SRF2023 - Classification: SRF Facilities / Operational experience and lessons learned

Paper	Title	Page
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)

MOIXA04	Operational Experience for RIKEN Superconducting Linear Accelerator	30
	K. Yamada, M. Fujimaki, H. Imao, O. Kamigaito, M. Komiyama, K. Kumagai, T. Nagatomo, T. Nishi, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe RIKEN Nishina Center, Wako, Japan
	The RIKEN superconducting heavy-ion linac, so-called SRILAC, has been successfully operating for almost four years, and continuously deliver a heavy ion beam for a super-heavy-element synthesis experiment. The effects of a broken coupler in the early days and four years of operation have resulted in increased X-ray emission levels in several superconducting cavities, which have been successfully corrected by pulse conditioning. This talk will share the experiences and lessons learned from four-year operation with low beta SC-cavities.
	Slides MOIXA04 [4.517 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOIXA04
About •	Received ※ 06 July 2023 — Revised ※ 10 July 2023 — Accepted ※ 19 August 2023 — Issue date ※ 22 August 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOIXA06	Operational Experience with the European XFEL SRF Linac	43
	Ch. Schmidt, M. Bousonville, J. Branlard, M. Diomede, S. Göller, D. Kostin, M. Scholz, V. Vogel (Fogel), N. Walker DESY, Hamburg, Germany
	The European X-ray Free Electron laser (EuXFEL) is a 3.4 km long research facility which generates ultrashort X-ray flashes of outstanding brilliance since 2017. Up to 27000 electron bunches per second are accelerated in a 1.3 km long superconducting radio frequency (SRF) linac to a maximum energy of 17.6 GeV. Within this time, operational experience with a pulsed RF machine has been gained and new operation modes simultaneously delivering electron bunches to 3 different SASE undulator beamlines have been successfully implemented. Recent activities on increasing the linac availability, power efficiency and duty cycle are discussed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOIXA06
About •	Received ※ 19 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 06 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB008	In-Situ Quality Factor Measurements of SRF Cavities at S-DALINAC	70
SUSPB004	use link to see paper's listing under its alternate paper code
	R. Grewe, M. Arnold, A. Brauch, M. Dutine, L.E. Jürgensen, N. Pietralla, F. Schließmann, D. Schneider TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by DFG (GRK 2128) and the State of Hesse within the Research Cluster ELEMENTS (Project ID 500/10.006) The Superconducting Darmstadt Linear Accelerator (S-DALINAC) is a thrice recirculating electron accelerator wich can be operated in a multi-turn energy recovery mode. The design parameters for kinetic energy and beam current are up to 130 MeV and up to 20 uA respectively. The injector consists of a six-cell capture cavity and two 20-cell srf cavities. The main linac consists of eight 20-cell cavities. The cavities are operated at a temperature of 2 K with a frequency of 2.9972(1) GHz. Monitoring of the srf cavities is important for the overall performance of the accelerator. A key parameter for the rating of the srf cavity performance is the intrinsic quality factor Q. At the S-DALINAC it is measured for selected cavities during the yearly maintenance procedures. The unique design of the rf input coupler allows for a wide tuning range for the input coupling strength. This makes in-situ quality factor measurements using the decay time measurement method* possible. The contribution illustrates the principal design of the input couplers and the benefits it yields for Q measurements. Recent results including the progression of the quality factors over time will be presented. Felix Schliessmann et al., Nat. Phys. 19, 597-602 (2023). *Tom Powers, Proc. of SRF’05, Cornell University, Ithaca, New York, USA, 2005, p.40.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB008
About •	Received ※ 19 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 04 August 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB081	Microphonics in the LCLS-II Superconducting Linac	302
	R.D. Porter, S. Aderhold, L.E. Alsberg, D. Gonnella, J. Nelson, N.R. Neveu, L.M. Zacarias SLAC, Menlo Park, California, USA A.T. Cravatta, J.P. Holzbauer, S. Posen Fermilab, Batavia, Illinois, USA M.A. Drury, M.D. McCaughan, C.M. Wilson JLab, Newport News, Virginia, USA G. Gaitan, N.A. Stilin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by the LCLS-II project The LCLS-II project has installed a new superconducting linac at SLAC that consists of 35 1.3 GHz cryomodules and 2 3.9 GHz cryomodules. The linac will provide a 4 GeV electron beam for generating soft and hard X-ray pulses. Cavity detuning induced by microphonics was a significant design challenge for the LCLS-II cryomodules. Cryomodules were produced that were within the detuning specification (10 Hz for 1.3 GHz cryomodules) on test stands. Here we present first measurements of the microphonics in the installed LCLS-II superconducting linac. Overall, the microphonics in the linac are manageable with 94% of cavities coming within the detune specification. Only two cavities are gradient limited due to microphonics. We identify a leaking cool down valve as the source of microphonics limiting those two cavities.
	Poster MOPMB081 [1.284 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB081
About •	Received ※ 18 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 01 July 2023
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MOPMB082	SRF Accelerating Modules Upgrade for Flash Linac at DESY	306
	D. Kostin, S. Barbanotti, J. Eschke, K. Jensch, N. Krupka, A. Muhs, D. Reschke, S. Saegebarth, J. Schaffran, P. Schilling, M. Schmökel, L. Steder, N. Steinhau-Kühl, A. Sulimov, E. Vogel, H. Weise, M. Wiencek, B. van der Horst DESY, Hamburg, Germany
	SRF accelerating modules with 8 TESLA-type 1.3 GHz SRF cavities are the main part of the linear accelerators currently in user operation at DESY, FLASH [1, 2] and the European XFEL [3, 4]. For the FLASH upgrade in 2022 [5] two accelerating modules have been exchanged in order to enhance the beam energy to 1.3 GeV. The two modules have been prototype modules for the European XFEL. After reassembly both modules were successfully tested and installed in the FLASH linac. Data taken during the commissioning at the end of 2022 did confirm the test results. This paper presents described efforts and their conclusions since last two years and continues the presentation given at SRF 2021 [6].
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB082
About •	Received ※ 16 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 27 June 2023
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MOPMB084	FRIB Driver Linac Integration to Support Operations and Protect SRF Cryomodules	316
	H. Ao, K. Elliott, D.D. Jager, S.H. Kim, L. Popielarski FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The driver linac for the Facility for Rare Isotope Beams (FRIB) at Michigan State University includes 324 superconducting radio-frequency (SRF) cavities, and the SRF particle-free beamline spans approximately 300 meters. Protecting the beamlines against contamination is critical to FRIB operations, and thus, various administrative and engineered controls have been put in place to protect the SRF cryomodules. These controls include local vacuum interlocks for cryomodule isolation, accelerator-wide interlocks, and software controls to safeguard the cryomodules and beamlines. Meanwhile, efforts are being made to provide training and develop programs with the goal of preventing critical failures during maintenance. This paper discusses the measures and approaches used for both system integration to support operations and SRF beamline protection.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB084
About •	Received ※ 14 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023
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MOPMB086	Development of Non-Destructive Beam Envelope Measurements in SRILAC with Low Beta Heavy Ion Beams Using BPMs	319
	T. Nishi, O. Kamigaito, N. Sakamoto, T. Watanabe, K. Yamada RIKEN Nishina Center, Wako, Japan T. Adachi RIKEN, Saitama, Japan
	The RIKEN SRILAC* has been providing heavy ion beams of a few puA for the synthesis of new superheavy elements since June 2020, utilizing 10 superconducting quarter-wavelength resonators (SC-QWRs). Although the beam supply has been stable, it is crucial to measure and control the beam dynamics in the SRILAC to increase the beam intensity up to 10 puA. However, destructive monitors cannot be used to avoid the generation of dust particles and outgassing. Beam has been precisely tuned by monitoring the beam center using Beam Energy Position Monitors (BEPMs) and the reactions of vacuum monitors. In our study, we are developing a method for estimating the beam envelope by combining the quadrupole moments from BEPMs, which consist of four cosine-shape electrodes, with calculations of the transfer matrix. While this method has been applied to electron and proton beams, it has not been practically demonstrated for heavy ion beams in beta – 0.1 regions. By combining BEPM simulations, we are making the progress towards the reproduction of experimental results, overcoming specific issues associated with low beta. We will report on the current status of our developments. K. Yamada et al., in Proc. SRF’21, paper MOOFAV01(2021). T. Watanabe et al., in Proc. IBIC’20, paper FRAO04 (2020). * R. H. Miller et al., in Proc. HEAC’83, pp. 603–605 (1983).
	Poster MOPMB086 [10.338 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB086
About •	Received ※ 30 June 2023 — Revised ※ 01 July 2023 — Accepted ※ 19 August 2023 — Issue date ※ 22 August 2023
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MOPMB089	Installation of LCLS-II Cryomodules	324
	D.A. White, S. Aderhold, R. Coy, D. Gonnella SLAC, Menlo Park, California, USA
	Funding: U.S. Department of Energy The Linac Coherent Light Source II (LCLS-II) super-conducting accelerator is fully installed and operational. Cryomodules were designed and manufactured by Fermi National Accelerator Laboratory (FNAL) and Thomas Jefferson National Laboratory (JLab) during 2017-2020. From November 2018 through March 2021, SLAC Na-tional Accelerator Laboratory installed 37 Cryomodules. Full system cooldown was completed in March 2022. Installation processes were optimized at SLAC for best quality, especially during particle-free and UHV assem-bly. These processes and successful Cavity and Cry-omodule manufacturing resulted in installed gradient exceeding design requirements by more than 20%. No statistical variation in field emission onsets or magni-tudes were observed between manufacturing and site testing. This paper summarizes SLAC experience during installation, and relevant testing results.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB089
About •	Received ※ 20 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 15 July 2023
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MOPMB090	Measuring Q₀ in LCLS-II Cryomodules Using Helium Liquid Level	327
	L.M. Zacarias, S. Aderhold, D. Gonnella, J.T. Maniscalco, J. Nelson, R.D. Porter SLAC, Menlo Park, California, USA A.T. Cravatta, J.P. Holzbauer, S. Posen Fermilab, Batavia, Illinois, USA M.A. Drury, M.D. McCaughan, C.M. Wilson JLab, Newport News, Virginia, USA
	The nitrogen-doped cavities used in the Linac Coherent Light Source II (LCLS-II) cryomodules have shown an unprecedented high Q₀ in vertical and cryomodule testing compared with cavities prepared with standard methods. While demonstration of high Q₀ in the test stand has been achieved, maintaining that performance in the linac is critical to the success of LCLS-II and future accelerator projects. The LCLS-II cryomodules required a novel method of measuring Q₀, due to hardware incompatibilities with existing procedures. Initially developed at Jefferson Lab during cryomodule acceptance testing before being used in the tunnel at SLAC, we use helium liquid level data to estimate the heat generated by cavities. We first establish the relationship between the rate of helium evaporation from known heat loads using electric heaters, and then use that relationship to determine heat from an RF load. Here we present the full procedure along with the development process, lessons learned, and reproducibility while demonstrating for the first time that world record Q₀ can be maintained within the real accelerator environment.
	Poster MOPMB090 [1.867 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB090
About •	Received ※ 20 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 13 July 2023
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MOPMB092	Performance of Contaminated Superconducting Linac after Vacuum Excursion	332
	Z.Y. Yao, R.E. Laxdal TRIUMF, Vancouver, Canada
	ISAC-II superconducting heavy ion linac is the high energy section of TRIUMF ISAC facility to accelerate rare isotopes with A/q <= 6 from 1.5 MeV/u to above the Cou-lomb barrier for experiments. There was a vacuum excur-sion caused by an operational error and the failure of the fast protection system in summer 2022. The beamline downstream to the SC linac was vented with atmosphere air from the experimental hall resulting in pollution of the linac. This paper reports the RF performance of the con-taminated linac. The typical cavity performance changes, the average magnitude of degradation, the impact range in the SC linac, the observations in the recovery processes and the analyses on the most distinct cavity are discussed. The cavity refurbishment in the recent winter shutdown with the observations and outcomes is also reported. The ISAC-II event provided a unique data set for the SRF community.
	Poster MOPMB092 [6.186 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB092
About •	Received ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 02 July 2023
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TUIAA01	Twenty Years of Cryogenic Operation of the Flash Superconducting Linac	347
	S. Barbanotti, DESY. Abassi, Y. Bozhko, K. Honkavaara, K. Jensch, D. Kostin, S. Lederer, T. Schnautz, S. Schreiber, A. Wagner, H. Weise DESY, Hamburg, Germany J. Roßbach University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany J. Zajac Linde Kryotechnik AG, Büro DESY Hamburg, Hamburg, Germany
	The FLASH superconducting linac is in operation at DESY since more than 20 years. Many changes and upgrades took place to transform a test stand for single cryomodules to a successful free electron laser. We summarize here the main steps of the FLASH history from the cryogenic point of view including the latest major upgrade that took place in 2022. We also give an overview of cryomodule performances like cavity gradient and heat load measurements and their evolution over the time.
	Slides TUIAA01 [6.861 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUIAA01
About •	Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 20 July 2023
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Paper

Title

Page

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)

MOIXA04

Operational Experience for RIKEN Superconducting Linear Accelerator

30

K. Yamada, M. Fujimaki, H. Imao, O. Kamigaito, M. Komiyama, K. Kumagai, T. Nagatomo, T. Nishi, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe
RIKEN Nishina Center, Wako, Japan

The RIKEN superconducting heavy-ion linac, so-called SRILAC, has been successfully operating for almost four years, and continuously deliver a heavy ion beam for a super-heavy-element synthesis experiment. The effects of a broken coupler in the early days and four years of operation have resulted in increased X-ray emission levels in several superconducting cavities, which have been successfully corrected by pulse conditioning. This talk will share the experiences and lessons learned from four-year operation with low beta SC-cavities.

Slides MOIXA04 [4.517 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOIXA04

About •

Received ※ 06 July 2023 — Revised ※ 10 July 2023 — Accepted ※ 19 August 2023 — Issue date ※ 22 August 2023

Cite •

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

MOIXA06

Operational Experience with the European XFEL SRF Linac

43

Ch. Schmidt, M. Bousonville, J. Branlard, M. Diomede, S. Göller, D. Kostin, M. Scholz, V. Vogel (Fogel), N. Walker
DESY, Hamburg, Germany

The European X-ray Free Electron laser (EuXFEL) is a 3.4 km long research facility which generates ultrashort X-ray flashes of outstanding brilliance since 2017. Up to 27000 electron bunches per second are accelerated in a 1.3 km long superconducting radio frequency (SRF) linac to a maximum energy of 17.6 GeV. Within this time, operational experience with a pulsed RF machine has been gained and new operation modes simultaneously delivering electron bunches to 3 different SASE undulator beamlines have been successfully implemented. Recent activities on increasing the linac availability, power efficiency and duty cycle are discussed.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOIXA06

About •

Received ※ 19 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 06 July 2023

Cite •

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

MOPMB008

In-Situ Quality Factor Measurements of SRF Cavities at S-DALINAC

70

SUSPB004

use link to see paper's listing under its alternate paper code

R. Grewe, M. Arnold, A. Brauch, M. Dutine, L.E. Jürgensen, N. Pietralla, F. Schließmann, D. Schneider
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG (GRK 2128) and the State of Hesse within the Research Cluster ELEMENTS (Project ID 500/10.006)
The Superconducting Darmstadt Linear Accelerator (S-DALINAC) is a thrice recirculating electron accelerator wich can be operated in a multi-turn energy recovery mode*. The design parameters for kinetic energy and beam current are up to 130 MeV and up to 20 uA respectively. The injector consists of a six-cell capture cavity and two 20-cell srf cavities. The main linac consists of eight 20-cell cavities. The cavities are operated at a temperature of 2 K with a frequency of 2.9972(1) GHz. Monitoring of the srf cavities is important for the overall performance of the accelerator. A key parameter for the rating of the srf cavity performance is the intrinsic quality factor Q. At the S-DALINAC it is measured for selected cavities during the yearly maintenance procedures. The unique design of the rf input coupler allows for a wide tuning range for the input coupling strength. This makes in-situ quality factor measurements using the decay time measurement method** possible. The contribution illustrates the principal design of the input couplers and the benefits it yields for Q measurements. Recent results including the progression of the quality factors over time will be presented.
*Felix Schliessmann et al., Nat. Phys. 19, 597-602 (2023).
**Tom Powers, Proc. of SRF’05, Cornell University, Ithaca, New York, USA, 2005, p.40.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB008

About •

Received ※ 19 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 04 August 2023

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

MOPMB081

Microphonics in the LCLS-II Superconducting Linac

302

R.D. Porter, S. Aderhold, L.E. Alsberg, D. Gonnella, J. Nelson, N.R. Neveu, L.M. Zacarias
SLAC, Menlo Park, California, USA
A.T. Cravatta, J.P. Holzbauer, S. Posen
Fermilab, Batavia, Illinois, USA
M.A. Drury, M.D. McCaughan, C.M. Wilson
JLab, Newport News, Virginia, USA
G. Gaitan, N.A. Stilin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by the LCLS-II project
The LCLS-II project has installed a new superconducting linac at SLAC that consists of 35 1.3 GHz cryomodules and 2 3.9 GHz cryomodules. The linac will provide a 4 GeV electron beam for generating soft and hard X-ray pulses. Cavity detuning induced by microphonics was a significant design challenge for the LCLS-II cryomodules. Cryomodules were produced that were within the detuning specification (10 Hz for 1.3 GHz cryomodules) on test stands. Here we present first measurements of the microphonics in the installed LCLS-II superconducting linac. Overall, the microphonics in the linac are manageable with 94% of cavities coming within the detune specification. Only two cavities are gradient limited due to microphonics. We identify a leaking cool down valve as the source of microphonics limiting those two cavities.

Poster MOPMB081 [1.284 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB081

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Received ※ 18 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 01 July 2023

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MOPMB082

SRF Accelerating Modules Upgrade for Flash Linac at DESY

306

D. Kostin, S. Barbanotti, J. Eschke, K. Jensch, N. Krupka, A. Muhs, D. Reschke, S. Saegebarth, J. Schaffran, P. Schilling, M. Schmökel, L. Steder, N. Steinhau-Kühl, A. Sulimov, E. Vogel, H. Weise, M. Wiencek, B. van der Horst
DESY, Hamburg, Germany

SRF accelerating modules with 8 TESLA-type 1.3 GHz SRF cavities are the main part of the linear accelerators currently in user operation at DESY, FLASH [1, 2] and the European XFEL [3, 4]. For the FLASH upgrade in 2022 [5] two accelerating modules have been exchanged in order to enhance the beam energy to 1.3 GeV. The two modules have been prototype modules for the European XFEL. After reassembly both modules were successfully tested and installed in the FLASH linac. Data taken during the commissioning at the end of 2022 did confirm the test results. This paper presents described efforts and their conclusions since last two years and continues the presentation given at SRF 2021 [6].

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB082

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Received ※ 16 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 27 June 2023

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MOPMB084

FRIB Driver Linac Integration to Support Operations and Protect SRF Cryomodules

316

H. Ao, K. Elliott, D.D. Jager, S.H. Kim, L. Popielarski
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The driver linac for the Facility for Rare Isotope Beams (FRIB) at Michigan State University includes 324 superconducting radio-frequency (SRF) cavities, and the SRF particle-free beamline spans approximately 300 meters. Protecting the beamlines against contamination is critical to FRIB operations, and thus, various administrative and engineered controls have been put in place to protect the SRF cryomodules. These controls include local vacuum interlocks for cryomodule isolation, accelerator-wide interlocks, and software controls to safeguard the cryomodules and beamlines. Meanwhile, efforts are being made to provide training and develop programs with the goal of preventing critical failures during maintenance. This paper discusses the measures and approaches used for both system integration to support operations and SRF beamline protection.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB084

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Received ※ 14 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023

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MOPMB086

Development of Non-Destructive Beam Envelope Measurements in SRILAC with Low Beta Heavy Ion Beams Using BPMs

319

T. Nishi, O. Kamigaito, N. Sakamoto, T. Watanabe, K. Yamada
RIKEN Nishina Center, Wako, Japan
T. Adachi
RIKEN, Saitama, Japan

The RIKEN SRILAC* has been providing heavy ion beams of a few puA for the synthesis of new superheavy elements since June 2020, utilizing 10 superconducting quarter-wavelength resonators (SC-QWRs). Although the beam supply has been stable, it is crucial to measure and control the beam dynamics in the SRILAC to increase the beam intensity up to 10 puA. However, destructive monitors cannot be used to avoid the generation of dust particles and outgassing. Beam has been precisely tuned by monitoring the beam center using Beam Energy Position Monitors (BEPMs)** and the reactions of vacuum monitors. In our study, we are developing a method for estimating the beam envelope by combining the quadrupole moments from BEPMs, which consist of four cosine-shape electrodes, with calculations of the transfer matrix***. While this method has been applied to electron and proton beams, it has not been practically demonstrated for heavy ion beams in beta – 0.1 regions. By combining BEPM simulations, we are making the progress towards the reproduction of experimental results, overcoming specific issues associated with low beta. We will report on the current status of our developments.
* K. Yamada et al., in Proc. SRF’21, paper MOOFAV01(2021).
** T. Watanabe et al., in Proc. IBIC’20, paper FRAO04 (2020).
*** R. H. Miller et al., in Proc. HEAC’83, pp. 603–605 (1983).

Poster MOPMB086 [10.338 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB086

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Received ※ 30 June 2023 — Revised ※ 01 July 2023 — Accepted ※ 19 August 2023 — Issue date ※ 22 August 2023

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MOPMB089

Installation of LCLS-II Cryomodules

324

D.A. White, S. Aderhold, R. Coy, D. Gonnella
SLAC, Menlo Park, California, USA

Funding: U.S. Department of Energy
The Linac Coherent Light Source II (LCLS-II) super-conducting accelerator is fully installed and operational. Cryomodules were designed and manufactured by Fermi National Accelerator Laboratory (FNAL) and Thomas Jefferson National Laboratory (JLab) during 2017-2020. From November 2018 through March 2021, SLAC Na-tional Accelerator Laboratory installed 37 Cryomodules. Full system cooldown was completed in March 2022. Installation processes were optimized at SLAC for best quality, especially during particle-free and UHV assem-bly. These processes and successful Cavity and Cry-omodule manufacturing resulted in installed gradient exceeding design requirements by more than 20%. No statistical variation in field emission onsets or magni-tudes were observed between manufacturing and site testing. This paper summarizes SLAC experience during installation, and relevant testing results.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB089

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Received ※ 20 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 15 July 2023

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MOPMB090

Measuring Q₀ in LCLS-II Cryomodules Using Helium Liquid Level

327

L.M. Zacarias, S. Aderhold, D. Gonnella, J.T. Maniscalco, J. Nelson, R.D. Porter
SLAC, Menlo Park, California, USA
A.T. Cravatta, J.P. Holzbauer, S. Posen
Fermilab, Batavia, Illinois, USA
M.A. Drury, M.D. McCaughan, C.M. Wilson
JLab, Newport News, Virginia, USA

The nitrogen-doped cavities used in the Linac Coherent Light Source II (LCLS-II) cryomodules have shown an unprecedented high Q₀ in vertical and cryomodule testing compared with cavities prepared with standard methods. While demonstration of high Q₀ in the test stand has been achieved, maintaining that performance in the linac is critical to the success of LCLS-II and future accelerator projects. The LCLS-II cryomodules required a novel method of measuring Q₀, due to hardware incompatibilities with existing procedures. Initially developed at Jefferson Lab during cryomodule acceptance testing before being used in the tunnel at SLAC, we use helium liquid level data to estimate the heat generated by cavities. We first establish the relationship between the rate of helium evaporation from known heat loads using electric heaters, and then use that relationship to determine heat from an RF load. Here we present the full procedure along with the development process, lessons learned, and reproducibility while demonstrating for the first time that world record Q₀ can be maintained within the real accelerator environment.

Poster MOPMB090 [1.867 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB090

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Received ※ 20 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 13 July 2023

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MOPMB092

Performance of Contaminated Superconducting Linac after Vacuum Excursion

332

Z.Y. Yao, R.E. Laxdal
TRIUMF, Vancouver, Canada

ISAC-II superconducting heavy ion linac is the high energy section of TRIUMF ISAC facility to accelerate rare isotopes with A/q <= 6 from 1.5 MeV/u to above the Cou-lomb barrier for experiments. There was a vacuum excur-sion caused by an operational error and the failure of the fast protection system in summer 2022. The beamline downstream to the SC linac was vented with atmosphere air from the experimental hall resulting in pollution of the linac. This paper reports the RF performance of the con-taminated linac. The typical cavity performance changes, the average magnitude of degradation, the impact range in the SC linac, the observations in the recovery processes and the analyses on the most distinct cavity are discussed. The cavity refurbishment in the recent winter shutdown with the observations and outcomes is also reported. The ISAC-II event provided a unique data set for the SRF community.

Poster MOPMB092 [6.186 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB092

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Received ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 02 July 2023

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TUIAA01

Twenty Years of Cryogenic Operation of the Flash Superconducting Linac

347

S. Barbanotti, DESY. Abassi, Y. Bozhko, K. Honkavaara, K. Jensch, D. Kostin, S. Lederer, T. Schnautz, S. Schreiber, A. Wagner, H. Weise
DESY, Hamburg, Germany
J. Roßbach
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
J. Zajac
Linde Kryotechnik AG, Büro DESY Hamburg, Hamburg, Germany

The FLASH superconducting linac is in operation at DESY since more than 20 years. Many changes and upgrades took place to transform a test stand for single cryomodules to a successful free electron laser. We summarize here the main steps of the FLASH history from the cryogenic point of view including the latest major upgrade that took place in 2022. We also give an overview of cryomodule performances like cavity gradient and heat load measurements and their evolution over the time.

Slides TUIAA01 [6.861 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUIAA01

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Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 20 July 2023

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