SRF2021 - List of Keywords (cryogenics)

Paper	Title	Other Keywords	Page
MOOFAV02	Status of the RAON Superconducting Linear Accelerator	cavity, cryomodule, MMI, linac	175
	Y.U. Sohn, T.Y. Ki, Y. Kim, M. Lee, K.T. Seol IBS, Daejeon, Republic of Korea
	Funding: Ministry of Science and ICT (MSIT) RAON, being constructed as the Rare Isotope Science Project (RISP) by the Institute for Basic Science (IBS) since 2011 is a flagship heavy ion accelerator facility in Korea to promote fundamental science and application of isotope nuclei and related science. The installation of the heavy ion accelerator systems including injector, rare isotope (RI) production systems, and experimental systems are currently being progressed toward to commissioning of RAON, while the civil construction of the RAON site in Shindong, Daejeon of Korea, is going to finish in 2021. The superconducting LINAC with low energy, so-call SCL3 as the 1st phase will be commissioned on the December of 2021. The overview RAON accelerator facility and status of RISP are reported in this paper.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOOFAV02
About •	Received ※ 26 August 2021 — Accepted ※ 05 April 2022 — Issue date ※ 16 May 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPCAV004	Mechanical Properties of Directly Sliced Medium Grain Niobium for 1.3 GHz SRF Cavity	cavity, niobium, SRF, collider	259
	A. Kumar, K. Abe, T. Dohmae, S. Michizono, T. Saeki, Y. Watanabe, A. Yamamoto, M. Yamanaka KEK, Ibaraki, Japan A. Fajardo, N. Lannoy ATI, Albany, Oregon, USA G.R. Myneni JLab, Newport News, Virginia, USA G.R. Myneni BSCE, Yorktown, Virginia, USA
	At KEK, research is being conducted to manufacture cost-effective 1.3 GHz superconducting radio frequency cavities based on the fine grain (FG) and large grain (LG) Niobium (Nb) materials. Medium grain (MG) Nb has been proposed and developed as an alternative to the FG and LG Nb, being expected to have better mechanical stability with a cost-effective and clean manufacturing approach. MG Nb has an average grain size of 200 - 300 µm, which is approximately 100 times smaller than the LG Nb, however, there are occasional grains as large as 1-2 mm. As such, it is expected to have isotropic properties rather than the anisotropic properties of LG Nb. In this paper, we will outline the mechanical properties of the directly sliced high RRR MG Nb material (manufactured by ATI), and a comparative study will be presented with respect to FG and LG Nb. Moreover, the viability of MG Nb for the global high-pressure regulation for 1.3 GHz SRF cavity will be presented.
	Poster MOPCAV004 [1.796 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV004
About •	Received ※ 21 June 2021 — Revised ※ 11 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 25 March 2022
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MOPCAV012	Fabrication of 1.3 GHz SRF Cavities Using Medium Grain Niobium Discs Directly Sliced from Forged Ingot	niobium, cavity, SRF, linear-collider	287
	T. Dohmae, K. Abe, H. Inoue, A. Kumar, S. Michizono, T. Saeki, K. Umemori, Y. Watanabe, A. Yamamoto, M. Yamanaka, K. Yoshida KEK, Ibaraki, Japan A. Fajardo, N. Lannoy ATI, Albany, Oregon, USA G.R. Myneni JLab, Newport News, USA
	Medium grain (MG) niobium disc which is directly sliced from forged ingot is newly investigated for the cavity material. An effective cost reduction can be achieved using MG niobium since rolling process which is necessary for typical niobium sheet can be skipped during MG niobium production. Grain size of MD niobium is 200-300 um which is much smaller than large grain (LG) niobium directly sliced from melted niobium ingot. Hence, the formability of MG niobium is expected to be much better than LG niobium. KEK has started fabrication of cavity using MG niobium. In this talk, characteristic of MG niobium during fabrication will be reported.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV012
About •	Received ※ 20 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 17 September 2021
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MOPFAV002	Commissioning of the UKRI STFC Daresbury Vertical Test Facility for Jacketed SRF Cavities	cavity, SRF, MMI, operation	308
	A.J. May, A.E.T. Akintola, A.R. Bainbridge, R.K. Buckley, G. Collier, P.A. Corlett, K.D. Dumbell, M.J. Ellis, S. Hitchen, P.C. Hornickel, G. Hughes, C.R. Jenkins, P.A. McIntosh, K.J. Middleman, A.J. Moss, N. Pattalwar, S.M. Pattalwar, M.D. Pendleton, P.A. Smith, A.E. Wheelhouse, AAJ. White, S. Wilde STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom M.D. Hancock, J. Hathaway, C. Hodgkinson, G. Jones, M. Lowe, D.A. Mason, G. Miller, J. Mutch, A. Oates, P. Sollars, J.T.G. Wilson STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	A novel vertical test facility has been developed at the STFC Daresbury Laboratory. The VTF is designed to test 3 jacketed SRF cavities in a horizontal configuration in a single cool-down run at 2 K. Cavities were tested at low power levels for HOMs and passband modes, and Q vs E field measurements at high power levels. The specification requires an unloaded Q of 5·10⁹ at a field gradient of 19.9 MV/m. The cavities are cooled with superfluid helium filled into their individual helium jackets. This reduces the liquid helium consumption by more than 70% in comparison with the conventional facilities operational elsewhere. The facility will be used to conduct a 2-year program to qualify 84 high-beta SRF cavities for the European Spallation Source as part of the UK’s in-kind contribution. This paper reports on the commissioning program, along with a detailed discussion of the RF and cryogenic operations and performance of the facility.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPFAV002
About •	Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 20 October 2021
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MOPFDV002	High Density Mapping Sytems for SRF Cavities	cavity, SRF, experiment, superconducting-cavity	323
	Y. Fuwa JAEA/J-PARC, Tokai-mura, Japan R.L. Geng JLab, Newport News, Virginia, USA H. Hayano KEK, Ibaraki, Japan Y. Iwashita, Y. Kuriyama Kyoto University, Research Reactor Institute, Osaka, Japan H. Tongu Kyoto ICR, Uji, Kyoto, Japan
	High density mapping systems for superconducting cavities are prepared. They include sX-map, XT-map and B-map. Each strip of the sX-map system has 32 X-ray sensors approximately 10 mm apart, which can be installed under the stiffener rings to show uniform higher sensitivities. This is suitable to get X-ray distribution around iris areas. The XT-map system enables temperature distribution mapping of cavity cells with high spatial resolution at approximately 10 mm intervals in both azimuth and latitude. It also gives X-ray distribution on cells, as well. Magnetic field distributions can be obtained by B-map system using AMR sensors. Since all these systems are based on the technology of multiplexing at cryogenic side, less number of wires can carry the huge number of signals. The systems are described.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPFDV002
About •	Received ※ 02 July 2021 — Revised ※ 19 December 2021 — Accepted ※ 22 January 2022 — Issue date ※ 02 May 2022
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TUPCAV009	AMR Sensors Studies and Development for Cavities Tests Magnetometry at CEA	cavity, SRF, superconducting-cavity, detector	457
	J. Plouin, E. Cenni, L. Maurice CEA-DRF-IRFU, France
	Studying flux expulsion during superconducting cavities test increases the need for exhaustive magnetometric cartography. The use of Anistropic Magneto Resistance (AMR) sensors, much cheaper than commercial fluxgates, allows the use of tens of sensors simultaneously. Such sensors are developed and sold for room temperature application but are resistant to cryogenic temperatures. However, they need proper calibration, which is more difficult at cryogenic temperature. Actually, this calibration uses the flip of the magnetization of the anisotropic ferromagnetic element, which coercitive field is increased at low temperature. We will present the development of method and software carried out at CEA for the use of such sensors, as well as the preliminary design of a rotating magnetometric device destined to elliptical cavities.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV009
About •	Received ※ 22 June 2021 — Revised ※ 13 January 2022 — Accepted ※ 22 February 2022 — Issue date ※ 22 February 2022
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WEPFAV004	Status of the Cryogenic Infrastructure for MESA	cryomodule, experiment, SRF, operation	539
	T. Stengler, K. Aulenbacher, F. Hug, D. Simon KPH, Mainz, Germany
	Funding: supported by the German Research Foundation (DFG): EXC 2118/2019 The Institute of Nuclear Physics at the Johannes Gutenberg University Mainz, Germany is currently constructing the Mainz Energy-recovering Superconducting Accelerator (MESA). The centerpiece of the MESA consists of two superconducting cryomodules of the ELBE/Rossendorf type, which are operated at 1.8 K. Furthermore, accelerator elements for polarimetry, a 10 T solenoid, and the external SRF test facility of the Helmholtz Institute Mainz have to be supplied with 4 K helium. One challenge here is to supply the components located throughout the accelerator according to their requirements and to establish a 16mbar system for 1.8 K operation. To ensure the required supply of helium at the different temperature levels, the existing helium liquefier has to be upgraded. The cryogenic infrastructure has to be adapted to the accelerator. The concept of the future cryogenic distribution network is presented in this paper and the design of the cryogenic facilities including the modifications is described in detail.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPFAV004
About •	Received ※ 21 June 2021 — Accepted ※ 21 August 2021 — Issue date ※ 10 April 2022
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WEPFAV005	Design Optimization of the 166-MHz and 500-MHz Fundamental Power Couplers for Superconducting RF Cavities at High Energy Photon Source	cavity, multipactoring, simulation, photon	544
	T.M. Huang, Z.Z. Chang, L. Guo, H.Y. Lin, Q. Ma, W.M. Pan, P. Zhang, X.Y. Zhang IHEP, Beijing, People’s Republic of China
	Funding: Supported in part by High Energy Photon Source, a major national science and technology infrastructure in China, and in part by the National Natural Science Foundation of China under Grant 12075263. Five 166-MHz quarter-wave ß=1 cavities have been chosen for the fundamental srf system while two 500-MHz single-cell elliptical cavities for the third-harmonic system for High Energy Photon Source (HEPS). Each cavity will be equipped with one fundamental power coupler (FPC) capable of delivering 250-kW continuous-wave rf power. For the 166-MHz FPC, two prototypes were developed and excellent performances were demonstrated in the high-power operations. However, the inner air part was observed to be warmer than predictions. Therefore, an innovative cooling scheme was adopted. In addition, the Nb extension tube has been elongated to solve the overheating in the cavity-coupler interface region. Concerning the 500-MHz FPC, several improvements were proposed. First, a doorknob adopting WR1800 instead of WR1500 waveguide was chosen to better match the operating frequency; Second, the window position was optimized to ensure multipacting-free on the window; Third, the cryogenic heat load was estimated carefully to obtain an optimum helium gas cooling. The main parameters and the design optimizations of the 166-MHz and 500-MHz FPCs are presented in this paper.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPFAV005
About •	Received ※ 21 June 2021 — Accepted ※ 21 August 2021 — Issue date ※ 20 January 2022
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WEPTEV007	Review of the Application Piezoelectric Actuators for SRF Cavity Tuners	SRF, cavity, operation, vacuum	642
	Y.M. Pischalnikov Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authorized by Fermi Research Alliance LLC under Contract N. DE-AC02-07CH11359 with U.S. Department of Energy Large SRF Linacs and HEP experiments require accurate frequency control, which is achieved using cavity tuners typically actuated by the piezoelectric ceramic stacks. The piezoelectric ceramic stacks became ’standard’ components of the SRF cavity tuner and, depending on the application, could be operated in the different environment: in air, at cryogenic temperature, in vacuum, and submerged in liquid helium. Different applications place different requirements on the piezo actuators, but the important parameters, common to all applications, are the lifetime and reliability of the actuators. Several R&D programs targeting the development of reliable piezo actuators are reviewed in this contribution.
	Poster WEPTEV007 [1.220 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPTEV007
About •	Received ※ 22 June 2021 — Revised ※ 27 August 2021 — Accepted ※ 18 September 2021 — Issue date ※ 22 November 2021
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THPFAV002	Fabrication and Installation of Newly Designed Cryostats and Top Flanges for the Vertical Test of RISP	cavity, SRF, vacuum, cryomodule	733
	M.O. Hyun, M.S. Kim, Y. Kim, J. Lee, M. Lee, J.H. Shin IBS, Daejeon, Republic of Korea D.W. Kim, S.R. Kim CVE, Suwon, Gyeonggi, Republic of Korea
	Funding: This paper was supported by the Rare Isotope Science Project (RISP), which is funded by the Ministry of Science and ICT (MSIT) and National Research Foundation (NRF) of the Republic of Korea. Rare Isotope Science Project (RISP) in the Institute of Basic Science (IBS), South Korea, is now operating SRF test facility in Sindong, Daejeon. Sindong SRF test facility has three vertical test pits and three horizontal test bunkers, 900 W cryogenic system, RF power system, and radiation protection system. This paper explains about detail procedures of constructing cryostats and top flanges for the vertical test of RISP, Installed cryostats and top flanges have insulation vacuum layer, magnetic and thermal shield, 4K/2K reservoir, heat exchanger, cryogenic valves for supplying liquid helium, vacuum lines, and electrical instrumentations for the superconducting cavity tests.
	Poster THPFAV002 [2.015 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPFAV002
About •	Received ※ 22 June 2021 — Revised ※ 21 August 2021 — Accepted ※ 23 October 2021 — Issue date ※ 22 November 2021
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THPFDV006	Seebeck Coefficient Measurement at Cryogenic Temperatures for the LCLS-II HE Project	experiment, niobium, cryomodule, cavity	768
	M. Ge, A.T. Holic, M. Liepe, J. Sears Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Reducing thermoelectric currents during cooldown is important to maintain high-quality factors (Q₀) of the cavities in the LCLS-II HE cryomodules. The temperature-dependent Seebeck coefficients of the materials used in the cryomodules are needed for quantitative estimations of thermoelectric currents. In this work, we present a setup for cryogenic Seebeck coefficient measurements as well as the measured Seebeck coefficients of high-pure niobium at cryogenic temperatures between 4K and 200K.
	Poster THPFDV006 [0.511 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPFDV006
About •	Received ※ 29 June 2021 — Revised ※ 10 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 26 November 2021
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THPCAV007	Thermal Mapping Studies on Nb/Su SRF Cavities	cavity, SRF, interface, experiment	796
	A. Bianchi, M. Chiodini, G. Vandoni, W. Venturini Delsolaro CERN, Meyrin, Switzerland
	A thermal mapping system is one of the most useful diagnostic tools to identify the mechanisms responsible of performance degradation in superconducting radio frequency (SRF) cavities. Unlike most of the thermal mapping systems currently in operation, we want to develop a system for mapping copper coated SRF cavities. This thermal mapping system, based on contact thermometry, will operate in both superfluid and normal liquid helium for the study of thin film cavities on copper built at CERN. This paper describes the R&D studies to design and develop the system. The characterisation of thermometers and the validation of their thermal contact are presented. Thanks to the use of some heaters with the aim of reproducing the presence of heat losses in a SRF cavity, temperature profiles on a copper surface will be shown at different conditions of the helium bath. In addition, preliminary results on magnetic field sensors, based on the anisotropic magnetoresistance effect, will be reported in view of their possible implementation in the thermal mapping system.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPCAV007
About •	Received ※ 18 June 2021 — Revised ※ 23 August 2021 — Accepted ※ 25 November 2021 — Issue date ※ 12 May 2022
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Paper

Title

Other Keywords

Page

MOOFAV02

Status of the RAON Superconducting Linear Accelerator

cavity, cryomodule, MMI, linac

175

Y.U. Sohn, T.Y. Ki, Y. Kim, M. Lee, K.T. Seol
IBS, Daejeon, Republic of Korea

Funding: Ministry of Science and ICT (MSIT)
RAON, being constructed as the Rare Isotope Science Project (RISP) by the Institute for Basic Science (IBS) since 2011 is a flagship heavy ion accelerator facility in Korea to promote fundamental science and application of isotope nuclei and related science. The installation of the heavy ion accelerator systems including injector, rare isotope (RI) production systems, and experimental systems are currently being progressed toward to commissioning of RAON, while the civil construction of the RAON site in Shindong, Daejeon of Korea, is going to finish in 2021. The superconducting LINAC with low energy, so-call SCL3 as the 1st phase will be commissioned on the December of 2021. The overview RAON accelerator facility and status of RISP are reported in this paper.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOOFAV02

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Received ※ 26 August 2021 — Accepted ※ 05 April 2022 — Issue date ※ 16 May 2022

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MOPCAV004

Mechanical Properties of Directly Sliced Medium Grain Niobium for 1.3 GHz SRF Cavity

cavity, niobium, SRF, collider

259

A. Kumar, K. Abe, T. Dohmae, S. Michizono, T. Saeki, Y. Watanabe, A. Yamamoto, M. Yamanaka
KEK, Ibaraki, Japan
A. Fajardo, N. Lannoy
ATI, Albany, Oregon, USA
G.R. Myneni
JLab, Newport News, Virginia, USA
G.R. Myneni
BSCE, Yorktown, Virginia, USA

At KEK, research is being conducted to manufacture cost-effective 1.3 GHz superconducting radio frequency cavities based on the fine grain (FG) and large grain (LG) Niobium (Nb) materials. Medium grain (MG) Nb has been proposed and developed as an alternative to the FG and LG Nb, being expected to have better mechanical stability with a cost-effective and clean manufacturing approach. MG Nb has an average grain size of 200 - 300 µm, which is approximately 100 times smaller than the LG Nb, however, there are occasional grains as large as 1-2 mm. As such, it is expected to have isotropic properties rather than the anisotropic properties of LG Nb. In this paper, we will outline the mechanical properties of the directly sliced high RRR MG Nb material (manufactured by ATI), and a comparative study will be presented with respect to FG and LG Nb. Moreover, the viability of MG Nb for the global high-pressure regulation for 1.3 GHz SRF cavity will be presented.

Poster MOPCAV004 [1.796 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV004

About •

Received ※ 21 June 2021 — Revised ※ 11 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 25 March 2022

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MOPCAV012

Fabrication of 1.3 GHz SRF Cavities Using Medium Grain Niobium Discs Directly Sliced from Forged Ingot

niobium, cavity, SRF, linear-collider

287

T. Dohmae, K. Abe, H. Inoue, A. Kumar, S. Michizono, T. Saeki, K. Umemori, Y. Watanabe, A. Yamamoto, M. Yamanaka, K. Yoshida
KEK, Ibaraki, Japan
A. Fajardo, N. Lannoy
ATI, Albany, Oregon, USA
G.R. Myneni
JLab, Newport News, USA

Medium grain (MG) niobium disc which is directly sliced from forged ingot is newly investigated for the cavity material. An effective cost reduction can be achieved using MG niobium since rolling process which is necessary for typical niobium sheet can be skipped during MG niobium production. Grain size of MD niobium is 200-300 um which is much smaller than large grain (LG) niobium directly sliced from melted niobium ingot. Hence, the formability of MG niobium is expected to be much better than LG niobium. KEK has started fabrication of cavity using MG niobium. In this talk, characteristic of MG niobium during fabrication will be reported.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV012

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Received ※ 20 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 17 September 2021

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MOPFAV002

Commissioning of the UKRI STFC Daresbury Vertical Test Facility for Jacketed SRF Cavities

cavity, SRF, MMI, operation

308

A.J. May, A.E.T. Akintola, A.R. Bainbridge, R.K. Buckley, G. Collier, P.A. Corlett, K.D. Dumbell, M.J. Ellis, S. Hitchen, P.C. Hornickel, G. Hughes, C.R. Jenkins, P.A. McIntosh, K.J. Middleman, A.J. Moss, N. Pattalwar, S.M. Pattalwar, M.D. Pendleton, P.A. Smith, A.E. Wheelhouse, AAJ. White, S. Wilde
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
M.D. Hancock, J. Hathaway, C. Hodgkinson, G. Jones, M. Lowe, D.A. Mason, G. Miller, J. Mutch, A. Oates, P. Sollars, J.T.G. Wilson
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

A novel vertical test facility has been developed at the STFC Daresbury Laboratory. The VTF is designed to test 3 jacketed SRF cavities in a horizontal configuration in a single cool-down run at 2 K. Cavities were tested at low power levels for HOMs and passband modes, and Q vs E field measurements at high power levels. The specification requires an unloaded Q of 5·10⁹ at a field gradient of 19.9 MV/m. The cavities are cooled with superfluid helium filled into their individual helium jackets. This reduces the liquid helium consumption by more than 70% in comparison with the conventional facilities operational elsewhere. The facility will be used to conduct a 2-year program to qualify 84 high-beta SRF cavities for the European Spallation Source as part of the UK’s in-kind contribution. This paper reports on the commissioning program, along with a detailed discussion of the RF and cryogenic operations and performance of the facility.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPFAV002

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Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 20 October 2021

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MOPFDV002

High Density Mapping Sytems for SRF Cavities

cavity, SRF, experiment, superconducting-cavity

323

Y. Fuwa
JAEA/J-PARC, Tokai-mura, Japan
R.L. Geng
JLab, Newport News, Virginia, USA
H. Hayano
KEK, Ibaraki, Japan
Y. Iwashita, Y. Kuriyama
Kyoto University, Research Reactor Institute, Osaka, Japan
H. Tongu
Kyoto ICR, Uji, Kyoto, Japan

High density mapping systems for superconducting cavities are prepared. They include sX-map, XT-map and B-map. Each strip of the sX-map system has 32 X-ray sensors approximately 10 mm apart, which can be installed under the stiffener rings to show uniform higher sensitivities. This is suitable to get X-ray distribution around iris areas. The XT-map system enables temperature distribution mapping of cavity cells with high spatial resolution at approximately 10 mm intervals in both azimuth and latitude. It also gives X-ray distribution on cells, as well. Magnetic field distributions can be obtained by B-map system using AMR sensors. Since all these systems are based on the technology of multiplexing at cryogenic side, less number of wires can carry the huge number of signals. The systems are described.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPFDV002

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Received ※ 02 July 2021 — Revised ※ 19 December 2021 — Accepted ※ 22 January 2022 — Issue date ※ 02 May 2022

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TUPCAV009

AMR Sensors Studies and Development for Cavities Tests Magnetometry at CEA

cavity, SRF, superconducting-cavity, detector

457

J. Plouin, E. Cenni, L. Maurice
CEA-DRF-IRFU, France

Studying flux expulsion during superconducting cavities test increases the need for exhaustive magnetometric cartography. The use of Anistropic Magneto Resistance (AMR) sensors, much cheaper than commercial fluxgates, allows the use of tens of sensors simultaneously. Such sensors are developed and sold for room temperature application but are resistant to cryogenic temperatures. However, they need proper calibration, which is more difficult at cryogenic temperature. Actually, this calibration uses the flip of the magnetization of the anisotropic ferromagnetic element, which coercitive field is increased at low temperature. We will present the development of method and software carried out at CEA for the use of such sensors, as well as the preliminary design of a rotating magnetometric device destined to elliptical cavities.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV009

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Received ※ 22 June 2021 — Revised ※ 13 January 2022 — Accepted ※ 22 February 2022 — Issue date ※ 22 February 2022

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WEPFAV004

Status of the Cryogenic Infrastructure for MESA

cryomodule, experiment, SRF, operation

539

T. Stengler, K. Aulenbacher, F. Hug, D. Simon
KPH, Mainz, Germany

Funding: supported by the German Research Foundation (DFG): EXC 2118/2019
The Institute of Nuclear Physics at the Johannes Gutenberg University Mainz, Germany is currently constructing the Mainz Energy-recovering Superconducting Accelerator (MESA). The centerpiece of the MESA consists of two superconducting cryomodules of the ELBE/Rossendorf type, which are operated at 1.8 K. Furthermore, accelerator elements for polarimetry, a 10 T solenoid, and the external SRF test facility of the Helmholtz Institute Mainz have to be supplied with 4 K helium. One challenge here is to supply the components located throughout the accelerator according to their requirements and to establish a 16mbar system for 1.8 K operation. To ensure the required supply of helium at the different temperature levels, the existing helium liquefier has to be upgraded. The cryogenic infrastructure has to be adapted to the accelerator. The concept of the future cryogenic distribution network is presented in this paper and the design of the cryogenic facilities including the modifications is described in detail.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPFAV004

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

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WEPFAV005

Design Optimization of the 166-MHz and 500-MHz Fundamental Power Couplers for Superconducting RF Cavities at High Energy Photon Source

cavity, multipactoring, simulation, photon

544

T.M. Huang, Z.Z. Chang, L. Guo, H.Y. Lin, Q. Ma, W.M. Pan, P. Zhang, X.Y. Zhang
IHEP, Beijing, People’s Republic of China

Funding: Supported in part by High Energy Photon Source, a major national science and technology infrastructure in China, and in part by the National Natural Science Foundation of China under Grant 12075263.
Five 166-MHz quarter-wave ß=1 cavities have been chosen for the fundamental srf system while two 500-MHz single-cell elliptical cavities for the third-harmonic system for High Energy Photon Source (HEPS). Each cavity will be equipped with one fundamental power coupler (FPC) capable of delivering 250-kW continuous-wave rf power. For the 166-MHz FPC, two prototypes were developed and excellent performances were demonstrated in the high-power operations. However, the inner air part was observed to be warmer than predictions. Therefore, an innovative cooling scheme was adopted. In addition, the Nb extension tube has been elongated to solve the overheating in the cavity-coupler interface region. Concerning the 500-MHz FPC, several improvements were proposed. First, a doorknob adopting WR1800 instead of WR1500 waveguide was chosen to better match the operating frequency; Second, the window position was optimized to ensure multipacting-free on the window; Third, the cryogenic heat load was estimated carefully to obtain an optimum helium gas cooling. The main parameters and the design optimizations of the 166-MHz and 500-MHz FPCs are presented in this paper.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPFAV005

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

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WEPTEV007

Review of the Application Piezoelectric Actuators for SRF Cavity Tuners

SRF, cavity, operation, vacuum

642

Y.M. Pischalnikov
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authorized by Fermi Research Alliance LLC under Contract N. DE-AC02-07CH11359 with U.S. Department of Energy
Large SRF Linacs and HEP experiments require accurate frequency control, which is achieved using cavity tuners typically actuated by the piezoelectric ceramic stacks. The piezoelectric ceramic stacks became ’standard’ components of the SRF cavity tuner and, depending on the application, could be operated in the different environment: in air, at cryogenic temperature, in vacuum, and submerged in liquid helium. Different applications place different requirements on the piezo actuators, but the important parameters, common to all applications, are the lifetime and reliability of the actuators. Several R&D programs targeting the development of reliable piezo actuators are reviewed in this contribution.

Poster WEPTEV007 [1.220 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPTEV007

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Received ※ 22 June 2021 — Revised ※ 27 August 2021 — Accepted ※ 18 September 2021 — Issue date ※ 22 November 2021

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THPFAV002

Fabrication and Installation of Newly Designed Cryostats and Top Flanges for the Vertical Test of RISP

cavity, SRF, vacuum, cryomodule

733

M.O. Hyun, M.S. Kim, Y. Kim, J. Lee, M. Lee, J.H. Shin
IBS, Daejeon, Republic of Korea
D.W. Kim, S.R. Kim
CVE, Suwon, Gyeonggi, Republic of Korea

Funding: This paper was supported by the Rare Isotope Science Project (RISP), which is funded by the Ministry of Science and ICT (MSIT) and National Research Foundation (NRF) of the Republic of Korea.
Rare Isotope Science Project (RISP) in the Institute of Basic Science (IBS), South Korea, is now operating SRF test facility in Sindong, Daejeon. Sindong SRF test facility has three vertical test pits and three horizontal test bunkers, 900 W cryogenic system, RF power system, and radiation protection system. This paper explains about detail procedures of constructing cryostats and top flanges for the vertical test of RISP, Installed cryostats and top flanges have insulation vacuum layer, magnetic and thermal shield, 4K/2K reservoir, heat exchanger, cryogenic valves for supplying liquid helium, vacuum lines, and electrical instrumentations for the superconducting cavity tests.

Poster THPFAV002 [2.015 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPFAV002

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Received ※ 22 June 2021 — Revised ※ 21 August 2021 — Accepted ※ 23 October 2021 — Issue date ※ 22 November 2021

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THPFDV006

Seebeck Coefficient Measurement at Cryogenic Temperatures for the LCLS-II HE Project

experiment, niobium, cryomodule, cavity

768

M. Ge, A.T. Holic, M. Liepe, J. Sears
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Reducing thermoelectric currents during cooldown is important to maintain high-quality factors (Q₀) of the cavities in the LCLS-II HE cryomodules. The temperature-dependent Seebeck coefficients of the materials used in the cryomodules are needed for quantitative estimations of thermoelectric currents. In this work, we present a setup for cryogenic Seebeck coefficient measurements as well as the measured Seebeck coefficients of high-pure niobium at cryogenic temperatures between 4K and 200K.

Poster THPFDV006 [0.511 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPFDV006

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Received ※ 29 June 2021 — Revised ※ 10 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 26 November 2021

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THPCAV007

Thermal Mapping Studies on Nb/Su SRF Cavities

cavity, SRF, interface, experiment

796

A. Bianchi, M. Chiodini, G. Vandoni, W. Venturini Delsolaro
CERN, Meyrin, Switzerland

A thermal mapping system is one of the most useful diagnostic tools to identify the mechanisms responsible of performance degradation in superconducting radio frequency (SRF) cavities. Unlike most of the thermal mapping systems currently in operation, we want to develop a system for mapping copper coated SRF cavities. This thermal mapping system, based on contact thermometry, will operate in both superfluid and normal liquid helium for the study of thin film cavities on copper built at CERN. This paper describes the R&D studies to design and develop the system. The characterisation of thermometers and the validation of their thermal contact are presented. Thanks to the use of some heaters with the aim of reproducing the presence of heat losses in a SRF cavity, temperature profiles on a copper surface will be shown at different conditions of the helium bath. In addition, preliminary results on magnetic field sensors, based on the anisotropic magnetoresistance effect, will be reported in view of their possible implementation in the thermal mapping system.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPCAV007

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Received ※ 18 June 2021 — Revised ※ 23 August 2021 — Accepted ※ 25 November 2021 — Issue date ※ 12 May 2022

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