SRF2023 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOPMB019	Numerical Calculations of Superheating Field in Superconductors with Nanostructured Surfaces	cavity, radio-frequency, SRF, superconductivity	114
	M.R.P. Walive Pathiranage VMI, Lexington, USA A.V. Gurevich ODU, Norfolk, Virginia, USA
	Funding: This work was supported by DOE under Grant DE-SC 100387-020 and by Virginia Military Institute (VMI) under Jackson-Hope Grant for faculty travel and for New Directions in Teaching and Research Grants. We report calculations of a dc superheating field Hs in superconductors with nanostructured surfaces. Particularly, we performed numerical simulations of the Ginzburg-Landau (GL) equations for a superconductor with an inhomogeneous profile of impurity concentration, a thin superconducting layer on top of another superconductor, and S-I-S multilayers. The superheating field was calculated taking into account the instability of the Meissner state at a finite wavelength along the surface depending on the value of the GL parameter. Simulations were done for the materials parameters of Nb and Nb₃Sn at different values of the GL parameter and the mean free paths. We show that the impurity concentration profile at the surface and thicknesses of superconducting layers in S-I-S structures can be optimized to reach the maximum Hs, which exceeds the bulk superheating fields of both Nb and Nb₃Sn. For example, a S-I-S structure with 90 nm thick Nb₃Sn layer on Nb can boost the superheating field up to ~ 500 mT, while protecting the SRF cavity from dendritic thermomagnetic avalanches caused by local penetration of vortices.
	Poster MOPMB019 [1.214 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB019
About •	Received ※ 17 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 16 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB023	Magnetic Flux Expulsion in TRIUMF’s Multi-Mode Coaxial Cavities	cavity, SRF, experiment, controls	135
	R.R. Gregory, T. Junginger, M.W. McMullin UVIC, Victoria, Canada T. Junginger, P. Kolb, R.E. Laxdal, M.W. McMullin, Z.Y. Yao TRIUMF, Vancouver, Canada
	The external magnetic flux sensitivity of SRF cavities is an important characteristic of SRF accelerator design. Previous studies have shown that n-doped elliptical cavities are very sensitive to external fields, resulting in stringent requirements for residual field and cavity cool-down speed. Few such studies have been done on HWRs and QWRs. The impact of applied field direction and cool-down speed of flux expulsion for these cavities is poorly understood. This study explores the effect of these cool-down characteristics on TRIUMF¿s QWR using COMSOL ® simulations and experimental results. This study seeks to maximize the flux expulsion that occurs when a cavity is cooled down through its superconducting temperature. Flux expulsion is affected by the cool-down speed, temperature gradient, and orientation of the cavity relative to an applied magnetic field. It was found that for a vertically applied magnetic field the cool-down speed and temperature gradient did not have a significant effect on flux expulsion. Contrarily, a horizontal magnetic field can be nearly completely expelled by a fast, high temperature gradient cool-down.
	Poster MOPMB023 [2.191 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB023
About •	Received ※ 17 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 30 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB024	Flux Expulsion Studies of Niobium Material of 650 MHz Cavities for PIP-II	cavity, niobium, factory, radio-frequency	141
	K.E. McGee FRIB, East Lansing, Michigan, USA F. Furuta, M. Martinello, O.S. Melnychuk, A.V. Netepenko, G. Wu, Y. Xie Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. Two different vendors supplied the niobium sheet material for PIP-II 5-cell 650 MHz cavities, which was characterized by multiple different ASTM sizes. Cavities subsequently fabricated from these sheets were heat-treated at various temperatures, then the cavities’ flux-expulsion performance was measured. Where the initial measurements of vendor O materials showed that nearly all flux remained trapped despite a high thermal gradient, 900C heat treatment subsequently improved the flux expulsion to an acceptable rate. Understanding and characterizing vendor O materials in this way is key for upcoming and future projects planning to employ niobium sheet from this supplier.
	Poster MOPMB024 [4.064 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB024
About •	Received ※ 26 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 21 August 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB049	Plasma Processing: Ignition Testing and Simulation Models for a 172 MHz HWR Cavity	plasma, cavity, vacuum, SRF	219
	M.E. McIntyre, B.R. Blomberg, M.P. Kelly, J.T. McLain, K.M. Villafania, G.P. Zinkann ANL, Lemont, Illinois, USA Z. Wei GIT, Atlanta, Georgia, USA
	Maintenance and cleaning of superconducting RF cavities is labor intensive task that involves disassembling the cryostat holding the resonators and removing them to be cleaned. At the Argonne Tandem Linac Accelerating System (ATLAS) at Argonne National Laboratory, a project is underway to research cleaning the cavities in-situ by plasma processing. Previous plasma processing research by SNS, MSU, FNAL, and IJCLab has been successful in improving field emissions post processing. It is advantageous to pursue research in this method, allowing for possible use on modern ATLAS cryomodules, A-tank and G-tank quarter-wave resonators. The results presented show initial plasma ignition testing and plasma simulations for the coupled E and B fields, both done on a 172 MHz HWR cavity previously designed as early R&D for FRIB. Future plans are also included, laying out next steps to test plasma processing on the same HWR cavity and eventually a QWR.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB049
About •	Received ※ 05 July 2023 — Revised ※ 25 July 2023 — Accepted ※ 24 September 2023 — Issue date ※ 24 September 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB065	Design Status of BCC Cryomodule for LCLS-II HE	cryomodule, cavity, solenoid, cryogenics	263
	C.S. Narug, T.T. Arkan, S. Cheban, M. Chen, B.D. Hartsell, J.A. Kaluzny, V.S. Kashikhin, Y.M. Orlov Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. A Buncher or Capture Cavity (BCC) Cryomodule is currently in development at Fermilab for use in a second injector for LCLS-II-HE. The BCC Cryomodule is designed to contain one 1.3 GHz cavity and one solenoid magnet as part of a 100MeV low emittance injector. The design considerations for the Cryomodule are similar to the LCLS-II cryomodule with additional requirements to account for additional vacuum loading at the end of this vessel due to the termination of the insulating vacuum. To accomplish this design, the cryomodule is being developed using the experience gained during the development of the LCLS-II cryomodule. The design, analysis, and status of the Cryomodule will be discussed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB065
About •	Received ※ 18 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 13 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB078	Design and Prototyping of the Electron Ion Collider Electron Storage Ring SRF Cavity	cavity, HOM, operation, electron	293
	J. Guo, E.F. Daly, E. Drachuk, R.R. Fernandes, J. Henry, J. Matalevich, G.-T. Park, R.A. Rimmer, D. Savransky JLab, Newport News, Virginia, USA D. Holmes, K.S. Smith, W. Xu, A. Zaltsman BNL, Upton, New York, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 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.
	Poster MOPMB078 [1.489 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB078
About •	Received ※ 12 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 19 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB086	Development of Non-Destructive Beam Envelope Measurements in SRILAC with Low Beta Heavy Ion Beams Using BPMs	cavity, quadrupole, operation, heavy-ion	319
	T. Nishi, O. Kamigaito, N. Sakamoto, T. Watanabe, K. Yamada RIKEN Nishina Center, Wako, Japan T. Adachi RIKEN, Saitama, Japan
	The RIKEN SRILAC* has been providing heavy ion beams of a few puA for the synthesis of new superheavy elements since June 2020, utilizing 10 superconducting quarter-wavelength resonators (SC-QWRs). Although the beam supply has been stable, it is crucial to measure and control the beam dynamics in the SRILAC to increase the beam intensity up to 10 puA. However, destructive monitors cannot be used to avoid the generation of dust particles and outgassing. Beam has been precisely tuned by monitoring the beam center using Beam Energy Position Monitors (BEPMs) and the reactions of vacuum monitors. In our study, we are developing a method for estimating the beam envelope by combining the quadrupole moments from BEPMs, which consist of four cosine-shape electrodes, with calculations of the transfer matrix. While this method has been applied to electron and proton beams, it has not been practically demonstrated for heavy ion beams in beta – 0.1 regions. By combining BEPM simulations, we are making the progress towards the reproduction of experimental results, overcoming specific issues associated with low beta. We will report on the current status of our developments. K. Yamada et al., in Proc. SRF’21, paper MOOFAV01(2021). T. Watanabe et al., in Proc. IBIC’20, paper FRAO04 (2020). * R. H. Miller et al., in Proc. HEAC’83, pp. 603–605 (1983).
	Poster MOPMB086 [10.338 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB086
About •	Received ※ 30 June 2023 — Revised ※ 01 July 2023 — Accepted ※ 19 August 2023 — Issue date ※ 22 August 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTB026	Measurements of High Values of Dielectric Permittivity Using Transmission Lines	GUI, resonance, higher-order-mode, cavity	447
	V.D. Shemelin, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: DOE Usage of lossy materials is necessary for absorption of higher order modes excited in the RF cavities. Presently, measurements of lossy materials with usage of transmission lines give errors rapidly increasing with increase of the dielectric permittivity. A method is presented for measurements of high values of dielectric permittivity epsilon in a waveguide at high frequencies with lower errors. This method supplements the method of measurements evolved for low values of epsilon and is close to resonant methods, when a sample is placed into a cavity and the measurement is done at one only frequency. The new approach with use of Microwave Studio simulations makes possible to measure this value in several frequency points at one measurement.
	Poster TUPTB026 [0.872 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB026
About •	Received ※ 20 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 02 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTB031	Operational Consideration in the LIPAc SRF with Potential Solenoid Failure Modes	solenoid, SRF, operation, cryomodule	467
	T. Ebisawa, K. Hasegawa, A. Kasugai, K. Kondo, K. Masuda QST Rokkasho, Aomori, Japan Y. Carin, H. Dzitko, D. Gex, G. Phillips F4E, Germany J.K. Chambrillon Fusion for Energy, Garching, Germany N. Chauvin CEA-DRF-IRFU, France E. Kako, H. Sakai KEK, Ibaraki, Japan
	The commissioning of LIPAc (Linear IFMIF Prototype Accelerator) is ongoing at Rokkasho institute of QST for the engineering validation of the accelerator system up to 9 MeV/125 mA. Several SRF cryomodules will be required for IFMIF to accelerate deuterons from 5 MeV to 40 MeV. The prototype of the first of these cryomodules has been manufactured and will be installed and tested on the LIPAc. It holds the eight HWRs (Half Wave Resonator) and RF couplers to accelerate the beam and the eight superconducting solenoids to focus it. During the solenoid HPR process, carried out after fixing welding issues on the solenoid beam line bellows, some concerns appeared about the integrity of two solenoids. The examination with CT scanning of the solenoids revealed that one screw and a few pins had leaved their socket. Although it should be no critical problem, we tried the beam simulation with PIC code TraceWin to determine the location of solenoids whose impact will be minimized to manage in case of failure of solenoid as mitigation action. This paper presents the recommended locations of the suspicious solenoids in the cryomodule and resultant beam conditions through the beam dynamics study.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB031
About •	Received ※ 28 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 07 July 2023 — Issue date ※ 16 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTB033	On the Way to a 10 MeV, Conduction-Cooled, Compact SRF Accelerator	cavity, SRF, electron, cryogenics	471
	H. Vennekate, G. Cheng, G. Ciovati, J. Guo, K.A. Harding, J. Henry, U. Pudasaini, R.A. Rimmer JLab, Newport News, VA, USA A. Castilla JLAB, Newport News, USA F.E. Hannon Phase Space Tech, Bjärred, Sweden D.A. Packard GA, San Diego, California, USA J. Rathke TechSource, Los Alamos, New Mexico, USA T. Schultheiss TJS Technologies, Commack, New York, USA
	Funding: The presentation has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. 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.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB033
About •	Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTB038	Novel Approaches in Characterization and Modelling of Fabrication Processes for SRF Components	cavity, SRF, FEM, experiment	490
	J.S. Swieszek, A. Gallifa Terricabras, M. Garlasché, D. Smakulska CERN, Meyrin, Switzerland J.S. Swieszek Kraftanlagen Nukleartechnik GmbH, Heidelberg, Germany
	In the past years, Finite Element Methods have been increasingly applied at CERN, with the aim of modelling fabrication processes for SRF components. Currently, many large deformation processes such as deep drawing, forging, hydroforming, and spinning, are being simulat-ed. Taking the initial trials out of the workshop via simu-lation has proven very efficient for steering fabrication strategy, avoiding unnecessary trials, and helping to re-duce time and costs. This contribution will present a novel approach for studying fabrication process feasibil-ity and failure prediction using numerical tools, based on the Forming Limit Diagram method, developed for OFE copper sheets. This contribution will show the applica-tion of the mentioned method on the study of tubular hydroforming, as an alternative way to produce seamless elliptical RF cavities. Analysis of past hydroforming trials is also discussed, together with the comparison of different fabrication strategies.
	Poster TUPTB038 [1.674 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB038
About •	Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 17 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTB039	Simulation of High Pressure Rinse in Superconducting Radio Frequency Cavities	cavity, SRF, radio-frequency, site	496
	B.E. Gower, K. Elliott, E.S. Metzgar, T. Xu FRIB, East Lansing, Michigan, USA
	Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics. Resources of the Facility for Rare Isotope Beams, a DOE Office of Science User Facility, under Award Number DE-SC0000661. The finish of radio frequency (RF) surfaces inside superconducting RF (SRF) cavities is of utmost importance as it dictates ultimate cavity performance. After the cavity surfaces have undergone chemical etching, polishing, and hydrogen degassing, the final step in surface preparation involves cleaning using a high pressure rinse (HPR) with ultra-high purity water (UPW) to remove any residue from the previous chemical processes. The complex surface geometry of cavities poses difficulties in achieving effective and thorough HPR cleaning. This study introduces a versatile simulation tool created in MATLAB, which has the potential to be applied to various SRF cavities. The detail of the algorithm used and nozzle and motion setup will be described using an FRIB 0.53 half wave resonator (HWR) cavity as an example.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB039
About •	Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 07 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTB061	Status of the ESS Medium Beta Cavities at INFN LASA	cavity, cryomodule, linac, SRF	559
	D. Sertore, M. Bertucci, M. Bonezzi, A. Bosotti, D. Cardelli, A. D’Ambros, E. Del Core, F. Fiorina, A.T. Grimaldi, L. Monaco, C. Pagani, R. Paparella, G.M. Zaggia INFN/LASA, Segrate (MI), Italy
	The INFN LASA’s contribution to the ESS Medium Beta Superconducting Linac consists of 36 cavities that raise the proton beam energy from 216 MeV to 571 MeV. Out of the 36 cavities, 28 have been successfully qualified and delivered for assembly into a cryomodule at CEA Saclay. The remaining cavities have been reprocessed in order to bring them up to ESS specifications. To mitigate further delays in the delivery of the cavities, four new ones are currently under construction. We are reporting on the current status of both the recovery actions we have developed so far and the performance of the newly produced resonators.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB061
About •	Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 14 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTB067	Fabrication and Surface Treatment of Superconducting Rf Single Spoke Cavities for the Myrrha Project	cavity, niobium, MMI, linac	578
	M. Moretti, Y.N. Hoerstensmeyer, A. Navitski RI Research Instruments GmbH, Bergisch Gladbach, Germany F. Marhauser SCK•CEN, Mol, Belgium
	The MYRRHA project, based at SCK•CEN (Belgium), aims at coupling a 600 MeV proton accelerator to a subcritical fission core with a maximal output of 100 MWth. The first phase of the project, MINERVA, includes the design, construction, and commissioning of a 100 MeV superconducting RF linac in order to demonstrate the machine requirements in terms of reliability and fault tolerance. The MINERVA linac comprises several cryomodules, each containing two Single Spoke 352.2 MHz cavities made out of high RRR niobium and operating at 2K. The fabrication and surface treatment of the Single Spoke RF Cavities is currently ongoing and completely carried out by RI Research Instruments GmbH (Germany); the first pre-series cavities were completed and delivered for cold testing. Main highlights of the fabrication include the deep-drawing of complex shapes, such as central spokes and outer caps of the cavity, which was successfully accomplished. As for the surface treatment, RI has commissioned, tested, and effectively started utilizing a new rotational buffered chemical polishing facility; this is required to polish the cavity inner surface, while ensuring an almost uniform material removal.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB067
About •	Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 09 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEIXA03	Optimizing the Manufacture of High-Purity Niobium SRF Cavities Using the Forming Limit Diagram: A Case Study of the HL-LHC Crab Cavities RFD Pole	cavity, niobium, SRF, luminosity	627
	A. Gallifa Terricabras, I. Aviles Santillana, S. Barrière, M. Garlasché, L. Prever-Loiri, J.S. Swieszek CERN, Meyrin, Switzerland E. Cano-Pleite UC3M, Leganes, Spain M. Narduzzi Fermilab, Batavia, Illinois, USA S. Pfeiffer European Organization for Nuclear Research (CERN), Geneva, Switzerland
	Funding: CERN HL-LHC The Crab Cavities are key components of the High Luminosity Large Hadron Collider (HL-LHC) project at CERN, which aims to increase the integrated luminosity of the LHC, the world’s largest particle accelerator, by a factor of ten. This paper explores the application of the Forming Limit Diagram (FLD) to enhance the manufacturing process of complex-shape Nb-based cavities, with a focus on the formability challenges experienced with the pole of the Radio Frequency Dipole (RFD) Crab Cavities. The study includes the material characterization of ultra-high-purity niobium (Nb RRR300) sheets, namely mechanical tests and microstructural analysis; it also contains large-deformation Finite Element simulations of the pole deep drawing process, and the translation of the resulting strains in a FLD diagram, together with several suggestions on how to improve the manufacturing process of such deep drawn parts. The results of this study can provide valuable insights into improving the design and fabrication of complex-shaped superconducting radio-frequency cavities made by large-deformation metal-sheet forming processes.
	Slides WEIXA03 [15.991 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIXA03
About •	Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 27 June 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWB048	Geometry Optimization for a Quadrupole Resonator at Jefferson Lab	quadrupole, SRF, cavity, ECR	670
	S. Bira, M. Ge, A-M. Valente-Feliciano JLab, Newport News, Virginia, USA L. Vega Cid, W. Venturini Delsolaro CERN, Meyrin, Switzerland
	Funding: This manuscript is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-6OR23177 with Jefferson Science Associates The quadrupole resonator (QPR) is a sample characterization tool to measure the RF properties of superconducting materials using the calorimetry method at different temperatures, magnetic fields, and frequencies. Such resonators are currently operating at CERN and HZB but suffer from Lorentz force detuning and modes overlapping, resulting in higher uncertainties in surface resistance measurement. Using the two CERN’s QPR model iterations, the geometry was optimized via electromagnetic and mechanical simulations to eliminate these issues. The new QPR version was modeled for an increasing range of magnetic fields. The magnetic field is concentrated at the center of the sample to reduce the uncertainty in surface resistance measurements significantly. This paper will discuss the QPR geometry optimization for the new version of QPR, which is now progressing towards fabrication.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB048
About •	Received ※ 19 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 21 August 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWB049	Multipacting in C75 Cavities	cavity, electron, SRF, multipactoring	674
	G. Ciovati, P. Dhakal, R.A. Rimmer, H. Wang, S. Wang JLab, Newport News, Virginia, USA
	Funding: This work was supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Cavities for the C75 cryomodule refurbishment program are currently being built, processed, tested and installed in the CEBAF accelerator at Jefferson Lab. They consist of 5-cell, 1497 MHz cavities with waveguide-type power coupler and for higher-order modes. Most of the cavities rf tests in a vertical cryostat at 2.07 K were limited by strong multipacting at accelerating gradients in the range 18 - 23 MV/m. A softer multipacting barrier was sometimes found at 13 - 15 MV/m. An unusual feature of the multipacting was that the barrier often shifted to a lower gradient ~17 MV/m, after multiple quenches at ~20 MV/m. This phenomenon was reproduced in a single-cell cavity of the same shape. The cavity was tested after different amounts of mechanical tuning and residual magnetic field, with no significant impact to the multipacting behavior. This contribution summarizes the experimental results from cavity rf tests, some of which were complemented by additional diagnostic instrumentation. Results from 2D and 3D simulations are also presented, indicating favorable conditions for multipacting at the equator in the range 20 - 29 MV/m.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB049
About •	Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 01 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWB053	Simulation of the Dynamics of Gas Mixtures during Plasma Processing in the C75 Cavity	cavity, plasma, electron, SRF	696
	N.K. Raut, P. Dhakal, T.D. Ganey, T. Powers JLab, Newport News, Virginia, USA
	Funding: The work is supported by SC Nuclear Physics Program through DOE SC Lab funding announcement DE-FOA-0002670 & is authored by JSA, LLC under U.S. DOE Contract No. DE-AC05- 06OR23177 Plasma processing using a mixture of noble gas and oxygen is a technique that is currently being used to reduce field emission and multipacting in accelerating cavities. Plasma is created inside the cavity when the gas mixture is exposed to an electromagnetic field that is generated by applying RF power through the fundamental power or higher-order mode couplers. Oxygen ions and atomic oxygen are created in the plasma which breaks down the hydrocarbons on the surface of the cavity and the residuals from this process are removed as part of the process gas flow. Removal of hydrocarbons from the surface increases the work function and reduces the secondary emission coefficient. This work describes the initial results of plasma simulation, which provides insight into the ignition process, distribution of different species, and interactions of free oxygen and oxygen ions with the cavity surfaces. The simulations have been done with an Ar/¿2 plasma using COMSOL® multiphysics. These simulations help in understanding the dynamics and control of plasma inside the cavity and the exploration of different gas mixtures.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB053
About •	Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 29 June 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWB063	Final Design of the LB650 Cryomodule for the PIP-II Linear Accelerator	cryomodule, cavity, vacuum, interface	721
	R. Cubizolles, S. Ladegaillerie, A. Moreau CEA-IRFU, Gif-sur-Yvette, France N. Bazin, S. Berry, J. Drant, P. Garin, A. Raut, C. Simon CEA-DRF-IRFU, France S.K. Chandrasekaran, O. Napoly, V. Roger Fermilab, Batavia, Illinois, USA
	The Proton Improvement Plan II (PIP-II) that will be installed at Fermilab is the first U.S. accelerator project that will have significant contributions from international partners. CEA joined the international collaboration in 2018, and its scope covers the supply of the 650 MHz low-beta cryomodule section, with the design of the cryostat (i.e the cryomodule without the cavities, the power couplers and the frequency tuning systems) and the manufacturing of its components, the assembly and tests of the pre-production cryomodule and 9 production modules. An important milestone was reached in April 2023 with the Final Design Review. This paper presents the detailed design of the 650 MHz low-beta cryomodules.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB063
About •	Received ※ 21 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 04 July 2023 — Issue date ※ 20 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWB103	Simulations and First RF Measurements of Coaxial HOM Coupler Prototypes for PERLE SRF Cavities	HOM, cavity, damping, coupling	831
	C. Barbagallo, P. Duchesne, W. Kaabi, G. Olivier, G. Olry, S. Roset, Z.F. Zomer Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France B.S. Barriere, C.S. Clement, R.L.A. Gerard, F. Gerigk, P.M. Maurin CERN, Meyrin, Switzerland J. Henry, S.A. Overstreet, G.-T. Park, R.A. Rimmer, H. Wang JLab, Newport News, Virginia, USA
	Superconducting Radio-Frequency (SRF) linac cryomodules are foreseen for the high-current multi-turn energy recovery linac PERLE (Powerful Energy Recovery Linac for Experiments). Coaxial higher order mode (HOM) couplers are the primary design choice to absorb beam-induced power and avoid beam instabilities. We have used 3D-printed and copper-coated HOM couplers for the prototyping and bench RF measurements on the copper PERLE cavities. We have started a collaboration with JLab and CERN on this effort. This paper presents electromagnetic simulations of the cavity HOM-damping performance on those couplers. Bench RF measurements of the HOMs on an 801.58 MHz 2-cell copper cavity performed at JLab are detailed. The results are compared to eigenmode simulations in CST to confirm the design. RF-thermal simulations are conducted to investigate if the studied HOM couplers undergo quenching.
	Poster WEPWB103 [1.533 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB103
About •	Received ※ 18 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 02 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWB108	Update on Cornell High Pulsed Power Sample Host Cavity	cavity, SRF, coupling, pulsed-power	841
	N.M. Verboncoeur, A.T. Holic, M. Liepe, T.E. Oseroff, R.D. Porter, J. Sears, L. Shpani Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA R.D. Porter SLAC, Menlo Park, California, USA
	The Cornell High Pulsed Power Sample Host Cavity (CHPPSHC) is designed to measure the temperature-dependent superheating fields of future SRF materials and thereby gain insights into the ultimate limits of their performance. Theoretical estimation of the superheating fields of SRF materials is challenging and mostly has been done for temperatures near the critical temperature or in the infinite kappa limit. Experimental data currently available is incomplete, and often impacted by material defects and their resulting thermal heating, preventing finding the fundamental limits of theses materials. The CHPPSHC system allows reaching RF fields in excess of half a Tesla within microseconds on material samples by utilizing high pulsed power, thereby outrunning thermal effects. We are principally interested in the superheating field of Nb₃Sn, a material of interest for the SRF community, and present here the current fabrication and assembly status of the CHPPSHC as well as early results.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB108
About •	Received ※ 27 June 2023 — Revised ※ 20 July 2023 — Accepted ※ 20 August 2023 — Issue date ※ 22 August 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWB109	PI Loop Resonance Control for the Dark Photon Experiment at 2 K using a 2.6 GHz SRF cavity	cavity, photon, experiment, SRF	847
	C. Contreras-Martinez, B. Giaccone, O.S. Melnychuk, A.V. Netepenko, Y.M. Pischalnikov, S. Posen, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Two 2.6 GHz cavities are being used for dark photon search at VTS in FNAL. During testing at 2 K the cavities experience frequency detuning caused by microphonics and slow frequency drifts. The experiment requires that the two cavities have the same frequency within 5 Hz. These two cavities are equipped with frequency tuners consisting of three piezo actuators. The piezo actuators are used for fine-fast frequency tuning. A PI loop utilizing the piezos was used to maintain both cavities at the same frequency, and the results are presented.
	Poster WEPWB109 [1.151 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB109
About •	Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 18 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWB113	Evaluation of Photo-Cathode Port Multipacting in the SRF Photo-Injector Cryomodule for the LCLS-II High-Energy Upgrade	cathode, electron, SRF, experiment	859
	Z.Y. Yin, W. Hartung, S.H. Kim, T. Konomi, T. Xu FRIB, East Lansing, Michigan, USA
	The high-energy upgrade of the Linac Coherent Light Source (LCLS-II-HE) will increase the photon energy and brightness. A low-emittance injector (LEI) was proposed to increase the photon flux for high X-ray energies. FRIB, HZDR, Argonne, and SLAC are developing a 185.7 MHz superconducting radio-frequency photo-injector (SRF-PI) cryomodule for the LEI. The photo-cathode system requirements are challenging, as cathodes must be maintained at the desired temperature, precisely aligned, and operated without multipacting (MP); to avoid field emission, cathode exchange must be particulate-free. A support stalk has been designed to hold the cathode in position under these requirements. A DC bias is used to inhibit MP. We simulated MP for various surface conditions and bias levels. An RF/DC test was developed to evaluate the cathode stalk performance as a subsystem and to identify and correct issues before assembly into the full cryomodule. The RF/DC test makes use of a resonant coaxial line to generate an RF magnetic field similar to that of the cathode-in-SRF-PI-cavity case. High-power test results will be presented and compared to the MP simulations. * Work supported by the Department of Energy Contract DE-AC02-76SF00515
	Poster WEPWB113 [1.410 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB113
About •	Received ※ 20 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 26 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWB118	Study and Improvements of Liquid Tin Diffusion Process to Synthesize Nb₃Sn Cylindrical Targets	target, niobium, experiment, cavity	868
	D. Ford, E. Chyhyrynets, D. Fonnesu, G. Keppel, G. Marconato, C. Pira, A. Salmaso INFN/LNL, Legnaro (PD), Italy
	Funding: This project has received funding from the European Union¿s Horizon 2020 Research and Innovation programme under Grant Agreement No 101004730. Work supported by the INFN CSNV experiment SAMARA. Nb₃Sn thin films on bulk Nb cavities exhibit comparable performance to bulk Nb at lower temperatures, and using Cu as a substrate material can further improve performance and reduce costs. However, coating substrates with curved geometries like elliptical cavities can be challenging due to the brittleness of Nb₃Sn targets produced by a classical sintering technique. This work explores the use of the Liquid Tin Diffusion (LTD) technique to produce sputtering targets for 6 GHz elliptical cavities, which allows for the deposition of thick and uniform coatings on Nb substrate, even for complex geometries. The study includes improvements in the LTD process and the production of a single-use LTD target, as well as the characterization of Nb₃Sn films coated by DC magnetron sputtering using these innovative targets.
	Poster WEPWB118 [5.462 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB118
About •	Received ※ 17 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 01 August 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWB127	Investigation of Coupler Breakdown Thresholds for Plasma Processing of FRIB Quarter-Wave Resonators with Fundamental and Higher-Order Modes	cavity, plasma, electron, HOM	893
	P.R. Tutt, W. Hartung, S.H. Kim, T. Xu FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics and used resources of the Facility for Rare Isotope Beams (FRIB) under Award Number DE-SC0000661. FRIB is developing plasma processing techniques for in-situ recovery of cavity performance in linac cryomodules during long-term user operation. While plasma processing has been shown to be effective for high-frequency (0.8 - 1.5 GHz) elliptical cavities, one of the challenges for FRIB is to avoid plasma breakdown in the fundamental input coupler (FPC), which has relatively weak coupling strength (Q_ext ranging from 2E6 to 1E7). FRIB cavities are not equipped with higher-order-mode (HOM) couplers; however, in preliminary tests, we found that HOMs are suitable for plasma processing of FRIB Quarter-Wave Resonators (QWRs) driven via the FPC. In this study, we investigated plasma breakdown thresholds in the fundamental and the first 2 HOMs for the FRIB β = 0.085 QWRs. Electric field distributions in the FPC region and cavity region were calculated for the room-temperature case using CST Microwave Studio’s frequency domain solver (FDS). Simulation results will be presented, with comparison of breakdown thresholds inferred from the RF modeling to the experimental results.
	Poster WEPWB127 [5.068 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB127
About •	Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 11 August 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

FRIBA02	Instrumentation for High Performance Cavities and Cryomodule Field Emission Analysis	cavity, radiation, electron, neutron	978
	G. Devanz CEA-IRFU, Gif-sur-Yvette, France M. Baudrier, E. Cenni, L. Maurice, O. Piquet CEA-DRF-IRFU, France
	Field emission (FE) is one of the main reasons for the degradation of accelerator cryomodules, as field emitted current tends to become more severe during the beam operation. It is essential to better understand how this phenomenon is generated and evolves from the SRF cavity preparation in the clean room, through their assembly in the cryomodule until their final test and operation. Due to the shielding environment of a cavity in its vertical test stand, or the architecture of a cryomodule, the more faint radiation occurring at the FE onset remains undetected. More precise diagnostic and analysis tools are required to gain more information. We present the developpement of dedicated time-resolved detectors for the FE radiation which aim at improving its coverage in terms of solid angle and lower energy threshold sensitivity. We approach this topic through detailed simulation based on the Geant4 toolkit in order to analyse the interaction of FE radiation with the cavity environement and optimize the detectors with respect to their application in cryomodule or vertical test stands. We illustrate by analysing recent cryomodule experimental test data.
	Slides FRIBA02 [9.606 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-FRIBA02
About •	Received ※ 27 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 05 July 2023 — Issue date ※ 09 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOPMB019

Numerical Calculations of Superheating Field in Superconductors with Nanostructured Surfaces

cavity, radio-frequency, SRF, superconductivity

114

M.R.P. Walive Pathiranage
VMI, Lexington, USA
A.V. Gurevich
ODU, Norfolk, Virginia, USA

Funding: This work was supported by DOE under Grant DE-SC 100387-020 and by Virginia Military Institute (VMI) under Jackson-Hope Grant for faculty travel and for New Directions in Teaching and Research Grants.
We report calculations of a dc superheating field Hs in superconductors with nanostructured surfaces. Particularly, we performed numerical simulations of the Ginzburg-Landau (GL) equations for a superconductor with an inhomogeneous profile of impurity concentration, a thin superconducting layer on top of another superconductor, and S-I-S multilayers. The superheating field was calculated taking into account the instability of the Meissner state at a finite wavelength along the surface depending on the value of the GL parameter. Simulations were done for the materials parameters of Nb and Nb₃Sn at different values of the GL parameter and the mean free paths. We show that the impurity concentration profile at the surface and thicknesses of superconducting layers in S-I-S structures can be optimized to reach the maximum Hs, which exceeds the bulk superheating fields of both Nb and Nb₃Sn. For example, a S-I-S structure with 90 nm thick Nb₃Sn layer on Nb can boost the superheating field up to ~ 500 mT, while protecting the SRF cavity from dendritic thermomagnetic avalanches caused by local penetration of vortices.

Poster MOPMB019 [1.214 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB019

About •

Received ※ 17 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 16 July 2023

Cite •

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

MOPMB023

Magnetic Flux Expulsion in TRIUMF’s Multi-Mode Coaxial Cavities

cavity, SRF, experiment, controls

135

R.R. Gregory, T. Junginger, M.W. McMullin
UVIC, Victoria, Canada
T. Junginger, P. Kolb, R.E. Laxdal, M.W. McMullin, Z.Y. Yao
TRIUMF, Vancouver, Canada

The external magnetic flux sensitivity of SRF cavities is an important characteristic of SRF accelerator design. Previous studies have shown that n-doped elliptical cavities are very sensitive to external fields, resulting in stringent requirements for residual field and cavity cool-down speed. Few such studies have been done on HWRs and QWRs. The impact of applied field direction and cool-down speed of flux expulsion for these cavities is poorly understood. This study explores the effect of these cool-down characteristics on TRIUMF¿s QWR using COMSOL ® simulations and experimental results. This study seeks to maximize the flux expulsion that occurs when a cavity is cooled down through its superconducting temperature. Flux expulsion is affected by the cool-down speed, temperature gradient, and orientation of the cavity relative to an applied magnetic field. It was found that for a vertically applied magnetic field the cool-down speed and temperature gradient did not have a significant effect on flux expulsion. Contrarily, a horizontal magnetic field can be nearly completely expelled by a fast, high temperature gradient cool-down.

Poster MOPMB023 [2.191 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB023

About •

Received ※ 17 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 30 July 2023

Cite •

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

MOPMB024

Flux Expulsion Studies of Niobium Material of 650 MHz Cavities for PIP-II

cavity, niobium, factory, radio-frequency

141

K.E. McGee
FRIB, East Lansing, Michigan, USA
F. Furuta, M. Martinello, O.S. Melnychuk, A.V. Netepenko, G. Wu, Y. Xie
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Two different vendors supplied the niobium sheet material for PIP-II 5-cell 650 MHz cavities, which was characterized by multiple different ASTM sizes. Cavities subsequently fabricated from these sheets were heat-treated at various temperatures, then the cavities’ flux-expulsion performance was measured. Where the initial measurements of vendor O materials showed that nearly all flux remained trapped despite a high thermal gradient, 900C heat treatment subsequently improved the flux expulsion to an acceptable rate. Understanding and characterizing vendor O materials in this way is key for upcoming and future projects planning to employ niobium sheet from this supplier.

Poster MOPMB024 [4.064 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB024

About •

Received ※ 26 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 21 August 2023

Cite •

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

MOPMB049

Plasma Processing: Ignition Testing and Simulation Models for a 172 MHz HWR Cavity

plasma, cavity, vacuum, SRF

219

M.E. McIntyre, B.R. Blomberg, M.P. Kelly, J.T. McLain, K.M. Villafania, G.P. Zinkann
ANL, Lemont, Illinois, USA
Z. Wei
GIT, Atlanta, Georgia, USA

Maintenance and cleaning of superconducting RF cavities is labor intensive task that involves disassembling the cryostat holding the resonators and removing them to be cleaned. At the Argonne Tandem Linac Accelerating System (ATLAS) at Argonne National Laboratory, a project is underway to research cleaning the cavities in-situ by plasma processing. Previous plasma processing research by SNS, MSU, FNAL, and IJCLab has been successful in improving field emissions post processing. It is advantageous to pursue research in this method, allowing for possible use on modern ATLAS cryomodules, A-tank and G-tank quarter-wave resonators. The results presented show initial plasma ignition testing and plasma simulations for the coupled E and B fields, both done on a 172 MHz HWR cavity previously designed as early R&D for FRIB. Future plans are also included, laying out next steps to test plasma processing on the same HWR cavity and eventually a QWR.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB049

About •

Received ※ 05 July 2023 — Revised ※ 25 July 2023 — Accepted ※ 24 September 2023 — Issue date ※ 24 September 2023

Cite •

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

MOPMB065

Design Status of BCC Cryomodule for LCLS-II HE

cryomodule, cavity, solenoid, cryogenics

263

C.S. Narug, T.T. Arkan, S. Cheban, M. Chen, B.D. Hartsell, J.A. Kaluzny, V.S. Kashikhin, Y.M. Orlov
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
A Buncher or Capture Cavity (BCC) Cryomodule is currently in development at Fermilab for use in a second injector for LCLS-II-HE. The BCC Cryomodule is designed to contain one 1.3 GHz cavity and one solenoid magnet as part of a 100MeV low emittance injector. The design considerations for the Cryomodule are similar to the LCLS-II cryomodule with additional requirements to account for additional vacuum loading at the end of this vessel due to the termination of the insulating vacuum. To accomplish this design, the cryomodule is being developed using the experience gained during the development of the LCLS-II cryomodule. The design, analysis, and status of the Cryomodule will be discussed.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB065

About •

Received ※ 18 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 13 July 2023

Cite •

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

MOPMB078

Design and Prototyping of the Electron Ion Collider Electron Storage Ring SRF Cavity

cavity, HOM, operation, electron

293

J. Guo, E.F. Daly, E. Drachuk, R.R. Fernandes, J. Henry, J. Matalevich, G.-T. Park, R.A. Rimmer, D. Savransky
JLab, Newport News, Virginia, USA
D. Holmes, K.S. Smith, W. Xu, A. Zaltsman
BNL, Upton, New York, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177
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.

Poster MOPMB078 [1.489 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB078

About •

Received ※ 12 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 19 July 2023

Cite •

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

MOPMB086

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

cavity, quadrupole, operation, heavy-ion

319

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

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

Poster MOPMB086 [10.338 MB]

DOI •

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

About •

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

Cite •

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

TUPTB026

Measurements of High Values of Dielectric Permittivity Using Transmission Lines

GUI, resonance, higher-order-mode, cavity

447

V.D. Shemelin, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: DOE
Usage of lossy materials is necessary for absorption of higher order modes excited in the RF cavities. Presently, measurements of lossy materials with usage of transmission lines give errors rapidly increasing with increase of the dielectric permittivity. A method is presented for measurements of high values of dielectric permittivity epsilon in a waveguide at high frequencies with lower errors. This method supplements the method of measurements evolved for low values of epsilon and is close to resonant methods, when a sample is placed into a cavity and the measurement is done at one only frequency. The new approach with use of Microwave Studio simulations makes possible to measure this value in several frequency points at one measurement.

Poster TUPTB026 [0.872 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB026

About •

Received ※ 20 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 02 July 2023

Cite •

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

TUPTB031

Operational Consideration in the LIPAc SRF with Potential Solenoid Failure Modes

solenoid, SRF, operation, cryomodule

467

T. Ebisawa, K. Hasegawa, A. Kasugai, K. Kondo, K. Masuda
QST Rokkasho, Aomori, Japan
Y. Carin, H. Dzitko, D. Gex, G. Phillips
F4E, Germany
J.K. Chambrillon
Fusion for Energy, Garching, Germany
N. Chauvin
CEA-DRF-IRFU, France
E. Kako, H. Sakai
KEK, Ibaraki, Japan

The commissioning of LIPAc (Linear IFMIF Prototype Accelerator) is ongoing at Rokkasho institute of QST for the engineering validation of the accelerator system up to 9 MeV/125 mA. Several SRF cryomodules will be required for IFMIF to accelerate deuterons from 5 MeV to 40 MeV. The prototype of the first of these cryomodules has been manufactured and will be installed and tested on the LIPAc. It holds the eight HWRs (Half Wave Resonator) and RF couplers to accelerate the beam and the eight superconducting solenoids to focus it. During the solenoid HPR process, carried out after fixing welding issues on the solenoid beam line bellows, some concerns appeared about the integrity of two solenoids. The examination with CT scanning of the solenoids revealed that one screw and a few pins had leaved their socket. Although it should be no critical problem, we tried the beam simulation with PIC code TraceWin to determine the location of solenoids whose impact will be minimized to manage in case of failure of solenoid as mitigation action. This paper presents the recommended locations of the suspicious solenoids in the cryomodule and resultant beam conditions through the beam dynamics study.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB031

About •

Received ※ 28 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 07 July 2023 — Issue date ※ 16 July 2023

Cite •

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

TUPTB033

On the Way to a 10 MeV, Conduction-Cooled, Compact SRF Accelerator

cavity, SRF, electron, cryogenics

471

H. Vennekate, G. Cheng, G. Ciovati, J. Guo, K.A. Harding, J. Henry, U. Pudasaini, R.A. Rimmer
JLab, Newport News, VA, USA
A. Castilla
JLAB, Newport News, USA
F.E. Hannon
Phase Space Tech, Bjärred, Sweden
D.A. Packard
GA, San Diego, California, USA
J. Rathke
TechSource, Los Alamos, New Mexico, USA
T. Schultheiss
TJS Technologies, Commack, New York, USA

Funding: The presentation has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
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.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB033

About •

Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023

Cite •

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

TUPTB038

Novel Approaches in Characterization and Modelling of Fabrication Processes for SRF Components

cavity, SRF, FEM, experiment

490

J.S. Swieszek, A. Gallifa Terricabras, M. Garlasché, D. Smakulska
CERN, Meyrin, Switzerland
J.S. Swieszek
Kraftanlagen Nukleartechnik GmbH, Heidelberg, Germany

In the past years, Finite Element Methods have been increasingly applied at CERN, with the aim of modelling fabrication processes for SRF components. Currently, many large deformation processes such as deep drawing, forging, hydroforming, and spinning, are being simulat-ed. Taking the initial trials out of the workshop via simu-lation has proven very efficient for steering fabrication strategy, avoiding unnecessary trials, and helping to re-duce time and costs. This contribution will present a novel approach for studying fabrication process feasibil-ity and failure prediction using numerical tools, based on the Forming Limit Diagram method, developed for OFE copper sheets. This contribution will show the applica-tion of the mentioned method on the study of tubular hydroforming, as an alternative way to produce seamless elliptical RF cavities. Analysis of past hydroforming trials is also discussed, together with the comparison of different fabrication strategies.

Poster TUPTB038 [1.674 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB038

About •

Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 17 July 2023

Cite •

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

TUPTB039

Simulation of High Pressure Rinse in Superconducting Radio Frequency Cavities

cavity, SRF, radio-frequency, site

496

B.E. Gower, K. Elliott, E.S. Metzgar, T. Xu
FRIB, East Lansing, Michigan, USA

Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics. Resources of the Facility for Rare Isotope Beams, a DOE Office of Science User Facility, under Award Number DE-SC0000661.
The finish of radio frequency (RF) surfaces inside superconducting RF (SRF) cavities is of utmost importance as it dictates ultimate cavity performance. After the cavity surfaces have undergone chemical etching, polishing, and hydrogen degassing, the final step in surface preparation involves cleaning using a high pressure rinse (HPR) with ultra-high purity water (UPW) to remove any residue from the previous chemical processes. The complex surface geometry of cavities poses difficulties in achieving effective and thorough HPR cleaning. This study introduces a versatile simulation tool created in MATLAB, which has the potential to be applied to various SRF cavities. The detail of the algorithm used and nozzle and motion setup will be described using an FRIB 0.53 half wave resonator (HWR) cavity as an example.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB039

About •

Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 07 July 2023

Cite •

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

TUPTB061

Status of the ESS Medium Beta Cavities at INFN LASA

cavity, cryomodule, linac, SRF

559

D. Sertore, M. Bertucci, M. Bonezzi, A. Bosotti, D. Cardelli, A. D’Ambros, E. Del Core, F. Fiorina, A.T. Grimaldi, L. Monaco, C. Pagani, R. Paparella, G.M. Zaggia
INFN/LASA, Segrate (MI), Italy

The INFN LASA’s contribution to the ESS Medium Beta Superconducting Linac consists of 36 cavities that raise the proton beam energy from 216 MeV to 571 MeV. Out of the 36 cavities, 28 have been successfully qualified and delivered for assembly into a cryomodule at CEA Saclay. The remaining cavities have been reprocessed in order to bring them up to ESS specifications. To mitigate further delays in the delivery of the cavities, four new ones are currently under construction. We are reporting on the current status of both the recovery actions we have developed so far and the performance of the newly produced resonators.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB061

About •

Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 14 July 2023

Cite •

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

TUPTB067

Fabrication and Surface Treatment of Superconducting Rf Single Spoke Cavities for the Myrrha Project

cavity, niobium, MMI, linac

578

M. Moretti, Y.N. Hoerstensmeyer, A. Navitski
RI Research Instruments GmbH, Bergisch Gladbach, Germany
F. Marhauser
SCK•CEN, Mol, Belgium

The MYRRHA project, based at SCK•CEN (Belgium), aims at coupling a 600 MeV proton accelerator to a subcritical fission core with a maximal output of 100 MWth. The first phase of the project, MINERVA, includes the design, construction, and commissioning of a 100 MeV superconducting RF linac in order to demonstrate the machine requirements in terms of reliability and fault tolerance. The MINERVA linac comprises several cryomodules, each containing two Single Spoke 352.2 MHz cavities made out of high RRR niobium and operating at 2K. The fabrication and surface treatment of the Single Spoke RF Cavities is currently ongoing and completely carried out by RI Research Instruments GmbH (Germany); the first pre-series cavities were completed and delivered for cold testing. Main highlights of the fabrication include the deep-drawing of complex shapes, such as central spokes and outer caps of the cavity, which was successfully accomplished. As for the surface treatment, RI has commissioned, tested, and effectively started utilizing a new rotational buffered chemical polishing facility; this is required to polish the cavity inner surface, while ensuring an almost uniform material removal.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB067

About •

Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 09 July 2023

Cite •

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

WEIXA03

Optimizing the Manufacture of High-Purity Niobium SRF Cavities Using the Forming Limit Diagram: A Case Study of the HL-LHC Crab Cavities RFD Pole

cavity, niobium, SRF, luminosity

627

A. Gallifa Terricabras, I. Aviles Santillana, S. Barrière, M. Garlasché, L. Prever-Loiri, J.S. Swieszek
CERN, Meyrin, Switzerland
E. Cano-Pleite
UC3M, Leganes, Spain
M. Narduzzi
Fermilab, Batavia, Illinois, USA
S. Pfeiffer
European Organization for Nuclear Research (CERN), Geneva, Switzerland

Funding: CERN HL-LHC
The Crab Cavities are key components of the High Luminosity Large Hadron Collider (HL-LHC) project at CERN, which aims to increase the integrated luminosity of the LHC, the world’s largest particle accelerator, by a factor of ten. This paper explores the application of the Forming Limit Diagram (FLD) to enhance the manufacturing process of complex-shape Nb-based cavities, with a focus on the formability challenges experienced with the pole of the Radio Frequency Dipole (RFD) Crab Cavities. The study includes the material characterization of ultra-high-purity niobium (Nb RRR300) sheets, namely mechanical tests and microstructural analysis; it also contains large-deformation Finite Element simulations of the pole deep drawing process, and the translation of the resulting strains in a FLD diagram, together with several suggestions on how to improve the manufacturing process of such deep drawn parts. The results of this study can provide valuable insights into improving the design and fabrication of complex-shaped superconducting radio-frequency cavities made by large-deformation metal-sheet forming processes.

Slides WEIXA03 [15.991 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIXA03

About •

Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 27 June 2023

Cite •

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

WEPWB048

Geometry Optimization for a Quadrupole Resonator at Jefferson Lab

quadrupole, SRF, cavity, ECR

670

S. Bira, M. Ge, A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA
L. Vega Cid, W. Venturini Delsolaro
CERN, Meyrin, Switzerland

Funding: This manuscript is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-6OR23177 with Jefferson Science Associates
The quadrupole resonator (QPR) is a sample characterization tool to measure the RF properties of superconducting materials using the calorimetry method at different temperatures, magnetic fields, and frequencies. Such resonators are currently operating at CERN and HZB but suffer from Lorentz force detuning and modes overlapping, resulting in higher uncertainties in surface resistance measurement. Using the two CERN’s QPR model iterations, the geometry was optimized via electromagnetic and mechanical simulations to eliminate these issues. The new QPR version was modeled for an increasing range of magnetic fields. The magnetic field is concentrated at the center of the sample to reduce the uncertainty in surface resistance measurements significantly. This paper will discuss the QPR geometry optimization for the new version of QPR, which is now progressing towards fabrication.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB048

About •

Received ※ 19 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 21 August 2023

Cite •

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

WEPWB049

Multipacting in C75 Cavities

cavity, electron, SRF, multipactoring

674

G. Ciovati, P. Dhakal, R.A. Rimmer, H. Wang, S. Wang
JLab, Newport News, Virginia, USA

Funding: This work was supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Cavities for the C75 cryomodule refurbishment program are currently being built, processed, tested and installed in the CEBAF accelerator at Jefferson Lab. They consist of 5-cell, 1497 MHz cavities with waveguide-type power coupler and for higher-order modes. Most of the cavities rf tests in a vertical cryostat at 2.07 K were limited by strong multipacting at accelerating gradients in the range 18 - 23 MV/m. A softer multipacting barrier was sometimes found at 13 - 15 MV/m. An unusual feature of the multipacting was that the barrier often shifted to a lower gradient ~17 MV/m, after multiple quenches at ~20 MV/m. This phenomenon was reproduced in a single-cell cavity of the same shape. The cavity was tested after different amounts of mechanical tuning and residual magnetic field, with no significant impact to the multipacting behavior. This contribution summarizes the experimental results from cavity rf tests, some of which were complemented by additional diagnostic instrumentation. Results from 2D and 3D simulations are also presented, indicating favorable conditions for multipacting at the equator in the range 20 - 29 MV/m.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB049

About •

Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 01 July 2023

Cite •

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

WEPWB053

Simulation of the Dynamics of Gas Mixtures during Plasma Processing in the C75 Cavity

cavity, plasma, electron, SRF

696

N.K. Raut, P. Dhakal, T.D. Ganey, T. Powers
JLab, Newport News, Virginia, USA

Funding: The work is supported by SC Nuclear Physics Program through DOE SC Lab funding announcement DE-FOA-0002670 & is authored by JSA, LLC under U.S. DOE Contract No. DE-AC05- 06OR23177
Plasma processing using a mixture of noble gas and oxygen is a technique that is currently being used to reduce field emission and multipacting in accelerating cavities. Plasma is created inside the cavity when the gas mixture is exposed to an electromagnetic field that is generated by applying RF power through the fundamental power or higher-order mode couplers. Oxygen ions and atomic oxygen are created in the plasma which breaks down the hydrocarbons on the surface of the cavity and the residuals from this process are removed as part of the process gas flow. Removal of hydrocarbons from the surface increases the work function and reduces the secondary emission coefficient. This work describes the initial results of plasma simulation, which provides insight into the ignition process, distribution of different species, and interactions of free oxygen and oxygen ions with the cavity surfaces. The simulations have been done with an Ar/¿2 plasma using COMSOL® multiphysics. These simulations help in understanding the dynamics and control of plasma inside the cavity and the exploration of different gas mixtures.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB053

About •

Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 29 June 2023

Cite •

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

WEPWB063

Final Design of the LB650 Cryomodule for the PIP-II Linear Accelerator

cryomodule, cavity, vacuum, interface

721

R. Cubizolles, S. Ladegaillerie, A. Moreau
CEA-IRFU, Gif-sur-Yvette, France
N. Bazin, S. Berry, J. Drant, P. Garin, A. Raut, C. Simon
CEA-DRF-IRFU, France
S.K. Chandrasekaran, O. Napoly, V. Roger
Fermilab, Batavia, Illinois, USA

The Proton Improvement Plan II (PIP-II) that will be installed at Fermilab is the first U.S. accelerator project that will have significant contributions from international partners. CEA joined the international collaboration in 2018, and its scope covers the supply of the 650 MHz low-beta cryomodule section, with the design of the cryostat (i.e the cryomodule without the cavities, the power couplers and the frequency tuning systems) and the manufacturing of its components, the assembly and tests of the pre-production cryomodule and 9 production modules. An important milestone was reached in April 2023 with the Final Design Review. This paper presents the detailed design of the 650 MHz low-beta cryomodules.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB063

About •

Received ※ 21 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 04 July 2023 — Issue date ※ 20 July 2023

Cite •

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

WEPWB103

Simulations and First RF Measurements of Coaxial HOM Coupler Prototypes for PERLE SRF Cavities

HOM, cavity, damping, coupling

831

C. Barbagallo, P. Duchesne, W. Kaabi, G. Olivier, G. Olry, S. Roset, Z.F. Zomer
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
B.S. Barriere, C.S. Clement, R.L.A. Gerard, F. Gerigk, P.M. Maurin
CERN, Meyrin, Switzerland
J. Henry, S.A. Overstreet, G.-T. Park, R.A. Rimmer, H. Wang
JLab, Newport News, Virginia, USA

Superconducting Radio-Frequency (SRF) linac cryomodules are foreseen for the high-current multi-turn energy recovery linac PERLE (Powerful Energy Recovery Linac for Experiments). Coaxial higher order mode (HOM) couplers are the primary design choice to absorb beam-induced power and avoid beam instabilities. We have used 3D-printed and copper-coated HOM couplers for the prototyping and bench RF measurements on the copper PERLE cavities. We have started a collaboration with JLab and CERN on this effort. This paper presents electromagnetic simulations of the cavity HOM-damping performance on those couplers. Bench RF measurements of the HOMs on an 801.58 MHz 2-cell copper cavity performed at JLab are detailed. The results are compared to eigenmode simulations in CST to confirm the design. RF-thermal simulations are conducted to investigate if the studied HOM couplers undergo quenching.

Poster WEPWB103 [1.533 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB103

About •

Received ※ 18 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 02 July 2023

Cite •

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

WEPWB108

Update on Cornell High Pulsed Power Sample Host Cavity

cavity, SRF, coupling, pulsed-power

841

N.M. Verboncoeur, A.T. Holic, M. Liepe, T.E. Oseroff, R.D. Porter, J. Sears, L. Shpani
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
R.D. Porter
SLAC, Menlo Park, California, USA

The Cornell High Pulsed Power Sample Host Cavity (CHPPSHC) is designed to measure the temperature-dependent superheating fields of future SRF materials and thereby gain insights into the ultimate limits of their performance. Theoretical estimation of the superheating fields of SRF materials is challenging and mostly has been done for temperatures near the critical temperature or in the infinite kappa limit. Experimental data currently available is incomplete, and often impacted by material defects and their resulting thermal heating, preventing finding the fundamental limits of theses materials. The CHPPSHC system allows reaching RF fields in excess of half a Tesla within microseconds on material samples by utilizing high pulsed power, thereby outrunning thermal effects. We are principally interested in the superheating field of Nb₃Sn, a material of interest for the SRF community, and present here the current fabrication and assembly status of the CHPPSHC as well as early results.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB108

About •

Received ※ 27 June 2023 — Revised ※ 20 July 2023 — Accepted ※ 20 August 2023 — Issue date ※ 22 August 2023

Cite •

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

WEPWB109

PI Loop Resonance Control for the Dark Photon Experiment at 2 K using a 2.6 GHz SRF cavity

cavity, photon, experiment, SRF

847

C. Contreras-Martinez, B. Giaccone, O.S. Melnychuk, A.V. Netepenko, Y.M. Pischalnikov, S. Posen, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Two 2.6 GHz cavities are being used for dark photon search at VTS in FNAL. During testing at 2 K the cavities experience frequency detuning caused by microphonics and slow frequency drifts. The experiment requires that the two cavities have the same frequency within 5 Hz. These two cavities are equipped with frequency tuners consisting of three piezo actuators. The piezo actuators are used for fine-fast frequency tuning. A PI loop utilizing the piezos was used to maintain both cavities at the same frequency, and the results are presented.

Poster WEPWB109 [1.151 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB109

About •

Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 18 July 2023

Cite •

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

WEPWB113

Evaluation of Photo-Cathode Port Multipacting in the SRF Photo-Injector Cryomodule for the LCLS-II High-Energy Upgrade

cathode, electron, SRF, experiment

859

Z.Y. Yin, W. Hartung, S.H. Kim, T. Konomi, T. Xu
FRIB, East Lansing, Michigan, USA

The high-energy upgrade of the Linac Coherent Light Source (LCLS-II-HE) will increase the photon energy and brightness. A low-emittance injector (LEI) was proposed to increase the photon flux for high X-ray energies. FRIB, HZDR, Argonne, and SLAC are developing a 185.7 MHz superconducting radio-frequency photo-injector (SRF-PI) cryomodule for the LEI. The photo-cathode system requirements are challenging, as cathodes must be maintained at the desired temperature, precisely aligned, and operated without multipacting (MP); to avoid field emission, cathode exchange must be particulate-free. A support stalk has been designed to hold the cathode in position under these requirements. A DC bias is used to inhibit MP. We simulated MP for various surface conditions and bias levels. An RF/DC test was developed to evaluate the cathode stalk performance as a subsystem and to identify and correct issues before assembly into the full cryomodule. The RF/DC test makes use of a resonant coaxial line to generate an RF magnetic field similar to that of the cathode-in-SRF-PI-cavity case. High-power test results will be presented and compared to the MP simulations.
* Work supported by the Department of Energy Contract DE-AC02-76SF00515

Poster WEPWB113 [1.410 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB113

About •

Received ※ 20 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 26 July 2023

Cite •

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

WEPWB118

Study and Improvements of Liquid Tin Diffusion Process to Synthesize Nb₃Sn Cylindrical Targets

target, niobium, experiment, cavity

868

D. Ford, E. Chyhyrynets, D. Fonnesu, G. Keppel, G. Marconato, C. Pira, A. Salmaso
INFN/LNL, Legnaro (PD), Italy

Funding: This project has received funding from the European Union¿s Horizon 2020 Research and Innovation programme under Grant Agreement No 101004730. Work supported by the INFN CSNV experiment SAMARA.
Nb₃Sn thin films on bulk Nb cavities exhibit comparable performance to bulk Nb at lower temperatures, and using Cu as a substrate material can further improve performance and reduce costs. However, coating substrates with curved geometries like elliptical cavities can be challenging due to the brittleness of Nb₃Sn targets produced by a classical sintering technique. This work explores the use of the Liquid Tin Diffusion (LTD) technique to produce sputtering targets for 6 GHz elliptical cavities, which allows for the deposition of thick and uniform coatings on Nb substrate, even for complex geometries. The study includes improvements in the LTD process and the production of a single-use LTD target, as well as the characterization of Nb₃Sn films coated by DC magnetron sputtering using these innovative targets.

Poster WEPWB118 [5.462 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB118

About •

Received ※ 17 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 01 August 2023

Cite •

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

WEPWB127

Investigation of Coupler Breakdown Thresholds for Plasma Processing of FRIB Quarter-Wave Resonators with Fundamental and Higher-Order Modes

cavity, plasma, electron, HOM

893

P.R. Tutt, W. Hartung, S.H. Kim, T. Xu
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics and used resources of the Facility for Rare Isotope Beams (FRIB) under Award Number DE-SC0000661.
FRIB is developing plasma processing techniques for in-situ recovery of cavity performance in linac cryomodules during long-term user operation. While plasma processing has been shown to be effective for high-frequency (0.8 - 1.5 GHz) elliptical cavities, one of the challenges for FRIB is to avoid plasma breakdown in the fundamental input coupler (FPC), which has relatively weak coupling strength (Q_ext ranging from 2E6 to 1E7). FRIB cavities are not equipped with higher-order-mode (HOM) couplers; however, in preliminary tests, we found that HOMs are suitable for plasma processing of FRIB Quarter-Wave Resonators (QWRs) driven via the FPC. In this study, we investigated plasma breakdown thresholds in the fundamental and the first 2 HOMs for the FRIB β = 0.085 QWRs. Electric field distributions in the FPC region and cavity region were calculated for the room-temperature case using CST Microwave Studio’s frequency domain solver (FDS). Simulation results will be presented, with comparison of breakdown thresholds inferred from the RF modeling to the experimental results.

Poster WEPWB127 [5.068 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB127

About •

Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 11 August 2023

Cite •

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

FRIBA02

Instrumentation for High Performance Cavities and Cryomodule Field Emission Analysis

cavity, radiation, electron, neutron

978

G. Devanz
CEA-IRFU, Gif-sur-Yvette, France
M. Baudrier, E. Cenni, L. Maurice, O. Piquet
CEA-DRF-IRFU, France

Field emission (FE) is one of the main reasons for the degradation of accelerator cryomodules, as field emitted current tends to become more severe during the beam operation. It is essential to better understand how this phenomenon is generated and evolves from the SRF cavity preparation in the clean room, through their assembly in the cryomodule until their final test and operation. Due to the shielding environment of a cavity in its vertical test stand, or the architecture of a cryomodule, the more faint radiation occurring at the FE onset remains undetected. More precise diagnostic and analysis tools are required to gain more information. We present the developpement of dedicated time-resolved detectors for the FE radiation which aim at improving its coverage in terms of solid angle and lower energy threshold sensitivity. We approach this topic through detailed simulation based on the Geant4 toolkit in order to analyse the interaction of FE radiation with the cavity environement and optimize the detectors with respect to their application in cryomodule or vertical test stands. We illustrate by analysing recent cryomodule experimental test data.

Slides FRIBA02 [9.606 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-FRIBA02

About •

Received ※ 27 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 05 July 2023 — Issue date ※ 09 July 2023

Cite •

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