SRF2023 - List of Keywords (interface)

Paper	Title	Other Keywords	Page
MOPMB005	Muon Spin Rotation Studies of Bilayer Superconductors and Low Temperature Baked Niobium	experiment, cavity, polarization, niobium	62
	M. Asaduzzaman, R.E. Laxdal, R.M.L. McFadden, E. Thoeng TRIUMF, Vancouver, Canada M. Asaduzzaman, T. Junginger, R.M.L. McFadden UVIC, Victoria, Canada E. Thoeng UBC & TRIUMF, Vancouver, British Columbia, Canada
	Funding: Financial support was provided by an Natural Sciences and Engineering Research Council of Canada (NSERC) Muon spin rotation (muSR) results have shown that vortex penetration into Nb can be delayed up to the superheating field Hsh by a single layer of a material with larger London penetration depth. For low temperature baked (LTB) Nb an increase in the vortex penetration field Hvp has also been observed. While clearly exceeding the lower critical field Hc1, Hvp was found to remain significantly below Hsh for LTB niobium (Superconductor Science and Technology 30 (12), 125012). Further, magnetometry experiments suggested that there is no interface barrier in LTB Nb and that the apparent Hvp increase as observed by muSR was due to surface pinning (Scientific Reports 12 (1), 5522). By varying the implantation depth of ~4.1 MeV muons using moderating foils, new muSR measurements confirm that the apparent Hvp increase in LTB Nb is indeed due to surface pinning, while for a Nb₃Sn/Nb bilayer we find an interface barrier for flux penetration. These results confirm the potential of using superconducting bilayers to achieve a flux free Meissner state up to the superheating field of the substrate.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB005
About •	Received ※ 17 June 2023 — Revised ※ 21 June 2023 — Accepted ※ 25 June 2023 — Issue date ※ 21 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB053	Theoretical Study of Thin Noble-Metal Films on the Niobium Surface	niobium, lattice, electron, experiment	230
	C.A. Méndez, T. Arias, M. Liepe, N. Sitaraman Cornell University, Ithaca, New York, USA
	Funding: The Center for Bright Beams, Supported by National Science Foundation award No. PHY-1549132 Recent experiments suggest that noble-metal deposition on niobium metal surfaces can remove the surface oxide and ultimately improve superconducting radio-frequency (SRF) cavities performance. In this preliminary study, we use density-functional theory to investigate the potential for noble-metal passivation of realistic, polycrystalline niobium surfaces for SRF. Specifically, we investigate the stability of gold and palladium monolayers on niobium surfaces with different crystal orientations and evaluate the impact of these impurities on superconducting properties. In particular, our results suggest that gold can grow in thin layers on the niobium surface, whereas palladium rather tends to dissolve into the niobium cavity. These results will help inform ongoing experimental efforts to passivate niobium surfaces of SRF cavities.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB053
About •	Received ※ 22 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 19 August 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

WEPWB094	Design, Manufacturing, Assembly, and Lessons Learned of the Pre-Production 325 MHz Couplers for the PIP-II Project at Fermilab	vacuum, cavity, SRF, 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 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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THIXA03	Cryocooler Application for Accelerator and Development Status of Powerful Cryocooler at SHI Ltd.	controls, SRF, cavity, 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 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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOPMB005

Muon Spin Rotation Studies of Bilayer Superconductors and Low Temperature Baked Niobium

experiment, cavity, polarization, niobium

62

M. Asaduzzaman, R.E. Laxdal, R.M.L. McFadden, E. Thoeng
TRIUMF, Vancouver, Canada
M. Asaduzzaman, T. Junginger, R.M.L. McFadden
UVIC, Victoria, Canada
E. Thoeng
UBC & TRIUMF, Vancouver, British Columbia, Canada

Funding: Financial support was provided by an Natural Sciences and Engineering Research Council of Canada (NSERC)
Muon spin rotation (muSR) results have shown that vortex penetration into Nb can be delayed up to the superheating field Hsh by a single layer of a material with larger London penetration depth. For low temperature baked (LTB) Nb an increase in the vortex penetration field Hvp has also been observed. While clearly exceeding the lower critical field Hc1, Hvp was found to remain significantly below Hsh for LTB niobium (Superconductor Science and Technology 30 (12), 125012). Further, magnetometry experiments suggested that there is no interface barrier in LTB Nb and that the apparent Hvp increase as observed by muSR was due to surface pinning (Scientific Reports 12 (1), 5522). By varying the implantation depth of ~4.1 MeV muons using moderating foils, new muSR measurements confirm that the apparent Hvp increase in LTB Nb is indeed due to surface pinning, while for a Nb₃Sn/Nb bilayer we find an interface barrier for flux penetration. These results confirm the potential of using superconducting bilayers to achieve a flux free Meissner state up to the superheating field of the substrate.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB005

About •

Received ※ 17 June 2023 — Revised ※ 21 June 2023 — Accepted ※ 25 June 2023 — Issue date ※ 21 July 2023

Cite •

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

MOPMB053

Theoretical Study of Thin Noble-Metal Films on the Niobium Surface

niobium, lattice, electron, experiment

230

C.A. Méndez, T. Arias, M. Liepe, N. Sitaraman
Cornell University, Ithaca, New York, USA

Funding: The Center for Bright Beams, Supported by National Science Foundation award No. PHY-1549132
Recent experiments suggest that noble-metal deposition on niobium metal surfaces can remove the surface oxide and ultimately improve superconducting radio-frequency (SRF) cavities performance. In this preliminary study, we use density-functional theory to investigate the potential for noble-metal passivation of realistic, polycrystalline niobium surfaces for SRF. Specifically, we investigate the stability of gold and palladium monolayers on niobium surfaces with different crystal orientations and evaluate the impact of these impurities on superconducting properties. In particular, our results suggest that gold can grow in thin layers on the niobium surface, whereas palladium rather tends to dissolve into the niobium cavity. These results will help inform ongoing experimental efforts to passivate niobium surfaces of SRF cavities.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB053

About •

Received ※ 22 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 19 August 2023

Cite •

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

WEPWB063

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

cryomodule, cavity, vacuum, simulation

721

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

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

DOI •

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

About •

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

Cite •

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

WEPWB094

Design, Manufacturing, Assembly, and Lessons Learned of the Pre-Production 325 MHz Couplers for the PIP-II Project at Fermilab

vacuum, cavity, SRF, 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 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

Cite •

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

THIXA03

Cryocooler Application for Accelerator and Development Status of Powerful Cryocooler at SHI Ltd.

controls, SRF, cavity, 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 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

Cite •

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