SRF2021 - List of Keywords (HOM)

Paper	Title	Other Keywords	Page
SUPCAV014	Design and Simulation of 500 MHz Single Cell Superconducting Cavity	cavity, superconducting-cavity, simulation, ECR	46
	Y.B. Sun, W. Ma Sun Yat-sen University, Zhuhai, Guangdong, People’s Republic of China G.M. Liu SSRF, Shanghai, People’s Republic of China L. Lu, L. Yang, Z. Zhang IMP/CAS, Lanzhou, People’s Republic of China
	Funding: Work supported by Shenzhen Development and Reform Commis-sion The Shenzhen Industrial Synchrotron Radiation Light Source is a fourth-generation medium-energy light source with a 3GeV storage ring electron energy and an emit-tance less than 100 pm·rad. In order to ensure the long-term stable and efficient operation of the light source, a new type of 500 MHz single-cell superconducting cavity was designed in this study to be used as a pre-research superconducting cavity for the Light Source. The 500 MHz superconducting cavity has a large beam aperture and low high order modes (HOMs) impedance, which can be used in accelerators with larger currents. In this design, we simply adopted the same design scheme as the KEKB-type and CESR-type superconducting cavity. Using CST electromagnetic field simulation software to calculate and simulate the characteristics of the cavity, the results show that the designed 500 MHz single-cell cavity can meet the requirements of a high acceleration gradient, a high r/Q value, and a low peak surface field.
	Poster SUPCAV014 [0.425 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPCAV014
About •	Received ※ 21 June 2021 — Revised ※ 07 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 05 May 2022
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MOPTEV013	The VSR Demo Module Design – A Spaceframe-Based Module for Cavities with Warm Waveguide HOM Absorbers	cavity, GUI, storage-ring, SRF	233
	F. Glöckner, D. Böhlick, M. Bürger, V. Dürr, A. Frahm, J. Knobloch, F. Pflocksch, A. Veléz, D. Wolk, N. Wunderer HZB, Berlin, Germany
	The VSR (Variable pulse length Storage Ring) demo module is a prototype for the superconducting upgrade of HZB’s Bessy II. The module houses two 1.5 GHz superconducting cavities operated at 1.8 K in continuous wave (CW) mode. Each cavity has five water cooled Waveguide HOM Absorbers with high thermal load (450 W), which requires them to be water cooled. This setup introduces several design challenges, concerning space restriction, the interconnection of warm and cold parts and the alignment. In order to provide support and steady alignment an innovative space frame was designed. The transition from cold to warm over the partially superconducting waveguides made a more complex design for shielding and cooling system necessary. With the design close to completion, we are now entering the purchase phase.
	Poster MOPTEV013 [3.239 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPTEV013
About •	Received ※ 21 June 2021 — Revised ※ 02 September 2021 — Accepted ※ 18 November 2021 — Issue date ※ 02 December 2021
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MOPCAV001	Cavity Production and Testing of the First C75 Cryomodule for CEBAF	cavity, cryomodule, GUI, operation	250
	G. Ciovati, G. Cheng, E. Daly, G.K. Davis, M.A. Drury, J.F. Fischer, D. Forehand, K. Macha, F. Marhauser, E.A. McEwen, A.L.A. Mitchell, A.V. Reilly, R.A. Rimmer, S. Wang JLab, Newport News, Virginia, USA
	Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. The CEBAF cryomodule rework program was updated over the last few years to increase the energy gain of refurbished cryomodules to 75 MeV. The concept recycles the waveguide end-groups from original CEBAF cavities fabricated in the 1990s and replaces the five elliptical cells in each with a new optimized cell shape fabricated from large-grain, ingot Nb material. Eight cavities were fabricated at Research Instruments, Germany, and two cavities were built at Jefferson Lab. Each cavity was processed by electropolishing and tested at 2.07 K. The best eight cavities were assembled into ’cavity pairs’ and re-tested at 2.07 K, before assembly into the cryomodule. All but one cavity in the cryomodule were within 10% of the target accelerating gradient of 19 MV/m with a quality factor of 8·10⁹. The performance limitations were field emission and multipacting.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV001
About •	Received ※ 17 June 2021 — Accepted ※ 21 February 2022 — Issue date ※ 10 April 2022
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MOPCAV010	Design of a HOM-Damped 166.6 MHz Compact Quarter-Wave β=1 Superconducting Cavity for High Energy Photon Source	cavity, superconducting-cavity, photon, impedance	278
	X.Y. Zhang, J. Dai, L. Guo, T.M. Huang, Z.Q. Li, Q. Ma, F. Meng, Z.H. Mi, P. Zhang, H.J. Zheng IHEP, Beijing, People’s Republic of China
	Funding: This work was supported by High Energy Photon Source, a major national science and technology infrastructure in China. Superconducting cavities with low RF frequencies and heavy damping of higher order modes (HOM) are desired for the main accelerator of High Energy Photon Source (HEPS), a 6 GeV synchrotron light source promising ultralow emittance currently under construction in Beijing. A compact 166.6 MHz superconducting cavity was proposed adopting a quarter-wave β=1 geometry. Based on the successful development of a proof-of-principle cavity, a HOM-damped 166.6 MHz compact superconducting cavity was subsequently designed. Ferrite damper was installed on the beam pipe to reduce HOM impedance below stringent threshold of coupled-bunch instabilities. Being compact, RF field heating on the cavity vacuum seal was carefully examined against quenching the NbTi flange. The cavity was later dressed with helium vessel and the tuning mechanism was also realized. Excellent RF and mechanical properties were eventually achieved. Finally, the two-cavity string was designed to ensure smooth transitions among components and proper shielding of synchrotron light. This paper presents a complete design of a fully dressed HOM-damped low-frequency β=1 superconducting cavity for HEPS.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV010
About •	Received ※ 20 June 2021 — Accepted ※ 21 August 2021 — Issue date ※ 14 April 2022
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MOPCAV013	LCLS-II-HE Vertical Acceptance Testing Plans	cavity, multipactoring, cryomodule, accelerating-gradient	291
	J.T. Maniscalco, S. Aderhold, J.D. Fuerst, D. Gonnella SLAC, Menlo Park, California, USA T.T. Arkan, M. Checchin, J.A. Kaluzny, S. Posen Fermilab, Batavia, Illinois, USA J. Hogan, A.D. Palczewski, C.E. Reece, K.M. Wilson JLab, Newport News, Virginia, USA
	LCLS-II-HE has performance requirements similar to but generally more demanding than those of LCLS-II, with an operating gradient of 21 MV/m (up from 16 MV/m in LCLS-II) and tighter restrictions on field emission and multipacting. In this paper, we outline the requirements for the 1.3 GHz cavities and the plans for qualification of these cavities by vertical test. We discuss lessons learned from LCLS-II and highlight the changes implemented in the vertical test procedure for the new project.
	Poster MOPCAV013 [0.418 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV013
About •	Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 02 May 2022
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MOPCAV016	HOM Couplers and RF Antennas for HL-LHC Crab Cavities: Developments for Manufacturing	cavity, niobium, SRF, operation	303
	S. Barrière, S. Atieh, B. Bulat, R. Calaga, S.J. Calvo, O. Capatina, T. Demazière, G. Favre, A. Gallifa Terricabras, M. Garlasché, J.-M. Geisser, J.A. Mitchell, E. Montesinos, F. Motschmann, P. Naisson, R. Ninet, L. Prever-Loiri, L.R.A. Renaglia, K. Scibor, N. Villanti CERN, Meyrin, Switzerland
	Superconducting RF crab cavities are being manufactured as part of the HL-LHC upgrade at CERN. Amongst its related ancillaries, radiofrequency HOM (High Order Modes) suppressors and field antennas are essential for reaching nominal performance during operation with high energy beams, as they monitor and control the electromagnetic fields in the cavities. Several concepts of such equipment have been engineered and manufactured, for both design validation and RF performance assessment. The following paper highlights manufacturing process definition, its challenges and the assembly strategies focusing on the ongoing RFD prototypes for the SPS beam tests. Specific tooling development and test campaigns are also described.
	Poster MOPCAV016 [1.457 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV016
About •	Received ※ 21 June 2021 — Revised ※ 10 July 2021 — Accepted ※ 11 November 2021 — Issue date ※ 18 November 2021
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MOPFDV003	Measuring Flux Trapping Using Flat Samples	cavity, simulation, experiment, controls	326
	F. Kramer, S. Keckert, J. Knobloch, O. Kugeler HZB, Berlin, Germany J. Knobloch University of Siegen, Siegen, Germany
	With modern superconducting cavities flux trapping is a limiting factor for the achievable quality factor. Flux trapping is influenced by various parameters such as geometry, material, and cooldown dynamics. At SRF2019 we presented data showing the magnetic field surrounding a cavity. We now present supplemental simulations for this data focusing on geometric effects. As these simulations are inconclusive, we have designed a new setup to measure trapped flux in superconducting samples which is presented as well. The advantages compared to a cavity test are the simpler sample geometry, and quicker sample production, as well as shorter measurement times. With this setup we hope to identify fundamental mechanisms of flux trapping, including geometry effects, different materials, and different treatments. First results are presented along with the setup itself.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPFDV003
About •	Received ※ 21 June 2021 — Accepted ※ 03 April 2022 — Issue date ※ 02 May 2022
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TUPCAV002	HOM Excitation in Spoke Resonator for SRF Studies	cavity, coupling, simulation, multipactoring	435
	D. Longuevergne, N. Bippus, F. Chatelet, V. Delpech, N. Hu, C. Joly, T. Pépin-Donat, F. Rabehasy, L. Renard Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France M. Baudrier CEA-DRF-IRFU, France E. Cenni, L. Maurice CEA-IRFU, Gif-sur-Yvette, France
	The excitation of Higher Order Modes (HOM) or Lower Order Modes (LOM) has been performed for years on multi-cell superconducting accelerating cavities as a mean to coarsely locate a quench, a defective area or ignite a plasma for surface cleaning. Moreover, such multi-mode testing is very useful to understand more accurately the frequency dependence of the surface resistance in a wide range of surface magnetic fields (0<B<150mT). In that sense, several type of dedicated non-accelerating resonators like Quadrupole Resonator (QPR), Half- or Quarter- Wave resonators have been built to specifically study new superconducting materials or new surface or heat treatments. What is proposed in this paper is to perform such multi-mode analysis (352 MHz, 720 MHz and 1300 MHz) in an existing accelerating cavity, in particular a Spoke Resonator. Baseline results will be presented and perspectives of such technique will be discussed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV002
About •	Received ※ 22 June 2021 — Revised ※ 19 July 2021 — Accepted ※ 23 August 2021 — Issue date ※ 15 April 2022
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TUPCAV014	Design of a Third Harmonic Cavity With Low R/Q for the ESR in BNL EIC	cavity, multipactoring, simulation, electron	469
	B.P. Xiao BNL, Upton, New York, USA
	Funding: The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. For the electron Storage Ring (ESR) of Brookhaven National Lab Electron Ion Collider (BNL EIC), beam loading is a great concern due to the high beam current together with abortion gap, especially for harmonic cavities due to higher operational frequency. There were attempts to use feedback/feedforward control, using multiple cavities with counter-phasing. A straightforward way to lower beam loading effect is to design a cavity with low R/Q. In this paper, we show such a design for the 3rd harmonic cavity for BNL EIC ESR.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV014
About •	Received ※ 22 June 2021 — Revised ※ 12 November 2021 — Accepted ※ 11 February 2022 — Issue date ※ 22 February 2022
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TUPTEV004	In Situ Plasma Processing of Superconducting Cavities at Jefferson Lab	cavity, cryomodule, plasma, software	485
	T. Powers, N.C. Brock, T.D. Ganey JLab, Newport News, Virginia, USA
	Funding: Funding provided by SC Nuclear Physics Program through DOE SC Lab funding announcement Lab-20-2310 Jefferson Lab began a plasma processing program starting in the spring of 2019. Plasma processing is a common technique for removing hydrocarbons from surfaces, which increases the work function and reduces the secondary emission coefficient. Unlike helium processing which relies on ion bombardment of the field emitters, plasma processing uses free oxygen produced in the plasma to break down the hydrocarbons on the surface of the cavity. The residuals of the hydrocarbons in the form of water, carbon monoxide and carbon dioxide are removed from the cryomodule as part of the process gas flow. The initial focus of the effort is processing C100 cavities by injecting RF power into the HOM coupler ports. We will then start investigating processing of C50 cavities by introducing RF into the fundamental power coupler. The plan is to start processing cryomodules in the CEBAF tunnel in the mid-term future, with a goal of improving the operational gradients and the energy margin of the linacs. This work will describe the systems and methods used at JLAB for processing cavities using an argon oxygen gas mixture. Before and after plasma processing results will also be presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPTEV004
About •	Received ※ 21 June 2021 — Accepted ※ 05 October 2021 — Issue date ※ 02 May 2022
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TUPTEV016	Upgrade of the RHIC 56 MHz Superconducting Quarter-Wave Resonator Cryomodule	cavity, coupling, operation, cryomodule	522
	Z.A. Conway, R. Anderson, D. Holmes, K. Mernick, S. Polizzo, S.K. Seberg, F. Severino, K.S. Smith, Q. Wu, B.P. Xiao, W. Xu, A. Zaltsman BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. In preparation for the 2023 RHIC sPHENIX experi-mental program the superconducting 56 MHz quarter-wave resonator cryomodule, used operationally for longitudinal bunch compression with up to 1 MV RF voltage, is being refit to accommodate an expected beam current of 418 mA per ring, an increase of ~1.5 relative to previous operation. The upgrades to the system include an improved fundamental mode damp-er, and dual function fundamental power and higher-order mode damper couplers. This paper will describe the preliminary testing, select subsystem changes and plans for testing the cryomodule prior to installation in the RHIC beam line in 2022.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPTEV016
About •	Received ※ 21 June 2021 — Revised ※ 09 February 2022 — Accepted ※ 22 February 2022 — Issue date ※ 28 April 2022
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WEPCAV002	Improvement of Chemical Etching Capabilities (BCP) for SRF Spoke Resonators at IJCLab	cavity, simulation, SRF, niobium	590
	J. Demercastel-Soulier, P. Duchesne, D. Longuevergne, G. Olry, T. Pépin-Donat, F. Rabehasy, D. Reynet, S. Roset, L.M. Vogt Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
	Buffered chemical polishing (BPC) is the reference surface polishing adopted for ESS and MYRRHA SRF spoke resonators at IJCLab. This chemical treatment, in addition to improving the RF performance, fits into the frequency adjustment strategy of the jacketed cavity during its preparation phase. In the framework of the collaboration with Fermilab for PIP-II project, IJCLab has developed a new setup to perform rotational BCP. The implementation of a rotation during chemical etching improves significantly the homogeneity and quality of surface polishing. In this paper, we present the numerical analysis based on a fluid dynamics model. The goal is to estimate the acid flow characteristics inside the cavity, determine the influence of several parameters as mass flow rate and rotation speed and propose the best configuration for the new experimental setup
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPCAV002
About •	Received ※ 23 June 2021 — Revised ※ 18 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 14 January 2022
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WEPCAV012	Research and Development of 650 MHz Cavities for CEPC	cavity, cryomodule, SRF, higher-order-mode	616
	P. Sha, C. Dong, F.S. He, S. Jin, Z.Q. Li, B.Q. Liu, Z.H. Mi, W.M. Pan, J.Y. Zhai, X.Y. Zhang, H.J. Zheng IHEP, Beijing, People’s Republic of China
	Funding: This work was supported by the National Key Programme for S&T Research and Development (No. 2016YFA0400400), the Platform of Advanced Photon Source Technology R&D. 650 MHz 2-cell superconducting cavities are proposed for the main ring of the Circular Electron Positron Collider (CEPC). The design, fabrication, surface treatment (buffered chemical polishing) and vertical tests of the cavities with HOM couplers were conducted. The performance of the cavity at 2 K is not affected by the HOM coupler. The maximum intrinsic quality factor of the cavity with the HOM coupler reached 3.1·10¹⁰ at 20 MV/m. The vertical test results showed that the fundamental mode external quality factor of all HOM couplers is an order of magnitude larger than quality factor of the cavity. The HOM damping results for the 650 MHz 2-cell cavity were also measured at cryogenic temperature and compared with the simulated and measured results at room temperature. Two 650 MHz 2-cell cavities jacketed have been integrated into a test cryomodule for CEPC. Another 650 MHz 2-cell cavity reached 6·10¹⁰ at 22 MV/m after nitrogen infusion. In addition, two 650 MHz 1-cell cavities reached 2.7·10¹⁰ at 35 MV/m (fine grain) and 3.6·10¹⁰ at 32 MV/m (large grain) after electro-polishing, respectively. In future, electro-polishing will be applied to 650 MHz 2-cell cavity soon.
	Poster WEPCAV012 [1.961 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPCAV012
About •	Received ※ 21 June 2021 — Accepted ※ 07 December 2021 — Issue date ※ 02 May 2022
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WEPCAV014	HOM Damper Design for BNL EIC 197 MHz Crab Cavity	cavity, impedance, GUI, cryomodule	624
	B.P. Xiao, Q. Wu BNL, Upton, New York, USA S.U. De Silva, J.R. Delayen ODU, Norfolk, Virginia, USA J.R. Delayen, R.A. Rimmer JLab, Newport News, Virginia, USA Z. Li SLAC, Menlo Park, California, USA S. Verdú-Andrés Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
	Funding: The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. The interaction region (IR) crab cavity system is a special RF system to compensate the loss of luminosity due to a 25 mrad crossing angle at the interaction point (IP) for BNL EIC. There will be six crab cavities, with four 197 MHz crab cavities and two 394 MHz crab cavities, installed on each side of the IP in the proton/ion ring, and one 394 MHz crab cavity on each side of the IP in the electron ring. Both rings share identical 394 MHz crab cavity design to minimize the cost and risk in designing a new RF system, and it will be scaled from 197 MHz crab cavity. In this paper, the HOM damper design for 197 MHz crab cavity is introduced.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPCAV014
About •	Received ※ 22 June 2021 — Revised ※ 17 October 2021 — Accepted ※ 17 December 2021 — Issue date ※ 07 April 2022
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WEPTEV008	VSR Demo Cold String: Recent Developments and Manufacturing Status	cavity, SRF, operation, storage-ring	647
	N. Wunderer, V. Dürr, A. Frahm, H.-W. Glock, F. Glöckner, J. Knobloch, E. Sharples-Milne, A.V. Tsakanian, A. Veléz HZB, Berlin, Germany M. Bonezzi, A. D’Ambros, R. Paparella INFN/LASA, Segrate (MI), Italy J. Guo, J. Henry, R.A. Rimmer JLab, Newport News, Virginia, USA J. Knobloch University of Siegen, Siegen, Germany A. Veléz Technical University Dortmund, Dortmund, Germany
	The BESSY VSR project aims to demonstrate the possibility to simultaneously run both long (15ps) and short bunches (1.7ps) within BESSY II storage ring. To achieve this, a new SRF cavity system with higher harmonic cavities (3 and 3.5 harm.) needs to be installed. The combined cavity SRF beating allows for stable bunch shortening for half of the buckets while standard lengths remaining for the other half. These SRF cavities will be equipped with waveguide-connected HOM absorbers and will be controlled with a blade tuner plus piezos. To demonstrate the feasibility of this complex system the VSR DEMO cold string consists of two 1.5 GHz cavities, each featuring five waveguides and a higher power coupler, plus all interconnecting elements coupled to the beam vacuum. For most of these components the fundamental development work is completed and has been reported in the past. This paper summarizes recent enhancements, component detailing and manufacturing status. The key cold string components such as cavities, higher power couplers and blade tuners have already entered the manufacturing phase. All other cold string components will be ready for purchase at the latest beginning of 2022.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPTEV008
About •	Received ※ 18 June 2021 — Revised ※ 09 August 2021 — Accepted ※ 22 November 2021 — Issue date ※ 05 January 2022
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WEPTEV009	The 1.5 GHz Coupler for VSR DEMO: Final Design Studies, Fabrication Status and Initial Testing Plans	cavity, SRF, coupling, vacuum	652
	E. Sharples-Milne, V. Dürr, J. Knobloch, S. Schendler, A. Veléz, N. Wunderer HZB, Berlin, Germany J. Knobloch University of Siegen, Siegen, Germany A. Veléz Technical University Dortmund, Dortmund, Germany
	The variable pulse length storage ring demo (VSR DEMO) is a research and development project at the Helmholtz Zentrum Berlin (HZB) to develop and validate a 1.5 GHz SRF system capable of accelerating high CW currents (up to 300 mA) at high accelerating fields (20 MV/m) for application in electron storage rings. Such a system can be employed to tailor the bunch length in synchrotron light source such as BESSY II. VSR DEMO requires a module equipped with two 1.5 GHz 4-cell SRF cavities and all ancillary components required for accelerator operations. This includes one 1.5 GHz fundamental power coupler (FPC) per cavity, designed to handle 16 kW peak and 1.5 kW average power. The final design studies, fabrication status and initial testing plans for these FPCs will be presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPTEV009
About •	Received ※ 21 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 09 November 2021
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WEOCAV03	RF Dipole Crab Cavity Testing for HL-LHC	cavity, dipole, controls, target	687
	N. Valverde Alonso, R. Calaga, S.J. Calvo, O. Capatina, O. Capatina, A. Castilla, M. Chiodini, C. Duval, L.M.A. Ferreira, M. Gourragne, P.J. Kohler, T. Mikkola, J.A. Mitchell, E. Montesinos, C. Pasquino, G. Pechaud, N. Stapley, M. Therasse, K. Turaj, J.D. Walker CERN, Meyrin, Switzerland A. Castilla Cockcroft Institute, Lancaster University, Lancaster, United Kingdom A. Castilla Lancaster University, Lancaster, United Kingdom
	RF Crab Cavities are an essential element of the High Luminosity LHC (HL-LHC) upgrade at CERN. Two RF dipole crab cavity used for the compensation of the horizontal crossing angle were recently manufactured and integrated into Titanium Helium tank and RF ancillaries necessary for the beam operation. The two cavities will be integrated into a cryomodule in collaboration with UK-STFC and tested with proton beams in the SPS in 2023. This paper will highlight the RF measurements during the important manufacturing steps, surface preparation and cavity performance at 2K.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEOCAV03
About •	Received ※ 18 June 2021 — Revised ※ 07 September 2021 — Accepted ※ 16 September 2021 — Issue date ※ 22 November 2021
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THPTEV014	Managing Procurements in the Time of Covid-19: SNS-PPU as a Case Study	operation, site, status, cryomodule	863
	K.M. Wilson, G. Cheng, E. Daly, N.A. Huque, T. Huratiak, M. Laney, K. Macha, D.J. Maddox, M. Marchlik, P.D. Owen, T. Peshehonoff, M. Torres, M. Wiseman JLab, Newport News, Virginia, USA
	Funding: Supported by the Dept of Energy, Office of Nuclear Physics under contract DE-AC05-06OR23177 (JSA); and by UT-B which manages Oak Ridge National Laboratory under contract DE-AC05-00OR22725. In early 2020, COVID-19 swept across the world. The accelerator industry, like many others, was impacted by disease, delays, shortages, and new working conditions. All Thomas Jefferson National Accelerator Facility (JLab) employees were sent home in mid-March 2020, with many still working remotely now. At the time, JLab was working on the Proton Power Upgrade (PPU) to the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). Procurements had been placed and were being managed, parts were being received and inspected. This paper details the JLab procurement plan for the SNS PPU project, and the mitigations that were developed to continue to support this project smoothly under the limitations imposed by COVID-19.
	Poster THPTEV014 [1.081 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV014
About •	Received ※ 15 June 2021 — Revised ※ 30 November 2021 — Accepted ※ 21 January 2022 — Issue date ※ 01 May 2022
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THPTEV017	Status of the LCLS-II-HE Project at Jefferson Lab	cavity, cryomodule, SRF, vacuum	876
	K.M. Wilson, J. Hogan, M. Laney, A.D. Palczewski, C.E. Reece JLab, Newport News, Virginia, USA
	Funding: This work was supported by the U.S. Department of Energy Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 (JSA); and for BES under contract DE’AC02’76SF00515 (SLAC). The Linac Coherent Light Source II High Energy (LCLS-II-HE) upgrade at the SLAC National Accelerator Laboratory is being constructed in partnership with the Thomas Jefferson National Accelerator Facility (JLab) and the Fermi National Accelerator Laboratory (FNAL). The cryomodule production scope consists of the design, procurement, construction, and acceptance testing of 24 eight-cavity, 1.3 GHz cryomodules, as well as R&D activities necessary to develop the required technology. To achieve this, JLab and FNAL are also contributing to SLAC’s effort to develop the cavity recipe and production processes necessary to meet the LCLS-II-HE goal of 20.8 MV/m and average Q₀ of 2.7·10¹⁰. This paper details the JLab scope, focusing on the project initiation phase, in particular technology development and prototyping, project development and planning, and implementation of lessons learned from LCLS-II.
	Poster THPTEV017 [1.536 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV017
About •	Received ※ 21 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 02 March 2022 — Issue date ※ 01 May 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

SUPCAV014

Design and Simulation of 500 MHz Single Cell Superconducting Cavity

cavity, superconducting-cavity, simulation, ECR

46

Y.B. Sun, W. Ma
Sun Yat-sen University, Zhuhai, Guangdong, People’s Republic of China
G.M. Liu
SSRF, Shanghai, People’s Republic of China
L. Lu, L. Yang, Z. Zhang
IMP/CAS, Lanzhou, People’s Republic of China

Funding: Work supported by Shenzhen Development and Reform Commis-sion
The Shenzhen Industrial Synchrotron Radiation Light Source is a fourth-generation medium-energy light source with a 3GeV storage ring electron energy and an emit-tance less than 100 pm·rad. In order to ensure the long-term stable and efficient operation of the light source, a new type of 500 MHz single-cell superconducting cavity was designed in this study to be used as a pre-research superconducting cavity for the Light Source. The 500 MHz superconducting cavity has a large beam aperture and low high order modes (HOMs) impedance, which can be used in accelerators with larger currents. In this design, we simply adopted the same design scheme as the KEKB-type and CESR-type superconducting cavity. Using CST electromagnetic field simulation software to calculate and simulate the characteristics of the cavity, the results show that the designed 500 MHz single-cell cavity can meet the requirements of a high acceleration gradient, a high r/Q value, and a low peak surface field.

Poster SUPCAV014 [0.425 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPCAV014

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Received ※ 21 June 2021 — Revised ※ 07 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 05 May 2022

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MOPTEV013

The VSR Demo Module Design – A Spaceframe-Based Module for Cavities with Warm Waveguide HOM Absorbers

cavity, GUI, storage-ring, SRF

233

F. Glöckner, D. Böhlick, M. Bürger, V. Dürr, A. Frahm, J. Knobloch, F. Pflocksch, A. Veléz, D. Wolk, N. Wunderer
HZB, Berlin, Germany

The VSR (Variable pulse length Storage Ring) demo module is a prototype for the superconducting upgrade of HZB’s Bessy II. The module houses two 1.5 GHz superconducting cavities operated at 1.8 K in continuous wave (CW) mode. Each cavity has five water cooled Waveguide HOM Absorbers with high thermal load (450 W), which requires them to be water cooled. This setup introduces several design challenges, concerning space restriction, the interconnection of warm and cold parts and the alignment. In order to provide support and steady alignment an innovative space frame was designed. The transition from cold to warm over the partially superconducting waveguides made a more complex design for shielding and cooling system necessary. With the design close to completion, we are now entering the purchase phase.

Poster MOPTEV013 [3.239 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPTEV013

About •

Received ※ 21 June 2021 — Revised ※ 02 September 2021 — Accepted ※ 18 November 2021 — Issue date ※ 02 December 2021

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MOPCAV001

Cavity Production and Testing of the First C75 Cryomodule for CEBAF

cavity, cryomodule, GUI, operation

250

G. Ciovati, G. Cheng, E. Daly, G.K. Davis, M.A. Drury, J.F. Fischer, D. Forehand, K. Macha, F. Marhauser, E.A. McEwen, A.L.A. Mitchell, A.V. Reilly, R.A. Rimmer, S. Wang
JLab, Newport News, Virginia, USA

Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
The CEBAF cryomodule rework program was updated over the last few years to increase the energy gain of refurbished cryomodules to 75 MeV. The concept recycles the waveguide end-groups from original CEBAF cavities fabricated in the 1990s and replaces the five elliptical cells in each with a new optimized cell shape fabricated from large-grain, ingot Nb material. Eight cavities were fabricated at Research Instruments, Germany, and two cavities were built at Jefferson Lab. Each cavity was processed by electropolishing and tested at 2.07 K. The best eight cavities were assembled into ’cavity pairs’ and re-tested at 2.07 K, before assembly into the cryomodule. All but one cavity in the cryomodule were within 10% of the target accelerating gradient of 19 MV/m with a quality factor of 8·10⁹. The performance limitations were field emission and multipacting.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV001

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Received ※ 17 June 2021 — Accepted ※ 21 February 2022 — Issue date ※ 10 April 2022

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MOPCAV010

Design of a HOM-Damped 166.6 MHz Compact Quarter-Wave β=1 Superconducting Cavity for High Energy Photon Source

cavity, superconducting-cavity, photon, impedance

278

X.Y. Zhang, J. Dai, L. Guo, T.M. Huang, Z.Q. Li, Q. Ma, F. Meng, Z.H. Mi, P. Zhang, H.J. Zheng
IHEP, Beijing, People’s Republic of China

Funding: This work was supported by High Energy Photon Source, a major national science and technology infrastructure in China.
Superconducting cavities with low RF frequencies and heavy damping of higher order modes (HOM) are desired for the main accelerator of High Energy Photon Source (HEPS), a 6 GeV synchrotron light source promising ultralow emittance currently under construction in Beijing. A compact 166.6 MHz superconducting cavity was proposed adopting a quarter-wave β=1 geometry. Based on the successful development of a proof-of-principle cavity, a HOM-damped 166.6 MHz compact superconducting cavity was subsequently designed. Ferrite damper was installed on the beam pipe to reduce HOM impedance below stringent threshold of coupled-bunch instabilities. Being compact, RF field heating on the cavity vacuum seal was carefully examined against quenching the NbTi flange. The cavity was later dressed with helium vessel and the tuning mechanism was also realized. Excellent RF and mechanical properties were eventually achieved. Finally, the two-cavity string was designed to ensure smooth transitions among components and proper shielding of synchrotron light. This paper presents a complete design of a fully dressed HOM-damped low-frequency β=1 superconducting cavity for HEPS.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV010

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Received ※ 20 June 2021 — Accepted ※ 21 August 2021 — Issue date ※ 14 April 2022

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MOPCAV013

LCLS-II-HE Vertical Acceptance Testing Plans

cavity, multipactoring, cryomodule, accelerating-gradient

291

J.T. Maniscalco, S. Aderhold, J.D. Fuerst, D. Gonnella
SLAC, Menlo Park, California, USA
T.T. Arkan, M. Checchin, J.A. Kaluzny, S. Posen
Fermilab, Batavia, Illinois, USA
J. Hogan, A.D. Palczewski, C.E. Reece, K.M. Wilson
JLab, Newport News, Virginia, USA

LCLS-II-HE has performance requirements similar to but generally more demanding than those of LCLS-II, with an operating gradient of 21 MV/m (up from 16 MV/m in LCLS-II) and tighter restrictions on field emission and multipacting. In this paper, we outline the requirements for the 1.3 GHz cavities and the plans for qualification of these cavities by vertical test. We discuss lessons learned from LCLS-II and highlight the changes implemented in the vertical test procedure for the new project.

Poster MOPCAV013 [0.418 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV013

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Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 02 May 2022

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MOPCAV016

HOM Couplers and RF Antennas for HL-LHC Crab Cavities: Developments for Manufacturing

cavity, niobium, SRF, operation

303

S. Barrière, S. Atieh, B. Bulat, R. Calaga, S.J. Calvo, O. Capatina, T. Demazière, G. Favre, A. Gallifa Terricabras, M. Garlasché, J.-M. Geisser, J.A. Mitchell, E. Montesinos, F. Motschmann, P. Naisson, R. Ninet, L. Prever-Loiri, L.R.A. Renaglia, K. Scibor, N. Villanti
CERN, Meyrin, Switzerland

Superconducting RF crab cavities are being manufactured as part of the HL-LHC upgrade at CERN. Amongst its related ancillaries, radiofrequency HOM (High Order Modes) suppressors and field antennas are essential for reaching nominal performance during operation with high energy beams, as they monitor and control the electromagnetic fields in the cavities. Several concepts of such equipment have been engineered and manufactured, for both design validation and RF performance assessment. The following paper highlights manufacturing process definition, its challenges and the assembly strategies focusing on the ongoing RFD prototypes for the SPS beam tests. Specific tooling development and test campaigns are also described.

Poster MOPCAV016 [1.457 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV016

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Received ※ 21 June 2021 — Revised ※ 10 July 2021 — Accepted ※ 11 November 2021 — Issue date ※ 18 November 2021

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MOPFDV003

Measuring Flux Trapping Using Flat Samples

cavity, simulation, experiment, controls

326

F. Kramer, S. Keckert, J. Knobloch, O. Kugeler
HZB, Berlin, Germany
J. Knobloch
University of Siegen, Siegen, Germany

With modern superconducting cavities flux trapping is a limiting factor for the achievable quality factor. Flux trapping is influenced by various parameters such as geometry, material, and cooldown dynamics. At SRF2019 we presented data showing the magnetic field surrounding a cavity. We now present supplemental simulations for this data focusing on geometric effects. As these simulations are inconclusive, we have designed a new setup to measure trapped flux in superconducting samples which is presented as well. The advantages compared to a cavity test are the simpler sample geometry, and quicker sample production, as well as shorter measurement times. With this setup we hope to identify fundamental mechanisms of flux trapping, including geometry effects, different materials, and different treatments. First results are presented along with the setup itself.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPFDV003

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Received ※ 21 June 2021 — Accepted ※ 03 April 2022 — Issue date ※ 02 May 2022

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TUPCAV002

HOM Excitation in Spoke Resonator for SRF Studies

cavity, coupling, simulation, multipactoring

435

D. Longuevergne, N. Bippus, F. Chatelet, V. Delpech, N. Hu, C. Joly, T. Pépin-Donat, F. Rabehasy, L. Renard
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
M. Baudrier
CEA-DRF-IRFU, France
E. Cenni, L. Maurice
CEA-IRFU, Gif-sur-Yvette, France

The excitation of Higher Order Modes (HOM) or Lower Order Modes (LOM) has been performed for years on multi-cell superconducting accelerating cavities as a mean to coarsely locate a quench, a defective area or ignite a plasma for surface cleaning. Moreover, such multi-mode testing is very useful to understand more accurately the frequency dependence of the surface resistance in a wide range of surface magnetic fields (0<B<150mT). In that sense, several type of dedicated non-accelerating resonators like Quadrupole Resonator (QPR), Half- or Quarter- Wave resonators have been built to specifically study new superconducting materials or new surface or heat treatments. What is proposed in this paper is to perform such multi-mode analysis (352 MHz, 720 MHz and 1300 MHz) in an existing accelerating cavity, in particular a Spoke Resonator. Baseline results will be presented and perspectives of such technique will be discussed.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV002

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Received ※ 22 June 2021 — Revised ※ 19 July 2021 — Accepted ※ 23 August 2021 — Issue date ※ 15 April 2022

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TUPCAV014

Design of a Third Harmonic Cavity With Low R/Q for the ESR in BNL EIC

cavity, multipactoring, simulation, electron

469

B.P. Xiao
BNL, Upton, New York, USA

Funding: The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
For the electron Storage Ring (ESR) of Brookhaven National Lab Electron Ion Collider (BNL EIC), beam loading is a great concern due to the high beam current together with abortion gap, especially for harmonic cavities due to higher operational frequency. There were attempts to use feedback/feedforward control, using multiple cavities with counter-phasing. A straightforward way to lower beam loading effect is to design a cavity with low R/Q. In this paper, we show such a design for the 3rd harmonic cavity for BNL EIC ESR.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV014

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Received ※ 22 June 2021 — Revised ※ 12 November 2021 — Accepted ※ 11 February 2022 — Issue date ※ 22 February 2022

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TUPTEV004

In Situ Plasma Processing of Superconducting Cavities at Jefferson Lab

cavity, cryomodule, plasma, software

485

T. Powers, N.C. Brock, T.D. Ganey
JLab, Newport News, Virginia, USA

Funding: Funding provided by SC Nuclear Physics Program through DOE SC Lab funding announcement Lab-20-2310
Jefferson Lab began a plasma processing program starting in the spring of 2019. Plasma processing is a common technique for removing hydrocarbons from surfaces, which increases the work function and reduces the secondary emission coefficient. Unlike helium processing which relies on ion bombardment of the field emitters, plasma processing uses free oxygen produced in the plasma to break down the hydrocarbons on the surface of the cavity. The residuals of the hydrocarbons in the form of water, carbon monoxide and carbon dioxide are removed from the cryomodule as part of the process gas flow. The initial focus of the effort is processing C100 cavities by injecting RF power into the HOM coupler ports. We will then start investigating processing of C50 cavities by introducing RF into the fundamental power coupler. The plan is to start processing cryomodules in the CEBAF tunnel in the mid-term future, with a goal of improving the operational gradients and the energy margin of the linacs. This work will describe the systems and methods used at JLAB for processing cavities using an argon oxygen gas mixture. Before and after plasma processing results will also be presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPTEV004

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Received ※ 21 June 2021 — Accepted ※ 05 October 2021 — Issue date ※ 02 May 2022

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TUPTEV016

Upgrade of the RHIC 56 MHz Superconducting Quarter-Wave Resonator Cryomodule

cavity, coupling, operation, cryomodule

522

Z.A. Conway, R. Anderson, D. Holmes, K. Mernick, S. Polizzo, S.K. Seberg, F. Severino, K.S. Smith, Q. Wu, B.P. Xiao, W. Xu, A. Zaltsman
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
In preparation for the 2023 RHIC sPHENIX experi-mental program the superconducting 56 MHz quarter-wave resonator cryomodule, used operationally for longitudinal bunch compression with up to 1 MV RF voltage, is being refit to accommodate an expected beam current of 418 mA per ring, an increase of ~1.5 relative to previous operation. The upgrades to the system include an improved fundamental mode damp-er, and dual function fundamental power and higher-order mode damper couplers. This paper will describe the preliminary testing, select subsystem changes and plans for testing the cryomodule prior to installation in the RHIC beam line in 2022.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPTEV016

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Received ※ 21 June 2021 — Revised ※ 09 February 2022 — Accepted ※ 22 February 2022 — Issue date ※ 28 April 2022

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WEPCAV002

Improvement of Chemical Etching Capabilities (BCP) for SRF Spoke Resonators at IJCLab

cavity, simulation, SRF, niobium

590

J. Demercastel-Soulier, P. Duchesne, D. Longuevergne, G. Olry, T. Pépin-Donat, F. Rabehasy, D. Reynet, S. Roset, L.M. Vogt
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France

Buffered chemical polishing (BPC) is the reference surface polishing adopted for ESS and MYRRHA SRF spoke resonators at IJCLab. This chemical treatment, in addition to improving the RF performance, fits into the frequency adjustment strategy of the jacketed cavity during its preparation phase. In the framework of the collaboration with Fermilab for PIP-II project, IJCLab has developed a new setup to perform rotational BCP. The implementation of a rotation during chemical etching improves significantly the homogeneity and quality of surface polishing. In this paper, we present the numerical analysis based on a fluid dynamics model. The goal is to estimate the acid flow characteristics inside the cavity, determine the influence of several parameters as mass flow rate and rotation speed and propose the best configuration for the new experimental setup

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPCAV002

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Received ※ 23 June 2021 — Revised ※ 18 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 14 January 2022

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WEPCAV012

Research and Development of 650 MHz Cavities for CEPC

cavity, cryomodule, SRF, higher-order-mode

616

P. Sha, C. Dong, F.S. He, S. Jin, Z.Q. Li, B.Q. Liu, Z.H. Mi, W.M. Pan, J.Y. Zhai, X.Y. Zhang, H.J. Zheng
IHEP, Beijing, People’s Republic of China

Funding: This work was supported by the National Key Programme for S&T Research and Development (No. 2016YFA0400400), the Platform of Advanced Photon Source Technology R&D.
650 MHz 2-cell superconducting cavities are proposed for the main ring of the Circular Electron Positron Collider (CEPC). The design, fabrication, surface treatment (buffered chemical polishing) and vertical tests of the cavities with HOM couplers were conducted. The performance of the cavity at 2 K is not affected by the HOM coupler. The maximum intrinsic quality factor of the cavity with the HOM coupler reached 3.1·10¹⁰ at 20 MV/m. The vertical test results showed that the fundamental mode external quality factor of all HOM couplers is an order of magnitude larger than quality factor of the cavity. The HOM damping results for the 650 MHz 2-cell cavity were also measured at cryogenic temperature and compared with the simulated and measured results at room temperature. Two 650 MHz 2-cell cavities jacketed have been integrated into a test cryomodule for CEPC. Another 650 MHz 2-cell cavity reached 6·10¹⁰ at 22 MV/m after nitrogen infusion. In addition, two 650 MHz 1-cell cavities reached 2.7·10¹⁰ at 35 MV/m (fine grain) and 3.6·10¹⁰ at 32 MV/m (large grain) after electro-polishing, respectively. In future, electro-polishing will be applied to 650 MHz 2-cell cavity soon.

Poster WEPCAV012 [1.961 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPCAV012

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Received ※ 21 June 2021 — Accepted ※ 07 December 2021 — Issue date ※ 02 May 2022

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WEPCAV014

HOM Damper Design for BNL EIC 197 MHz Crab Cavity

cavity, impedance, GUI, cryomodule

624

B.P. Xiao, Q. Wu
BNL, Upton, New York, USA
S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA
J.R. Delayen, R.A. Rimmer
JLab, Newport News, Virginia, USA
Z. Li
SLAC, Menlo Park, California, USA
S. Verdú-Andrés
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA

Funding: The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
The interaction region (IR) crab cavity system is a special RF system to compensate the loss of luminosity due to a 25 mrad crossing angle at the interaction point (IP) for BNL EIC. There will be six crab cavities, with four 197 MHz crab cavities and two 394 MHz crab cavities, installed on each side of the IP in the proton/ion ring, and one 394 MHz crab cavity on each side of the IP in the electron ring. Both rings share identical 394 MHz crab cavity design to minimize the cost and risk in designing a new RF system, and it will be scaled from 197 MHz crab cavity. In this paper, the HOM damper design for 197 MHz crab cavity is introduced.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPCAV014

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Received ※ 22 June 2021 — Revised ※ 17 October 2021 — Accepted ※ 17 December 2021 — Issue date ※ 07 April 2022

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WEPTEV008

VSR Demo Cold String: Recent Developments and Manufacturing Status

cavity, SRF, operation, storage-ring

647

N. Wunderer, V. Dürr, A. Frahm, H.-W. Glock, F. Glöckner, J. Knobloch, E. Sharples-Milne, A.V. Tsakanian, A. Veléz
HZB, Berlin, Germany
M. Bonezzi, A. D’Ambros, R. Paparella
INFN/LASA, Segrate (MI), Italy
J. Guo, J. Henry, R.A. Rimmer
JLab, Newport News, Virginia, USA
J. Knobloch
University of Siegen, Siegen, Germany
A. Veléz
Technical University Dortmund, Dortmund, Germany

The BESSY VSR project aims to demonstrate the possibility to simultaneously run both long (15ps) and short bunches (1.7ps) within BESSY II storage ring. To achieve this, a new SRF cavity system with higher harmonic cavities (3 and 3.5 harm.) needs to be installed. The combined cavity SRF beating allows for stable bunch shortening for half of the buckets while standard lengths remaining for the other half. These SRF cavities will be equipped with waveguide-connected HOM absorbers and will be controlled with a blade tuner plus piezos. To demonstrate the feasibility of this complex system the VSR DEMO cold string consists of two 1.5 GHz cavities, each featuring five waveguides and a higher power coupler, plus all interconnecting elements coupled to the beam vacuum. For most of these components the fundamental development work is completed and has been reported in the past. This paper summarizes recent enhancements, component detailing and manufacturing status. The key cold string components such as cavities, higher power couplers and blade tuners have already entered the manufacturing phase. All other cold string components will be ready for purchase at the latest beginning of 2022.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPTEV008

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Received ※ 18 June 2021 — Revised ※ 09 August 2021 — Accepted ※ 22 November 2021 — Issue date ※ 05 January 2022

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WEPTEV009

The 1.5 GHz Coupler for VSR DEMO: Final Design Studies, Fabrication Status and Initial Testing Plans

cavity, SRF, coupling, vacuum

652

E. Sharples-Milne, V. Dürr, J. Knobloch, S. Schendler, A. Veléz, N. Wunderer
HZB, Berlin, Germany
J. Knobloch
University of Siegen, Siegen, Germany
A. Veléz
Technical University Dortmund, Dortmund, Germany

The variable pulse length storage ring demo (VSR DEMO) is a research and development project at the Helmholtz Zentrum Berlin (HZB) to develop and validate a 1.5 GHz SRF system capable of accelerating high CW currents (up to 300 mA) at high accelerating fields (20 MV/m) for application in electron storage rings. Such a system can be employed to tailor the bunch length in synchrotron light source such as BESSY II. VSR DEMO requires a module equipped with two 1.5 GHz 4-cell SRF cavities and all ancillary components required for accelerator operations. This includes one 1.5 GHz fundamental power coupler (FPC) per cavity, designed to handle 16 kW peak and 1.5 kW average power. The final design studies, fabrication status and initial testing plans for these FPCs will be presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPTEV009

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Received ※ 21 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 09 November 2021

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WEOCAV03

RF Dipole Crab Cavity Testing for HL-LHC

cavity, dipole, controls, target

687

N. Valverde Alonso, R. Calaga, S.J. Calvo, O. Capatina, O. Capatina, A. Castilla, M. Chiodini, C. Duval, L.M.A. Ferreira, M. Gourragne, P.J. Kohler, T. Mikkola, J.A. Mitchell, E. Montesinos, C. Pasquino, G. Pechaud, N. Stapley, M. Therasse, K. Turaj, J.D. Walker
CERN, Meyrin, Switzerland
A. Castilla
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
A. Castilla
Lancaster University, Lancaster, United Kingdom

RF Crab Cavities are an essential element of the High Luminosity LHC (HL-LHC) upgrade at CERN. Two RF dipole crab cavity used for the compensation of the horizontal crossing angle were recently manufactured and integrated into Titanium Helium tank and RF ancillaries necessary for the beam operation. The two cavities will be integrated into a cryomodule in collaboration with UK-STFC and tested with proton beams in the SPS in 2023. This paper will highlight the RF measurements during the important manufacturing steps, surface preparation and cavity performance at 2K.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEOCAV03

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Received ※ 18 June 2021 — Revised ※ 07 September 2021 — Accepted ※ 16 September 2021 — Issue date ※ 22 November 2021

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THPTEV014

Managing Procurements in the Time of Covid-19: SNS-PPU as a Case Study

operation, site, status, cryomodule

863

K.M. Wilson, G. Cheng, E. Daly, N.A. Huque, T. Huratiak, M. Laney, K. Macha, D.J. Maddox, M. Marchlik, P.D. Owen, T. Peshehonoff, M. Torres, M. Wiseman
JLab, Newport News, Virginia, USA

Funding: Supported by the Dept of Energy, Office of Nuclear Physics under contract DE-AC05-06OR23177 (JSA); and by UT-B which manages Oak Ridge National Laboratory under contract DE-AC05-00OR22725.
In early 2020, COVID-19 swept across the world. The accelerator industry, like many others, was impacted by disease, delays, shortages, and new working conditions. All Thomas Jefferson National Accelerator Facility (JLab) employees were sent home in mid-March 2020, with many still working remotely now. At the time, JLab was working on the Proton Power Upgrade (PPU) to the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). Procurements had been placed and were being managed, parts were being received and inspected. This paper details the JLab procurement plan for the SNS PPU project, and the mitigations that were developed to continue to support this project smoothly under the limitations imposed by COVID-19.

Poster THPTEV014 [1.081 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV014

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Received ※ 15 June 2021 — Revised ※ 30 November 2021 — Accepted ※ 21 January 2022 — Issue date ※ 01 May 2022

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THPTEV017

Status of the LCLS-II-HE Project at Jefferson Lab

cavity, cryomodule, SRF, vacuum

876

K.M. Wilson, J. Hogan, M. Laney, A.D. Palczewski, C.E. Reece
JLab, Newport News, Virginia, USA

Funding: This work was supported by the U.S. Department of Energy Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 (JSA); and for BES under contract DE’AC02’76SF00515 (SLAC).
The Linac Coherent Light Source II High Energy (LCLS-II-HE) upgrade at the SLAC National Accelerator Laboratory is being constructed in partnership with the Thomas Jefferson National Accelerator Facility (JLab) and the Fermi National Accelerator Laboratory (FNAL). The cryomodule production scope consists of the design, procurement, construction, and acceptance testing of 24 eight-cavity, 1.3 GHz cryomodules, as well as R&D activities necessary to develop the required technology. To achieve this, JLab and FNAL are also contributing to SLAC’s effort to develop the cavity recipe and production processes necessary to meet the LCLS-II-HE goal of 20.8 MV/m and average Q₀ of 2.7·10¹⁰. This paper details the JLab scope, focusing on the project initiation phase, in particular technology development and prototyping, project development and planning, and implementation of lessons learned from LCLS-II.

Poster THPTEV017 [1.536 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV017

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Received ※ 21 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 02 March 2022 — Issue date ※ 01 May 2022

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