on scope, on cost, and ahead of schedule, the Facility for Rare Isotope Beams began operations for scientific users in May of 2022. During the first 12 months of user operations, the FRIB accelerator complex delivered 5250 beam hours, including 1528 hours to nine science experiments conducted with primary beams of 36Ar, 48Ca, 70Zn, 82Se, 124Xe, and 198Pt at beam energies >200 MeV/u; 2724 hours for beam developments, studies, and tuning; and 998 hours to industrial users and non-scientific programs using the FRIB Single Event Effect (FSEE) beam line. The ramp-up to a beam power of 400 kW is planned over a six-year period; 1 kW was delivered for initial user runs from in 2022, and 5 kW was delivered as of February 2023. Upgrade plans include doubling the primary-beam energy to 400 MeV/nucleon for enhanced discovery potential (¿FRIB 400¿). This talk reports on FRIB status and progress since SRF2021, emphasizing lessons learned during the transition from beam commissioning to machine operations, challenges and resolutions for the power ramp-up, progress with accelerator improvements, and R&D for the energy upgrade.

Slides MOIAA01 [7.037 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOIAA01

About •

Received ※ 20 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 03 July 2023 — Issue date ※ 19 July 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB026

Development of Transformative Cavity Processing - Superiority of Electropolishing on High Gradient Performance over Buffered Chemical Polishing at Low Frequency (322 MHz)

145

K. Saito, C. Compton, K. Elliott, W. Hartung, S.H. Kim, T.K. Konomi, E.S. Metzgar, S.J. Miller, L. Popielarski, A.T. Taylor, T. Xu
FRIB, East Lansing, Michigan, USA

Funding: The work is supported by DOE Awards DE-SC0022994.
A DOE grant R&D titled ¿Development of Transformative Preparation Technology to Push up High Q/G Performance of FRIB Spare HWR Cryomodule Cavities¿ is ongoing at FRIB. This R&D is for 2 years since September 2022. This project proposes four objectives: 1) Superiority on high gradient performance of electropolishing (EP) over buffered chemical polishing at low frequency (322 MHz), 2) High Qo performance by the local magnetic shield, 3) Development of HFQS-free BCP and, 4) Wet N-doping method. This paper will report the result of first object, and a local magnetic shield design and simulation to reduce the residual magnetic field < 0.1 mG in the vertical test Dewar, for the object 2.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB026

About •

Received ※ 14 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 08 July 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB027

Successful Superheating Field Formulas from an Intuitive Model

151

K. Saito, T. Konomi
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy Office of Science DE-S0000661 and the National Science Foundation under Cooperative Agreement PHY-1102511
To date, many theoretical formulas for superheating field on SRF cavity are already proposed based rather complicated calculations. This paper proposes the formulas by a very intuitive simple model: energy balance between RF magnetic energy and superconducting condensed one, and a condition of vanishing the mirror vortex line image. The penetration of a single vortex determines the superheating field for a type II superconductor. On the other hand, for type I superconductors, the surface flux penetration determines it. The formula fits very well quantitatively the results of niobium cavity and Nb₃Sn one. In addition, it gives a nice guideline for new material beyond niobium.
male, senior

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB027

About •

Received ※ 23 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 15 July 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB067

Design of a Cathode Insertion and Transfer System for LCLS-II-HE SRF Gun

267

R. Xiang, A. Arnold, S. Gatzmaga, A. Hoffmann, P. Murcek, R. Steinbrück, J. Teichert
HZDR, Dresden, Germany
C. Adolphsen, J. Smedley
SLAC, Menlo Park, California, USA
W. Hartung, S.H. Kim, T.K. Konomi, S.J. Miller, L. Popielarski, K. Saito, T. Xu
FRIB, East Lansing, Michigan, USA
M.P. Kelly, T.B. Petersen
ANL, Lemont, Illinois, USA
J.W. Lewellen
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by cooperation project between MSU and HZDR RC113062 from the U.S. Department of Energy Office of Science under Cooperative Agreement DE-AC02-76SF00515.
Superconducting radio frequency photo injectors (SRF gun) offer advantages for operating in continuous wave (CW) mode and generating high-brightness and high-current beams. A new SRF gun is designed as a low emittance photo injector for LCLS-II-HE and a prototype gun is currently being developed under collaboration between SLAC, FRIB, HZDR and ANL. The aim is to demonstrate stable CW operation at a cathode gradient of 30 MV/m. One of the crucial component for successful SRF gun operation is the photocathode system. The new SRF gun will adopt the HZDR-type cathode, which includes a cathode holder fixture (cathode stalk) developed by FRIB and a sophisticated cathode exchange system designed by HZDR. This innovative cathode insertion system ensures accurate, particle-free and warm cathode exchanges. A novel alignment process targets the cathode to the stalk axis without touching cathode plug itself. To commission the prototype gun, metallic cathodes will be used. A specifically designed vacuum system ensures vacuum pressure of 10^-9 mbar for transport of a single cathode from the cleanroom to the gun. Thus maintaining cathode quality.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB067

About •

Received ※ 18 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTB063

Fabrication Efforts Toward a Superconducting Rf Photo-Infector Quarter-Wave Cavity for Use in Low Emittance Injector Applications

568

C. Compton
NSCL, East Lansing, Michigan, USA
K. Elliott, W. Hartung, J.D. Hulbert, S.H. Kim, T. Konomi, S.J. Miller, M.S. Patil, J.T. Popielarski, L. Popielarski, K. Saito, K. Witgen, T. Xu
FRIB, East Lansing, Michigan, USA
M. Kedzie, M.P. Kelly, T.B. Petersen
ANL, Lemont, Illinois, USA
J.W. Lewellen, J. Smedley
SLAC, Menlo Park, California, USA

Funding: * Work supported by the Department of Energy Contract DE-AC02- 76SF00515
The Facility for Rare Isotope Beams (FRIB), in collaboration with Argonne National Laboratory (ANL) and Helmholtz-Zentrum Dresden-Rossendorf (HDZR), is working on the design and fabrication of a photo-injector cryomodule; suitable for operation as part of accelerator systems at SLAC National Accelerator Laboratory. Project scope requires the fabrication of two 185.7 MHz superconducting, quarter-wave resonators (QWR) based, injector cavities. Cavity fabrication will be completed at FRIB with contracted vendors supporting subcomponent fabrication and electron-beam welding. Fabrication will use poly-crystalline and large grain RRR niobium materials. The current status of cavity fabrication will be presented including material procurement, prototype forming, and electron-beam welding development.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB063

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Received ※ 17 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 21 August 2023 — Issue date ※ 21 August 2023

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TUPTB069

Design and Tests of a Cathode Stalk for the LCLS-II-HE Low Emittance Injector SRF Gun

589

T.K. Konomi, W. Hartung, S.H. Kim, S.J. Miller, D.G. Morris, K. Saito, A.T. Taylor, T. Xu, Z.Y. Yin
FRIB, East Lansing, Michigan, USA
C. Adolphsen, J. Smedley, L. Xiao
SLAC, Menlo Park, California, USA
S. Gatzmaga, P. Murcek, R. Xiang
HZDR, Dresden, Germany
M.P. Kelly, T.B. Petersen
ANL, Lemont, Illinois, USA
J.W. Lewellen
LANL, Los Alamos, New Mexico, USA

A SRF gun can operate CW with a high gradient and ultra-low vacuum for high-quantum efficiency, low MTE photocathodes, useful features for delivery of high-brightness, high-repetition-rate beams. For these reasons, an SRF gun based photoinjector was chosen for a proposed Low Emittance Injector addition to the LCLS-II-HE facility, which will operate CW with bunch rates up to 1 MHz. For this injector, a prototype 185.7 MHz QWR gun is being developed in a collaborative effort among FRIB, HZDR, ANL and SLAC, with the goal of achieving a photocathode gradient of at least 30 MV/m. The photocathode is held by a coaxial fixture (cathode stalk) for thermal isolation from the cavity body. The system must allow for precise alignment of the photocathode, particle-free photocathode exchange, cryogenic (55-70 K) or warm (273-300 K) photocathode operating temperatures, and DC biasing to inhibit multipacting. A prototype cathode stalk has been built and bench tests are underway to validate the design. Measurements include RF power dissipation, DC bias hold-off, multipacting suppression and heat transfer effectiveness. This paper describes the cathode stalk design and the test results.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB069

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Received ※ 03 July 2023 — Revised ※ 27 July 2023 — Accepted ※ 19 August 2023 — Issue date ※ 20 August 2023

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THIXA01

Investigation of Plasma Processing for Coaxial Resonators

960

W. Hartung, W. Chang, K. Elliott, S.H. Kim, T. Konomi, K. Saito, P.R. Tutt, T. Xu
FRIB, East Lansing, Michigan, USA

Plasma processing has been investigated by several facilities as a method to mitigate degradation of SRF cavity performance. It provides an alternative to removal and disassembly of cryomodules for refurbishment of each cavity via repeat etching and rinsing. Promising results have been obtained by several groups. Studies of plasma processing for quarter-wave resonators (QWRs) and half-wave resonators (HWRs) were undertaken at FRIB, where a total of 324 such resonators are presently in operation. Plasma ignition and optimization measurements were done with room-temperature-matched input couplers. Plasma cleaning tests were done on several QWRs using the fundamental power coupler (FPC) to drive the plasma. We investigated the usefulness of higher-order modes (HOMs) to drive the plasma. HOMs allow for less mismatch at the FPC and hence lower field in the coupler relative to the cavity. Before-and-after cold tests showed a significant reduction in field emission X-rays with judicious application of plasma processing.

Slides THIXA01 [2.060 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-THIXA01

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Received ※ 01 September 2023 — Accepted ※ 02 September 2023 — Issue date ※ 02 September 2023

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FRIBA05

Automation of FRIB SRF Cavities and SC Solenoids Turn-on/off

999

W. Chang, Y. Choi, X.J. Du, W. Hartung, S.H. Kim, T. Konomi, S.R. Kunjir, H. Nguyen, K. Saito, T. Xu, S. Zhao
FRIB, East Lansing, Michigan, USA
A. Facco
INFN/LNL, Legnaro (PD), Italy

The superconducting driver Linac for the Facility for Rare Isotope Beams (FRIB) is a heavy ion accelerator that accelerate ions to 200 MeV per nucleon. The Linac has 46 cryomodules that contain 324 superconducting radio frequency (SRF) cavities and 69 superconducting (SC) solenoid packages. For operation of all cryomodules with high efficiency and reliability, automation for SRF cavity and SC solenoid fast turn-on/off is essentially. Based on cryomodule commissioning results and expert experience, all manual cavity and solenoid turn-on/off procedures and steps have been replaced by automatic programs for FRIB linac operation. This allows the operators to turn the systems on and off without expert-level training. Automation reduces the risk of human error, speeds up beam recovery after user access to experimental areas, and increases beam availability. The cavity turn-on procedure makes sure that the cavity can operate at low field with expected read backs, ramps up the field, and makes sure that the RF amplitude and phase are stable. The design, implementation, and operating experience with automation will be presented.

Slides FRIBA05 [3.503 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-FRIBA05

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Received ※ 29 June 2023 — Revised ※ 16 August 2023 — Accepted ※ 21 August 2023 — Issue date ※ 21 August 2023

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FRIBA07

Status of the SLAC/MSU SRF Gun Development Project

1003

S.J. Miller, Y. Al-Mahmoud, W. Chang, Y. Choi, C. Compton, X.J. Du, K. Elliott, W. Hartung, J.D. Hulbert, S.H. Kim, T. Konomi, D.G. Morris, M.S. Patil, L. Popielarski, K. Saito, A. Taylor, B.P. Tousignant, J. Wei, J.D. Wenstrom, K. Witgen, T. Xu
FRIB, East Lansing, Michigan, USA
C. Adolphsen, R. Coy, F. Ji, M.J. Murphy, J. Smedley, L. Xiao
SLAC, Menlo Park, California, USA
A. Arnold, S. Gatzmaga, P. Murcek, J. Teichert, R. Xiang
HZDR, Dresden, Germany
M.P. Kelly, T.B. Petersen, P. Piot
ANL, Lemont, Illinois, USA
J.W. Lewellen
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the Department of Energy under Contract DE-AC02-76SF00515
The Linac Coherent Light Source II High Energy (LCLS-II-HE) Project at SLAC includes the construction of a low-emittance injector (LEI) and a superconducting quarter-wave resonator (QWR) at 185.7 MHz. Several alternatives to a superconducting radio frequency (SRF) QWR gun were considered for the LEI, including nor-mal-conducting RF guns evolved from the LCLS-II gun design. Compared to normal-conducting designs, the combination of an intrinsically outstanding vacuum environment (for cathode lifetime), and the potential for a larger ultimate performance envelope, led to the deci-sion to pursue development of the QWR-SRF gun. A prototype gun is currently being designed and fabricated at the Facility for Rare Isotope Beams (FRIB) at Michi-gan State University (MSU). This paper presents perfor-mance goals for the new gun design, an overview of the prototype development effort, status, and future plans including fabrication.

Slides FRIBA07 [9.655 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-FRIBA07

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Received ※ 15 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 11 July 2023

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