TY  - CONF
AU  - Wei, J.
AU  - Ao, H.
AU  - Arend, B.
AU  - Beher, S.
AU  - Bollen, G.
AU  - Bultman, N.K.
AU  - Casagrande, F.
AU  - Chang, W.
AU  - Choi, Y.
AU  - Cogan, S.
AU  - Compton, C.
AU  - Cortesi, M.
AU  - Curtin, J.C.
AU  - Davidson, K.D.
AU  - Du, X.J.
AU  - Elliott, K.
AU  - Ewert, B.
AU  - Facco, A.
AU  - Fila, A.
AU  - Fukushima, K.
AU  - Ganni, V.
AU  - Ganshyn, A.
AU  - Ginter, T.N.
AU  - Glasmacher, T.
AU  - Guo, J.-W.
AU  - Hao, Y.
AU  - Hartung, W.
AU  - Hasan, N.M.
AU  - Hausmann, M.
AU  - Holland, K.
AU  - Hosoyama, K.
AU  - Hseuh, H.-C.
AU  - Hurh, P.
AU  - Ikegami, M.
AU  - Jager, D.D.
AU  - Jones, S.
AU  - Joseph, N.
AU  - Kanemura, T.
AU  - Kelly, M.P.
AU  - Kim, S.H.
AU  - Knowles, C.
AU  - Konomi, T.
AU  - Kortum, B.R.
AU  - Kwan, E.
AU  - Lange, T.
AU  - Larmann, M.
AU  - Larter, T.L.
AU  - Laturkar, K.
AU  - Laxdal, R.E.
AU  - LeTourneau, J.
AU  - Li, Z.
AU  - Lidia, S.M.
AU  - Machicoane, G.
AU  - Magsig, C.
AU  - Manwiller, P.E.
AU  - Marti, F.
AU  - Maruta, T.
AU  - Metzgar, E.S.
AU  - Miller, S.J.
AU  - Momozaki, Y.
AU  - Morris, D.G.
AU  - Mugerian, M.
AU  - Nesterenko, I.N.
AU  - Nguyen, C.
AU  - Ostroumov, P.N.
AU  - Patil, M.S.
AU  - Plastun, A.S.
AU  - Popielarski, L.
AU  - Portillo, M.
AU  - Prestemon, S.O.
AU  - Priller, J.
AU  - Rao, X.
AU  - Reaume, M.A.
AU  - Saito, K.
AU  - Sherrill, B.M.
AU  - Smith, M.K.
AU  - Song, J.
AU  - Steiner, M.
AU  - Stolz, A.
AU  - Tarasov, O.
AU  - Tousignant, B.P.
AU  - Walker, R.
AU  - Wang, X.
AU  - Wenstrom, J.D.
AU  - West, G.
AU  - Wiseman, M.
AU  - Witgen, K.
AU  - Wright, M.
AU  - Xu, T.
AU  - Yamazaki, Y.
AU  - Zhang, T.
AU  - Zhao, Q.
AU  - Zhao, S.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - FRIB Transition to User Operations, Power Ramp Up, and Upgrade Perspectives
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - 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.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 1
EP  - 8
KW  - cavity
KW  - cryomodule
KW  - operation
KW  - linac
KW  - target
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOIAA01
UR  - https://jacow.org/srf2023/papers/moiaa01.pdf
ER  - 

TY  - CONF
AU  - McGee, K.E.
AU  - Furuta, F.
AU  - Martinello, M.
AU  - Melnychuk, O.S.
AU  - Netepenko, A.V.
AU  - Wu, G.
AU  - Xie, Y.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Flux Expulsion Studies of Niobium Material of 650 MHz Cavities for PIP-II
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - Two different vendors supplied the niobium sheet material for PIP-II 5-cell 650 MHz cavities, which was characterized by multiple different ASTM sizes. Cavities subsequently fabricated from these sheets were heat-treated at various temperatures, then the cavities’ flux-expulsion performance was measured. Where the initial measurements of vendor O materials showed that nearly all flux remained trapped despite a high thermal gradient, 900C heat treatment subsequently improved the flux expulsion to an acceptable rate. Understanding and characterizing vendor O materials in this way is key for upcoming and future projects planning to employ niobium sheet from this supplier.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 141
EP  - 144
KW  - cavity
KW  - niobium
KW  - simulation
KW  - factory
KW  - radio-frequency
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB024
UR  - https://jacow.org/srf2023/papers/mopmb024.pdf
ER  - 

TY  - CONF
AU  - Saito, K.
AU  - Compton, C.
AU  - Elliott, K.
AU  - Hartung, W.
AU  - Kim, S.H.
AU  - Konomi, T.K.
AU  - Metzgar, E.S.
AU  - Miller, S.J.
AU  - Popielarski, L.
AU  - Taylor, A.T.
AU  - Xu, T.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Development of Transformative Cavity Processing - Superiority of Electropolishing on High Gradient Performance over Buffered Chemical Polishing at Low Frequency (322 MHz)
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - 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.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 145
EP  - 150
KW  - cavity
KW  - SRF
KW  - operation
KW  - cryomodule
KW  - MMI
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB026
UR  - https://jacow.org/srf2023/papers/mopmb026.pdf
ER  - 

TY  - CONF
AU  - Saito, K.
AU  - Konomi, T.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Successful Superheating Field Formulas from an Intuitive Model
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - 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.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 151
EP  - 154
KW  - niobium
KW  - cavity
KW  - experiment
KW  - SRF
KW  - superconductivity
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB027
UR  - https://jacow.org/srf2023/papers/mopmb027.pdf
ER  - 

TY  - CONF
AU  - Xiang, R.
AU  - Adolphsen, C.
AU  - Arnold, A.
AU  - Gatzmaga, S.
AU  - Hartung, W.
AU  - Hoffmann, A.
AU  - Kelly, M.P.
AU  - Kim, S.H.
AU  - Konomi, T.K.
AU  - Lewellen, J.W.
AU  - Miller, S.J.
AU  - Murcek, P.
AU  - Petersen, T.B.
AU  - Popielarski, L.
AU  - Saito, K.
AU  - Smedley, J.
AU  - Steinbrück, R.
AU  - Teichert, J.
AU  - Xu, T.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Design of a Cathode Insertion and Transfer System for LCLS-II-HE SRF Gun
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - 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.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 267
EP  - 270
KW  - cathode
KW  - gun
KW  - SRF
KW  - insertion
KW  - operation
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB067
UR  - https://jacow.org/srf2023/papers/mopmb067.pdf
ER  - 

TY  - CONF
AU  - Ao, H.
AU  - Elliott, K.
AU  - Jager, D.D.
AU  - Kim, S.H.
AU  - Popielarski, L.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - FRIB Driver Linac Integration to Support Operations and Protect SRF Cryomodules
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - 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.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 316
EP  - 318
KW  - operation
KW  - linac
KW  - cryomodule
KW  - SRF
KW  - vacuum
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB084
UR  - https://jacow.org/srf2023/papers/mopmb084.pdf
ER  - 

TY  - CONF
AU  - Metzgar, E.S.
AU  - Barker, B.W.
AU  - Elliott, K.
AU  - Hulbert, J.D.
AU  - Knowles, C.
AU  - Nguyen, L.
AU  - Nunham, A.R.
AU  - Popielarski, L.
AU  - Taylor, A.T.
AU  - Xu, T.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Summary of the FRIB Electropolishing Facility Design and Commissioning, Cavity Processing, and Cavity Test Results
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - Recently, a new Electropolishing (EP) facility was con-structed and commissioned at the Facility for Rare Isotope Beam (FRIB) with the purpose of supporting advanced surface processing techniques for SRF R&D activities. The FRIB production cavities opted for a Buffered Chemical Polish (BCP) method due to its cost effectiveness and was supported by successful outcomes in other facilities with low beta cavities in a similar frequency range. All 324 cavities used in FRIB Linac were processed in-house at MSU using BCP and exhibited satisfactory performance during testing. As part of the FRIB energy upgrade R&D, 5-cell 644 MHz elliptical resonators will be employed, desiring the use of EP and advanced techniques such as nitrogen doping and medium-T baking. The EP facility is designed to accommodate all types of cavities used in FRIB and possesses the capability for performing EP at low temperatures. Here we report the details of design and commissioning of the EP facility, highlights of encountered issues and subsequent improvements, and preliminary results from vertical tests conducted on the cavities.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 419
EP  - 424
KW  - cavity
KW  - cathode
KW  - MMI
KW  - power-supply
KW  - controls
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-TUPTB016
UR  - https://jacow.org/srf2023/papers/tuptb016.pdf
ER  - 

TY  - CONF
AU  - Gower, B.E.
AU  - Elliott, K.
AU  - Metzgar, E.S.
AU  - Xu, T.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Simulation of High Pressure Rinse in Superconducting Radio Frequency Cavities
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - The finish of radio frequency (RF) surfaces inside superconducting RF (SRF) cavities is of utmost importance as it dictates ultimate cavity performance. After the cavity surfaces have undergone chemical etching, polishing, and hydrogen degassing, the final step in surface preparation involves cleaning using a high pressure rinse (HPR) with ultra-high purity water (UPW) to remove any residue from the previous chemical processes. The complex surface geometry of cavities poses difficulties in achieving effective and thorough HPR cleaning. This study introduces a versatile simulation tool created in MATLAB, which has the potential to be applied to various SRF cavities. The detail of the algorithm used and nozzle and motion setup will be described using an FRIB 0.53 half wave resonator (HWR) cavity as an example.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 496
EP  - 500
KW  - cavity
KW  - simulation
KW  - SRF
KW  - radio-frequency
KW  - site
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-TUPTB039
UR  - https://jacow.org/srf2023/papers/tuptb039.pdf
ER  - 

TY  - CONF
AU  - Patil, M.S.
AU  - Compton, C.
AU  - Kim, S.H.
AU  - Miller, S.J.
AU  - Xu, T.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Mechanical Design and Analysis of SRF Gun Cavity Using ASME BPVC Section Viii, Division-2, Design by Analysis Requirement
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - A prototype SRF gun is currently being designed at FRIB, MSU for the Low Emittance Injector of the Linac Coherent Light Source high energy upgrade at SLAC. This employs a 185.7 MHz superconducting quarter-wave resonator (QWR). The mechanical design of this cavity has been optimized for performance and to comply with ASME Section VIII, Div 2, Design by analysis requirements. This paper presents the various design by analysis procedures and how they have been adopted for the SRF gun cavity design.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 501
EP  - 506
KW  - cavity
KW  - SRF
KW  - gun
KW  - niobium
KW  - vacuum
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-TUPTB040
UR  - https://jacow.org/srf2023/papers/tuptb040.pdf
ER  - 

TY  - CONF
AU  - Wu, G.
AU  - Adams, S.D.
AU  - Bice, D.J.
AU  - Chandrasekaran, S.K.
AU  - Gonin, I.V.
AU  - Grimm, C.J.
AU  - Holzbauer, J.P.
AU  - Khabiboulline, T.N.
AU  - McGee, K.E.
AU  - Narug, C.S.
AU  - Ozelis, J.P.
AU  - Park, H.
AU  - Romanov, G.V.
AU  - Thiede, R.
AU  - Treece, R.
AU  - Wixson, A.D.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - The Evaluation of Mechanical Properties of LB650 Cavities
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - The 650 MHz cavities have a stronger requirement of niobium mechanical properties because of the geometric shape of the cavity due to reduced beta. The mechanical property of the niobium half-cell was measured following various heat treatments. The 5-cell cavities were tested in a controlled drop test fashion and the real-world road test. The result showed that the 900C heat treatment was compatible with cavity handling and transportation during production. The test provides the bases of the transportation specification and shipping container design guidelines.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 536
EP  - 539
KW  - cavity
KW  - controls
KW  - cryomodule
KW  - niobium
KW  - SRF
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-TUPTB047
UR  - https://jacow.org/srf2023/papers/tuptb047.pdf
ER  - 

TY  - CONF
AU  - Compton, C.
AU  - Elliott, K.
AU  - Hartung, W.
AU  - Hulbert, J.D.
AU  - Kedzie, M.
AU  - Kelly, M.P.
AU  - Kim, S.H.
AU  - Konomi, T.
AU  - Lewellen, J.W.
AU  - Miller, S.J.
AU  - Patil, M.S.
AU  - Petersen, T.B.
AU  - Popielarski, J.T.
AU  - Popielarski, L.
AU  - Saito, K.
AU  - Smedley, J.
AU  - Witgen, K.
AU  - Xu, T.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Fabrication Efforts Toward a Superconducting Rf Photo-Infector Quarter-Wave Cavity for Use in Low Emittance Injector Applications
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - 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.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 568
EP  - 572
KW  - cavity
KW  - niobium
KW  - SRF
KW  - cryomodule
KW  - gun
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-TUPTB063
UR  - https://jacow.org/srf2023/papers/tuptb063.pdf
ER  - 

TY  - CONF
AU  - Konomi, T.K.
AU  - Adolphsen, C.
AU  - Gatzmaga, S.
AU  - Hartung, W.
AU  - Kelly, M.P.
AU  - Kim, S.H.
AU  - Lewellen, J.W.
AU  - Miller, S.J.
AU  - Morris, D.G.
AU  - Murcek, P.
AU  - Petersen, T.B.
AU  - Saito, K.
AU  - Smedley, J.
AU  - Taylor, A.T.
AU  - Xiang, R.
AU  - Xiao, L.
AU  - Xu, T.
AU  - Yin, Z.Y.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Design and Tests of a Cathode Stalk for the LCLS-II-HE Low Emittance Injector SRF Gun
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - 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.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 589
EP  - 592
KW  - cathode
KW  - gun
KW  - SRF
KW  - emittance
KW  - operation
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-TUPTB069
UR  - https://jacow.org/srf2023/papers/tuptb069.pdf
ER  - 

TY  - CONF
AU  - Yin, Z.Y.
AU  - Hartung, W.
AU  - Kim, S.H.
AU  - Konomi, T.
AU  - Xu, T.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Evaluation of Photo-Cathode Port Multipacting in the SRF Photo-Injector Cryomodule for the LCLS-II High-Energy Upgrade
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - The high-energy upgrade of the Linac Coherent Light Source (LCLS-II-HE) will increase the photon energy and brightness. A low-emittance injector (LEI) was proposed to increase the photon flux for high X-ray energies. FRIB, HZDR, Argonne, and SLAC are developing a 185.7 MHz superconducting radio-frequency photo-injector (SRF-PI) cryomodule for the LEI. The photo-cathode system requirements are challenging, as cathodes must be maintained at the desired temperature, precisely aligned, and operated without multipacting (MP); to avoid field emission, cathode exchange must be particulate-free. A support stalk has been designed to hold the cathode in position under these requirements. A DC bias is used to inhibit MP. We simulated MP for various surface conditions and bias levels. An RF/DC test was developed to evaluate the cathode stalk performance as a subsystem and to identify and correct issues before assembly into the full cryomodule. The RF/DC test makes use of a resonant coaxial line to generate an RF magnetic field similar to that of the cathode-in-SRF-PI-cavity case. High-power test results will be presented and compared to the MP simulations.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 859
EP  - 862
KW  - cathode
KW  - simulation
KW  - electron
KW  - SRF
KW  - experiment
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-WEPWB113
UR  - https://jacow.org/srf2023/papers/wepwb113.pdf
ER  - 

TY  - CONF
AU  - Tutt, P.R.
AU  - Hartung, W.
AU  - Kim, S.H.
AU  - Xu, T.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Investigation of Coupler Breakdown Thresholds for Plasma Processing of FRIB Quarter-Wave Resonators with Fundamental and Higher-Order Modes
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - FRIB is developing plasma processing techniques for in-situ recovery of cavity performance in linac cryomodules during long-term user operation. While plasma processing has been shown to be effective for high-frequency (0.8 - 1.5 GHz) elliptical cavities, one of the challenges for FRIB is to avoid plasma breakdown in the fundamental input coupler (FPC), which has relatively weak coupling strength (Q_{ext} ranging from 2E6 to 1E7). FRIB cavities are not equipped with higher-order-mode (HOM) couplers; however, in preliminary tests, we found that HOMs are suitable for plasma processing of FRIB Quarter-Wave Resonators (QWRs) driven via the FPC. In this study, we investigated plasma breakdown thresholds in the fundamental and the first 2 HOMs for the FRIB β = 0.085 QWRs. Electric field distributions in the FPC region and cavity region were calculated for the room-temperature case using CST Microwave Studio’s frequency domain solver (FDS). Simulation results will be presented, with comparison of breakdown thresholds inferred from the RF modeling to the experimental results.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 893
EP  - 897
KW  - cavity
KW  - plasma
KW  - electron
KW  - HOM
KW  - simulation
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-WEPWB127
UR  - https://jacow.org/srf2023/papers/wepwb127.pdf
ER  - 

TY  - CONF
AU  - Brown, J.
AU  - Chang, W.
AU  - Hartung, W.
AU  - Kim, S.H.
AU  - Xu, T.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Experimental Study of Mechanical Dampers for the FRIB β=0.041 Quarter-Wave Resonators
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - The ’pendulum’ mechanical mode of quarter-wave resonators (QWR) often causes an issue with microphonics and/or ponderomotive instability unless otherwise the inner conductors are properly stiffened and/or damped. FRIB QWRs are equipped with a Legnaro-style frictional damper installed inside of the inner conductor such that it counteracts the oscillations of the inner conductor. In cryomodule tests and linac operation, we observed that the damping efficiency is different for a few β=0.041 QWRs. This study aimed to experimentally characterize the damping efficacy as a function of damper mass and surface roughness. We present damping measurements at room temperature and at two different masses and surface roughness as well as discuss future studies for damper re-optimization based on this follow-on study.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 898
EP  - 901
KW  - cavity
KW  - damping
KW  - operation
KW  - linac
KW  - ECR
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-WEPWB128
UR  - https://jacow.org/srf2023/papers/wepwb128.pdf
ER  - 

TY  - CONF
AU  - Hartung, W.
AU  - Chang, W.
AU  - Elliott, K.
AU  - Kim, S.H.
AU  - Konomi, T.
AU  - Saito, K.
AU  - Tutt, P.R.
AU  - Xu, T.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Investigation of Plasma Processing for Coaxial Resonators
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - 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.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 960
EP  - 967
KW  - plasma
KW  - cavity
KW  - SRF
KW  - HOM
KW  - coupling
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-THIXA01
UR  - https://jacow.org/srf2023/papers/thixa01.pdf
ER  - 

TY  - CONF
AU  - Chang, W.
AU  - Choi, Y.
AU  - Du, X.J.
AU  - Facco, A.
AU  - Hartung, W.
AU  - Kim, S.H.
AU  - Konomi, T.
AU  - Kunjir, S.R.
AU  - Nguyen, H.
AU  - Saito, K.
AU  - Xu, T.
AU  - Zhao, S.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Automation of FRIB SRF Cavities and SC Solenoids Turn-on/off
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - 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.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 999
EP  - 1002
KW  - cavity
KW  - cryomodule
KW  - solenoid
KW  - SRF
KW  - linac
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-FRIBA05
UR  - https://jacow.org/srf2023/papers/friba05.pdf
ER  - 

TY  - CONF
AU  - Miller, S.J.
AU  - Adolphsen, C.
AU  - Al-Mahmoud, Y.
AU  - Arnold, A.
AU  - Chang, W.
AU  - Choi, Y.
AU  - Compton, C.
AU  - Coy, R.
AU  - Du, X.J.
AU  - Elliott, K.
AU  - Gatzmaga, S.
AU  - Hartung, W.
AU  - Hulbert, J.D.
AU  - Ji, F.
AU  - Kelly, M.P.
AU  - Kim, S.H.
AU  - Konomi, T.
AU  - Lewellen, J.W.
AU  - Morris, D.G.
AU  - Murcek, P.
AU  - Murphy, M.J.
AU  - Patil, M.S.
AU  - Petersen, T.B.
AU  - Piot, P.
AU  - Popielarski, L.
AU  - Saito, K.
AU  - Smedley, J.
AU  - Taylor, A.
AU  - Teichert, J.
AU  - Tousignant, B.P.
AU  - Wei, J.
AU  - Wenstrom, J.D.
AU  - Witgen, K.
AU  - Xiang, R.
AU  - Xiao, L.
AU  - Xu, T.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Status of the SLAC/MSU SRF Gun Development Project
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - 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.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 1003
EP  - 1010
KW  - cryomodule
KW  - SRF
KW  - cathode
KW  - cavity
KW  - alignment
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-FRIBA07
UR  - https://jacow.org/srf2023/papers/friba07.pdf
ER  -