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  - McCaughan, M.D.
AU  - Ciovati, G.
AU  - Davis, G.K.
AU  - Drury, M.A.
AU  - Powers, T.
AU  - Reilly, A.V.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Commissioning of the Second JLAB C75 Cryomodule & Performance Evaluation of Installed C75 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  - JLAB has long been a hub of SRF technology with the CEBAF accelerator as one of its first large scale adopters. As SRF technology has advanced, the C50 and C100 programs have allowed for the extension of CEBAF’s total energy to 6 GeV and nearly 12 GeV respectively. Along with the increase in energy reach, rates of accelerating gradient degradation have been extracted for these cryomodule designs. A plan to mitigate these losses & maintain robust gradient headroom to deliver the 12 GeV program ¿ the CEBAF Performance Plan¿ established a multi-year effort of cryomodule refurbishments and replacements. Part of this plan included a cost optimization of the C50 program with more modern processing techniques and the replacement of existing cavities with larger grain boundary cavities produced from ingot Niobium (dubbed C75 for 75 MeV gain). Reports have been made on the prototype pair of C75 cavities installed in a C50 cryomodule and the first full C75 cryomodule installed in 2017 and 2021. This paper reports on the results from the qualification of the cavities for the second C75 module in both a vertical cryostat and the commissioning results of the cryomodule in the CEBAF tunnel.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 14
EP  - 18
KW  - cavity
KW  - cryomodule
KW  - SRF
KW  - plasma
KW  - controls
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOIAA05
UR  - https://jacow.org/srf2023/papers/moiaa05.pdf
ER  - 

TY  - CONF
AU  - Mammosser, J.D.
AU  - Afanador, R.
AU  - Barnhart, D.L.
AU  - Bitter, A.
AU  - Bolz, K.B.
AU  - Champion, M.S.
AU  - Daly, E.F.
AU  - Davis, G.K.
AU  - Dayton, M.J.
AU  - DeGraff, B.
AU  - Dhakal, P.
AU  - Doleans, M.
AU  - Fischer, J.F.
AU  - Forehand, D.
AU  - Galambos, J.
AU  - Gold, S.W.
AU  - Greenwood, M.N.
AU  - Hine, G.A.
AU  - Howell, M.P.
AU  - Huque, N.A.
AU  - Kim, S.-H.
AU  - Kraft, D.D.
AU  - Maekawa, R.
AU  - McMahan, C.J.
AU  - Navitski, A.
AU  - Pinion, L.
AU  - Pizzol, P.
AU  - Robertson, B.E.
AU  - Stewart, S.E.
AU  - Vandygriff, D.J.
AU  - Vandygriff, D.M.
AU  - Wilson, K.M.
AU  - Zweibäumer, L.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Proton Power Upgrade Project Progress and Plans at the Spallation Neutron Source in Oak Ridge Tennessee
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 Proton Power Upgrade project is well underway at the Spallation Neutron Source (SNS) facility in Oak Ridge, Tennessee. This project aims at increasing the proton beam power capability from 1.4 to 2.8 MW, by adding linac energy, increasing the beam current and implementing target developments to handle the increased beam power. This talk will cover the current status of increasing the beam energy, issues encountered along the way, operational experience with the new SRF cryomodules and target improvements and results from operation with beam so far.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 25
EP  - 29
KW  - target
KW  - cryomodule
KW  - cavity
KW  - operation
KW  - linac
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOIXA03
UR  - https://jacow.org/srf2023/papers/moixa03.pdf
ER  - 

TY  - CONF
AU  - Reece, C.E.
AU  - Angle, J.W.
AU  - Kelley, M.J.
AU  - Lechner, E.M.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - SIMS Characterization of Nitrogen Doping of LCLS-II-HE Production 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 thermal diffusion of nitrogen into the surface of niobium has been shown to yield superior low-loss SRF performance. An effective solution was identified and promptly employed in the production of cryomodules for LCLS-II. With added experience and R&D, a modified process was chosen for use in the upgrade for LCLS-II-HE. Largely motivated by this circumstance, supporting research has significantly refined the technique for making calibrated secondary ion mass spectrometry (SIMS) measurements of the N concentration depth profiles produced by production processes. Standardized reference samples were included with four HE production cavities in their N-doping furnace runs. We report the calibrated dynamic SIMS depth profiles of N, C, and O for these samples, together with the cryogenic acceptance test performance of the associated cavities. Interpretation and comparison with similar samples acquired in other furnaces highlights the importance of intentional process quality control of furnace conditions.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 67
EP  - 69
KW  - cavity
KW  - SRF
KW  - niobium
KW  - vacuum
KW  - controls
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB006
UR  - https://jacow.org/srf2023/papers/mopmb006.pdf
ER  - 

TY  - CONF
AU  - Pathak, A.
AU  - Pozdeyev, E.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Exploring the Dynamics of Transverse Inter-Planar Coupling in the Superconducting Section of the PIP-II Linac
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  - This study investigates the crucial role that an accurate understanding of inter-planar coupling in the transverse plane plays in regulating charged particle dynamics in a high-intensity linear accelerator and minimizing foil/septum impacts during injection from the linac to a ring. We in-depth analyze the emergence and evolution of transverse inter-planar coupling through multiple active lattice elements, taking into account space charge and field nonlinearities in the superconducting section of the PIP-II linac. The article compares various analytical, numerical, and experimental techniques for measuring transverse coupling using beam and lattice matrices and provides insight into effective strategies for its mitigation prior to ring injectio
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 155
EP  - 157
KW  - coupling
KW  - space-charge
KW  - linac
KW  - lattice
KW  - quadrupole
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB029
UR  - https://jacow.org/srf2023/papers/mopmb029.pdf
ER  - 

TY  - CONF
AU  - Parajuli, I.P.
AU  - Ciovati, G.
AU  - Delayen, J.R.
AU  - Gurevich, A.V.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Magnetic Field Mapping of a Large-Grain 1.3 GHz Single-Cell Cavity
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 new magnetic field mapping system for 1.3 GHz single-cell cavities was developed in order to reveal the impact of ambient magnetic field and temperature gradients during cool-down on the flux trapping phenomenon. Measurements were done at 2 K for different cool-down conditions of a large-grain cavity before and after 120 °C bake. The fraction of applied magnetic field trapped in the cavity walls was ~ 50% after slow cool-down and ~20% after fast cool-down. The results showed a weak correlation between between trapped flux locations and hot-spots causing the high-field Q-slope. The results also showed an increase of the trapped flux at the quench location, after quenching, and a local redistribution of trapped flux with increasing RF field.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 172
EP  - 177
KW  - cavity
KW  - radio-frequency
KW  - niobium
KW  - SRF
KW  - cryogenics
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB036
UR  - https://jacow.org/srf2023/papers/mopmb036.pdf
ER  - 

TY  - CONF
AU  - Balachandran, S.
AU  - Bieler, T.R.
AU  - Chetri, S.
AU  - Dhakal, P.
AU  - Lee, P.J.
AU  - Thune, Z.L.
AU  - Valente-Feliciano, A-M.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Microstructure Development in a Cold Worked SRF Niobium Sheet After Heat Treatments
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  - Bulk Nb for TESLA shaped SRF cavities is a mature technology. Significant advances are in order to push Q₀’s to 10¹0⁻¹¹(T= 2K), and involve modifications to the sub-surface Nb layers by impurity doping. In order to achieve the lowest surface resistance any trapped flux needs to be expelled for cavities to reach high Q₀’s. There is clear evidence that cavities fabricated from polycrystalline sheets meeting current specifications require higher temperatures beyond 800 °C leads to better flux expulsion, and hence improves Q₀. Recently, cavities fabricated with a non-traditional Nb sheet with initial cold work due to cold rolling expelled flux better after 800 °C/3h heat treatment than cavities fabricated using fine-grain poly-crystalline Nb sheets. Here, we analyze the microstructure development in Nb from the vendor supplied cold work non- annealed sheet that was fabricated into an SRF cavity as a function of heat treatment building upon the methodology development to analyze microstructure being developed by the FSU-MSU-UT, Austin-JLAB collaboration. The results indicate correlation between full recrystallization and better flux expulsion.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 191
EP  - 196
KW  - cavity
KW  - ECR
KW  - SRF
KW  - niobium
KW  - radio-frequency
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB041
UR  - https://jacow.org/srf2023/papers/mopmb041.pdf
ER  - 

TY  - CONF
AU  - Khanal, B.D.
AU  - Dhakal, P.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Evaluation of Flux Expulsion and Flux Trapping Sensitivity of SRF Cavities Fabricated from Cold Work Nb Sheet with Successive Heat Treatment
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 main source of RF losses leading to lower quality factor of superconducting radio-frequency cavities is due to the residual magnetic flux trapped during cool-down. The loss due to flux trapping is more pronounced for cavities subjected to impurities doping. The flux trapping and its sensitivity to rf losses are related to several intrinsic and extrinsic phenomena. To elucidate the effect of re-crystallization by high temperature heat treatment on the flux trapping sensitivity, we have fabricated two 1.3 GHz single cell cavities from cold-worked Nb sheets and compared with cavities made from standard fine-grain Nb. Flux expulsion ratio and flux trapping sensitivity were measured after successive high temperature heat treatments. The cavity made from cold worked Nb showed better flux expulsion after 800 C/3h heat treatment and similar behavior when heat treated with additional 900 C/3h and 1000 C/3h. In this contribution, we present the summary of flux expulsion, trapping sensitivity, and RF results.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 197
EP  - 201
KW  - cavity
KW  - SRF
KW  - niobium
KW  - ECR
KW  - radio-frequency
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB042
UR  - https://jacow.org/srf2023/papers/mopmb042.pdf
ER  - 

TY  - CONF
AU  - Lechner, E.M.
AU  - Ciovati, G.
AU  - Gurevich, A.V.
AU  - Iavarone, M.
AU  - Makita, J.
AU  - Oli, B.D.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Characterization of Dissipative Regions of an N-Doped SRF Cavity
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  - We report scanning tunneling microscopy measurements on N-doped cavity hot and cold spot cutouts. Analysis of the electron tunneling spectra using a proximity effect theory shows that hot spots have a reduced superconducting gap and a wider distribution of the contact resistance. Alone, these degraded superconducting properties account for a much weaker excess dissipation as compared with the vortex contribution. Based on the correlation between the quasiparticle density of states and temperature mapping, we suggest that degraded superconducting properties may facilitate vortex nucleation or settling of trapped flux during cooling the cavity through the critical temperature.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 202
EP  - 206
KW  - cavity
KW  - niobium
KW  - radio-frequency
KW  - electron
KW  - experiment
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB043
UR  - https://jacow.org/srf2023/papers/mopmb043.pdf
ER  - 

TY  - CONF
AU  - Lechner, E.M.
AU  - Angle, J.W.
AU  - Baxley, C.G.
AU  - Kelley, M.J.
AU  - Reece, C.E.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Topographic Evolution of Nitrogen Doped Nb Subjected to Electropolishing
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  - Surface quality is paramount in facilitating high perfor-mance SRF cavity operation. Here, we investigate the topographic evolution of samples subjected to N-doping and 600 °C vacuum anneal. We show that in N-doped Nb, niobium nitrides may grow continuously along grain boundaries. Upon electropolishing high slope angle grooves are revealed which sets up a condition that may facilitate a supression of the superheating field.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 207
EP  - 210
KW  - SRF
KW  - cavity
KW  - niobium
KW  - vacuum
KW  - ECR
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB044
UR  - https://jacow.org/srf2023/papers/mopmb044.pdf
ER  - 

TY  - CONF
AU  - Khanal, B.D.
AU  - Ciovati, G.
AU  - Dhakal, P.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Quench Detection in a Superconducting Radio Frequency Cavity with Combined Temperature and Magnetic Field Mapping
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  - Local dissipation of rf power in SRF cavities create so called ’hot-spots’, primary precursors of cavity quench driven by either thermal or magnetic instability. These hot spots are may be detected by a temperature mapping system, and a large increase in temperature on the outer surface is detected during cavity quench events. Here, we have used combined magnetic and temperature mapping systems using anisotropic magneto-resistance sensors and carbon resisters to locate the hot spots and areas with high trapped flux on a 3 GHz single-cell Nb cavity during the rf tests at 2 K. The effect of global and localized flux trapping on the rf performance will be presented.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 211
EP  - 215
KW  - cavity
KW  - radio-frequency
KW  - niobium
KW  - SRF
KW  - ECR
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB045
UR  - https://jacow.org/srf2023/papers/mopmb045.pdf
ER  - 

TY  - CONF
AU  - Cravatta, A.T.
AU  - Aderhold, S.
AU  - Arkan, T.T.
AU  - Bafia, D.
AU  - Checchin, M.
AU  - Drury, M.A.
AU  - Gonnella, D.
AU  - Hogan, J.
AU  - Kaluzny, J.A.
AU  - Maniscalco, J.T.
AU  - Nelson, J.
AU  - Porter, R.D.
AU  - Posen, S.
AU  - Vennekate, H.
AU  - Zacarias, L.M.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Multipacting Processing in Cryomodules for LCLS-II and LCLS-II-HE
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  - Multipacting (MP) is a phenomenon which can affect stability in particle accelerators and limit performance in superconducting radio frequency cavities. In the TESLA shaped, 1.3 GHz, 9-cell cavities used in the LCLS-II (L2) and LCLS-II-HE (HE) projects, the MP-band (~17-24 MV/m) lies within the required accelerating gradients. For HE, the operating gradient of 20.8 MV/m lies well within the MP-band and cryomodule testing has confirmed that this is an issue. As such, MP processing for the HE cryomodule test program will be discussed. Early results on MP processing in cryomodules installed in the L2 linac will also be presented, demonstrating that the methods used in cryomodule acceptance testing are also successful at conditioning MP in the accelerator and that this processing is preserved in the mid-term.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 259
EP  - 262
KW  - cavity
KW  - cryomodule
KW  - linac
KW  - radiation
KW  - multipactoring
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB063
UR  - https://jacow.org/srf2023/papers/mopmb063.pdf
ER  - 

TY  - CONF
AU  - Maniscalco, J.T.
AU  - Aderhold, S.
AU  - Arkan, T.T.
AU  - Bafia, D.
AU  - Bevins, M.E.
AU  - Checchin, M.
AU  - Cravatta, A.T.
AU  - Gonnella, D.
AU  - Grabowski, A.J.
AU  - Hogan, J.
AU  - Kaluzny, J.A.
AU  - Porter, R.D.
AU  - Posen, S.
AU  - Reece, C.E.
AU  - Vennekate, H.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - LCLS-II-HE Cavity Qualification Testing
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  - Acceptance testing of the LCLS-II-HE production cavities is approximately 65% complete. In this report, we present details of the test results, including summaries of the quench fields, intrinsic quality factors, and experience with field emission. We also offer an outlook on the remaining tests to be performed.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 279
EP  - 281
KW  - cavity
KW  - cryomodule
KW  - radiation
KW  - SRF
KW  - accelerating-gradient
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB072
UR  - https://jacow.org/srf2023/papers/mopmb072.pdf
ER  - 

TY  - CONF
AU  - Guo, J.
AU  - Daly, E.F.
AU  - Drachuk, E.
AU  - Fernandes, R.R.
AU  - Henry, J.
AU  - Holmes, D.
AU  - Matalevich, J.
AU  - Park, G.-T.
AU  - Rimmer, R.A.
AU  - Savransky, D.
AU  - Smith, K.S.
AU  - Xu, W.
AU  - Zaltsman, A.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Design and Prototyping of the Electron Ion Collider Electron Storage Ring SRF Cavity
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  - Among the EIC¿s numerous RF subsystems, the electron storage ring¿s (ESR) 591 MHz fundamental RF system is one of the most challenging. Each cavity in the system will handle up to 2.5 A of beam current and supply up to 600 kW beam power under a wide range of voltage. The EIC R&D plan includes the design, fabrication and testing of such a cavity. In this paper, we will report the latest status and findings of the ongoing design and prototyping of this cavity, including the RF and mechanical/thermal design, fabrication design, and the progress of fabrication.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 293
EP  - 297
KW  - cavity
KW  - simulation
KW  - HOM
KW  - operation
KW  - electron
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB078
UR  - https://jacow.org/srf2023/papers/mopmb078.pdf
ER  - 

TY  - CONF
AU  - Porter, R.D.
AU  - Aderhold, S.
AU  - Alsberg, L.E.
AU  - Cravatta, A.T.
AU  - Drury, M.A.
AU  - Gaitan, G.
AU  - Gonnella, D.
AU  - Holzbauer, J.P.
AU  - McCaughan, M.D.
AU  - Nelson, J.
AU  - Neveu, N.R.
AU  - Posen, S.
AU  - Stilin, N.A.
AU  - Wilson, C.M.
AU  - Zacarias, L.M.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Microphonics in the LCLS-II Superconducting Linac
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 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.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 302
EP  - 305
KW  - cryomodule
KW  - cavity
KW  - linac
KW  - operation
KW  - vacuum
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB081
UR  - https://jacow.org/srf2023/papers/mopmb081.pdf
ER  - 

TY  - CONF
AU  - Senevirathne, I.H.
AU  - Beverstock, D.R.
AU  - Delayen, J.R.
AU  - Gurevich, A.V.
AU  - Valente-Feliciano, A-M.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Investigation of the Multilayer Shielding Effect through NbTiN-AlN Coated Bulk Niobium
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  - We report measurements of the dc field onset B_{p} of magnetic flux penetration through NbTiN-AlN coating on bulk niobium using the Hall probe experimental setup. The measurements of Bp reveal the multilayer shielding effect on bulk niobium under high magnetic fields at cryogenic temperatures. We observed a significant enhancement in Bp for the NbTiN-AlN coated Nb samples as compared to bare Nb samples. The observed dependence of B_{p} on the coating thickness is consistent with theoretical predictions.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 311
EP  - 315
KW  - site
KW  - cavity
KW  - SRF
KW  - niobium
KW  - shielding
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB083
UR  - https://jacow.org/srf2023/papers/mopmb083.pdf
ER  - 

TY  - CONF
AU  - Zacarias, L.M.
AU  - Aderhold, S.
AU  - Cravatta, A.T.
AU  - Drury, M.A.
AU  - Gonnella, D.
AU  - Holzbauer, J.P.
AU  - Maniscalco, J.T.
AU  - McCaughan, M.D.
AU  - Nelson, J.
AU  - Porter, R.D.
AU  - Posen, S.
AU  - Wilson, C.M.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Measuring Q₀ in LCLS-II Cryomodules Using Helium Liquid Level
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 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.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 327
EP  - 331
KW  - cavity
KW  - cryomodule
KW  - linac
KW  - MMI
KW  - SRF
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB090
UR  - https://jacow.org/srf2023/papers/mopmb090.pdf
ER  - 

TY  - CONF
AU  - Eremeev, G.V.
AU  - Cheban, S.
AU  - Fischer, J.F.
AU  - Forehand, D.
AU  - Posen, S.
AU  - Pudasaini, U.
AU  - Reilly, A.V.
AU  - Rimmer, R.A.
AU  - Tennis, B.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Preservation of the High Quality Factor and Accelerating Gradient of Nb₃Sn-Coated Cavity During Pair Assembly
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 CEBAF 5-cell accelerator cavities have been coated with Nb₃Sn film using the vapor diffusion technique. One cavity was coated in the Jefferson Lab Nb₃Sn cavity coating system, and the other in the Fermilab Nb₃Sn coating system. Both cavities were measured at 4 K and 2 K in the vertical dewar test in each lab and then assembled into a cavity pair at Jefferson Lab. Previous attempts to assemble Nb₃Sn cavities into a cavity pair degraded the superconducting properties of Nb₃Sn-coated cavities. This contribution discusses the efforts to identify and mitigate the pair assembly challenges and will present the results of the vertical tests before and after pair assembly. Notably, one of the cavities reached the highest gradient above 80 mT in the vertical test after the pair assembly.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 405
EP  - 409
KW  - cavity
KW  - SRF
KW  - accelerating-gradient
KW  - cryomodule
KW  - niobium
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-TUPTB010
UR  - https://jacow.org/srf2023/papers/tuptb010.pdf
ER  - 

TY  - CONF
AU  - Shakel, M.S.
AU  - Elsayed-Ali, H.
AU  - Eremeev, G.V.
AU  - Pudasaini, U.
AU  - Valente-Feliciano, A-M.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - First Results from Nb₃Sn Coatings of 2.6 GHz Nb SRF Cavities Using DC Cylindrical Magnetron Sputtering System
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 DC cylindrical magnetron sputtering system has been commissioned and operated to deposit Nb₃Sn onto 2.6 GHz Nb SRF cavities. After optimizing the deposition conditions in a mock-up cavity, Nb-Sn films are deposited first on flat samples by multilayer sequential sputtering of Nb and Sn, and later annealed at 950 °C for 3 hours. X-ray diffraction of the films showed multiple peaks for the Nb₃Sn phase and Nb (substrate). No peaks from any Nb-Sn compound other than Nb₃Sn were detected. Later three 2.6 GHz Nb SRF cavities are coated with ~1 µm thick Nb₃Sn. The first Nb₃Sn coated cavity reached close to E_{acc} = 8 MV/m, demonstrating a quality factor Q₀ of 3.2 × 10⁸ at Tbath = 4.4 K and E_{acc} = 5 MV/m, about a factor of three higher than that of Nb at this temperature. Q₀ was close to 1.1 × 10⁹, dominated by the residual resistance, at 2 K and E_{acc} = 5 MV/m. The Nb₃Sn coated cavities demonstrated Tc in the range of 17.9 ¿ 18 K. Here we present the commissioning experience, system optimization, and the first results from the Nb₃Sn fabrication on flat samples and SRF cavities.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 429
EP  - 432
KW  - cavity
KW  - SRF
KW  - site
KW  - vacuum
KW  - MMI
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-TUPTB019
UR  - https://jacow.org/srf2023/papers/tuptb019.pdf
ER  - 

TY  - CONF
AU  - Tiskumara, J.K.
AU  - Delayen, J.R.
AU  - Eremeev, G.V.
AU  - Pudasaini, U.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Surface Properties and RF Performance of Vapor Diffused Nb₃Sn on Nb after Sequential Anneals below 1000 °C
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  - Nb₃Sn is a next-generation superconducting material that can be used for future superconducting radiofrequency (SRF) accelerator cavities, promising better performance, cost reduction, and higher operating temperature than Nb. The Sn vapor diffusion method is currently the most preferred and successful technique to coat niobium cavities with Nb₃Sn. Among post-coating treatments to optimize the coating quality, higher temperature annealing without Sn is known to degrade Nb₃Sn because of Sn loss. We have investigated Nb₃Sn/Nb samples briefly annealed at 800-1000 °C, for 10 and 20 minutes to potentially improve the surface to enhance the performance of Nb₃Sn-coated cavities. Following the sample studies, a coated single-cell cavity was sequentially annealed at 900 °C and tested its performance each time, improving the cavity’s quality factor relatively. This paper summarizes the sample studies and discusses the RF test results from sequentially annealed SRF Nb₃Sn/Nb cavity.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 433
EP  - 437
KW  - cavity
KW  - SRF
KW  - ECR
KW  - electron
KW  - experiment
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-TUPTB020
UR  - https://jacow.org/srf2023/papers/tuptb020.pdf
ER  - 

TY  - CONF
AU  - Vennekate, H.
AU  - Castilla, A.
AU  - Cheng, G.
AU  - Ciovati, G.
AU  - Guo, J.
AU  - Hannon, F.E.
AU  - Harding, K.A.
AU  - Henry, J.
AU  - Packard, D.A.
AU  - Pudasaini, U.
AU  - Rathke, J.
AU  - Rimmer, R.A.
AU  - Schultheiss, T.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - On the Way to a 10 MeV, Conduction-Cooled, Compact SRF Accelerator
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 the success of designing a compact 1 MeV, 1 MW accelerator based on conduction-cooled SRF, Jefferson Lab is now pursuing a concept to provide a tenfold increase of the beam energy. The higher energy significantly extends the range of applications for environmental remediation and industry in general. The obvious challenge for SRF is to move from a single-cell to a multicell cavity while maintaining high efficiency and the ability to operate the machine without a complex cryogenic plant. The contribution presents the latest results of this design study with respect to its centerpiece, a Nb₃Sn coated 915 MHz five-cell cavity and its corresponding RF components, i.e. FPC and HOM absorber, as well as the conduction-cooling concept based on commercially available cryocoolers.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 471
EP  - 476
KW  - cavity
KW  - SRF
KW  - electron
KW  - cryogenics
KW  - simulation
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-TUPTB033
UR  - https://jacow.org/srf2023/papers/tuptb033.pdf
ER  -