Keyword: SRF
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MOIAA05 Commissioning of the Second JLAB C75 Cryomodule & Performance Evaluation of Installed C75 Cavities cavity, cryomodule, plasma, controls 14
 
  • M.D. McCaughan, G. Ciovati, G.K. Davis, M.A. Drury, T. Powers, A.V. Reilly
    JLab, Newport News, Virginia, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
JLAB has long been a hub of SRF technology with the CEBAF accelerator as one of its first large scale adopters. As SRF technology has advanced, the C50 and C100 programs have allowed for the extension of CEBAF’s total energy to 6 GeV and nearly 12 GeV respectively. Along with the increase in energy reach, rates of accelerating gradient degradation have been extracted for these cryomodule designs. A plan to mitigate these losses & maintain robust gradient headroom to deliver the 12 GeV program ¿ the CEBAF Performance Plan¿ established a multi-year effort of cryomodule refurbishments and replacements. Part of this plan included a cost optimization of the C50 program with more modern processing techniques and the replacement of existing cavities with larger grain boundary cavities produced from ingot Niobium (dubbed C75 for 75 MeV gain). Reports have been made on the prototype pair of C75 cavities installed in a C50 cryomodule and the first full C75 cryomodule installed in 2017 and 2021. This paper reports on the results from the qualification of the cavities for the second C75 module in both a vertical cryostat and the commissioning results of the cryomodule in the CEBAF tunnel. 		 
slides icon Slides MOIAA05 [1.810 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOIAA05  
About • Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 02 July 2023
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MOIXA02 PIP-II Project Overview and Status linac, cryomodule, cavity, controls 19
 
  • R.P. Stanek, C. Boffo, S.K. Chandrasekaran, S.J. Dixon, E.R. Harms, L. Kokoska, I. Kourbanis, J.R. Leibfritz, O. Napoly, D. Passarelli, E. Pozdeyev, A.M. Rowe
    Fermilab, Batavia, Illinois, USA
  
  Funding: Prepared by PIP-II Project using resources of the Fermi National Accelerator Laboratory, a U.S. DOE facility, managed by Fermi Research Alliance, LLC, acting under Contract No. DE-AC02-07CH11359.
The Proton Improvement Plan II (PIP-II) project is an essential upgrade to Fermilab’s particle accelerator complex to enable the world’s most intense neutrino beam for LBNF/DUNE and a broad particle physics program for many decades to come. PIP-II will deliver 1.2 MW of proton beam power from the Main Injector, upgradeable to multi-MW capability. The central element of PIP-II is an 800 MeV superconducting radio frequency (SRF) linac, which comprises a room temperature front end followed by an SRF section. The SRF section consists of five different flavors of cavities/cryomodules, including Half Wave Resonators (HWR), Single Spoke and elliptical resonators operating at, or above, state-of-the-art parameters. The first two PIP-II cryomodules, Half Wave Resonator (HWR) and Single Spoke Resonator 1 (SSR1) were installed in the PIP-II Injector Test facility (PIP2IT) and have accelerated beam to above 17 MeV. PIP-II is the first U.S. accelerator project that will be constructed with significant contributions from international partners, including India, Italy, France, United Kingdom and Poland. The project was baselined in April 2022, and the construction phase is underway. 		 
slides icon Slides MOIXA02 [3.353 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOIXA02  
About • Received ※ 07 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 16 July 2023
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MOIXA05 Operating Experience of SRF System at High Beam Current in SuperKEKB cavity, operation, HOM, luminosity 38
 
  • M. Nishiwaki, K. Akai, T. Furuya, S. Mitsunobu, Y. Morita, T. Okada
    KEK, Ibaraki, Japan
  
  SuperKEKB aims for high luminosity on the order of 1035 cm-2s-1 with beam currents of 2.6 A for electron and 3.6 A for positron to search new physics beyond the Standard Model in the B meson regime. In recent operations, we achieved a new record of luminosity of 4.65×1034 cm-2s-1 with 1.1 A for electron and 1.3 A for positron. The SRF system that was designed for KEKB, the predecessor of SuperKEKB, is operating stably with the high beam currents owing to the measures against the large beam powers and the large higher-order-mode (HOM) powers. As a measure against the large beam powers, our SRF cavities have increased a coupling of high-power input couplers during the KEKB operation. As a measure against the large HOM power, newly developed SiC HOM dampers have been installed in the SuperKEKB ring. In addition, we have established the horizontal high-pressure rinse method to recover the cavity performance that has degraded due to vacuum works and accidents in the long-term operation. In this report, we will present our operation experience of SRF system under the high beam currents.  
slides icon Slides MOIXA05 [3.450 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOIXA05  
About • Received ※ 19 June 2023 — Revised ※ 21 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 20 July 2023
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MOPMB001 Development and Testing of Split 6 GHz Cavities With Niobium Coatings cavity, coupling, target, site 51
 
  • N.L. Leicester, G. Burt, H.S. Marks
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • E. Chyhyrynets, C. Pira
    INFN/LNL, Legnaro (PD), Italy
  • J.A. Conlon, O.B. Malyshev, B.S. Sian, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • D.J. Seal
    Lancaster University, Lancaster, United Kingdom
  
  Superconducting thin-films on a copper substrate are used in accelerator RF cavities as an alternative to bulk Nb due to the high thermal conductivity of copper and the lower production costs. Although thin-film coated RF cavities can match, or even exceed the performance of bulk Nb, there are some challenges around the deposition. The RF cavities are often produced as two half-cells with a weld across the centre where the RF surface current is highest, which could reduce cavity performance. To avoid this, a cavity can be produced in 2 longitudinally split halves, with the join parallel to the surface current. As the current doesn’t cross the join a simpler weld can be performed far from the fields, simplifying the manufacturing process, and potentially improving the cavities performance. This additionally allows for different deposition techniques and coating materials to be used, as well as easier post-deposition quality control. This paper discusses the development and testing of 6 GHz cavities that have been designed and coated at the Cockcroft Institute, using low temperature RF techniques to characterise cavities with different substrate preparations and coating techniques.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB001  
About • Received ※ 18 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 04 July 2023
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MOPMB003 Flux Expulsion Lens: Concept and Measurements FEL, cavity, niobium, site 56
 
  • D.A. Turner
    European Organization for Nuclear Research (CERN), Geneva, Switzerland
  • A. Gallifa Terricabras, T. Koettig, A. Macpherson, G.J. Rosaz, N. Stapley
    CERN, Meyrin, Switzerland
  • I. González Díaz-Palacio
    University of Hamburg, Hamburg, Germany
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • M. Wenskat
    DESY, Hamburg, Germany
  
  A magnetic flux expulsion lens (MFEL) has been designed and built at CERN. This device uses closed topology conduction cooling of samples to quantify magnetic flux expulsion of superconductors, and allows for systematic measurements of the cooling dynamics and the magnetic response during the superconducting transition. Measurements for bulk Nb, cold worked Nb, sputtered Nb on Cu, and SIS multilayer structures are given. Preliminary results for both sample characterization of expulsion dynamics, and observation of an enhanced flux expulsion in SIS samples are also reported.  
poster icon Poster MOPMB003 [2.459 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB003  
About • Received ※ 27 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 14 July 2023
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MOPMB006 SIMS Characterization of Nitrogen Doping of LCLS-II-HE Production Cavities cavity, niobium, vacuum, controls 67
 
  • C.E. Reece, M.J. Kelley, E.M. Lechner
    JLab, Newport News, Virginia, USA
  • J.W. Angle
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Office of High Energy Physics grant DE-SC-0014475.
The thermal diffusion of nitrogen into the surface of niobium has been shown to yield superior low-loss SRF performance. An effective solution was identified and promptly employed in the production of cryomodules for LCLS-II. With added experience and R&D, a modified process was chosen for use in the upgrade for LCLS-II-HE. Largely motivated by this circumstance, supporting research has significantly refined the technique for making calibrated secondary ion mass spectrometry (SIMS) measurements of the N concentration depth profiles produced by production processes. Standardized reference samples were included with four HE production cavities in their N-doping furnace runs. We report the calibrated dynamic SIMS depth profiles of N, C, and O for these samples, together with the cryogenic acceptance test performance of the associated cavities. Interpretation and comparison with similar samples acquired in other furnaces highlights the importance of intentional process quality control of furnace conditions. 		 
poster icon Poster MOPMB006 [1.380 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB006  
About • Received ※ 16 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 18 July 2023
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MOPMB008 In-Situ Quality Factor Measurements of SRF Cavities at S-DALINAC cavity, linac, coupling, resonance 70
 
  • R. Grewe, M. Arnold, A. Brauch, M. Dutine, L.E. Jürgensen, N. Pietralla, F. Schließmann, D. Schneider
    TU Darmstadt, Darmstadt, Germany
  
  Funding: Work supported by DFG (GRK 2128) and the State of Hesse within the Research Cluster ELEMENTS (Project ID 500/10.006)
The Superconducting Darmstadt Linear Accelerator (S-DALINAC) is a thrice recirculating electron accelerator wich can be operated in a multi-turn energy recovery mode*. The design parameters for kinetic energy and beam current are up to 130 MeV and up to 20 uA respectively. The injector consists of a six-cell capture cavity and two 20-cell srf cavities. The main linac consists of eight 20-cell cavities. The cavities are operated at a temperature of 2 K with a frequency of 2.9972(1) GHz. Monitoring of the srf cavities is important for the overall performance of the accelerator. A key parameter for the rating of the srf cavity performance is the intrinsic quality factor Q. At the S-DALINAC it is measured for selected cavities during the yearly maintenance procedures. The unique design of the rf input coupler allows for a wide tuning range for the input coupling strength. This makes in-situ quality factor measurements using the decay time measurement method** possible. The contribution illustrates the principal design of the input couplers and the benefits it yields for Q measurements. Recent results including the progression of the quality factors over time will be presented.
*Felix Schliessmann et al., Nat. Phys. 19, 597-602 (2023).
**Tom Powers, Proc. of SRF’05, Cornell University, Ithaca, New York, USA, 2005, p.40. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB008  
About • Received ※ 19 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 04 August 2023
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MOPMB009 Plasma Electrolytic Polishing Technology Progress Development for Nb and Cu Substrates Preparation cavity, cathode, plasma, experiment 75
 
  • E. Chyhyrynets, O. Azzolini, R. Caforio, D. Fonnesu, D. Ford, G. Keppel, C. Pira, A. Salmaso, F. Stivanello
    INFN/LNL, Legnaro (PD), Italy
  • G. Marconato
    Università degli Studi di Padova, Padova, Italy
  
  Funding: Work supported by the INFN CSNV experiment SAMARA. Fundings from the EU’s Horizon 2020 Research and Innovation programme under Grant Agreement N 101004730. PNRR MUR project PE0000023-NQSTI.
Superconducting radio frequency (SRF) cavity performance is highly dependent on surface preparation. Conventionally, electropolishing (EP) is used to achieve a clean surface and low roughness for both Nb and Cu substrates, but it requires harsh and corrosive solutions like concentrated acids. Plasma Electrolytic Polishing (PEP) is a promising alternative that uses only diluted salt solutions and has several advantages over EP. PEP can replace intermediate steps like mechanical or chemical polishing, thanks to its superior removal rate of up to 2-8 um/min of Nb and 3-30 um/min of Cu. It achieves Ra roughness of 100 nm for both substrates and has a higher smoothing effect than EP. PEP is also suitable for normal conducting cavities and other accelerator components, including couplers. We demonstrate the effectiveness of PEP on SRF substrates and analyse substrate defect evaluation. We demonstrate the application of PEP onto SRF substrates and analyse the substrate’s defect evaluation. The ongoing work includes Nb bulk and Nb on Cu QPR treatments and RF tests in collaboration with HZB. 		 
poster icon Poster MOPMB009 [11.877 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB009  
About • Received ※ 17 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 17 July 2023
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MOPMB010 Analysis of Semiconductor Components as Temperature Sensors for Cryogenic Investigation of SRF Materials cavity, controls, cryogenics, experiment 80
 
  • A. Cierpka, S. Keckert, J. Knobloch, F. Kramer, O. Kugeler
    HZB, Berlin, Germany
  
  Temperature mapping systems have been used for many years to detect local heating in an SRF cavity surface or materials sample. They require a large number of temperature sensors. Most often, low-cost Allen-Bradley resistors are used for this purpose. Since they have poor sensitivity and reproducibility above 4 K, sensor alternatives that combine the precision of Cernox sensors with the low-cost of Allen-Bradley resistors would be highly desirable. In this work various semiconductor components that exhibit a temperature dependent electrical response, such as diodes and LEDs were analyzed with respect to sensitivity, reproducibility and response speed in a temperature range between 6.5 K and 22 K. In this range, many diodes and LEDs were found to be more sensitive than Cernox sensors. However, in some components the response time was slow - possibly due to poor thermal contact.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB010  
About • Received ※ 08 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 17 July 2023
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MOPMB011 Deposition and Characterisation of V₃Si films for SRF Applications cavity, site, target, vacuum 84
 
  • C. Benjamin, J.A. Conlon, O.B. Malyshev, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Burt, O.B. Malyshev, D.J. Seal, R. Valizadeh
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • G. Burt, D.J. Seal
    Lancaster University, Lancaster, United Kingdom
  • N.L. Leicester, H.S. Marks
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • L.G.P. Smith
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  
  Funding: This project has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No 101004730.
A15 superconducting materials, like V₃Si and Nb₃Sn, are potential alternatives to Nb for next generation thin film SRF cavities when operated at 4 K. Their relatively high Tc and superconducting properties could allow for higher accelerating gradients and elevated operating temperatures. We present work on the deposition of V₃Si thin films on planar Cu substrates and an open structure 6 GHz cavity, using physical vapour deposition (PVD) and a V₃Si single target. The surface structure, composition and DC superconducting properties of two planar samples were characterised via secondary electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX) and in a magnetic field penetration facility. Furthermore, the first deposition using PVD of a V₃Si film on a 6 GHz split cavity and the RF performance is presented. 		 
poster icon Poster MOPMB011 [7.496 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB011  
About • Received ※ 16 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 19 July 2023
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MOPMB012 Investigation, Using Nb Foils to Characterise the Optimal Dimensions of Samples Measured by the Magnetic Field Penetration Facility cavity, experiment, ECR, niobium 88
 
  • L.G.P. Smith, D.A. Turner
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Burt, O.B. Malyshev, D.A. Turner
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • G. Burt
    Lancaster University, Lancaster, United Kingdom
  • T. Junginger
    TRIUMF, Vancouver, Canada
  • T. Junginger
    UVIC, Victoria, Canada
  • O.B. Malyshev
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  SRF cavities made of bulk Nb are reaching their theoretical limits in the maximum accelerating gradient, Eacc, where Eacc is limited by the maximum magnetic field, Bmax, that can be applied on the surface of the accelerating cavity wall. To increase Eacc, Bmax, which can be applied to the surface, must also be increased. The A15 materials or multilayer structures are the potential solution to increase Bmax. Since coating and RF testing of full size RF cavities is both expensive and time consuming, one need to evaluate new ideas in superconducting thin films quickly and at low cost. A magnetic field penetration experiment has been designed and built at Daresbury Laboratory to test small superconducting samples. The facility produces a parallel DC magnetic field, which applied from one side of the sample to the other similar to that in an RF cavity. The facility applies an increasing magnetic field at a set temperature to determine the field of full flux penetration which can give an insight into the quality and structure of the superconducting structure. The facility has been characterised using both type I and II superconductors and is now producing results from novel materials.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB012  
About • Received ※ 18 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 17 July 2023
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MOPMB013 Influence of the Coating Parameters on the Tc of Nb₃Sn Thin Films on Copper Deposited via DC Magnetron Sputtering site, niobium, cavity, cathode 92
 
  • D. Fonnesu, O. Azzolini, R. Caforio, E. Chyhyrynets, D. Ford, V.A. Garcia, G. Keppel, C. Pira, A. Salmaso, F. Stivanello
    INFN/LNL, Legnaro (PD), Italy
  • G. Marconato
    Università degli Studi di Padova, Padova, Italy
  
  Funding: The I.FAST 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.
The I.FAST collaboration aims at pushing the performance of particle accelerators by developing sustainable innovative technologies. Among its goals, the development of thin film-coated copper elliptical accelerating cavities covers both the optimization of the manufacturing of seamless substrates and the development of functional coatings able to conform to the 3D cavity geometry while delivering the needed performance. For the latter, the optimization of the deposition recipe is central to a successful outcome. The work presented here focuses on the deposition of Nb₃Sn films on flat, small copper samples. The films are deposited via DCMS from a planar stoichiometric Nb₃Sn commercial target. The results of the film characterization are presented here. The observed dependencies between the film properties and, in particular, Tc(90%-10%) = (17.9±0.1)K is reported for Nb₃Sn on sapphire and Tc(90%-10%) = (16.9±0.2)K for Nb₃Sn on copper with a 30 micron thick niobium buffer layer. 		 
poster icon Poster MOPMB013 [1.749 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB013  
About • Received ※ 18 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 02 July 2023
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MOPMB014 NbTi Thin Film SRF Cavities for Dark Matter Search cavity, target, photon, cryogenics 96
 
  • G. Marconato
    Università degli Studi di Padova, Padova, Italy
  • D. Alesini, A. D’Elia, D. Di Gioacchino, C. Gatti, C. Ligi, G. Maccarrone, A. Rettaroli, S. Tocci
    LNF-INFN, Frascati, Italy
  • O. Azzolini, R. Caforio, E. Chyhyrynets, D. Fonnesu, D. Ford, V.A. Garcia, G. Keppel, C. Pira, A. Salmaso, F. Stivanello
    INFN/LNL, Legnaro (PD), Italy
  • C. Braggio
    Univ. degli Studi di Padova, Padova, Italy
  • D. D’Agostino, U. Gambardella
    INFN-Salerno, Baronissi, Salerno, Italy
  • S. Posen
    Fermilab, Batavia, Illinois, USA
  
  Funding: Resources from U.S. DOE, Ofce of Science, NQISRC, SQMS contract No DE-AC02-07CH11359. Also from EU’s Horizon 2020 Research and Innovation programme, Grant Agreement No 101004730; INFN CSNV exp. SAMARA
The search for dark matter is now looking at ALPs (axion-like particles) as a very promising candidate to understand our universe. Within this framework, we explore the possibility to use NbTi thin film coatings on Cu resonating cavities to investigate the presence of axions in the range of 35-45 µeV mass by coupling the axion to a very strong magnetic field inside the cavity, causing its conversion to a photon which is subsequently detected. In this work the chemical treatments and DC magnetron sputtering details of the preparation of 9 GHz, 7 GHz, and 3.9 GHz resonant cavities and their quality factor measurements at different applied magnetic fields are presented. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB014  
About • Received ※ 18 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 26 July 2023
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MOPMB015 Development of a Plasma-Enhanced Chemical Vapor Deposition System for High-Performance SRF Cavities cavity, plasma, vacuum, controls 100
 
  • G. Gaitan, A.T. Holic, W.I. Howes, G. Kulina, P. Quigley, J. Sears, Z. Sun
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • M. Liepe
    Cornell University, Ithaca, New York, USA
  • B.W. Wendland
    University of Minnesota, Minnesota, USA
  
  Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams
Next-generation, thin-film surfaces employing Nb₃Sn, NbN, NbTiN, or other compound superconductors are essential for reaching enhanced RF performance levels in SRF cavities. However, optimized, advanced deposition processes are required to enable high-quality films of such materials on large and complex-shaped cavities. For this purpose, Cornell University is developing a plasma-enhanced chemical vapor deposition (CVD) system that facilitates coating on complicated geometries with a high deposition rate. This system is based on a high-temperature tube furnace with a high-vacuum, gas, and precursor delivery system, and uses plasma to significantly reduce the required processing temperature and promote precursor decomposition. Here we present an update on the development of this system, including final system design, safety considerations, assembly, and commissioning. 		 
poster icon Poster MOPMB015 [1.951 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB015  
About • Received ※ 16 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 01 July 2023 — Issue date ※ 16 July 2023
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MOPMB016 Successful Al₂O₃ Coating of Superconducting Niobium Cavities by Thermal ALD cavity, niobium, HOM, experiment 104
 
  • G.K. Deyu, W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • R.H. Blick, I. González Díaz-Palacio, R. Zierold
    University of Hamburg, Hamburg, Germany
  
  Funding: This work is supported by the BMBF under the research Grant 05K19GUB.
Al₂O₃ is one of the potential insulator materials in the superconductor-insulator-superconductor (SIS) multilayer coatings of superconducting radio-frequency (SRF) cavities for pushing their performance limits. We report on the successful coating of two 1.3 GHz Tesla-shaped SRF cavities with 18 nm and 36 nm layers of Al₂O₃ deposited by thermal atomic layer deposition (ALD). The coating recipe was developed by thermal atomic layer deposition (ALD). The coating recipe was optimized with respect to different the applied process parameters such as exposure and purge times, substrate temperature and flow rates. After a proof-of-principle Al₂O₃ coating of a cavity, second the cavity maintained its maximum achievable accelerating field of more than 40 MV/m and no deterioration was observed [1]. On the contrary, an improvement of the surface resistance above 10 MV/m has been observed, which is now further under investigation.
[1].Wenskat, Marc, et al. "Successful Al₂O₃ coating of superconducting niobium cavities with thermal ALD." Superconductor Science and Technology 36.1 (2022): 015010. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB016  
About • Received ※ 17 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 28 June 2023
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MOPMB019 Numerical Calculations of Superheating Field in Superconductors with Nanostructured Surfaces cavity, simulation, radio-frequency, 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 icon 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
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MOPMB020 A Comprehensive Picture of Hydride Formation and Dissipation cavity, site, superconductivity, niobium 119
 
  • N. Sitaraman, T. Arias
    Cornell University, Ithaca, New York, USA
  • A.V. Harbick, M.K. Transtrum
    Brigham Young University, Provo, USA
  • M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.
Research linking surface hydrides to Q-disease, and the subsequent development of methods to eliminate surface hydrides, is one of the great successes of SRF cavity R\&D. We use time-dependent Ginzburg-Landau to extend the theory of hydride dissipation to sub-surface hydrides. Just as surface hydrides cause Q-disease behavior, we show that sub-surface hydrides cause high-field Q-slope (HFQS) behavior. We find that the abrupt onset of HFQS is due to a transition from a vortex-free state to a vortex-penetration state. We show that controlling hydride size and depth through impurity doping can eliminate HFQS. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB020  
About • Received ※ 30 June 2023 — Revised ※ 18 July 2023 — Accepted ※ 19 August 2023 — Issue date ※ 19 August 2023
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MOPMB021 Correlating Lambda Shift Measurements with RF Performance in Mid-T Heat Treated Cavities cavity, niobium, radio-frequency, ECR 124
 
  • R. Ghanbari, G.K. Deyu, W. Hillert, R. Monroy-Villa, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • C. Bate, D. Reschke, L. Steder, J.C. Wolff
    DESY, Hamburg, Germany
  
  Funding: This work was supported by the BMBF under the research grants 05K19GUB and 05H2021.
Heat treatment procedures have been identified as cru-cial for the performance of niobium SRF cavities, which are the key technology of modern accelerators. The so called "mid-T heat treatments", invert the dependence of losses on the applied accelerating field (anti-Q slope) and significantly reduce the absolute value of losses. The mechanism behind these improvements is still under investigation, and further research is needed to fully understand the principle processes involved. Anomalies in the frequency shift near the transition temperature (Tc), known as "dip" can provide insight into fundamental material properties and allow us to study the relation-ship of frequency response with surface treatments. Therefore, we have measured the frequency versus temperature of multiple mid-T heat treated cavities with different recipes and studied the correlation of SRF properties with frequency shift features. The maximum quality factor correlates with two such shift features, namely the dip magnitude per temperature width and the total frequency shift. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB021  
About • Received ※ 20 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 15 August 2023
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MOPMB022 Recent mid-T Single-Cell Treatments R&D at DESY cavity, niobium, vacuum, controls 129
 
  • C. Bate, D. Reschke, J. Schaffran, L. Steder, L. Trelle, H. Weise
    DESY, Hamburg, Germany
  
  The challenge of improving the performance of SRF cavities is being faced worldwide. One approach is to modify the superconducting surface properties through certain baking procedures. Recently a niobium retort furnace placed directly under an ISO4 clean room has been refurbished at DESY. Thanks to an inter-vacuum chamber and cryopumps, with high purity values in the mass spectrum it is working in the UHV range of 2·10-8 mbar. The medium temperature (mid-T) heat treatments around 300°C are promising and successfully deliver reproducible very high Q₀ values of 2-5·1010 at medium field strengths of 16 MV/m. Since the first DESY and ZRI mid-T campaign yielded promising results, further results of 1.3 GHz single-cell cavities are presented here after several modified treatments of the mid-T recipe. In addition, samples were added to each treatment, the RRR value change was examined, and surface analyses were subsequently performed. The main focus of the sample study is the precise role of the changes in the concentration of impurities on the surface. In particular, the change in oxygen content due to diffusion processes is suspected to be the cause of enhancing the performance.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB022  
About • Received ※ 18 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 01 July 2023
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MOPMB023 Magnetic Flux Expulsion in TRIUMF’s Multi-Mode Coaxial Cavities cavity, simulation, 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 icon 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
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MOPMB026 Development of Transformative Cavity Processing - Superiority of Electropolishing on High Gradient Performance over Buffered Chemical Polishing at Low Frequency (322 MHz) cavity, operation, cryomodule, MMI 145
 
  • K. Saito, C. Compton, K. Elliott, W. Hartung, S.H. Kim, T.K. Konomi, E.S. Metzgar, S.J. Miller, L. Popielarski, A.T. Taylor, T. Xu
    FRIB, East Lansing, Michigan, USA
  
  Funding: The work is supported by DOE Awards DE-SC0022994.
A DOE grant R&D titled ¿Development of Transformative Preparation Technology to Push up High Q/G Performance of FRIB Spare HWR Cryomodule Cavities¿ is ongoing at FRIB. This R&D is for 2 years since September 2022. This project proposes four objectives: 1) Superiority on high gradient performance of electropolishing (EP) over buffered chemical polishing at low frequency (322 MHz), 2) High Qo performance by the local magnetic shield, 3) Development of HFQS-free BCP and, 4) Wet N-doping method. This paper will report the result of first object, and a local magnetic shield design and simulation to reduce the residual magnetic field < 0.1 mG in the vertical test Dewar, for the object 2. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB026  
About • Received ※ 14 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 08 July 2023
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MOPMB027 Successful Superheating Field Formulas from an Intuitive Model niobium, cavity, experiment, superconductivity 151
 
  • K. Saito, T. Konomi
    FRIB, East Lansing, Michigan, USA
  
  Funding: Work supported by the U.S. Department of Energy Office of Science DE-S0000661 and the National Science Foundation under Cooperative Agreement PHY-1102511
To date, many theoretical formulas for superheating field on SRF cavity are already proposed based rather complicated calculations. This paper proposes the formulas by a very intuitive simple model: energy balance between RF magnetic energy and superconducting condensed one, and a condition of vanishing the mirror vortex line image. The penetration of a single vortex determines the superheating field for a type II superconductor. On the other hand, for type I superconductors, the surface flux penetration determines it. The formula fits very well quantitatively the results of niobium cavity and Nb₃Sn one. In addition, it gives a nice guideline for new material beyond niobium.
male, senior 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB027  
About • Received ※ 23 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 15 July 2023
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MOPMB030 Medium Temperature Furnace Baking of Low-beta 650 MHz Five-cell Cavities cavity, niobium, radio-frequency, multipactoring 158
 
  • G. Wu, S.K. Chandrasekaran, V. Chouhan, G.V. Eremeev, F. Furuta, K.E. McGee, A.A. Murthy, A.V. Netepenko, J.P. Ozelis, H. Park, S. Posen
    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.
Medium Temperature baking of low beta 650 MHz cavities was conducted in a UHV furnace. A systematic study of cavity surface resistance components, residual and BCS, was conducted, including analyzing surface resistance due to trapped magnetic flux. Cavities showed an average 4.5 nano-ohm surface resistance at 17 MV/m under 2 K, which meets PIP-II specifications with a 40% margin. The results provided helpful information for the PIP-II project to optimize the cavity processing recipe for cryomodule application. The results were compared to the 1.3 GHz cavity that received a similar furnace baking. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB030  
About • Received ※ 19 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023
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MOPMB032 The Collaborative Effects of Intrinsic and Extrinsic Impurities in Low RRR SRF Cavities cavity, niobium, radio-frequency, accelerating-gradient 162
 
  • K. Howard, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • D. Bafia, A. Grassellino
    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.
The SRF community has shown that introducing certain impurities into high-purity niobium can improve quality factors and accelerating gradients. We question why some impurities improve RF performance while others hinder it. The purpose of this study is to characterize the impurity profile of niobium coupons with a low residual resistance ratio (RRR) and correlate these impurities with the RF performance of low RRR cavities so that the mechanism of impurity-based improvements can be better understood and improved upon. The combination of RF testing and material analysis reveals a microscopic picture of why low RRR cavities experience low BCS resistance behavior more prominently than their high RRR counterparts. We performed surface treatments, low temperature baking and nitrogen-doping, on low RRR cavities to evaluate how the intentional addition of oxygen and nitrogen to the RF layer further improves performance through changes in the mean free path and impurity profile. The results of this study have the potential to unlock a new understanding on SRF materials and enable the next generation of high Q/high gradient surface treatments. 		 
poster icon Poster MOPMB032 [1.444 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB032  
About • Received ※ 21 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 23 July 2023
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MOPMB033 Efforts to Suppress Field Emission in SRF Cavities at KEK cavity, laser, acceleration, site 167
 
  • M. Omet, H. Araki, T. Dohmae, H. Ito, R. Katayama, K. Umemori, Y. Yamamoto
    KEK, Ibaraki, Japan
  
  Our main objective is to achieve as high as possible quality factors Q₀ and maximal accelerating voltages Eacc within 1.3 GHz superconducting radio frequency (SRF) cavities. Beside an adequate surface treatment, key to achieve good performance is a proper assembly in the clean room prior cavity testing or operation. In this contribution we present the methods and results of our efforts to get a better understanding of our clean room environment and the particulate generation caused during the assembly work. Furthermore, we present the measures taken to suppress filed emission, followed by an analysis of vertical test results of the last six years.  
poster icon Poster MOPMB033 [1.532 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB033  
About • Received ※ 14 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 02 September 2023 — Issue date ※ 02 September 2023
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MOPMB036 Magnetic Field Mapping of a Large-Grain 1.3 GHz Single-Cell Cavity cavity, radio-frequency, niobium, cryogenics 172
 
  • I.P. Parajuli, J.R. Delayen, A.V. Gurevich
    ODU, Norfolk, Virginia, USA
  • G. Ciovati
    JLab, Newport News, Virginia, USA
  
  Funding: This work was supported by the National Science Foundation under Grant No. PHY 100614-010. G.C. is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A new magnetic field mapping system for 1.3 GHz single-cell cavities was developed in order to reveal the impact of ambient magnetic field and temperature gradients during cool-down on the flux trapping phenomenon. Measurements were done at 2 K for different cool-down conditions of a large-grain cavity before and after 120 °C bake. The fraction of applied magnetic field trapped in the cavity walls was ~ 50% after slow cool-down and ~20% after fast cool-down. The results showed a weak correlation between between trapped flux locations and hot-spots causing the high-field Q-slope. The results also showed an increase of the trapped flux at the quench location, after quenching, and a local redistribution of trapped flux with increasing RF field. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB036  
About • Received ※ 15 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 05 July 2023
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MOPMB037 Exploration of Parameters that Affect High Field Q-Slope cavity, niobium, accelerating-gradient, radio-frequency 178
 
  • K. Howard, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • D. Bafia, A. Grassellino
    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.
The onset of high field Q-slope (HFQS) around 25 MV/m prevents cavities in electropolished (EP) condition from reaching high quality factors at high gradients due to the precipitation of niobium hydrides during cooldown. These hydrides are non-superconducting at 2 K, and contribute to losses such as Q disease and HFQS. We are interested in exploring the parameters that affect the behavior of HFQS. We study a high RRR cavity that received an 800 C by 3 hour bake and EP treatment to observe HFQS. First, we explore the effect of trapped magnetic flux. The cavity is tested after cooling slowly through Tc while applying various levels of ambient field. We observe the onset of the HFQS and correlate this behavior with the amount of trapped flux. Next, we investigate the effect of the size/concentration of hydrides. The cavity is tested after holding the temperature at 100 K for 12 hours during the cooldown to promote the growth of hydrides. We can correlate the behavior of the HFQS with the increased hydride concentration. Our results will help further the understanding of the mechanism of HFQS. 		 
poster icon Poster MOPMB037 [1.648 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB037  
About • Received ※ 12 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 19 August 2023
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MOPMB038 Temperature Mapping for Coaxial Cavities at TRIUMF cavity, LabView, data-acquisition, ECR 183
 
  • P. Kolb, T. Junginger, J.J. Keir, R.E. Laxdal, B. Matheson, Z.Y. Yao
    TRIUMF, Vancouver, Canada
  • H. Al Hassini, T. Junginger
    UVIC, Victoria, Canada
  • L. Fearn
    UW/Physics, Waterloo, Ontario, Canada
  
  Temperature mapping (T-map) on superconducting radio-frequency (SRF) cavities has been shown as a useful tool to identify defects and other abnormal sources of losses. So far T-map systems have only been realized for elliptical cavities that have an easily accessible outer surface. TEM mode cavities such as quarterwave and halfwave resonators (QWR, HWR) dissipate most of their power on the inner conductor of the coaxial structure. The limited access and constrained space are a challenge for the design of a temperature mapping system. This paper describes the mechanical and electrical design including the data acquisition of a T-map system for the TRIUMF multi-mode coaxial cavities, and first results are shown.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB038  
About • Received ※ 20 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 30 June 2023
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MOPMB040 Comparing the Effectiveness of Low Temperature Bake in EP and BCP Cavities cavity, niobium, radio-frequency, factory 187
 
  • H. Hu, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • D. Bafia
    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.
Electropolishing (EP) and buffered chemical polishing (BCP) are conventional surface preparation techniques for superconducting radiofrequency (SRF) cavities. Both EP and BCP treated SRF cavities display high field Q-slope (HFQS) which degrades performance at high gradients. While high gradient performance in EP cavities can be improved by introducing oxygen via a low temperature bake (LTB) of 120°C by 48 hours, LTB does not consistently remove HFQS in BCP cavities. There is no consensus as to why LTB is not effective on BCP prepared cavities. We examine quench in EP, BCP, EP+LTB, and BCP+LTB treated 1.3 GHz single-cell Nb cavities by studying the heating behavior with field using a temperature mapping system. Cavity performance is correlated to characterizations of surface impurity profile obtained via time of flight secondary ion mass spectrometry studies. We observe a difference in near surface hydrogen concentration following BCP compared to EP that may suggest that the causes of quench in EP and BCP cavities are different. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB040  
About • Received ※ 14 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 03 July 2023
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MOPMB041 Microstructure Development in a Cold Worked SRF Niobium Sheet After Heat Treatments cavity, ECR, niobium, radio-frequency 191
 
  • S. Balachandran, P. Dhakal, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  • T.R. Bieler
    Michigan State University, East Lansing, Michigan, USA
  • S. Chetri, P.J. Lee
    NHMFL, Tallahassee, Florida, USA
  • Z.L. Thune
    MSU, East Lansing, USA
  
  Funding: Jefferson Science Associates, LLC under U.S. DOE Grant DEAC05-06OR23177, U.S. DOE, Office of HEP under Grant DE-SC0009960, and NHMFL through NSF Grant DMR-1644779 and the State of Florida.
Bulk Nb for TESLA shaped SRF cavities is a mature technology. Significant advances are in order to push Q0’s to 1010-11(T= 2K), and involve modifications to the sub-surface Nb layers by impurity doping. In order to achieve the lowest surface resistance any trapped flux needs to be expelled for cavities to reach high Q0’s. There is clear evidence that cavities fabricated from polycrystalline sheets meeting current specifications require higher temperatures beyond 800 °C leads to better flux expulsion, and hence improves Q0. Recently, cavities fabricated with a non-traditional Nb sheet with initial cold work due to cold rolling expelled flux better after 800 °C/3h heat treatment than cavities fabricated using fine-grain poly-crystalline Nb sheets. Here, we analyze the microstructure development in Nb from the vendor supplied cold work non- annealed sheet that was fabricated into an SRF cavity as a function of heat treatment building upon the methodology development to analyze microstructure being developed by the FSU-MSU-UT, Austin-JLAB collaboration. The results indicate correlation between full recrystallization and better flux expulsion. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB041  
About • Received ※ 19 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 09 July 2023
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MOPMB042 Evaluation of Flux Expulsion and Flux Trapping Sensitivity of SRF Cavities Fabricated from Cold Work Nb Sheet with Successive Heat Treatment cavity, niobium, ECR, radio-frequency 197
 
  • B.D. Khanal
    ODU, Norfolk, Virginia, USA
  • P. Dhakal
    JLab, Newport News, Virginia, USA
  
  Funding: The work is partially supported by DOE HEP under Awards No. DE-SC 0009960. This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The main source of RF losses leading to lower quality factor of superconducting radio-frequency cavities is due to the residual magnetic flux trapped during cool-down. The loss due to flux trapping is more pronounced for cavities subjected to impurities doping. The flux trapping and its sensitivity to rf losses are related to several intrinsic and extrinsic phenomena. To elucidate the effect of re-crystallization by high temperature heat treatment on the flux trapping sensitivity, we have fabricated two 1.3 GHz single cell cavities from cold-worked Nb sheets and compared with cavities made from standard fine-grain Nb. Flux expulsion ratio and flux trapping sensitivity were measured after successive high temperature heat treatments. The cavity made from cold worked Nb showed better flux expulsion after 800 C/3h heat treatment and similar behavior when heat treated with additional 900 C/3h and 1000 C/3h. In this contribution, we present the summary of flux expulsion, trapping sensitivity, and RF results. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB042  
About • Received ※ 19 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 25 June 2023 — Issue date ※ 04 July 2023
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MOPMB044 Topographic Evolution of Nitrogen Doped Nb Subjected to Electropolishing cavity, niobium, vacuum, ECR 207
 
  • E.M. Lechner, C.G. Baxley, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
  • J.W. Angle, M.J. Kelley
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  
  Funding: DE-AC05-06OR23177 DE-SC-0014475
Surface quality is paramount in facilitating high perfor-mance SRF cavity operation. Here, we investigate the topographic evolution of samples subjected to N-doping and 600 °C vacuum anneal. We show that in N-doped Nb, niobium nitrides may grow continuously along grain boundaries. Upon electropolishing high slope angle grooves are revealed which sets up a condition that may facilitate a supression of the superheating field. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB044  
About • Received ※ 19 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 17 July 2023
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MOPMB045 Quench Detection in a Superconducting Radio Frequency Cavity with Combined Temperature and Magnetic Field Mapping cavity, radio-frequency, niobium, ECR 211
 
  • B.D. Khanal, G. Ciovati
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, P. Dhakal
    JLab, Newport News, Virginia, USA
  
  Funding: This is authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
Local dissipation of rf power in SRF cavities create so called ’hot-spots’, primary precursors of cavity quench driven by either thermal or magnetic instability. These hot spots are may be detected by a temperature mapping system, and a large increase in temperature on the outer surface is detected during cavity quench events. Here, we have used combined magnetic and temperature mapping systems using anisotropic magneto-resistance sensors and carbon resisters to locate the hot spots and areas with high trapped flux on a 3 GHz single-cell Nb cavity during the rf tests at 2 K. The effect of global and localized flux trapping on the rf performance will be presented. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB045  
About • Received ※ 19 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 12 August 2023
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MOPMB047 Commissioning of Dedicated Furnace for Nb₃Sn Coatings of 2.6 GHz Single Cell Cavities cavity, niobium, MMI, factory 216
 
  • P.A. Kulyavtsev, G.V. Eremeev, S. Posen, B. Tennis
    Fermilab, Batavia, Illinois, USA
  • J. Zasadzinski
    IIT, Chicago, 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.
We present the results of commissioning a dedicated furnace for Nb₃Sn coatings of 2.6GHz single cell cavities. Nb₃Sn is a desired coating due to its high critical temperature and smaller surface resistance compared to bulk Nb. Usage of Nb₃Sn coated cavities will greatly reduce operating costs due to its higher operating temperature providing decreased cooling costs. Tin is deposited in the bulk Nb cavity by use of a tin chloride nucleation agent and tin vapor diffusion. Analysis of the resultant coating was performed using SEM/EDS to verify successful formation of desired Nb:Sn phase. Witness samples located in line of sight of the source were analyzed in order to understand the coating efficacy. The cavity’s performance was assessed in the Vertical Test Stand (VTS) at Fermilab. 		 
poster icon Poster MOPMB047 [4.858 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB047  
About • Received ※ 26 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 08 July 2023
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MOPMB049 Plasma Processing: Ignition Testing and Simulation Models for a 172 MHz HWR Cavity plasma, cavity, vacuum, simulation 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
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MOPMB050 Thermal Feedback in Coaxial SRF Cavities cavity, niobium, feedback, ECR 224
 
  • M.W. McMullin, P. Kolb, R.E. Laxdal, Z.Y. Yao
    TRIUMF, Vancouver, Canada
  • T. Junginger
    UVIC, Victoria, Canada
  
  Funding: Natural Sciences and Engineering Research Council of Canada
The phenomenon of Q-slope in SRF cavities is caused by a combination of thermal feedback and field-dependent surface resistance. There is currently no commonly accepted model of field-dependent surface resistance, and studies of Q-slope generally treat thermal feedback as a correction to whichever surface resistance model is being used. In the present study, we treat thermal feedback as a distinct physical effect whose effect on Q-slope is calculated using a novel finite-element code. We performed direct measurements of liquid helium pool boiling from niobium surfaces to obtain input parameters for the finite-element code. This code was used to analyze data from TRIUMF’s coaxial test cavity program, which has provided a rich dataset of Q-curves at temperatures between 1.7 K and 4.4 K at five different frequencies. Preliminary results show that thermal feedback makes only a small contribution to Q-slope at temperatures near 4.2 K, but has stronger effects as the bath temperature is lowered. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB050  
About • Received ※ 17 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 09 August 2023
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MOPMB055 CEA Contribution to the PIP-II Linear Accelerator cryomodule, cavity, controls, linac 234
 
  • N. Bazin, S. Berry, J. Drant, M. Fontaine, P. Garin, H. Jenhani, A. Raut, P. Sahuquet, C. Simon
    CEA-DRF-IRFU, France
  • J. Belorgey, Q. Bertrand, P. Brédy, E. Cenni, C. Cloué, R. Cubizolles, S. Ladegaillerie, A. Le Baut, A. Moreau, O. Piquet, J. Plouin
    CEA-IRFU, Gif-sur-Yvette, France
  
  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 will deliver 10 low-beta cryomodules as In-Kind Contributions to the PIP-II project, with cavities supplied by LASA-INFN (Italy) and VECC-DAE (India), and power couplers and tuning systems supplied by Fermilab. An important milestone was reached in March 2023 with the Final Design Review of the cryomodule, launching the pre-production phase. This paper presents the status CEA activities on the design, manufacturing, assembly and tests of the cryomodules and the upgrade of the existing infrastructures to the PIP-II requirements.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB055  
About • Received ※ 25 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 03 July 2023
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MOPMB057 Implementation of the Test Bench for the PIP-II LB650 Cryomodules at CEA cryomodule, cavity, cryogenics, operation 243
 
  • H. Jenhani, N. Bazin, Q. Bertrand, P. Brédy, L. Maurice, O. Piquet, P. Sahuquet, C. Simon
    CEA-IRFU, Gif-sur-Yvette, France
  
  The Proton Improvement Plan II (PIP-II) at Fermilab is the first U.S. accelerator project that will have significant contributions from international partners. As a part of the French In-Kind Contributions to this project, CEA will provide ten 650 MHz low-beta cryomodules (LB650) equipped with LASA-INFN (Italy) and VECC-DAE (India) cavities and Fermilab power couplers and RF tuning systems. CEA is accordingly in charge of the design, manufacturing, assembly and testing of these cryomodules. This paper presents the future implementation of the test stand dedicated to the cryogenic and RF power testing of the LB650 cryomodules. The choice of the equipment and the current status will be detailed, as well.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB057  
About • Received ※ 19 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 05 July 2023
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MOPMB058 Summary of the Superconducting Rf Measurements in AMTF Hall at DESY cavity, cryomodule, FEL, superconductivity 248
 
  • M. Wiencek, K. Kasprzak, D. Kostin, D. Reschke, L. Steder
    DESY, Hamburg, Germany
  
  The AMTF (Accelerator Module Test Facility) in DESY was built for the tests of all superconducting cavities and cryomodules for the EuXFEL linac. After successful commissioning of the EuXFEL, the AMTF has been adapted in order to perform SRF (super conducting radio frequency) measurements of cavities and accelerating modules for different projects. Several SRF cavities related projects are still ongoing, while other were just finished. Some of those projects are dedicated to test components for the infrastructure of accelerators which are under construction, while the other ones are devoted to new R&D paths aiming for cavities and modules with high performance which are under investigation at DESY. This paper describes present activities performed at AMTF with special emphasis on performing SRF measurements for the ongoing cavities production. Most of the presented data is related to vertical cryostat cavity testing. However, some data about cryomodules and a new coupler test stand will be shown as well. Detailed statistics about the number of vertical tests performed within the last two years are also presented.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB058  
About • Received ※ 16 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 02 July 2023
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MOPMB062 Optimisation of Niobium Thin Film Deposition Parameters for SRF Cavities cavity, site, target, niobium 253
 
  • D.J. Seal, O.B. Malyshev, R. Valizadeh
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • J.A. Conlon, O.B. Malyshev, K.T. Morrow, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  In order to accelerate the progression of thin film (TF) development for future SRF cavities, it is desirable to optimise material properties on small flat samples. Most importantly, this requires the ability to measure their superconducting properties. At Daresbury Laboratory, it has been possible for many years to characterise these films under DC conditions; however, it is not yet fully understood whether this correlates with RF measurements. Recently, a high-throughput RF facility was commissioned that uses a novel 7.8 GHz choke cavity. The facility is able to evaluate the RF performance of planar-coated TF samples at low peak magnetic fields with a high throughput rate of 2-3 samples per week. Using this facility, an optimisation study of the deposition parameters of TF Nb samples deposited by HiPIMS has begun. The ultimate aim is to optimise TF Nb as a base layer for multilayer studies and replicate planar magnetron depositions on split 6 GHz cavities. The initial focus of this study was to investigate the effect of substrate temperature during deposition. A review of the RF facility used and results of this study will be presented.  
poster icon Poster MOPMB062 [2.395 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB062  
About • Received ※ 17 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 24 July 2023
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MOPMB067 Design of a Cathode Insertion and Transfer System for LCLS-II-HE SRF Gun cathode, gun, insertion, operation 267
 
  • R. Xiang, A. Arnold, S. Gatzmaga, A. Hoffmann, P. Murcek, R. Steinbrück, J. Teichert
    HZDR, Dresden, Germany
  • C. Adolphsen, J. Smedley
    SLAC, Menlo Park, California, USA
  • W. Hartung, S.H. Kim, T.K. Konomi, S.J. Miller, L. Popielarski, K. Saito, T. Xu
    FRIB, East Lansing, Michigan, USA
  • M.P. Kelly, T.B. Petersen
    ANL, Lemont, Illinois, USA
  • J.W. Lewellen
    LANL, Los Alamos, New Mexico, USA
  
  Funding: Work supported by cooperation project between MSU and HZDR RC113062 from the U.S. Department of Energy Office of Science under Cooperative Agreement DE-AC02-76SF00515.
Superconducting radio frequency photo injectors (SRF gun) offer advantages for operating in continuous wave (CW) mode and generating high-brightness and high-current beams. A new SRF gun is designed as a low emittance photo injector for LCLS-II-HE and a prototype gun is currently being developed under collaboration between SLAC, FRIB, HZDR and ANL. The aim is to demonstrate stable CW operation at a cathode gradient of 30 MV/m. One of the crucial component for successful SRF gun operation is the photocathode system. The new SRF gun will adopt the HZDR-type cathode, which includes a cathode holder fixture (cathode stalk) developed by FRIB and a sophisticated cathode exchange system designed by HZDR. This innovative cathode insertion system ensures accurate, particle-free and warm cathode exchanges. A novel alignment process targets the cathode to the stalk axis without touching cathode plug itself. To commission the prototype gun, metallic cathodes will be used. A specifically designed vacuum system ensures vacuum pressure of 10-9 mbar for transport of a single cathode from the cleanroom to the gun. Thus maintaining cathode quality. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB067  
About • Received ※ 18 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023
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MOPMB068 Loading Test of Hom Dampers for Superconducting Cavities for High Current at Superkekb HOM, cavity, superconducting-cavity, operation 271
 
  • T. Okada, K. Akai, T. Furuya, S. Mitsunobu, Y. Morita, M. Nishiwaki
    KEK, Ibaraki, Japan
  
  SuperKEKB is an e⁻e⁺ collider, which is an upgraded accelerator of KEKB with the aim to increase the luminosity by more than one order. The superconducting cavities are used in the electron ring. The superconducting cavities were designed as a HOM-damped structure for KEKB and were operated up to 1.4 A in KEKB. However, the design storage current of the electron ring for SuperKEKB is 2.6 A, which is about twice the achievement current of KEKB. The HOM power is estimated to increase from 16 kW, which is the performance value in KEKB, to over 35 kW. This large load is unacceptable for the ferrite HOM dampers mounted on both sides of the cavity. As a countermeasure, duct type SiC HOM dampers are inserted between the cavities. The HOM damper load tests were performed during normal beam operation with a maximum current of 1.1 A. The load on the downstream ferrite HOM damper decreased due to the HOM power absorbed by the upstream SiC damper. In addition, the load was found to be dependent on the beam filling pattern. We will present the results and discussion of beam tests on the loading of HOM dampers and the dependence on the beam filling pattern in SuperKEKB.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB068  
About • Received ※ 18 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 30 June 2023
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MOPMB070 Development of a Non-Intrusive Leak Detection Method for SRF Linacs cryomodule, radiation, ISOL, operation 275
 
  • P. Pizzol, R.L. Geng
    ORNL, Oak Ridge, Tennessee, USA
  • R. Afanador, J.D. Mammosser, V.S. Morozov, D.M. Vandygriff
    ORNL RAD, Oak Ridge, Tennessee, USA
  
  The SNS accelerator has been vital in delivering high-impact research for the world scientific community since 2006, with an availability of 99%. This high availability rate is crucial to the success of the facility, and after 16 years of operations, the aging of the components could start to impact this parameter. To mitigate this, condi-tion-based maintenance can be applied to areas of the LINAC to reduce or nullify the possibility of unwanted events that may damage the accelerator functionality. In this work, we describe the development of a non-intrusive leak detection methodology that verifies the health condition of the cryomodule isolation gate valve seals. In case of a sudden vacuum leak in a warm section between the cryomodules, these valves act as a final line of defense to protect the SRF cavities from atmosphere gases contamination, hence knowing their sealing integ-rity condition is paramount. Data taken from the ma-chine during different maintenance periods will be pre-sented, together with the analysis done, to verify the robustness of the numerical method vs. the experimental findings.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB070  
About • Received ※ 16 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 02 July 2023
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MOPMB072 LCLS-II-HE Cavity Qualification Testing cavity, cryomodule, radiation, accelerating-gradient 279
 
  • J.T. Maniscalco, S. Aderhold, M. Checchin, D. Gonnella, J. Hogan, R.D. Porter
    SLAC, Menlo Park, California, USA
  • T.T. Arkan, D. Bafia, A.T. Cravatta, J.A. Kaluzny, S. Posen
    Fermilab, Batavia, Illinois, USA
  • M.E. Bevins, A.J. Grabowski, C.E. Reece, H. Vennekate
    JLab, Newport News, Virginia, USA
  
  Acceptance testing of the LCLS-II-HE production cavities is approximately 65% complete. In this report, we present details of the test results, including summaries of the quench fields, intrinsic quality factors, and experience with field emission. We also offer an outlook on the remaining tests to be performed.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB072  
About • Received ※ 20 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 03 July 2023 — Issue date ※ 07 July 2023
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MOPMB080 Dedicate SRF Cryomodule Test Facilities for S3FEL cryomodule, FEL, electron, linac 298
 
  • H. Li, C.F. He
    Institute of Advanced Science Facilities, Shenzhen, People’s Republic of China
  • X.L. Wang, W.M. Yue, W.Q. Zhang
    IASF, Shenzhen, Guangdong, People’s Republic of China
  
  Shenzhen Superconducting Soft-X-Ray Free Electron Laser (S3FEL) has been proposed to build a continuous wave (CW) superconducting linear accelerator and produce FEL in the soft X-ray wavelength region. The proposed S3FEL LINAC consists of twenty-eight SRF cryomodules to accelerate beam energy up to 2.5 GeV. Prior to the cryomodules installed in the tunnel, SRF cavities and cryomodules will be conditioned and tested at a delicate SRF Cryomodule Test Facility (SMTF).The SMTF for S3FEL is currently under design which equipped with two vertical cryostats and three horizontal test benches. R&D work for the SMTF and its corresponding cryomodule assembly procedure is now on going. This paper describes the full set of layout design and implementation of the SMTF for S3FEL project as well as its latest status.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB080  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 07 July 2023
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MOPMB082 SRF Accelerating Modules Upgrade for Flash Linac at DESY cavity, FEL, linac, radiation 306
 
  • D. Kostin, S. Barbanotti, J. Eschke, K. Jensch, N. Krupka, A. Muhs, D. Reschke, S. Saegebarth, J. Schaffran, P. Schilling, M. Schmökel, L. Steder, N. Steinhau-Kühl, A. Sulimov, E. Vogel, H. Weise, M. Wiencek, B. van der Horst
    DESY, Hamburg, Germany
  
  SRF accelerating modules with 8 TESLA-type 1.3 GHz SRF cavities are the main part of the linear accelerators currently in user operation at DESY, FLASH [1, 2] and the European XFEL [3, 4]. For the FLASH upgrade in 2022 [5] two accelerating modules have been exchanged in order to enhance the beam energy to 1.3 GeV. The two modules have been prototype modules for the European XFEL. After reassembly both modules were successfully tested and installed in the FLASH linac. Data taken during the commissioning at the end of 2022 did confirm the test results. This paper presents described efforts and their conclusions since last two years and continues the presentation given at SRF 2021 [6].  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB082  
About • Received ※ 16 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 27 June 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPMB083 Investigation of the Multilayer Shielding Effect through NbTiN-AlN Coated Bulk Niobium site, cavity, niobium, shielding 311
 
  • I.H. Senevirathne, J.R. Delayen, A.V. Gurevich
    ODU, Norfolk, Virginia, USA
  • D.R. Beverstock, J.R. Delayen, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  • D.R. Beverstock
    The College of William and Mary, Williamsburg, Virginia, USA
  
  We report measurements of the dc field onset Bp of magnetic flux penetration through NbTiN-AlN coating on bulk niobium using the Hall probe experimental setup. The measurements of Bp reveal the multilayer shielding effect on bulk niobium under high magnetic fields at cryogenic temperatures. We observed a significant enhancement in Bp for the NbTiN-AlN coated Nb samples as compared to bare Nb samples. The observed dependence of Bp on the coating thickness is consistent with theoretical predictions.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB083  
About • Received ※ 18 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 12 August 2023
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MOPMB084 FRIB Driver Linac Integration to Support Operations and Protect SRF Cryomodules operation, linac, cryomodule, vacuum 316
 
  • H. Ao, K. Elliott, D.D. Jager, S.H. Kim, L. Popielarski
    FRIB, East Lansing, Michigan, USA
  
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The driver linac for the Facility for Rare Isotope Beams (FRIB) at Michigan State University includes 324 superconducting radio-frequency (SRF) cavities, and the SRF particle-free beamline spans approximately 300 meters. Protecting the beamlines against contamination is critical to FRIB operations, and thus, various administrative and engineered controls have been put in place to protect the SRF cryomodules. These controls include local vacuum interlocks for cryomodule isolation, accelerator-wide interlocks, and software controls to safeguard the cryomodules and beamlines. Meanwhile, efforts are being made to provide training and develop programs with the goal of preventing critical failures during maintenance. This paper discusses the measures and approaches used for both system integration to support operations and SRF beamline protection. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB084  
About • Received ※ 14 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023
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MOPMB090 Measuring Q₀ in LCLS-II Cryomodules Using Helium Liquid Level cavity, cryomodule, linac, MMI 327
 
  • L.M. Zacarias, S. Aderhold, D. Gonnella, J.T. Maniscalco, J. Nelson, R.D. Porter
    SLAC, Menlo Park, California, USA
  • A.T. Cravatta, J.P. Holzbauer, S. Posen
    Fermilab, Batavia, Illinois, USA
  • M.A. Drury, M.D. McCaughan, C.M. Wilson
    JLab, Newport News, Virginia, USA
  
  The nitrogen-doped cavities used in the Linac Coherent Light Source II (LCLS-II) cryomodules have shown an unprecedented high Q₀ in vertical and cryomodule testing compared with cavities prepared with standard methods. While demonstration of high Q₀ in the test stand has been achieved, maintaining that performance in the linac is critical to the success of LCLS-II and future accelerator projects. The LCLS-II cryomodules required a novel method of measuring Q₀, due to hardware incompatibilities with existing procedures. Initially developed at Jefferson Lab during cryomodule acceptance testing before being used in the tunnel at SLAC, we use helium liquid level data to estimate the heat generated by cavities. We first establish the relationship between the rate of helium evaporation from known heat loads using electric heaters, and then use that relationship to determine heat from an RF load. Here we present the full procedure along with the development process, lessons learned, and reproducibility while demonstrating for the first time that world record Q₀ can be maintained within the real accelerator environment.  
poster icon Poster MOPMB090 [1.867 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB090  
About • Received ※ 20 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 13 July 2023
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MOPMB093 Optimizing Growth of Niobium-3 Tin Through Pre-nucleation Chemical Treatments site, niobium, cavity, controls 337
 
  • S.G. Arnold, G. Gaitan, M. Liepe, L. Shpani, Z. Sun
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • T. Arias, N. Sitaraman
    Cornell University, Ithaca, New York, USA
  
  Funding: This work was supported by the U.S. National Science Foundation under award PHY-1549132, the Center for Bright Beams.
Nb₃Sn is a promising alternative material for SRF cavities that is close to reaching practical applications. To date, one of the most effective growth methods for this material is vapor diffusion, yet further improvement is needed for Nb₃Sn to reach its full potential. The major issues faced by vapor diffusion are tin depleted regions and surface roughness, both of which lead to impaired performance. Literature has shown that the niobium surface oxide plays an important role in the binding of tin to niobium. In this study, we performed various chemical treatments on niobium samples pre-nucleation to enhance tin nucleation. We quantify the effect that these various treatments had through scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). These methods reveal information on tin nucleation density and uniformity, and a thin tin film present on most samples, even in the absence of nucleation sites. We present our findings from these surface characterization methods and introduce a framework for quantitatively comparing the samples. We plan to apply the most effective treatment to a cavity and conduct an RF test soon. 		 
poster icon Poster MOPMB093 [1.118 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB093  
About • Received ※ 21 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 26 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPMB094 Design of a 1.3 GHz High-Power RF Coupler for Conduction-Cooled Systems cavity, cryomodule, radio-frequency, operation 342
 
  • N.A. Stilin, A.T. Holic, M. Liepe, T.I. O’Connell, P. Quigley, J. Sears, V.D. Shemelin, J. Turco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Cornell is designing a new standalone, compact SRF cryomodule which uses cryocoolers in place of liquid helium for cooling. One of the biggest challenges in implementing such a system is designing a high-power input coupler which is able to be cooled by the cryocoolers without any additional liquid cryogenics. Due to the limited heat load capacity of the cryocoolers at 4.2 K, this requires very careful thermal isolation of the 4.2 K portion of the coupler and thorough optimization of the RF behavior to minimize losses. This paper will present the various design considerations which enabled the creating of a conduction-cooled 1.3 GHz input coupler capable of delivering up to 100 kW CW RF power.  
poster icon Poster MOPMB094 [0.964 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB094  
About • Received ※ 16 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 23 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUIBA01 A Three-Fluid Model of Dissipation at Surfaces in Superconducting Radiofrequency Cavities scattering, cavity, electron, niobium 361
 
  • M.M. Kelley, T. Arias, S. Deyo, D. Liarte, J.P. Sethna, N. Sitaraman
    Cornell University, Ithaca, New York, USA
  • M. Liepe, T.E. Oseroff
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.
Experiments on superconducting cavities have found that under large RF fields the quality factor can improve with increasing field amplitude, a so-called anti-Q slope. We numerically solve the Bogoliubov-de Gennes equations at a superconducting surface in a parallel magnetic field, finding at large fields there are surface quasiparticle states with energies below the bulk superconducting gap that emerge and disappear as the field cycles. Modifying the standard two-fluid model, we introduce a ‘‘three’’-fluid model where we partition the normal fluid to consider continuum and surface quasiparticle states separately. We compute dissipation in a semi-classical theory of conductivity, where we provide physical estimates of elastic scattering times of Bogoliubov quasiparticles with point-like impurities having potential strengths informed from complementary ab initio calculations of impurities in bulk niobium. We show, in this simple yet effective framework, how the relative scattering rates of surface and continuum quasiparticle states can play a role in producing an anti-Q slope while demonstrating how this model naturally includes a mechanism for turning the anti-Q slope on and off.
S. Deyo, M. Kelley et al. Phys. Rev. B 106, 104502 (2022) 		 
slides icon Slides TUIBA01 [2.019 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUIBA01  
About • Received ※ 19 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 08 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUCBA01 Measurements of the Amplitude-Dependent Microwave Surface Resistance of a Proximity-Coupled Au/Nb Bilayer niobium, cavity, factory, extraction 369
 
  • T.E. Oseroff, M. Liepe, Z. Sun
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  A sample host cavity is used to measure the surface resistance of a niobium substrate with a gold film deposited in place of its surface oxide. This talk will report about this measurement result. The film thickness of the gold layer was increased from 0.1 nm to 2.0 nm in five steps to study the impact of the normal layer thickness. The 0.1 nm film was found to reduce the surface resistance below its value with the surface oxide present and to enhance the quench field. The magnitude of the surface resistance increased substantially with gold film thickness. The surface resistance field-dependence appeared to be independent from the normal layer thickness. The observations reported in this work have profound implications for both low-field and high-field S.C. microwave devices. By controlling or eliminating the niobium oxide using a gold layer to passivate the niobium surface, it may be possible to improve the performance of SRF cavities used for particle acceleration. This method to reduce surface oxidation while maintaining low surface resistance could also be relevant for minimizing dissipation due to two-level systems observed in low-field low-temperature devices.  
slides icon Slides TUCBA01 [2.292 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUCBA01  
About • Received ※ 19 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 26 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUIXA04 First Results from beta-SRF- Testing SRF Samples at High Parallel Field polarization, experiment, niobium, ISAC 374
 
  • E. Thoeng, R. Kiefl, W.A. MacFarlane, J.O. Ticknor
    UBC & TRIUMF, Vancouver, British Columbia, Canada
  • M. Asaduzzaman, S.R. Dunsiger, D. Fujimoto, T. Junginger, V.L. Karner, P. Kolb, R.E. Laxdal, R. Li, R.M.L. McFadden, G. Morris, M. Stachura
    TRIUMF, Vancouver, Canada
  • T. Junginger, R.M.L. McFadden
    UVIC, Victoria, Canada
  
  The new ¿-SRF facility at TRIUMF has recently been commissioned. A new 1 m extension has been added to an existing ¿-NMR beamline with a large Helmholtz coil to produce fields up to 200 mT parallel to sample surfaces. The ¿-NMR technique allows depth dependent characterization of the local magnetic field in the first 100 nm of the sample surface making the probe ideal for studying Meissner screen- ing in heat treated Niobium or layered SRF materials. First measurements of Meissner screening at fields up to 200 mT have been analyzed. The results show clear differences in the Meissner screening of baseline treatments compared to mid-T baked (O-doped) Niobium.  
slides icon Slides TUIXA04 [1.644 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUIXA04  
About • Received ※ 24 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 06 July 2023 — Issue date ※ 09 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB001 Demonstration of Niobium Tin in 218 MHz Low-Beta Quarter Wave Accelerator Cavity cavity, niobium, multipactoring, vacuum 388
 
  • T.B. Petersen, G. Chen, B.M. Guilfoyle, M. Kedzie, M.P. Kelly, T. Reid
    ANL, Lemont, Illinois, USA
  • G.V. Eremeev, S. Posen, B. Tennis
    Fermilab, Batavia, Illinois, USA
  
  A 218 MHz quarter wave niobium cavity has been fabricated for the purpose of demonstrating Nb₃Sn technology on a low-beta accelerator cavity. Niobium-tin has been established as a promising next generation SRF material, but development has focused primarily in high-beta elliptical cell cavities. This material has a significantly higher TC than niobium, allowing for design of higher frequency quarter wave cavities (that are subsequently smaller) as well as for significantly lowered cooling requirements (possibly leading to cryocooler based de-signs). The fabrication, initial cold testing, and Nb₃Sn coating are discussed as well as test plans and details of future applications.  
poster icon Poster TUPTB001 [0.653 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB001  
About • Received ※ 16 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 08 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB006 Materials Design for Superconducting RF Cavities: Electroplating Sn, Zr, and Au onto Nb and and Chemical Vapor Deposition cavity, plasma, controls, niobium 401
 
  • Z. Sun, M. Liepe, T.E. Oseroff
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • Z. Baraissov, D.A. Muller, M.O. Thompson
    Cornell University, Ithaca, New York, USA
  
  Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.
Materials scientists seek to contribute to the development of next-generation superconducting radio-frequency (SRF) accelerating cavities. Here, we summarize our achievements and learnings in designing advanced SRF materials and surfaces, including Nb₃Sn [1¿3], ZrNb(CO) [4, 5], and Au/Nb surface design [6,7]. Our efforts involve electrochemical synthesis, phase transformation, and surface chemistry, which are closely coupled with superconducting properties, SRF performance, and engineering considerations. We develop electrochemical processes for Sn, Zr, and Au on the Nb surface, an essential step in our investigation for producing high-quality Nb₃Sn, ZrNb(CO), and Au/Nb structures. Additionally, we design a custom chemical vapor deposition system to offer additional growth options. Notably, we find the second-phase NbC formation in ZrNb(CO) and in ultra-high-vacuum baked or nitrogen-processed Nb. We also identify low-dielectric-loss ZrO2 on Nb and NbZr(CO) surfaces. These advancements provide materials science approaches dealing with fundamental and technical challenges to build high-performance, multi-scale, robust SRF cavities for particle accelerators and quantum applications. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB006  
About • Received ※ 30 June 2023 — Revised ※ 11 August 2023 — Accepted ※ 20 August 2023 — Issue date ※ 21 August 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB010 Preservation of the High Quality Factor and Accelerating Gradient of Nb₃Sn-Coated Cavity During Pair Assembly cavity, accelerating-gradient, cryomodule, niobium 405
 
  • G.V. Eremeev, S. Cheban, S. Posen, B. Tennis
    Fermilab, Batavia, Illinois, USA
  • J.F. Fischer, D. Forehand, U. Pudasaini, A.V. Reilly, R.A. Rimmer
    JLab, Newport News, Virginia, 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 CEBAF 5-cell accelerator cavities have been coated with Nb₃Sn film using the vapor diffusion technique. One cavity was coated in the Jefferson Lab Nb₃Sn cavity coating system, and the other in the Fermilab Nb₃Sn coating system. Both cavities were measured at 4 K and 2 K in the vertical dewar test in each lab and then assembled into a cavity pair at Jefferson Lab. Previous attempts to assemble Nb₃Sn cavities into a cavity pair degraded the superconducting properties of Nb₃Sn-coated cavities. This contribution discusses the efforts to identify and mitigate the pair assembly challenges and will present the results of the vertical tests before and after pair assembly. Notably, one of the cavities reached the highest gradient above 80 mT in the vertical test after the pair assembly. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB010  
About • Received ※ 23 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 02 July 2023 — Issue date ※ 09 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB013 Commissioning of a New Sample Test Cavity for Rapid RF Characterization of SRF Materials cavity, niobium, MMI, operation 410
 
  • S. Keckert, J. Knobloch, F. Kramer, O. Kugeler
    HZB, Berlin, Germany
  • J. Knobloch
    University of Siegen, Siegen, Germany
  
  RaSTA, the Rapid Superconductor Test Apparatus, is a new sample test cavity that is currently being commissioned at HZB. It uses the established QPR sample geometry but with a much smaller cylindrical cavity operating in the TM020 mode at 4.8 GHz. Its compact design allows for smaller cryogenic test stands and reduced turnaround time, enabling iterative measurement campaigns for thin film R&D. Using the same calorimetric measurement technique as known from the QPR allows direct measurements of the residual resistance. We report first prototype results obtained from a niobium sample that demonstrate the capabilities of the system.  
poster icon Poster TUPTB013 [0.464 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB013  
About • Received ※ 16 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 28 June 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB014 Development of Nb₃Sn Coating System and RF Measurement Results at KEK cavity, radio-frequency, accelerating-gradient, controls 414
 
  • H. Ito, H. Sakai, K. Umemori, T. Yamada
    KEK, Ibaraki, Japan
  • K. Takahashi
    Sokendai, Ibaraki, Japan
  
  We have constructed an Nb₃Sn cavity coating system based on the Sn vapor diffusion method. After the construction, improvement of our coating system and environment has been conducted through sample and cavity coating research. Our cavity achieves a Q-value above 1E10 at 4 K after improvement. We will report on the detail of improvement on our coating system and RF measurement results of single-cell Nb₃Sn cavity.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB014  
About • Received ※ 18 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 28 June 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB018 MgB₂ Coating Parameter Optimization Using a 1.3-GHz 1-Cell Cavity cavity, controls, experiment, vacuum 425
 
  • T. Tajima, T.P. Grumstrup, J.D. Thompson
    LANL, Los Alamos, New Mexico, USA
  • H. Ito, E. Kako, T. Okada, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
  
  Funding: DOE Office of Science, Office of High Energy Physics
We have started parameter optimization for the coating of MgB₂ using a 1-cell 1.3-GHz elliptical cavity with holes for small samples. Our coating method is based on a 2-step technique, i.e., coat a B layer by flowing diborane gas in the first step and react it with Mg vapor in the 2nd step. Three 6 mm x 6 mm B-coated flat samples are attached at inlet, outlet beam pipes, and at a cell equator and reacted with Mg vapor with different parameters and conditions. We started to see the superconducting transitions on samples but Tc is still lower than our goal of >35 K. We will present our current status of B-Mg reaction tests and construction of B coating system. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB018  
About • Received ※ 06 July 2023 — Revised ※ 26 July 2023 — Accepted ※ 02 September 2023 — Issue date ※ 03 September 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB019 First Results from Nb₃Sn Coatings of 2.6 GHz Nb SRF Cavities Using DC Cylindrical Magnetron Sputtering System cavity, site, vacuum, MMI 429
 
  • M.S. Shakel, H. Elsayed-Ali
    ODU, Norfolk, Virginia, USA
  • G.V. Eremeev
    Fermilab, Batavia, Illinois, USA
  • U. Pudasaini, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  
  Funding: Supported by DOE, Office of Accelerator R&D and Production, Contact No. DE-SC0022284, with partial support by DOE, Office of Nuclear Physics DE-AC05-06OR23177, Early Career Award to G. Eremeev.
A DC cylindrical magnetron sputtering system has been commissioned and operated to deposit Nb₃Sn onto 2.6 GHz Nb SRF cavities. After optimizing the deposition conditions in a mock-up cavity, Nb-Sn films are deposited first on flat samples by multilayer sequential sputtering of Nb and Sn, and later annealed at 950 °C for 3 hours. X-ray diffraction of the films showed multiple peaks for the Nb₃Sn phase and Nb (substrate). No peaks from any Nb-Sn compound other than Nb₃Sn were detected. Later three 2.6 GHz Nb SRF cavities are coated with ~1 µm thick Nb₃Sn. The first Nb₃Sn coated cavity reached close to Eacc = 8 MV/m, demonstrating a quality factor Q₀ of 3.2 × 108 at Tbath = 4.4 K and Eacc = 5 MV/m, about a factor of three higher than that of Nb at this temperature. Q₀ was close to 1.1 × 109, dominated by the residual resistance, at 2 K and Eacc = 5 MV/m. The Nb₃Sn coated cavities demonstrated Tc in the range of 17.9 ¿ 18 K. Here we present the commissioning experience, system optimization, and the first results from the Nb₃Sn fabrication on flat samples and SRF cavities. 		 
poster icon Poster TUPTB019 [1.216 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB019  
About • Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 10 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB020 Surface Properties and RF Performance of Vapor Diffused Nb₃Sn on Nb after Sequential Anneals below 1000 °C cavity, ECR, electron, experiment 433
 
  • J.K. Tiskumara, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • G.V. Eremeev
    Fermilab, Batavia, Illinois, USA
  • U. Pudasaini
    JLab, Newport News, Virginia, USA
  
  Nb₃Sn is a next-generation superconducting material that can be used for future superconducting radiofrequency (SRF) accelerator cavities, promising better performance, cost reduction, and higher operating temperature than Nb. The Sn vapor diffusion method is currently the most preferred and successful technique to coat niobium cavities with Nb₃Sn. Among post-coating treatments to optimize the coating quality, higher temperature annealing without Sn is known to degrade Nb₃Sn because of Sn loss. We have investigated Nb₃Sn/Nb samples briefly annealed at 800-1000 °C, for 10 and 20 minutes to potentially improve the surface to enhance the performance of Nb₃Sn-coated cavities. Following the sample studies, a coated single-cell cavity was sequentially annealed at 900 °C and tested its performance each time, improving the cavity’s quality factor relatively. This paper summarizes the sample studies and discusses the RF test results from sequentially annealed SRF Nb₃Sn/Nb cavity.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB020  
About • Received ※ 19 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 01 July 2023 — Issue date ※ 07 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB024 Cobotisation of ESS Cryomodule Assembly at CEA cavity, operation, cryomodule, MMI 438
 
  • S. Berry, A. Bouygues, J. Drant, C. Madec
    CEA-DRF-IRFU, France
  • A. Gonzalez-Moreau, C. Servouin
    CEA-IRFU, Gif-sur-Yvette, France
  
  The assembly of cavity string in the clean room is a tedious work that has noisy and painful steps such as cleaning the taped holes of a part. CEA together with the company INGELIANCE has developed a cobot: a collaborative robot operated by an technician one time and repeating the action without the operator. The cobot can work anytime without any operators : therefore it is working at night reducing the assembly duration by some hours. The cobot consists of a FANUC CRX10 a 6-axis arm on an Arvis cart. At CEA, the cobot is used to blow the flange holes of the cavities and bellows. This allows to reduce the noisy steps that the technicians are exposed to. The process is also more reproducible since the cobot does always the same steps. The cobot is used on ESS cavity string to clean the coupler and cavity flanges. Our activities and results will be presented in this poster.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB024  
About • Received ※ 18 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 03 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB027 Cleanroom Assembly of the LIPAc Cryomodule solenoid, cavity, cryomodule, pick-up 452
 
  • J.K. Chambrillon, P. Cara, Y. Carin, G. Duglue, H. Dzitko, D. Gex, G. Phillips, F. Scantamburlo
    Fusion for Energy, Garching, Germany
  • N. Bazin, N. Chauvin
    CEA-DRF-IRFU, France
  • Y. Carin, D. Gex, K. Masuda, F. Scantamburlo, M. Sugimoto
    IFMIF/EVEDA, Rokkasho, Japan
  • T. Ebisawa, K. Hasegawa, K. Kondo, K. Masuda, M. Sugimoto, T.Y. Yanagimachi
    QST Rokkasho, Aomori, Japan
  • D. Jimenez-Rey, J. Mollá, I. Podadera
    CIEMAT, Madrid, Spain
  • E. Kako, H. Sakai
    KEK, Ibaraki, Japan
  • W.-D. Möller
    Private Address, Hamburg, Germany
  
  In complement to the development activities for fusion reactors (JT-60SA & ITER), Fusion for Energy contributes to the R&D for material characterisation facilities. LIPAc is the technical demonstrator for the production and acceleration of a D+ beam that will be used for neutron production by nuclear stripping reaction on a liquid Li target. Since its first beam in 2014, the LIPAc construction and commissioning continues and will be concluded with the cryomodule installation, aiming for beam validation at nominal power. The cryomodule assembly, started in March 2019, was paused due to welding issues on the solenoid bellows. The slow pumping group used for the cleanroom assembly also needed improvement to overcome helium contamination. Two and half years were devoted to the pumping improvement and, repair, cold tests and high pressure rinsing of the solenoids. In August 2022, the cleanroom assembly resumed with the mounting of all power couplers to the SRF cavities. Despite good progress, the assembly had to be paused again to fix leaks on different vacuum components and a solenoid BPM port. This paper presents the issues faced and their solutions along the cold mass assembly.  
poster icon Poster TUPTB027 [2.384 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB027  
About • Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 16 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB029 Measurement of Particulates under Slow Pumping after High Pressure Rinsing of Superconducting Cavity by Using Modified Slow Pumping System cavity, vacuum, controls, cryomodule 458
 
  • H. Sakai, E. Kako, R. Katayama, K. Umemori
    KEK, Ibaraki, Japan
  
  Funding: This research was partially supported by the research fund from Ministry of Education, Culture, Sports, Science and Technology (MEXT).
Slow pumping system was used for particle free vacuum pumping in Superconducting rf accelerator. In KEK, recently slow pumping system was developed for the cryomodule assembly work for STF 9-cell cavities and worked well to reduce the particulates movements under pumping. However, this slow pumping system want to be used for preparation of vertical test. Before assembly work in clean room for vertical test, we normally apply high pressure rinsing. There were many waters in the cavity. Therefore, we kept one night to dry inside cavity in clean room. Unfortunately, there were some waters in the cavity even though we kept drying in clean room for one night. This water might make some icing under pumping and stop pumping in mass flow meter, which used for slow pumping to control the mass flow. Therefore, we modify the slow pumping system to be robust under slow pumping even when water exists in the cavity. In this paper, we present the modified slow pumping system in KEK and the results of the vacuum trend through slow pumping of 9-cell superconducting cavity. Under slow pumping, we measure the particulates after high pressure rinsing by using vacuum particle monitor. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB029  
About • Received ※ 16 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 21 August 2023 — Issue date ※ 22 August 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, simulation, 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, electron, cryogenics, simulation 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)  
 
TUPTB035 Design, Fabrication, and Test of a 175 MHz, β = 0.18, Half Wave Resonator for the IFMIF-DONES SRF-Linac cavity, linac, multipactoring, target 477
 
  • J. Plouin, M. Baudrier, S. Chel, G. Devanz, A. Madur, L. Maurice, C. Servouin
    CEA-DRF-IRFU, France
  • N. Bazin, G. Jullien
    CEA-IRFU, Gif-sur-Yvette, France
  
  The IFMIF-DONES facility will serve as a fusion-like neutron source for the assessment of materials damage in future fusion reactors. The neutron flux will be generated by the interaction between the lithium curtain and the deuteron beam from an RF linear accelerator at 40 MeV and nominal CW current of 125 mA. The last accelerating stage is a superconducting (SRF) Linac hosting five cryomodules. This SRF-Linac is equipped of two types of 175 MHz half wave superconducting cavities (HWRs). The first type of cavities (cryomodules 1 and 2), characterized by beta equal to 0.11, have been studied and qualified in the frame of IFMIF/EVEDA project. The development of the second type of cavities (cryomodules 3, 4 and 5), with higher beta of 0.18 is presented in this paper. A prototype has been designed, fabricated and tested in a vertical cryostat at CEA. The measured quality factor at nominal accelerating field (4.5 MV/m) is 2.3 109 and keeps higher than 109 up to 10 MV/m, which gives confidence in the cavity design and preparation to reach the expected performances after integration in the SRF linac.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB035  
About • Received ※ 20 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 15 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB036 Equidistant Optimization of Elliptical SRF Standing Wave Cavities cavity, ECR, linac, acceleration 480
 
  • V.D. Shemelin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  A record accelerating rate was achieved earlier in standing wave (SW) SRF cavities when their shape was optimized for lower peak surface magnetic field. In view of new materials with higher limiting magnetic fields, expected for SRF cavities, in the first line Nb₃Sn, the approach to optimization of cavity shape should be revised. A method of equidistant optimization, offered earlier for traveling wave cavities is applied to SW cavities. It is shown here that without limitation by magnetic field, the maximal accelerating rate is defined to a significant degree by the cavity shape. For example, for a cavity with the aperture radius Ra = 35 mm the minimal ratio of the peak surface electric field to the accelerating rate is about Epk/Eacc = 1.54. So, with the maximal surface field experimentally achieved Epk ¿ 125 MV/m, the maximal achievable accelerating rate is about 80 MeV/m even if there are no restrictions by the magnetic field. Another opportunity ¿ optimization for a low magnetic field, is opening for the same material, Nb₃Sn, with the purpose to have a high quality factor and increased accelerating rate that can be used for industrial linacs.  
poster icon Poster TUPTB036 [0.787 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB036  
About • Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 08 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, simulation, 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 icon 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
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TUPTB039 Simulation of High Pressure Rinse in Superconducting Radio Frequency Cavities cavity, simulation, 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)  
 
TUPTB040 Mechanical Design and Analysis of SRF Gun Cavity Using ASME BPVC Section Viii, Division-2, Design by Analysis Requirement cavity, gun, niobium, vacuum 501
 
  • M.S. Patil, C. Compton, S.H. Kim, S.J. Miller, T. Xu
    FRIB, East Lansing, Michigan, USA
  
  Funding: Work supported by the Department of Energy Contract DE-AC02- 76SF00515
A prototype SRF gun is currently being designed at FRIB, MSU for the Low Emittance Injector of the Linac Coherent Light Source high energy upgrade at SLAC. This employs a 185.7 MHz superconducting quarter-wave resonator (QWR). The mechanical design of this cavity has been optimized for performance and to comply with ASME Section VIII, Div 2, Design by analysis requirements. This paper presents the various design by analysis procedures and how they have been adopted for the SRF gun cavity design. 		 
poster icon Poster TUPTB040 [1.235 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB040  
About • Received ※ 15 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023
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TUPTB041 Visual, Optical and Replica Inspections: Surface Preparation of 650 MHz Nb Cavity for PIP-II Linac cavity, linac, niobium, embedded 507
 
  • V. Chouhan, D.J. Bice, D.A. Burk, M.K. Ng, G. Wu
    Fermilab, Batavia, Illinois, USA
  
  Surface preparation of niobium superconducting RF cavities is a critical step for achieving good RF performance under the superconducting state. Surface defect, roughness, and contamination affect the accelerating gradient and quality factor of the cavities. We report surface inspection methods used to control the surface processing of 650 MHz cavities that will be used in the pre-production cryomodule for PIP-II linac. The cavity surface was routinely inspected visually, with an optical camera, and by microscopic scanning of surface replicas. This article covers details on the surface inspection methods and surface polishing process used to repair the surface.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB041  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 12 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB042 Latest Development of Electropolishing Optimization for 650 MHz Cavity cavity, cathode, niobium, polarization 512
 
  • V. Chouhan, D.J. Bice, D.A. Burk, S.K. Chandrasekaran, A.T. Cravatta, P.F. Dubiel, G.V. Eremeev, F. Furuta, O.S. Melnychuk, A.V. Netepenko, M.K. Ng, J.P. Ozelis, H. Park, T.J. Ring, G. Wu
    Fermilab, Batavia, Illinois, USA
  • B.M. Guilfoyle, M.P. Kelly, T. Reid
    ANL, Lemont, Illinois, USA
  
  Electropolishing (EP) of 1.3 GHz niobium (Nb) superconducting RF cavities is conducted to achieve a desired smooth and contaminant-free surface that yields good RF performance. Achieving a smooth surface of a large-sized elliptical cavity with the standard EP conditions was found to be challenging. This work aimed to conduct a systematic parametric EP study to understand the effects of various EP parameters on the surface of 650 MHz cavities used in PIP-II linac. Parameters optimized in this study provided a smooth surface of the cavities. The electropolished cavities met the baseline requirement of field gradient and qualified for further surface treatment to improve the cavity quality factor.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB042  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 06 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB043 Development of 3-Cell Traveling Wave SRF Cavity cavity, resonance, cryogenics, GUI 517
 
  • F. Furuta, T.N. Khabiboulline, K.E. McGee, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  • P.V. Avrakhov, R.A. Kostin
    Euclid TechLabs, Solon, Ohio, 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
Traveling wave SRF cavity is a new technology and requires a multi-stage process for development. Concep-tual designs have been proposed to adopt TW resonance in an SRF cavity The early stages of developments have been funded by several SBIR grants to Euclid Techlabs which were completed in collaboration with Fermilab. A 3-cell proof-of-principle TW cavity was fabricated as part of that and demonstrated the TW resonance excita-tion at room temperature. A TW resonance control tuner for the 3-cell was also fabricated and the preliminary tests were performed. Now, the 3-cell cavity is being processed and prepared for the first cryogenic testing. 		 
poster icon Poster TUPTB043 [1.743 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB043  
About • Received ※ 17 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)  
 
TUPTB044 Compact Multicell Superconducting Crab Cavity for ILC cavity, HOM, impedance, dipole 521
 
  • A. Lunin, S.A. Belomestnykh, I.V. Gonin, T.N. Khabiboulline, Y.M. Orlov, V. Poloubotko, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by the Fermi National Accelerator Laboratory; managed by Fermi Research Alliance, LLC under Contract No. DEAC02-07CH11359 with the U.S. Department of Energy
We propose a novel design of a deflecting cavity for the ILC project with low parasitic HOM losses and preserving the beam emittance, which is critical for operation with high beam current intensity. Multiple electrodes immersed in the hollow waveguide form a trapped-mode resonator. The transverse components of the electromagnetic field of the trapped dipole mode induce a transverse kick and efficiently deflect charged particles passing through the cavity. We present a scalable design of a superconducting Quasi-waveguide Multicell Resonator (QMiR) seamlessly connected with a beam vacuum chamber. The cavity is completely open at both ends, which significantly reduces the maximum loaded quality factor of the higher order modes (HOM), avoids complex HOM couplers and thus simplifies the mechanical design of the cavity. The same port is used to feed RF power to the operating mode and to extract the same order modes (SOM). Finally, we estimate the expected cryogenic losses, HOM impedance limits, RF input power required, and frequency tuning for a QMiR cavity designed to operate at 2.6 GHz. 		 
poster icon Poster TUPTB044 [6.975 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB044  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 16 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB045 PIP-II SSR2 Cavities Fabrication and Processing Experience cavity, niobium, linac, target 526
 
  • M. Parise, P. Berrutti, D. Passarelli
    Fermilab, Batavia, Illinois, USA
  • P. Duchesne, D. Longuevergne
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  
  The Proton Improvement Plan-II (PIP-II) linac will include 35 Single Spoke Resonators type 2 (SSR2). A pre-production SSR2 cryomodule will contain 5 jacketed cavities. Several units are already manufactured and prepared for cold testing. In this work, data collected from the fabrication, processing and preparation of the cavities will be presented and the improvements implemented after the completion of the first unit will be highlighted.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB045  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 08 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB047 The Evaluation of Mechanical Properties of LB650 Cavities cavity, controls, cryomodule, niobium 536
 
  • G. Wu, S.D. Adams, D.J. Bice, S.K. Chandrasekaran, I.V. Gonin, C.J. Grimm, J.P. Holzbauer, T.N. Khabiboulline, C.S. Narug, J.P. Ozelis, H. Park, G.V. Romanov, R. Thiede, R. Treece, A.D. Wixson
    Fermilab, Batavia, Illinois, USA
  • K.E. McGee
    FRIB, East Lansing, Michigan, 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.
The 650 MHz cavities have a stronger requirement of niobium mechanical properties because of the geometric shape of the cavity due to reduced beta. The mechanical property of the niobium half-cell was measured following various heat treatments. The 5-cell cavities were tested in a controlled drop test fashion and the real-world road test. The result showed that the 900C heat treatment was compatible with cavity handling and transportation during production. The test provides the bases of the transportation specification and shipping container design guidelines. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB047  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 14 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB049 Horizontal Test Results of 1.3 GHz Superconducting RF Gun #2 at KEK gun, cavity, cathode, laser 540
 
  • T. Konomi, K. Hara, Y. Honda, K. Hosoyama, H. Inoue, E. Kako, Y. Kondo, M. Masuzawa, M. Omet, T. Takatomi, A. Terashima, K. Tsuchiya, R. Ueki, K. Umemori, X. Wang
    KEK, Ibaraki, Japan
  
  Superconducting radio-frequency (SRF) electron guns are attractive for delivery of beams at a high bunch repetition rate with a high accelerating field. KEK has been developing the SRF gun to demonstrate basic performance. The SRF gun consists of 1.3 GHz and 1.5 cell SRF gun cavity and K2CsSb photocathode coated on 2K cathode plug. In the vertical test, the surface peak electric field and the surface peak magnetic field reached to 75 MV/m and 170 mT respectively. The SRF gun was installed to horizontal multipurpose cryostat equipped with a superconducting solenoid, photocathode preparation chamber and beam diagnostic line. The results showed the peak surface electric field degraded to 42 MV/m. We suspect that cavity was contaminated during assembly. In this presentation, we will present the high gradient performance in vertical and horizontal test and individual test for each beam line components.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB049  
About • Received ※ 24 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 15 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB052 A Novel Manufacture of Niobium SRF Cavities by Cold Spray cavity, niobium, radio-frequency, experiment 545
 
  • M. Yamanaka
    KEK, Ibaraki, Japan
  • K. Shimada
    Nihon University, College of Engineering, Koriyama, Japan
  
  Cold spray is a lower-temperature solid-state thermal spray process that deposits metal powder using a heated inert gas through a supersonic nozzle. When the material hits at supersonic speed and reaches the critical speed, the particles themselves are plastically deformed to form a film. The material of the superconducting cavity is niobium, a very expensive rare metal. To reduce the amount of niobium and the cost, we propose a novel manufacturing method of forming a thick niobium film on the surface of a mandrel by cold spray using niobium powder and removing the mandrel to finish a hollow shape. We confirmed the feasibility of the proposed method using a model similar to a 3.9 GHz one-cell cavity. Also, the RRR measurement of the niobium specimen made by cold spray was carried out and the measured value of 11 was obtained. We report on these results.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB052  
About • Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 10 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB059 INFN LASA Experimental Activities for the PIP-II Project cavity, experiment, diagnostics, controls 549
 
  • M. Bertucci, M. Bonezzi, A. Bosotti, D. Cardelli, E. Del Core, F. Fiorina, A.T. Grimaldi, L. Monaco, C. Pagani, R. Paparella, D. Sertore, G.M. Zaggia
    INFN/LASA, Segrate (MI), Italy
  
  INFN LASA is upgrading its vertical test facility to allow high-Q measurements of the PIP-II LB650 SRF cavities. Such facility is equipped with a wide set of diagnostics for quench, field emission and magnetic flux expulsion studies and will offer a better understanding of cavity performance. At the same time, R&D on LB650 cavity prototypes is ongoing, in order to optimize the overall processing as well as the cavity Jacketing in view of the forthcoming series production with industry. This paper reports on the overall status of these experimental activities.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB059  
About • Received ※ 18 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)  
 
TUPTB061 Status of the ESS Medium Beta Cavities at INFN LASA cavity, cryomodule, linac, simulation 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)  
 
TUPTB063 Fabrication Efforts Toward a Superconducting Rf Photo-Infector Quarter-Wave Cavity for Use in Low Emittance Injector Applications cavity, niobium, cryomodule, gun 568
 
  • C. Compton
    NSCL, East Lansing, Michigan, USA
  • K. Elliott, W. Hartung, J.D. Hulbert, S.H. Kim, T. Konomi, S.J. Miller, M.S. Patil, J.T. Popielarski, L. Popielarski, K. Saito, K. Witgen, T. Xu
    FRIB, East Lansing, Michigan, USA
  • M. Kedzie, M.P. Kelly, T.B. Petersen
    ANL, Lemont, Illinois, USA
  • J.W. Lewellen, J. Smedley
    SLAC, Menlo Park, California, USA
  
  Funding: * Work supported by the Department of Energy Contract DE-AC02- 76SF00515
The Facility for Rare Isotope Beams (FRIB), in collaboration with Argonne National Laboratory (ANL) and Helmholtz-Zentrum Dresden-Rossendorf (HDZR), is working on the design and fabrication of a photo-injector cryomodule; suitable for operation as part of accelerator systems at SLAC National Accelerator Laboratory. Project scope requires the fabrication of two 185.7 MHz superconducting, quarter-wave resonators (QWR) based, injector cavities. Cavity fabrication will be completed at FRIB with contracted vendors supporting subcomponent fabrication and electron-beam welding. Fabrication will use poly-crystalline and large grain RRR niobium materials. The current status of cavity fabrication will be presented including material procurement, prototype forming, and electron-beam welding development. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB063  
About • Received ※ 17 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 21 August 2023 — Issue date ※ 21 August 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB069 Design and Tests of a Cathode Stalk for the LCLS-II-HE Low Emittance Injector SRF Gun cathode, gun, emittance, operation 589
 
  • T.K. Konomi, W. Hartung, S.H. Kim, S.J. Miller, D.G. Morris, K. Saito, A.T. Taylor, T. Xu, Z.Y. Yin
    FRIB, East Lansing, Michigan, USA
  • C. Adolphsen, J. Smedley, L. Xiao
    SLAC, Menlo Park, California, USA
  • S. Gatzmaga, P. Murcek, R. Xiang
    HZDR, Dresden, Germany
  • M.P. Kelly, T.B. Petersen
    ANL, Lemont, Illinois, USA
  • J.W. Lewellen
    LANL, Los Alamos, New Mexico, USA
  
  A SRF gun can operate CW with a high gradient and ultra-low vacuum for high-quantum efficiency, low MTE photocathodes, useful features for delivery of high-brightness, high-repetition-rate beams. For these reasons, an SRF gun based photoinjector was chosen for a proposed Low Emittance Injector addition to the LCLS-II-HE facility, which will operate CW with bunch rates up to 1 MHz. For this injector, a prototype 185.7 MHz QWR gun is being developed in a collaborative effort among FRIB, HZDR, ANL and SLAC, with the goal of achieving a photocathode gradient of at least 30 MV/m. The photocathode is held by a coaxial fixture (cathode stalk) for thermal isolation from the cavity body. The system must allow for precise alignment of the photocathode, particle-free photocathode exchange, cryogenic (55-70 K) or warm (273-300 K) photocathode operating temperatures, and DC biasing to inhibit multipacting. A prototype cathode stalk has been built and bench tests are underway to validate the design. Measurements include RF power dissipation, DC bias hold-off, multipacting suppression and heat transfer effectiveness. This paper describes the cathode stalk design and the test results.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB069  
About • Received ※ 03 July 2023 — Revised ※ 27 July 2023 — Accepted ※ 19 August 2023 — Issue date ※ 20 August 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEIAA03 Surface Roughness Reduction and Performance of Vapor-Diffusion Coating of Nb3Sn Film for SRF Application cavity, site, accelerating-gradient, factory 593
 
  • U. Pudasaini, M.J. Kelley, E.M. Lechner, C.E. Reece, O. Trofimova, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  
  Funding: This work is authored by Jefferson Science Associates LLC under U.S. DOE Contract No. DE-AC05- 06OR23177.
Nb₃Sn offers the prospect of better RF performance (Q and Eacc) than niobium at any given temperature because of its superior superconducting properties. Nb₃Sn-coated SRF cavities are routinely produced by growing a few microns thick Nb₃Sn film on Nb cavities via tin vapor diffusion. It has been observed that a clean and smooth surface can enhance the performance of the Nb₃Sn-coated cavity, typically, the attainable acceleration gradient. The reduction of surface roughness is often linked with a correlative reduction in average coating thickness and grain size. Besides Sn supply’s careful tuning, the temperature profiles were varied to reduce the surface roughness as low as ~40 nm in 20 µm × 20 µm AFM scans, one-third that of the typical coating. Samples were systematically coated inside a mock single-cell cavity and examined using different material characterization techniques. A few sets of coating parameters were used to coat 1.3 GHz single-cell cavities to understand the effects of roughness variation on the RF performance. This presentation will discuss ways to reduce surface roughness with results from a systematic analysis of the samples and Nb₃Sn-coated single-cell cavities. 		 
slides icon Slides WEIAA03 [7.231 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIAA03  
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)  
 
WEIAA04 Development of High-performance Niobium-3 Tin Cavities at Cornell University cavity, niobium, site, accelerating-gradient 600
 
  • L. Shpani, S.G. Arnold, G. Gaitan, M. Liepe, T.E. Oseroff, R.D. Porter, N.A. Stilin, Z. Sun, N.M. Verboncoeur
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • N. Sitaraman
    Cornell University, Ithaca, New York, USA
  
  Funding: Work supported by the National Science Foundation under Grant No. PHY-1549132, the Center for Bright Beam and U.S. DOE grant No. DE-SC0008431.
Niobium-3 tin is a promising material for next-generation superconducting RF cavities due to its high critical temperature and high theoretical field limit. There is currently significant worldwide effort aiming to improve Nb₃Sn growth to push this material to its ultimate performance limits. This talk will present an overview of Nb₃Sn cavity development at Cornell University. One approach we are pursuing is to further advance the vapor diffusion process through optimized nucleation and film thickness. Additionally, we are exploring alternative Nb₃Sn growth methods, such as the development of a plasma-enhanced chemical vapor deposition (CVD) system, as well as Nb₃Sn growth via electrochemical synthesis. 		 
slides icon Slides WEIAA04 [5.260 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIAA04  
About • Received ※ 29 June 2023 — Revised ※ 11 August 2023 — Accepted ※ 21 August 2023 — Issue date ※ 22 August 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WECAA01 Progress in European Thin Film Activities cavity, target, niobium, laser 607
 
  • C. Pira, O. Azzolini, R. Caforio, E. Chyhyrynets, D. Fonnesu, D. Ford, V.A. Garcia, G. Keppel, G. Marconato, A. Salmaso, F. Stivanello
    INFN/LNL, Legnaro (PD), Italy
  • C.Z. Antoine, Y. Kalboussi, Th. Proslier
    CEA-IRFU, Gif-sur-Yvette, France
  • C. Benjamin, O.B. Malyshev, N. Marks, B.S. Sian, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • C. Benjamin, J.W. Bradley, G. Burt, O.B. Malyshev, N. Marks, D.J. Seal, B.S. Sian, S. Simon, D.A. Turner, R. Valizadeh
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • S. Berry
    CEA-DRF-IRFU, France
  • R. Berton, D. Piccoli, F. Piccoli, G. Squizzato, F. Telatin
    Piccoli, Noale (VE), Italy
  • M. Bertucci, R. Paparella
    INFN/LASA, Segrate (MI), Italy
  • M. Bonesso, S. Candela, V. Candela, R. Dima, G. Favero, A. Pepato, P. Rebesan, M. Romanato
    INFN- Sez. di Padova, Padova, Italy
  • J.W. Bradley, S. Simon
    The University of Liverpool, Liverpool, United Kingdom
  • G. Burt, D.J. Seal, D.A. Turner
    Lancaster University, Lancaster, United Kingdom
  • O. Hryhorenko, D. Longuevergne
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • X. Jiang, T. Staedler, A.O. Zubtsovskii
    University Siegen, Siegen, Germany
  • S. Keckert, J. Knobloch, O. Kugeler
    HZB, Berlin, Germany
  • J. Knobloch
    University of Siegen, Siegen, Germany
  • N.L. Leicester
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • A. Medvids, A. Mychko, P. Onufrijevs
    Riga Technical University, Riga, Latvia
  • S. Prucnal, S. Zhou
    HZDR, Dresden, Germany
  • R. Ries
    Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
  • E. Seiler
    IEE, Bratislava, Slovak Republic
  • L.G.P. Smith
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  
  Funding: This project has received funding from the European Union s Horizon 2020 Research and Innovation programme under Grant Agreement No 101004730.
Thin-film cavities with higher Tc superconductors (SC) than Nb promise to move the operating temperature from 2 to 4.5 K with savings 3 orders of magnitude in cryogenic power consumption. Several European labs are coordinating their efforts to obtain a first 1.3 GHz cavity prototype through the I.FAST collaboration and other informal collaborations with CERN and DESY. R&D covers the entire production chain. In particular, new production techniques of seamless Copper and Niobium elliptical cavities via additive manufacturing are studied and evaluated. New acid-free polishing techniques to reduce surface roughness in a more sustainable way such as plasma electropolishing and metallographic polishing have been tested. Optimization of coating parameters of higher Tc SC than Nb (Nb₃Sn, V₃Si, NbTiN) via PVD and multilayer via ALD are on the way. Finally, rapid heat treatments such as Flash Lamp Annealing and Laser Annealing are used to avoid or reduce Cu diffusion in the SC film. The development and characterization of SC coatings is done on planar samples, 6 GHz cavities, choke cavities, QPR and 1.3 GHz cavities. This work presents the progress status of these coordinated efforts. 		 
slides icon Slides WECAA01 [15.846 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WECAA01  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 02 September 2023 — Issue date ※ 02 September 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEIBA01 Surface Engineering by ALD for Superconducting RF Cavities cavity, niobium, vacuum, site 615
 
  • Y. Kalboussi, C.Z. Antoine, M. Baudrier, Q. Bertrand, C. Boulch, B. Delatte, G. Jullien, L. Maurice, Th. Proslier, P. Sahuquet, T.V. Vacher
    CEA-IRFU, Gif-sur-Yvette, France
  • M. Asaduzzaman, T. Junginger
    UVIC, Victoria, Canada
  • M. Asaduzzaman
    TRIUMF, Vancouver, Canada
  • D. Dragoe
    ICMMO, Orsay, France
  • F. Éozénou
    CEA-DRF-IRFU, France
  • N. Lochet
    CEA, DES, Université Paris-Saclay, Gif-sur-Yvette, France
  • D. Longuevergne, T. Pépin-Donat
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • F. Miserque
    CEA, LECA, Université Paris-Saclay, Gif-sur-Yvette, France
  
  Atomic Layer Deposition is a synthesis method that enable a unique control of thin films chemical composition and thickness over complex shape objects such as SRF cavities. This level of control opens the way to new surface treatments and to study their effect on RF cavity performances. We will present coupon and, in some cases, preliminary cavity results, from various surface engineering routes based on the deposition of thin oxides and nitrides films combined with post annealing treatments and study their interactions with the niobium. Three main research directions will be presented: 1/ replacing the niobium oxides by other surface layers (Al₂O₃, Y2O3, MgO) and probe their effect on the low and high field performances, 2/ doping with N and combine approaches 1/ and 2/ and finally 3/ optimize the superconducting properties of NbTiN multilayers on Nb and Sapphire.  
slides icon Slides WEIBA01 [13.613 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIBA01  
About • Received ※ 06 July 2023 — Revised ※ 12 August 2023 — Accepted ※ 19 August 2023 — Issue date ※ 19 August 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEIXA02 Results of the R&D RF Testing Campaign of 1.3 GHz Nb/Cu Cavities cavity, niobium, operation, cryogenics 621
 
  • L. Vega Cid, S. Atieh, G. Bellini, A. Bianchi, L.M.A. Ferreira, C. Pereira Carlos, G.J. Rosaz, W. Venturini Delsolaro
    CERN, Meyrin, Switzerland
  • S.B. Leith
    European Organization for Nuclear Research (CERN), Geneva, Switzerland
  
  In the context of the R&D program on Nb/Cu carried out at CERN, a total of 25 tests have been performed since 2021. This talk will present these results. Three different manufacturing techniques have been used to produce the copper substrates, in order to investigate which is the most suitable in terms of quality and economy of scale. On one hand, the focus has been on optimizing the surface resistance at 4.2K, as this will be the operating temperature of FCC. The results at this temperature are encouraging, showing repeatable and optimized RF performance. On the other hand, RF tests have been done at 1.85 K too aiming at deepening the knowledge of the mechanisms behind the Q slope. This is key to work on the mitigation of this phenomenon and ultimately to extend the application of this technology to high energy, high gradient accelerators. The influence of the thermal cycles has been thoroughly investigated. A systematic improvement has been observed of both the Q slope and the residual resistance with slow thermal cycles.  
slides icon Slides WEIXA02 [5.385 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIXA02  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 02 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, simulation, niobium, 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 icon 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)  
 
WEIXA04 Development of the Directly-Sliced Niobium Material for High Performance SRF Cavities cavity, niobium, collider, linear-collider 634
 
  • A. Kumar, H. Araki, T. Dohmae, H. Ito, T. Saeki, K. Umemori, A. Yamamoto, M. Yamanaka
    KEK, Ibaraki, Japan
  • A. Yamamoto
    CERN, Meyrin, Switzerland
  
  For the purpose of cost reduction for the ILC, KEK has been conducting R&D on direct sliced Nb materials such as large grain and medium grain Nb. Single-cell, 3-cell, and 9-cell cavities have been manufactured, and each has demonstrated a high-performance accelerating gradient exceeding 35 MV/m. The results of applying high-Q/high-G recipes, such as two-step baking and furnace baking to these cavities are also shown. Moreover, mechanical tests have been carried out for the beforementioned materials to evaluate their strength for application to the High-Pressure Gas Safety Law. The status of development of these large grain and Medium grain Nb will be presented.  
slides icon Slides WEIXA04 [3.773 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIXA04  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 12 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEIXA05 Electropolishing Study on Nitrogen-Doped Niobium Surface cavity, niobium, cathode, radio-frequency 641
 
  • V. Chouhan, T.J. Ring, G. Wu
    Fermilab, Batavia, Illinois, USA
  • E.A.S. Viklund
    NU, Evanston, Illinois, USA
  
  The nitrogen doping (N-doping) process is applied to niobium (Nb) superconducting cavities to enhance their quality factors. The N-doping is followed by an electropolishing process that provides the final surface of the cavities. A controlled EP process is necessary to get the benefit of N-doping and achieve a high accelerating gradient. We have performed electropolishing of N-doped Nb surface under various conditions to understand their impact on the surface. A modified EP process was developed to obtain a smooth pit-free surface.  
slides icon Slides WEIXA05 [17.622 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIXA05  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 03 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEIXA06 Recent Advances in Metallographic Polishing for SRF Application cavity, niobium, laser, framework 646
 
  • O. Hryhorenko
    JLab, Newport News, Virginia, USA
  • C.Z. Antoine, F. Éozénou, Th. Proslier
    Université Paris-Saclay, CEA, Gif-sur-Yvette, France
  • T. Dohmae
    KEK, Ibaraki, Japan
  • S. Keckert, J. Knobloch, O. Kugeler
    HZB, Berlin, Germany
  • D. Longuevergne
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  
  Funding: ENSAR-2 under grant agreement N° 654002. IFAST under Grant Agreement No 101004730. The U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
This talk is an overview of the metallographic polishing R&D program covering Niobium and Copper substrates treatment for thin film coating as an alternative fabrication pathway for 1.3 GHz elliptical cavities. The presented research is the result of a collaborative effort between IJCLab, CEA/Irfu, HZB, and KEK in order to develop innovative surface processing and cavity fabrication protocols capable of meeting stringent requirements for SRF surfaces, including the reduction of safety risks and ecological footprint, enhancing reliability, improving the surface roughness, and potentially allowing cost reduction. The research findings will be disclosed. 		 
slides icon Slides WEIXA06 [7.469 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIXA06  
About • Received ※ 16 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 14 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB001 Preparation and Characterization of Nb Films Deposited in SRF Cavity via HiPIMS cavity, niobium, site, lattice 651
 
  • P. He, J. Dai, H.C. Duan, J.W. Kan, Y. Ma, T. Xin, Y.C. Yang, P. Zhang
    IHEP, Beijing, People’s Republic of China
  
  The RF performance of the niobium superconducting cavity has been continuously improved in recent 50 years. Since the maximum acceleration field (Eacc) has approached its theoretical limit, developing a more efficient and low-cost SRF cavity is one of the key challenges of the next generation particle accelerators. Niobium coated copper cavities are promising solutions because the SRF phenomenon occurrs within several hundred nanometers under the cavity surface. In literatures, the Nb coated Cu cavity prepared by direct current magnetron sputtering (DCMS) has serious Q-slope problem, which may be related to the low energy deposition. High power impulse magnetron sputtering (HiPIMS) can produce a high peak power and high ionization rate which may improve the thin film quality. Therefore, we prepared Nb coated Cu samples via HiPIMS on the 1.3 GHz dummy cavity at IHEP.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB001  
About • Received ※ 15 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 20 August 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB044 Realization of Accelerating Gradient Larger than 25 MV/m on High-Q 1.3 GHz 9-Cell Cavities for SHINE cavity, accelerating-gradient, experiment, FEL 658
 
  • Y. Zong, Q.X. Chen, X. Huang, Z. Wang
    SINAP, Shanghai, People’s Republic of China
  • J.F. Chen, P.C. Dong, H.T. Hou, X.Y. Pu, J. Shi, S. Sun, D. Wang, J.N. Wu, S. Xing, S.J. Zhao, Y.L. Zhao
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  • Y.W. Huang
    ShanghaiTech University, Shanghai, People’s Republic of China
  • X.W. Wu
    Zhangjiang Lab, Shanghai, People’s Republic of China
  
  Funding: This work was supported by Shanghai Municipal Science and Technology Major Project (No. 2017SHZDZX02).
We present our studies on the optimized nitrogen-doping and medium-temperature baking recipes applied on 1.3GHz SRF cavities, aiming at meeting the requirements of the SHINE project. The optimized nitrogen-doping process resulted in achieving a Q₀ of over 4.0×1010 at medium field and a maximum accelerating gradient exceeding 35 MV/m on single cell cavities, and a Q₀ of over 2.8×1010 at medium field and a maximum accelerating gradient exceeding 26 MV/m in 9-cell cavities. For 1.3 GHz 9-cell cavities subjected to medium-temperature baking, Q₀ values exceeding 3.5×1010 at 16 MV/m and maximum accelerating gradients surpassing 25 MV/m were achieved. These studies provide two options of high-Q recipes for SHINE cavities. The treatment processes of cavities and their vertical test results are described in this paper.
*chenjinfang@sari.ac.cn
 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB044  
About • Received ※ 19 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 26 June 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB045 The Oxidizing Responses of Baked Niobium Exposed to Various Gases via In-situ NAXPS niobium, cavity, experiment, vacuum 662
 
  • Z.T. Yang, J.K. Hao, K.X. Liu, S.W. Quan
    PKU, Beijing, People’s Republic of China
  
  We carried out in-situ NAXPS (Near-atmospheric X-ray Photoelectron Spectroscopy) on SRF-cavity class niobium to observe its oxidizing responses when exposed to various gases. The niobium samples were baked at 800°C until the peaks of niobium oxides disappeared in the spectrum. Then the revealed pure niobium samples were exposed to the air-proportion mixture of nitrogen and oxygen, pure oxygen, and pure water vapor respectively. And for the pure oxygen and water vapor group, we also carried out TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectroscopy) measurements before and after the baking and oxidation experiments. We found that pure oxygen and water vapor could oxidize niobium at similar rate which was faster than the N2/O2 mixture. After re-oxidized by pure oxygen and water vapor, the niobium sample presented a significant increase of interstitial carbon and a moderate increase of interstitial oxygen in the magnetic penetration depth, while it showed a mild decrease of interstitial hydrogen.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB045  
About • Received ※ 15 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 25 June 2023 — Issue date ※ 31 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB047 Higher Order Mode Analysis of a 915 MHz 2-Cell Cavity for a Prototype Industrial Accelerator cavity, impedance, HOM, higher-order-mode 667
 
  • A. Castilla
    JLAB, Newport News, USA
  • G. Ciovati, J. Guo, G.-T. Park, R.A. Rimmer, H. Vennekate
    JLab, Newport News, Virginia, USA
  
  A possible solution to reduce the complexity posed by the cryogenic systems in a superconducting RF accelerator for industrial applications, is to capitalize on the advances achieved by the Nb₃Sn superconducting RF technology, as well as the feasibility of a reliable 4 K cooling system, based on commercial cryocoolers. Following this philosophy, the conceptual design for a prototype, conduction-cooled, 4 MeV, 20 kW SRF electron linac, is being developed at Jefferson Lab. Such design is based on a 915 MHz two-cell Nb₃Sn cavity. In this contribution, we present the proposed cavity design, including the fundamental power coupler, and the preliminary analysis of the Higher Order Modes, using numerical simulations to estimate the potentially dangerous modes as a starting point to evaluate the requirements for damping for reliable operations with a cryocooler. Finally, different methods to calculate the Higher Order Modes’ Impedances are briefly discussed.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB047  
About • Received ※ 25 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 04 July 2023 — Issue date ※ 16 July 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, simulation, 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, simulation, 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)  
 
WEPWB050 Exploring Innovative Pathway for SRF Cavity Fabrication cavity, niobium, laser, electron 680
 
  • O. Hryhorenko
    JLab, Newport News, Virginia, USA
  • C.Z. Antoine
    Université Paris-Saclay, CEA, Gif-sur-Yvette, France
  • T. Dohmae
    KEK, Ibaraki, Japan
  • D. Longuevergne
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Funding: ENSAR-2 under grant agreement N° 654002. The U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
This article shows a study on an alternative pathway for the fabrication of a complete 1.3 GHz SRF cavity, aiming at improving production reliability, reducing the use of chemical polishing (EP or BCP) which is a costly and safety-critical step, and preserving surface quality after forming. Unlike the conventional pathway, the fabrication process is performed after polishing. This point is crucial as the used polishing technology could be applied only to flat geometries. The performed investigation demonstrates that damages during the fabrication process are considered minor, localized, and limited to the near-surface. Moreover, these studies confirm that the damaged layer (100-200 µm) is mainly caused by the rolling process, and not by the subsequent fabrication steps. A laser confocal microscope and SEM-EBSD technique were used to compare samples before and after forming. The preliminary results are discussed and presented in this paper. 		 
poster icon Poster WEPWB050 [2.263 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB050  
About • Received ※ 20 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 01 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB052 Temperature, RF Field, and Frequency Dependence Performance Evaluation of Superconducting Niobium Half-Wave Coaxial Cavity cavity, niobium, radio-frequency, experiment 691
 
  • N.K. Raut, G. Ciovati, P. Dhakal
    JLab, Newport News, Virginia, USA
  • S.U. De Silva, J.R. Delayen, B.D. Khanal, J.K. Tiskumara
    ODU, Norfolk, Virginia, USA
  
  Funding: This is authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05- 06OR23177
Recent advancement in superconducting radio frequency cavity processing techniques, with diffusion of impurities within the RF penetration depth, resulted in high quality factor with increase in quality factor with increasing accelerating gradient. The increase in quality factor is the result of a decrease in the surface resistance as a result of nonmagnetic impurities doping and change in electronic density of states. The fundamental understanding of the dependence of surface resistance on frequency and surface preparation is still an active area of research. Here, we present the result of RF measurements of the TEM modes in a coaxial half-wave niobium cavity resonating at frequencies between 0.3 - 1.3 GHz. The temperature dependence of the surface resistance was measured between 4.2 K and 1.6 K. The field dependence of the surface resistance was measured at 2.0 K. The baseline measurements were made after standard surface preparation by buffered chemical polishing. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB052  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 20 July 2023
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WEPWB053 Simulation of the Dynamics of Gas Mixtures during Plasma Processing in the C75 Cavity cavity, plasma, electron, simulation 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)  
 
WEPWB055 First Experience with Liquid Nitrogen Cleaning cavity, cryomodule, operation, booster 706
 
  • R.J.M.Y. Ruber, A.B. Eslinger, R.L. Geng
    JLab, Newport News, Virginia, USA
  
  Field emission caused by microscopic particulate contamination is a limiting factor for the performance of superconducting RF (SRF) cavities. In an SRF accelerator, particulates may be transported over the surface of an operational SRF cavity, becoming field emitters and consequentially degrading the performance of the SRF cavity. The most commonly used method for removing particulates from cavity surfaces is high-pressure ultra-pure water rinsing. We are developing a novel high-pressure liquid nitrogen cleaning technique that may possibly enable superior cleaning power and particulate removal from cavities in a cryomodule without taking apart the cryomodule components. This technique provides cleaning mechanisms beyond what are accessible by its high-pressure water counterpart and leaves no residues on the cleaned surface. We present the test setup and first experience.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB055  
About • Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 27 June 2023
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WEPWB058 Contribution of IN2P3 to PIP-II Project: Plans and Progress cavity, linac, vacuum, status 714
 
  • D. Longuevergne, N. Bippus, P. Duchesne, N. Gandolfo, D. Le Dréan, G. Mavilla, T. Pépin-Donat, S. Roset, L.M. Vogt, S. Wallon
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • P. Berrutti, J. Helsper, S. Kazakov, M. Parise, D. Passarelli, N. Solyak, A.I. Sukhanov
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by IN2P3. Work supported, in part, by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under U.S. DOE Contract No. DE-AC02-07CH11359.
IJCLab is one of the labs of IN2P3 (National institute of nuclear and particle physics), one of the ten research institutes composing the French National Center for Scientific Research (CNRS). Since 2018, IJCLab has been involved in the PIP-II project, assisting with the design, development, and qualification of accelerator components for the SSR2 (Single Spoke Resonator type 2) section of the superconducting linac. The first pre-production components (cavity, coupler, and tuner) have been fabricated, and some of the first qualification tests have been performed at IJCLab. This paper will summarize the complete scope of IJCLab¿s contributions to PIP-II and give updates on the performances of the first pre-production components. 		 
poster icon Poster WEPWB058 [1.727 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB058  
About • Received ※ 24 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 05 July 2023 — Issue date ※ 10 July 2023
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WEPWB065 Impact of Medium Temperature Heat Treatments on the Magnetic Flux Expulsion Behavior of SRF Cavities cavity, controls, niobium, experiment 731
 
  • J.C. Wolff, J. Eschke, A. Gössel, K. Kasprzak, D. Reschke, L. Steder, L. Trelle, M. Wiencek
    DESY, Hamburg, Germany
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  
  Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program.
Medium temperature (mid-T) heat treatments at 300 °C are used to enhance the intrinsic quality factor of superconducting radio frequency (SRF) cavities. Unfortunately, such treatments potentially increase the sensitivity to trapped magnetic flux and consequently the surface resistance of the cavity. For this reason, it is crucial to maximize the expulsion of magnetic flux during the cool down. The flux expulsion behavior is next to the heat treatment mainly determined by the geometry, the niobium grain size and the grain orientation. However, it is also affected by parameters of the cavity performance tests like the cool down velocity, the spatial temperature gradient along the cavity surface and the magnetic flux density during the transition of the critical temperature. To improve the flux expulsion behavior and hence the efficiency of future accelerator facilities, the impact of these adjustable parameters as well as the mid-T heat treatment on 1.3 GHz TESLA-Type single-cell cavities is investigated by a new approach of a magnetometric mapping system. In this contribution first performance test results of cavities before- and after mid-T heat treatment are presented. 		 
poster icon Poster WEPWB065 [3.077 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB065  
About • Received ※ 21 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 13 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB067 HB650 Cryomodule Design: From Prototype to Production cryomodule, cavity, radiation, vacuum 741
 
  • V. Roger, S.K. Chandrasekaran, C.J. Grimm, J.P. Holzbauer, O. Napoly, J.P. Ozelis, D. Passarelli
    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.
In early 2023 the assembly of the prototype HB650 cryomodule (pHB650 CM) was completed and cold tests started to evaluate its performance. The lessons learned from the design, assembly and preliminary cold tests of this cryomodule, and from the design of the SSR2 pre-production cryomodule played a fundamental role during the design optimization process of the production HB650 cryomodule (HB650 CM). Several workshops have been organized to share experiences and solve problems. This paper presents the main design changes from pHB650 to the HB650 production cryomodules and their impact on the heat loads. 		 
poster icon Poster WEPWB067 [2.178 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB067  
About • Received ※ 18 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 01 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB068 Characterization of Additive Manufacturing Materials for String Assembly in Cleanroom cryomodule, cavity, linac, detector 746
 
  • J. Bernardini, M. Parise, D. Passarelli
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy, Office of Science, Office of High Energy Physics.
Beamline components, such as superconducting radio frequency cavities and focusing lenses, need to be assembled together in a string while in a cleanroom environment. The present contribution identifies and characterizes materials for additive manufacturing that can be used in a cleanroom. The well known advantages of additive manufacturing processes would highly benefit the design and development of tooling needed for the mechanical support and alignment of string components. Cleanliness, mechanical properties, and leak tightness of the chosen materials are the main focus of this contribution, which also paves the way for the integration of such materials in cryomodule assemblies. Results reported here were obtained in the framework of the PIP-II project at Fermilab. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB068  
About • Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 04 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB070 Test Shipment of the PIP-II 650 MHz Transport Frame Between FNAL to STFC-UKRI cryomodule, ISOL, linac, acceleration 750
 
  • J.P. Holzbauer, S.K. Chandrasekaran, C.J. Grimm, J.P. Ozelis, R. Thiede, A.D. Wixson
    Fermilab, Batavia, Illinois, USA
  • M.T.W. Kane
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy
The PIP-II Project will receive fully assembled cryomodules from CEA and STFC-UKRI as in-kind contributions. Damage to these cryomodules during transport is understood to be a significant risk to the project, so an extensive testing and validation program is in process to mitigate this risk. The centerpiece of this effort is the eventual shipment from FNAL to STFC-UKRI and back of a prototype HB650 cryomodule with cold testing before and after shipment to verify no functionality changes from shipment. Most recently, a test shipment to the UK and back using a cryomodule analog was completed using realistic logistics, handling, instrumentation, and planning. The process of executing this test shipment, lessons learned, and plan moving forward will be presented here. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB070  
About • Received ※ 18 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 17 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB073 Prototype HB650 Cryomodule Heat Loads Simulations cryomodule, cavity, experiment, cryogenics 755
 
  • G. Coladonato
    University of Illinois at Chicago, Chicago, USA
  • D. Passarelli, V. Roger
    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.
During the design stages of the PIP-II cryomodules, many analytical calculations and FEA have been performed on simpler geometry in order to estimate the heat loads and also to optimize the design. To better analyze the cryomodule cold tests, simulations have been performed with MATLAB to determine the temperature of the main components during cool down and to determine the heat loads of the cryomodule. These simulations have been applied to the High Beta 650 MHz prototype cryomodule design and compared to the cold tests performed on it. 		 
poster icon Poster WEPWB073 [1.981 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB073  
About • Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 28 June 2023
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WEPWB075 Impact of Solenoid Induced Residual Magnetic Fields on the Prototype SSR1 CM Performance cavity, cryomodule, focusing, solenoid 760
 
  • D. Passarelli, J. Bernardini, C. Boffo, S.K. Chandrasekaran, A.H. Hogberg, T.N. Khabiboulline, J.P. Ozelis, M. Parise, V. Roger, G.V. Romanov, A.I. Sukhanov, G. Wu, Y. Xie, V.P. Yakovlev
    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 prototype cryomodule containing eight Single Spoke Resonators type-1 (SSR1) operating at 325 MHz and four superconducting focusing lenses was successfully assembled, cold tested, and accelerated beam in the framework of the PIP-II project at Fermilab. The impact of induced residual magnetic fields from the solenoids on performance of cavities is presented in this contribution. In addition, design optimizations for the production cryomodules as a result of this impact are highlighted. 		 
poster icon Poster WEPWB075 [2.429 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB075  
About • Received ※ 26 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 11 July 2023
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WEPWB076 Low Particulates Nitrogen Purge and Backfill during Prototype HB650 Cryomodule String Assembly cavity, controls, vacuum, cryomodule 765
 
  • T.J. Ring, M.B. Quinlan, G. Wu
    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 low particulate vacuum and purging system was developed to support PIP-II cryomodule string assembly. The overpressure can be controlled at a precision of 1 mbar above the atmospheric pressure regardless of the cavity or string assembly air volume. The system minimized the risk of uncontrolled nitrogen flow during the string assembly. Design features will be presented. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB076  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 09 July 2023
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WEPWB082 Operational Experience with Turn-Key SRF Systems for Small Accelerators Like MESA cryomodule, operation, cryogenics, cavity 768
 
  • T. Stengler, K. Aulenbacher, F. Hug, P.S. Plattner
    KPH, Mainz, Germany
  
  Funding: The work is funded by the German Research Foundation (DFG) under the Cluster of Excellence "PRISMA+" EXC 2118/2019 and the Federal Ministry of Education and Research (BMBF) through project 05H21UMRB1
New SRF-based accelerator development at sites without long-term experience in SRF development is a major challenge. Especially in-house development of cryomodules is an almost impossible obstacle to overcome for small projects. To minimize such obstacles, turn-key SRF systems provided by industry can be of great importance. For the multiturn ERL MESA, which is currently under construction at Johannes Gutenberg-Universität Mainz, two turnkey cryomodules have been purchased from industry and successfully tested. The specifications of a design gradient of 12.5 MV/m in CW operation with an unloaded Q of 1.25*1010 at 1.8 K had to be met. Since the design of the modules had to be modified for high current CW operation, a close cooperation with the manufacturer was of great importance. By purchasing such a turn-key SRF system, the MESA project successfully established the SRF accelerator technology at the site within six years. This was achieved through close monitoring of the manufacturing process and close cooperation with the manufacturer. An overview of the experience with the successful technology transfer of a complete turn-key SRF system for small accelerators will be given. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB082  
About • Received ※ 25 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 03 August 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB083 Basic Design and Consideration of Li-Vapor Contamination for A-FNS SRF cavity, solenoid, linac, operation 773
 
  • T. Ebisawa, K. Hasegawa, A. Kasugai, M. Oyaidzu, S. Sato
    QST Rokkasho, Aomori, Japan
  • E. Kako, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
  
  The Advanced Fusion Neutron Source (A-FNS) project is in progressing in Japan, QST Rokkasho institute. A-FNS will demonstrate a performance of the DEMO DT fusion reactor material. In order to perform the test, a high intensity deuteron beam accelerator will be used to produce a high flux neutron field which is similar to the 14 MeV DT neutron. The Superconducting Radio-Frequency linear accelerator (SRF) is one component of the A-FNS accelerator system. Although the A-FNS accelerator system design is based on the IFMIF design, the improvement of some subsystem has been considering by taking into account the lessons learnt from the LIPAc project. In order to keep a high stability and availability of the SRF performance, we plan to increase the number of SRF cavities and cryomodules considering the trouble or degradation of the cavity performance and modify the engineering design of some components. In addition, changing of the beam transport line design and Li vapor contamination study of SRF cavity are conducting. In this presentation, the progress of the SRF design and related activities for A-FNS in QST will be presented.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB083  
About • Received ※ 28 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 17 August 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB085 Degradation and Recovery of Cavity Performance in SRILAC Cryomodules at RIBF cavity, operation, vacuum, acceleration 784
 
  • N. Sakamoto, O. Kamigaito, K. Ozeki, K. Suda, K. Yamada
    RIKEN Nishina Center, Wako, Japan
  
  The RIKEN superconducting (SC) heavy-ion linear accelerator (SRILAC) has been providing beam supply for super-heavy elements synthesis experiments since its commissioning in January 2020. However, the long-term operation of SC radio-frequency (RF) cavities leads an increase in the X-ray levels caused by field emissions resulting from changes in the inner surface conditions. More than half of the ten SC 1/4 wavelength resonators (SC-QWRs) of SRILAC, operating at a frequency of 73 MHz, have experienced an increase in X-ray levels, thus, requiring adjustments to the acceleration voltage for continuous operation. While several conditioning methods have been employed for SC cavities, a fully established technique is yet to be determined. To address this situation, a relatively simple conditioning method was implemented at RIKEN. The proposed method uses high-voltage pulsed power and imposes a low load on the cavities.  
poster icon Poster WEPWB085 [12.789 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB085  
About • Received ※ 13 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 01 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB087 Copper Plating Qualification Process for the Fundamental Power Coupler Waveguides for CEBAF Cryomodules GUI, cryomodule, cavity, operation 790
 
  • L. Zhao, G. Cheng, G. Ciovati, K.M. Wilson
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC, supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
To provide sufficient energy for CEBAF operation, cryomodules and components are being refurbished yearly as necessary. Copper plated fundamental power coupler waveguides are important components of the cryomodules. The integrity and quality of copper plating is critical to reduce the heat load from the waveguides into the He bath at 2.07 K. A search of copper plating resources is underway for plating or re-plating CEBAF-style waveguides. This effort ensures a continuous capability of copper plating on cryomodule components, especially on waveguides. To qualify plating vendors, the waveguide copper plating specifications were revisited, and a thorough plating evaluation process is being developed. The evaluation process ranges from coupon testing to sample waveguide qualification. Recent results are summarized and future work is planned. 		 
poster icon Poster WEPWB087 [1.582 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB087  
About • Received ※ 15 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 11 July 2023
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WEPWB089 Theoretical Model of External Q Tuning for an SRF Cavity with Waveguide Tuner cavity, GUI, operation, electron 794
 
  • W. Xu, Z.A. Conway, K.S. Smith, A. Zaltsman
    BNL, Upton, New York, USA
  • E.F. Daly, J. Guo, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  
  Funding: The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
A wide range of electron beam energies (5 ¿ 18 GeV) and beam currents (0.2 ¿ 2.5 A) in EIC Electron Storage Ring (ESR) operating scenarios requires a capability of adjusting coupling factor up to a factor of 20 for the 591 MHz Superconducting Radio Frequency (SRF) cavities, which contains two fundamental power couplers (FPC) delivering continuous wave (CW) 800 kW RF power to the beam. Currently, adjusting external Q of a SRF cavity is done by varying protrusion of FPC¿s inner conductor in beam pipe or using three stub tuner to adjust external Q value, which either has limit on tuning range or limit on operating power. This paper presents a method of tuning the FPC external Q by a multiple-waveguide tuner, which allows for high power, wide tuning range operations. The theoretical model of matching beam impedance with waveguide tuner and detailed matching conditions and limits will be presented. Follow the theoretical model, a preliminary design of a 3D waveguide tuner will be presented.
The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
 		 
poster icon Poster WEPWB089 [1.269 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB089  
About • Received ※ 26 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 22 August 2023
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WEPWB093 Transportation Fatigue Testing of the pHB650 Power Coupler Antenna for the PIP-II Project at Fermilab vacuum, linac, cryomodule, resonance 801
 
  • J. Helsper, S.K. Chandrasekaran, J.P. Holzbauer, N. Solyak
    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.
The PIP-II Project will see international shipment of cryomodules from Europe to the United States, and as such, the shocks which can occur during shipment pose a risk to the internal components. Of particular concern is the coupler ceramic window and surrounding brazes, which can see relatively high stress during an excitation event. Since the antenna design is new, and because of the setback failure would create, a cyclic stress test was devised for the antenna. This paper presents the experimental methods, setup, and results of the test. 		 
poster icon Poster WEPWB093 [2.913 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB093  
About • Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 03 July 2023
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WEPWB094 Design, Manufacturing, Assembly, and Lessons Learned of the Pre-Production 325 MHz Couplers for the PIP-II Project at Fermilab vacuum, cavity, interface, cryomodule 806
 
  • J. Helsper, S. Kazakov, D. Passarelli, N. Solyak
    Fermilab, Batavia, Illinois, USA
  • D. Longuevergne, S. Wallon
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  
  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.
Five 325 MHz high-power couplers will be integrated into the pre-production Single Spoke Resonator Type-II (ppSSR2) cryomodule for the PIP-II project at Fermilab. Couplers were procured by both Fermilab and IJCLAB for this effort. The design of the coupler is described, including design optimizations from the previous generation. This paper then describes the coupler life cycle, including design, manufacturing, and assembly, along with the lessons learned at each stage. 		 
poster icon Poster WEPWB094 [3.561 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB094  
About • Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 29 June 2023
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WEPWB097 Testing and Processing of Pre-production 325 MHz Single Spoke Resonator Power Couplers for PIP-II Project vacuum, cavity, coupling, pick-up 816
 
  • N. Solyak, B.M. Hanna, J. Helsper, S. Kazakov, D. Passarelli
    Fermilab, Batavia, Illinois, USA
  • S. Wallon
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  
  Fundamental 325 MHz power couplers are designed, built and tested for SSR cavities in PIP-II project [1]. Couplers should work in CW mode at power level 7.5kW w/o beam and ~15 kW with the 2 mA beam. At pre-production stage we built and tested 6 couplers, produced by CPI (FNAL) and PMB (IJCLab) and 4 more couplers will be tested soon. Two of tested cou-plers had TiN coated ceramic window. In warm test stand two couplers were mounted on the coupling chamber and tested in SW regime at full reflection with phase controlled by position of short and reflection insert. Couplers were tested at pulse mode (up to 25kW) and cw mode (12kW) with HV bias or without bias. Test results demonstrated that 3.5 kV DC bias completely suppresses multipactor in coupler. Vacuum activity in coupler was controlled by e-pickups and build-in vacuum gauges, located near the vacuum side of window. Power processing without DC bias was done for several couplers with and without TiN coating on ceramic window. Test results are presented and discussing in paper.  
poster icon Poster WEPWB097 [2.439 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB097  
About • Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 29 June 2023
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WEPWB098 Development and Evaluation of STF-Type Power Coupler for Cost Reduction at the High Energy Accelerator Research Organization vacuum, GUI, cryomodule, cavity 820
 
  • Y. Yamamoto, T. Matsumoto, S. Michizono
    KEK, Ibaraki, Japan
  
  At KEK, cost reduction study for STF-type input power coupler used in the STF-2 accelerator has been attempted since FY2015. In FY2019, one coupler was fabricated by some cost-effective and non-conventional methods including different alumina-ceramic material, copper plating and TiN coating. In high power RF test at room temperature, this coupler achieved 1 MW at 900 µsec/5Hz, and 935 kW @1.65 msec/5Hz. After that, this coupler experienced 10 thermal cycle tests from room temperature to liquid nitrogen temperature without vacuum leakage. In this report, the detailed results will be presented.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB098  
About • Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 02 July 2023
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WEPWB101 Present Status of RIKEN Power Couplers for SRILAC vacuum, Windows, linac, operation 823
 
  • K. Ozeki, O. Kamigaito, N. Sakamoto, K. Suda, K. Yamada
    RIKEN Nishina Center, Wako, Japan
  
  The heavy ion linac of the RIKEN, utilizing superconducting technology, began operations in September 2019. Over the following 13 months, two of the ten superconducting accelerating cavities experienced vacuum leaks from the vacuum windows of the fundamental power couplers (FPCs). Currently, additional vacuum windows are installed on all ten FPCs and the beam supply continues without encountering any major issues with the FPCs. Additionally, the fabrication of ten replacement FPCs has been completed, addressing the underlying issues that led to the deterioration of the vacuum window strength. Currently, we are conducting radio frequency (RF) process of the new FPCs. In addition, we are designing a bias applying component to suppress multipacting in the FPCs. This paper reports the status of these issues related to the FPCs at the RIKEN.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB101  
About • Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 14 July 2023
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WEPWB108 Update on Cornell High Pulsed Power Sample Host Cavity cavity, coupling, pulsed-power, simulation 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
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WEPWB109 PI Loop Resonance Control for the Dark Photon Experiment at 2 K using a 2.6 GHz SRF cavity cavity, photon, simulation, experiment 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 icon 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
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WEPWB110 Prevention of Dual-Mode Excitation in 9-Cell Cavities for LCLSII-HE cavity, resonance, controls, feedback 852
 
  • P.D. Owen
    JLab, Newport News, Virginia, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Dual-Mode Excitation, also referred to as mode-mixing, is a superposition of two pi modes in an SRF cavity. In 9-cell TESLA cavities used for the LCLSII-HE project, the two modes that are commonly excited are the pi mode (1300.2 MHz), and the 7/9 pi mode (1297.8 MHz). During vertical cavity qualification testing, it is regularly observed that emitted power at the frequency of the 7/9 pi mode grows, despite the RF system only driving the pi mode. When this happens, the RF power measurement system is unable to differentiate between the superimposed modes which invalidates any data taken. A new RF control solution prevents the 7/9 pi mode from being excited. A second RF control system is connected to drive the 7/9 pi mode. The loop phase for driving this mode is determined, then shifted by 180 degrees, thus providing a negative feedback to the undesired mode. Because this off-resonance power can be very small, it does not interfere with the high-power measurements of the fundamental pi mode. At Jefferson Lab, we are now able to test a cavity for the LCLSII-HE project with no complications from mode-mixing, which allows for CW processing of high-gradient multipacting. 		 
poster icon Poster WEPWB110 [1.818 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB110  
About • Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 13 July 2023
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WEPWB111 A New Ultra-High Vacuum Furnace for SRF R&D cavity, vacuum, niobium, operation 855
 
  • M. Wenskat, C. Bate
    DESY, Hamburg, Germany
  • C. Bate, C. Martens
    University of Hamburg, Hamburg, Germany
  • R. Ghanbari, W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  
  Funding: This work was supported by the BMBF under the research grants 05K19GUB and 05H2021.
A new vacuum furnace has been designed and purchased by the University of Hamburg and is operating in an ISO5 cleanroom. This furnace can anneal single-cell TESLA cavities at temperatures up to 1000°C and with a pressure of less than 10-7mbar or in a nitrogen atmosphere of up to 10-2mbar. We will lay out the underlying design ideas, based on the gained experience from our previous annealing research, and present the commissioning of the furnace itself. Additionally, we will show for the first time the results of sample and cavity tests after annealing in the furnace. This will be accompanied by an overview of the intended R&D process and scientific questions to be addressed. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB111  
About • Received ※ 21 June 2023 — Revised ※ 15 July 2023 — Accepted ※ 20 August 2023 — Issue date ※ 21 August 2023
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WEPWB113 Evaluation of Photo-Cathode Port Multipacting in the SRF Photo-Injector Cryomodule for the LCLS-II High-Energy Upgrade cathode, simulation, electron, 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 icon 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
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WEPWB116 The Influence of Sample Preparation, Soak Time, and Heating Rate on Measured Recrystallization of Deformed Polycrystalline Niobium cavity, ECR, niobium, electron 863
 
  • Z.L. Thune
    MSU, East Lansing, USA
  • T.R. Bieler
    Michigan State University, East Lansing, Michigan, USA
  
  Funding: DOE/OHEP (Grant Number: DE-SC0009960)
Improving accelerator performance relies on consistent production of high-purity niobium superconducting radiofrequency (SRF) cavities. Current production uses an 800 °C 3 hr heat treatment, but 900-1000 °C can improve cavity performance via recrystallization (Rx) and grain growth. As Rx is thermally activated, increasing the temperature and/or the heating rate could facilitate a reduction in geometrically necessary dislocation (GND) density that is associated with the degradation of cavity performance via trapped magnetic flux. Recent work shows that increasing the annealing temperature increased the Rx fraction in cold-rolled polycrystalline niobium. However, the influence of heating rate on the extent of Rx was minimal with a 3 hr soak time. To further assess the influence of heating rate on measured Rx, as well as the effects of sample preparation, electron backscatter diffraction (EBSD) was used to quantify the extent of Rx on samples annealed at a single temperature with different soak times. Comparing samples with different surface preparation shows that pinned grain boundaries on the free surface reveal a much smaller grain size than below the surface.
* Z.L. Thune et al., "The Influence of Strain Path and Heat Treatment Variations on Recrystallization in Cold-Rolled High-Purity Niobium Polycrystals," doi: 10.1109/TASC.2023.3248533. 		 
poster icon Poster WEPWB116 [1.312 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB116  
About • Received ※ 23 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 20 August 2023 — Issue date ※ 21 August 2023
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WEPWB119 Additive Manufacturing of Pure Niobium and Copper Using Laser Powder Bed Fusion for Particle Accelerator Applications cavity, niobium, laser, plasma 872
 
  • D. Ford, R. Caforio, E. Chyhyrynets, G. Keppel, C. Pira
    INFN/LNL, Legnaro (PD), Italy
  • M. Bonesso, S. Candela, V. Candela, R. Dima, G. Favero, A. Pepato, P. Rebesan, M. Romanato
    INFN- Sez. di Padova, Padova, Italy
  • M. Pozzi
    Rösler Italiana s.r.l., Concorezzo, 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.
In this study, Metal Additive Manufacturing (MAM) was evaluated as a viable method for producing seamless 6 GHz pure copper and niobium prototypes without the use of internal supports. Preliminary tests were performed to evaluate printability, leading to further investigations into surface treatments to reduce surface roughness from 35 µm to less than 1 µm. Additional prototypes were printed using different powders and machines, exploring various printing parameters and innovative contactless supporting structures to improve the quality of downward-facing surfaces with small inclination angles. These structures enabled the fabrication of seamless SRF cavities with a relative density greater than 99.8%. Quality testing was conducted using techniques such as tomography, leak testing, resonant frequency assessment, and internal inspection. The results of this study are presented herein. 		 
poster icon Poster WEPWB119 [9.235 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB119  
About • Received ※ 18 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023
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WEPWB120 Flux Expulsion Testing for LCLS-II-HE Cavity Production cavity, cryomodule, niobium, ECR 876
 
  • J.T. Maniscalco, S. Aderhold, M. Checchin, D. Gonnella, R.D. Porter
    SLAC, Menlo Park, California, USA
  • T.T. Arkan, D. Bafia, J.A. Kaluzny, S. Posen
    Fermilab, Batavia, Illinois, USA
  • M.E. Bevins, A.J. Grabowski, J. Hogan, C.E. Reece, D. Savransky, H. Vennekate
    JLab, Newport News, Virginia, USA
  
  Nitrogen-doped niobium SRF cavities are sensitive to trapped magnetic flux, which decreases the cavity intrinsic Q₀. Prior experimental results have shown that heat treatments to 900°C and higher can result in stronger flux expulsion during cooldown; the precise temperature required tends to vary by vendor lot/ingot of the niobium material used in the cavity cells. For LCLS-II-HE, to ensure sufficient flux expulsion in all cavities, we built and tested single-cell cavities to determine this required temperature for each vendor lot of niobium material to be used in cavity cells. In this report, we present the results of the single-cell flux expulsion testing and the Q₀ of the nine-cell cavities built using the characterized vendor lots. We discuss mixing material from different vendor lots, examine the lessons learned, and finally present an outlook on possible refinements to the single-cell technique.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB120  
About • Received ※ 15 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 03 July 2023 — Issue date ※ 13 July 2023
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WEPWB125 Thermodynamic Properties of Srf Niobium cavity, niobium, radio-frequency, cryogenics 884
 
  • P. Dhakal
    JLab, Newport News, Virginia, USA
  
  Funding: This is authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05- 06OR23177.
Bulk and thin films of niobium are the materials of choice in fabricating superconducting radio frequency (SRF) cavities for modern particle accelerators and quantum computing applications. The thermodynamic properties of Nb are of particular interest in heat management in cryogenic environments. Here, we report the results of measurements of the thermodynamic properties of niobium used in the fabrication of superconducting radio frequency (SRF) cavities. The temperature and magnetic field dependence of thermal conductivity, Seebeck coefficient, and specific heat capacity was measured on bulk niobium samples. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB125  
About • Received ※ 11 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 04 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB126 First Results from Nanoindentation of Vapor Diffused Nb₃Sn Films on Nb cavity, linac, experiment, accelerating-gradient 888
 
  • U. Pudasaini
    JLab, Newport News, Virginia, USA
  • S. Cheban, G.V. Eremeev
    Fermilab, Batavia, Illinois, USA
  
  Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics & Office of High Energy Physics.
The mechanical vulnerability of the Nb₃Sn-coated cavities is identified as one of the significant technical hurdles toward deploying them in practical accelerator applications in the not-so-distant future. It is crucial to characterize the material’s mechanical properties in ways to address such vulnerability. Nanoindentation is a widely used technique for measuring the mechanical properties of thin films that involves indenting the film with a small diamond tip and measuring the force-displacement response to calculate the film’s elastic modulus, hardness, and other mechanical properties. The nanoindentation analysis was performed on multiple vapor-diffused Nb₃Sn samples coated at Jefferson Lab and Fermilab coating facilities for the first time. This contribution will discuss the first results obtained from the nanoindentation of Nb₃Sn-coated Nb samples prepared via the Sn vapor diffusion technique. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB126  
About • Received ※ 19 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 16 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB133 Testing of the 2.6 GHz SRF Cavity Tuner for the Dark Photon Experiment at 2 K cavity, photon, experiment, ECR 907
 
  • C. Contreras-Martinez, B. Giaccone, I.V. Gonin, T.N. Khabiboulline, O.S. Melnychuk, Y.M. Pischalnikov, S. Posen, O.V. Pronitchev, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  
  At FNAL two 2.6 GHz SRF cavities are being used to search for dark photons, the experiment can be conducted at 2 K or in a dilution refrigerator. Precise frequency tuning is required for these two cavities so they can be matched in frequency. A cooling capacity constraint on the dilution refrigerator only allows piezo actuators to be part of the design of the 2.6 GHz cavity tuner. The tuner is equipped with three encapsulated piezo that deliver the long- and short-range frequency tuning. Modifications were implemented on the first tuner design due to the low forces on the piezos due to the cavity. Three brass rods with Belleville washers were added to the design to increase the overall force on the piezos. The results at 2 K of testing this tuner with and without the modification will be presented.  
poster icon Poster WEPWB133 [0.829 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB133  
About • Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 04 July 2023
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WEPWB134 Study of Different Piezoelectric Material Stroke Displacement at Different Temperatures Using an SRF Cavity cavity, experiment, controls, resonance 911
 
  • C. Contreras-Martinez, Y.M. Pischalnikov, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  
  Piezoelectric actuators are used for resonance control in superconducting linacs. The level of frequency compensation depends on the piezoelectric stroke displacement. In this study, the stroke displacement will be measured with a 1.3 GHz SRF cavity by measuring the frequency shift with respect to the voltage applied. The entire system was submerged in liquid helium. This study characterizes the PZT piezoelectric actuator (P-844K093) and a lithium niobate (P-844B0005) piezoelectric actuator. All these actuators were developed at Physik Instrumente (PI). The piezo-electric displacement was measured at different temperatures.  
poster icon Poster WEPWB134 [0.776 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB134  
About • Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 13 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWB135 A Novel Twin Drive Tuner Mechanism for 1.3 GHz ILC Cavity cavity, FEL, operation, site 914
 
  • M. Yamanaka
    KEK, Ibaraki, Japan
  
  A tuner is a device that adjusts the resonant frequency of a cavity. Here we propose a new tuner mechanism for the 1.3 GHz ILC cavity. A bellow is provided in the central portion of the helium tank in the longitudinal direction, and flanges are provided on both sides of the bellows. A linear motion actuator is fixed to the flange on one side, and the frequency is changed by pushing and pulling the flange on the opposite side. Significantly, two linear motion actuators are placed in circumference and working simultaneously. It is named a twin-drive tuner. According to the ILC specification, the cavity has a spring constant of 3 KN/mm, requiring a stroke of 2 mm to adjust the 600 kHz range. A loading force of 6 kN is required. This is shared by two linear motion actuators. We developed a prototype actuator with a loading force of 4 kN per unit. It consists of a stepping motor and a sliding screw with a plastic nut. An experimental device was constructed using this actuator and a 1.3 GHz cavity with a helium tank, and the frequency tuning was evaluated. The displacement between the flanges and the frequency are proportional, both have good linearity, and the slope is 296 kHz/mm.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB135  
About • Received ※ 17 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 17 July 2023
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WEPWB137 Prototype SSR2 Tuner Procurement and Testing at IJCLab for PIP-II Project cavity, vacuum, insertion, cryomodule 917
 
  • N. Gandolfo, P. Duchesne, D. Le Dréan, D. Longuevergne, G. Mavilla, T. Pépin-Donat
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • M. Parise, D. Passarelli, Y.M. Pischalnikov
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by IN2P3. Work supported, in part, by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under U.S. DOE Contract No. DE-AC02-07CH11359.
IJCLab is involved in the PIP-II project on the design and development of accelerator components for the SSR2 (Single Spoke Resonator type 2) section of the superconducting linac. Five prototype tuners have been built and are being tested at IJCLab. After a short description of the tuner, this paper reports on the procurement strategy and the performance observed at both room and low temperatures in vertical cryostat test with SSR2 prototype cavities. This paper will also share results on accelerated lifetime tests performed in a dedicated nitrogen-cooled cryostat. 		 
poster icon Poster WEPWB137 [1.395 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB137  
About • Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 16 July 2023
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THIAA03 Completion of Testing Series Double-spoke Cavity Cryomodules for ESS cryomodule, cavity, vacuum, operation 932
 
  • R. Santiago Kern, K. Fransson, K.J. Gajewski, L. Hermansson, H. Li, T. Lofnes, A. Miyazaki, M. Olvegård, I.P. Profatilova, R.J.M.Y. Ruber, C.D.I. Svanberg, M. Zhovner
    Uppsala University, Uppsala, Sweden
  
  The FREIA Laboratory at Uppsala University, Sweden, has completed the evaluation of 13 double-spoke cavity cryomodules for ESS. This is the first time double-spoke cavities will be deployed in a real machine. This paper summarizes testing procedures and statistics of the results and lessons learned.  
slides icon Slides THIAA03 [4.687 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-THIAA03  
About • Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 29 June 2023
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THIAA04 Performance Analysis of Spoke Resonators, Statistics from Cavity Fabrication to Cryomodule Testing cavity, operation, cryomodule, proton 940
 
  • A. Miyazaki, P. Duchesne, D. Le Dréan, D. Longuevergne, G. Olry
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  
  Irène Joliot-Curie Laboratory (IJCLab) has been leading the development of spoke resonators in multiple interna- tional SRF projects, from fundamental R&D, prototyping, to series production. The European Spallation Source (ESS) superconducting linac is the first of its kind to put into op- eration the spoke resonators. After three prototype cavities, 29 ESS production cavities have been processed, tested, as- sembled into cryomodules at IJCLab, and then shipped to Uppsala for the site acceptance test. Seven prototypes for two other major projects, Multi-purpose hYbrid Research Reactor for High-tech Application (MYRRHA) and Proton Improvement Plan II (PIP-II), designed in collaboration with external institutions, have as well been processed and tested at IJCLab. A new challenge is to fully process series cavi- ties in industry, following the successful implementation of 1.3 GHz elliptical cavities in the other projects. This paper summarises main results obtained from fabrication to final testing, including frequency tuning strategy, performance, limitation in vertical cryostat, and identifies future direction of projects and R&D in the field of spoke cavities.  
slides icon Slides THIAA04 [4.623 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-THIAA04  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 19 July 2023
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THCAA01 Development of Single-spoke Cavities for ADS at JAEA cavity, linac, emittance, proton 947
 
  • Y. Kondo
    JAEA, Ibaraki-ken, Japan
  • T. Dohmae, E. Kako, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
  • F. Maekawa, S.I. Meigo, J. Tamura, B. Yee-Rendón
    JAEA/J-PARC, Tokai-mura, Japan
  
  Japan Atomic Energy Agency (JAEA) has been proposing an accelerator-driven system (ADS) as a future nuclear system to efficiently reduce the high-level radioactive waste generated at nuclear power plants. As the first step toward the full-scale CW proton linac for the JAEA-ADS, we are now prototyping a low-beta (around 0.2) single-spoke cavity. Because there is no experience in manufacturing superconducting spoke cavities in Japan, prototyping and performance testing of the cavity are essential to ensure the feasibility of the JAEA-ADS. The dimensional parameters of the prototype spoke cavity were optimized to obtain higher cavity performance. The actual cavity fabrication started in 2020. Most of the cavity parts were fabricated in fiscal year 2020 by press-forming and machining. In 2021, we started welding the cavity parts together. After investigating the optimum welding conditions using mock-up test pieces, each cavity part was joined with smooth welding beads. Currently, the cavity’s body section and the beam port sections have been assembled. This paper presents the current status of the JAEA-ADS and it’s cavity prototyping.  
slides icon Slides THCAA01 [8.433 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-THCAA01  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 10 July 2023
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THCAA02 Commissioning of the UHH Quadrupole Resonator at DESY cavity, quadrupole, dipole, operation 952
 
  • R. Monroy-Villa, W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • A. Gössel, D. Reschke, M. Röhling, M. Schmökel, J.H. Thie, M. Wiencek
    DESY, Hamburg, Germany
  • C. Martens
    University of Hamburg, Hamburg, Germany
  
  Funding: This work was supported by the BMBF under the research grants 05H18GURB1, 05K19GUB and 05H2021.
Pushing the limits of the accelerating field or quality factor of SRF cavities beyond pure Nb requires the implementation of specific inner surface treatments, which are yet to be studied and optimized. One of the fundamental challenges in exploring alternative materials is that only samples or cavity cuts can be fully characterized from a material point of view. On the other hand, complete cavities allow for the SRF characterization of the inner surface, while samples can usually only be analyzed using DC methods. To address this problem, a test resonator for samples, called "Quadrupole Resonator", was designed and operated at CERN and later at HZB. It allows for a full RF characterization of samples at frequencies of 0.42 GHz, 0.86 GHz, and 1.3 GHz, within a temperature range of 2-20 K and at magnetic fields up to 120 mT. This work presents the design process, which incorporated improvements motivated by mechanical and RF studies and experience, and the results from both warm and cold commissioning are discussed. More important, the results for the RF tests of a Nb sample after undergoing a series of heat treatments and an outlook of the further usage of the QPR is presented. 		 
slides icon Slides THCAA02 [6.677 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-THCAA02  
About • Received ※ 25 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 19 August 2023
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THIXA01 Investigation of Plasma Processing for Coaxial Resonators plasma, cavity, HOM, coupling 960
 
  • W. Hartung, W. Chang, K. Elliott, S.H. Kim, T. Konomi, K. Saito, P.R. Tutt, T. Xu
    FRIB, East Lansing, Michigan, USA
  
  Plasma processing has been investigated by several facilities as a method to mitigate degradation of SRF cavity performance. It provides an alternative to removal and disassembly of cryomodules for refurbishment of each cavity via repeat etching and rinsing. Promising results have been obtained by several groups. Studies of plasma processing for quarter-wave resonators (QWRs) and half-wave resonators (HWRs) were undertaken at FRIB, where a total of 324 such resonators are presently in operation. Plasma ignition and optimization measurements were done with room-temperature-matched input couplers. Plasma cleaning tests were done on several QWRs using the fundamental power coupler (FPC) to drive the plasma. We investigated the usefulness of higher-order modes (HOMs) to drive the plasma. HOMs allow for less mismatch at the FPC and hence lower field in the coupler relative to the cavity. Before-and-after cold tests showed a significant reduction in field emission X-rays with judicious application of plasma processing.  
slides icon Slides THIXA01 [2.060 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-THIXA01  
About • Received ※ 01 September 2023 — Accepted ※ 02 September 2023 — Issue date ※ 02 September 2023  
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THIXA03 Cryocooler Application for Accelerator and Development Status of Powerful Cryocooler at SHI Ltd. controls, cavity, interface, operation 968
 
  • T. Ikeda, S. Sasazaki
    SHI, Tokyo, Japan
  
  Advances in recent Nb₃Sn cavity development makes possible to operate the cavities with Qo ~ 1xE10 at 4.3 K and to design SRF accelerator in which the cavities are cooled directly with small mechanical cryocoolers instead of using liquid helium. Conduction-cooling with cryocoolers greatly simplify the overall design and also contribute for cost saving of an SRF accelerator, making the SRF technology feasible for industrial accelerators. However, in the case of using current cryocooler systems (like Gifford-McMahon cryocooler, Pulse-Tube cryocooler, etc.) for the conduction-cooling, since the cooling capacity per unit is small, multiple units will be used in combination depending on the required cooling capacity, it will cause problems in terms of power consumption (efficiency), footprint, and maintenance costs. Therefore, SHI have been developing a large-capacity and high-efficiency 4KGM-JT (Gifford-McMahon-Joule-Thomson) cryocooler system in the 10 W class at 4.2 K. This contribution will report the overview of this cryocooler system and its status of development.  
slides icon Slides THIXA03 [1.638 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-THIXA03  
About • Received ※ 20 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 04 July 2023
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THIXA05 Conduction-Cooled SRF Cavities: Opportunities and Challenges cavity, operation, cryomodule, radio-frequency 973
 
  • N.A. Stilin, H. Conklin, T. Gruber, A.T. Holic, M. Liepe, T.I. O’Connell, P. Quigley, J. Sears, V.D. Shemelin, J. Turco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Thanks to improvements in the performance of both commercial cryocoolers and Nb₃Sn-coated superconducting radio-frequency (SRF) cavities, it is now possible to design and build compact, SRF cryomodules without the need for liquid cryogenics. In addition, these systems offer robust, non-expert, turn-key operation, making SRF technology significantly more accessible for smaller-scale applications in fields such as industry, national security, medicine, environmental sustainability, etc. To fully realize these systems, many technical and operational challenges must be overcome. These include properly cooling the SRF cavity via thermal conduction and designing high-power (~ 100 kW continuous) RF couplers which dissipate minimal heat (~ 1 W) at 4.2 K. This presentation will discuss these challenges and the solutions which have been developed at Cornell University and elsewhere.  
slides icon Slides THIXA05 [7.219 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-THIXA05  
About • Received ※ 27 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 04 July 2023 — Issue date ※ 08 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
FRIBA04 Crab Cavities for ILC cavity, HOM, operation, impedance 990
 
  • P.A. McIntosh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • S.A. Belomestnykh, I.V. Gonin, T.N. Khabiboulline, A. Lunin, Y.M. Orlov, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • R. Calaga
    CERN, Meyrin, Switzerland
  • S.U. De Silva
    JLab, Newport News, Virginia, USA
  • J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • T. Okugi, A. Yamamoto
    KEK, Ibaraki, Japan
  • S. Verdú-Andrés, B.P. Xiao
    BNL, Upton, New York, USA
  
  For the 14 mrad crossing angle proposed, crab cavity systems are fundamentally anticipated for the viable operation of the International Linear Collider (ILC), in order to maximise its luminosity performance. Since 2021, a specialist development team have been defining optimum crab cavity technologies which can fulfil the operational requirements for ILC, both for its baseline centre-of-mass energy of 250 GeV, but also extending those requirements out to higher beam collision intensities. Five design teams have established crab cavity technology solutions, which have the capability to also operate up to 1 TeV centre-of-mass. This presentation showcases the key performance capabilities of these designs and their associated benefits for both manufacture and integration into the ILC Interaction Region. The recommended outcome of the recently conducted crab cavity technology down-selection, will also be highlighted.  
slides icon Slides FRIBA04 [2.526 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-FRIBA04  
About • Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 20 July 2023
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FRIBA05 Automation of FRIB SRF Cavities and SC Solenoids Turn-on/off cavity, cryomodule, solenoid, linac 999
 
  • W. Chang, Y. Choi, X.J. Du, W. Hartung, S.H. Kim, T. Konomi, S.R. Kunjir, H. Nguyen, K. Saito, T. Xu, S. Zhao
    FRIB, East Lansing, Michigan, USA
  • A. Facco
    INFN/LNL, Legnaro (PD), Italy
  
  The superconducting driver Linac for the Facility for Rare Isotope Beams (FRIB) is a heavy ion accelerator that accelerate ions to 200 MeV per nucleon. The Linac has 46 cryomodules that contain 324 superconducting radio frequency (SRF) cavities and 69 superconducting (SC) solenoid packages. For operation of all cryomodules with high efficiency and reliability, automation for SRF cavity and SC solenoid fast turn-on/off is essentially. Based on cryomodule commissioning results and expert experience, all manual cavity and solenoid turn-on/off procedures and steps have been replaced by automatic programs for FRIB linac operation. This allows the operators to turn the systems on and off without expert-level training. Automation reduces the risk of human error, speeds up beam recovery after user access to experimental areas, and increases beam availability. The cavity turn-on procedure makes sure that the cavity can operate at low field with expected read backs, ramps up the field, and makes sure that the RF amplitude and phase are stable. The design, implementation, and operating experience with automation will be presented.  
slides icon Slides FRIBA05 [3.503 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-FRIBA05  
About • Received ※ 29 June 2023 — Revised ※ 16 August 2023 — Accepted ※ 21 August 2023 — Issue date ※ 21 August 2023
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FRIBA07 Status of the SLAC/MSU SRF Gun Development Project cryomodule, cathode, cavity, alignment 1003
 
  • S.J. Miller, Y. Al-Mahmoud, W. Chang, Y. Choi, C. Compton, X.J. Du, K. Elliott, W. Hartung, J.D. Hulbert, S.H. Kim, T. Konomi, D.G. Morris, M.S. Patil, L. Popielarski, K. Saito, A. Taylor, B.P. Tousignant, J. Wei, J.D. Wenstrom, K. Witgen, T. Xu
    FRIB, East Lansing, Michigan, USA
  • C. Adolphsen, R. Coy, F. Ji, M.J. Murphy, J. Smedley, L. Xiao
    SLAC, Menlo Park, California, USA
  • A. Arnold, S. Gatzmaga, P. Murcek, J. Teichert, R. Xiang
    HZDR, Dresden, Germany
  • M.P. Kelly, T.B. Petersen, P. Piot
    ANL, Lemont, Illinois, USA
  • J.W. Lewellen
    LANL, Los Alamos, New Mexico, USA
  
  Funding: Work supported by the Department of Energy under Contract DE-AC02-76SF00515
The Linac Coherent Light Source II High Energy (LCLS-II-HE) Project at SLAC includes the construction of a low-emittance injector (LEI) and a superconducting quarter-wave resonator (QWR) at 185.7 MHz. Several alternatives to a superconducting radio frequency (SRF) QWR gun were considered for the LEI, including nor-mal-conducting RF guns evolved from the LCLS-II gun design. Compared to normal-conducting designs, the combination of an intrinsically outstanding vacuum environment (for cathode lifetime), and the potential for a larger ultimate performance envelope, led to the deci-sion to pursue development of the QWR-SRF gun. A prototype gun is currently being designed and fabricated at the Facility for Rare Isotope Beams (FRIB) at Michi-gan State University (MSU). This paper presents perfor-mance goals for the new gun design, an overview of the prototype development effort, status, and future plans including fabrication. 		 
slides icon Slides FRIBA07 [9.655 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-FRIBA07  
About • Received ※ 15 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 11 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)