SRF2023 - Table of Session: THIXA (SRF Technology V)

Paper	Title	Page
THIXA01	Investigation of Plasma Processing for Coaxial Resonators	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 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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THIXA02	Plasma Cleaning at FNAL: LCLS-II HE vCM Results and Ongoing Studies on Spoke Resonators
	P. Berrutti Fermilab, Batavia, Illinois, USA
	Funding: Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. Plasma cleaning has been proven effective in eliminating multipacting and in preserving the field emission free performance of the LCLS-II HE vCM. Using high order modes (HOMs) for plasma ignition allows overcoming limitations imposed by weakly coupled fundamental modes. HOMs ignition can be applied to different SRF cavities making plasma processing potentially possible for any cavity geometry, including spoke resonators like the SSR1 for PIP-II. The results of plasma processing of LCLS-II HE cavities in vCM are presented, along with the summary of the plasma cleaning operations in the CM test cave. The preliminary results of plasma cleaning tests of SSR1 cavities and future plans are discussed.
	Slides THIXA02 [7.045 MB]
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THIXA03	Cryocooler Application for Accelerator and Development Status of Powerful Cryocooler at SHI Ltd.	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)

THIXA04	Development of a Prototype Superconducting Radio-Frequency Cavity for Conduction-Cooled Accelerators
	G. Ciovati, S. Balachandran, G. Cheng, E.F. Daly, P. Dhakal, K.A. Harding, F. Marhauser, T. Powers, U. Pudasaini, R.A. Rimmer, H. Vennekate JLab, Newport News, Virginia, USA J.P. Anderson, B.R.L. Coriton, L.D. Holland, K.R. McLaughlin, D.A. Packard, D.M. Vollmer GA, San Diego, California, USA A.V. Gurevich ODU, Norfolk, Virginia, USA J. Rathke TechSource, Los Alamos, New Mexico, USA T. Schultheiss TJS Technologies, Commack, New York, USA
	Funding: Work supported by the U.S. DOE, ARDAP Office, under contract No. DE-AC05-06OR23177. SB¿s microscopy work at the NHMFL was partly supported by the U.S. DOE, HEP Office under Award No. DE-SC0009960. Recent progress in the development of high-quality Nb₃Sn film coatings along with the availability of cryocoolers with high cooling capacity at 4 K makes it feasible to operate SRF cavities cooled by thermal conduction at relevant accelerating gradients for use in accelerators. We have developed a prototype single-cell cavity to prove the feasibility of operation up to the accelerating gradient required for 1 MeV energy gain, cooled by conduction with cryocoolers. The cavity has a ~3 ¿m thick Nb₃Sn film on the inner surface, deposited on a ~4 mm thick bulk Nb substrate and a bulk ~7 mm thick Cu outer shell with three Cu attachment tabs. The cavity was tested up to a peak surface magnetic field of 53 mT in liquid He at 4.3 K. A horizontal test cryostat was designed and built to test the cavity cooled with three cryocoolers. The rf tests of the conduction-cooled cavity achieved a peak surface magnetic field of 50 mT and stable operation was possible with up to 18.5 W of rf heat load. The peak frequency shift due to microphonics was 23 Hz. These results represent the highest peak surface magnetic field achieved in a conduction-cooled SRF cavity to date
	Slides THIXA04 [3.906 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THIXA05	Conduction-Cooled SRF Cavities: Opportunities and Challenges	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 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)

THIXA06	Dark Matter and Gravitational Waves Experiments with SRF Cavities
	B. Giaccone, A. Grassellino, S. Posen, A.S. Romanenko Fermilab, Batavia, Illinois, USA
	Funding: This material is based upon work supported by the U.S. DOE, SC, National QIS Research Centers, Superconducting Quantum Materials and Systems Center (SQMS) under contract n. DE-AC02-07CH11359 Recent efforts have shown that the SRF technology developed for accelerators can be successfully applied to new applications, including quantum computing, dark matter searches and beyond the standard model physics. The ultra-high quality factor of SRF cavities can allow to achieve unprecedented sensitivity in fields outside of the usual accelerator applications, for examples in dark photon and axion searches (both as dark matter candidates and lab-produced particles). Applications of SRF cavities for gravitational waves searches are also being investigated. The SQMS Physics and Sensing thrust is leveraging SRF cavities and QIS to search for new particles and BSM physics. This talk will highlight experiments where SRF cavities have already set experimental bounds on new physics.
	Slides THIXA06 [5.984 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THIXA07	Compact, High-Power Superconducting Electron Linear Accelerators for Environmental and Industrial Applications: Projects and Status
	J.C.T. Thangaraj, R. Dhuley, C.J. Edwards, I.V. Gonin, S. Kazakov, T.N. Khabiboulline, T.K. Kroc, T.H. Nicol, W. Pellico, A. Saini, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	We have developed and demonstrated a novel superconducting accelerator technology ¿ conduction cooling - that eliminates the need for liquid Helium, thus dramatically simplifying the infrastructure needed to access SRF technology for industrial applications. Our machine combines R&D breakthroughs in high-temperature SRF cavities (Nb₃Sn), cost-effective radio-frequency sources, modern technology cryo-coolers, and high-average current electron guns. We will describe currently active conduction-cooled accelerator projects at 650 MHz and 1.3 GHz. We will also present the experimental results on the conduction cooling of SRF cavities and briefly discuss results from other labs. Our compact linac is designed to generate electron beam energies up to 10 MeV in continuous-wave operation. Our detailed thermal, RF, and beam transport simulations show that a single accelerator module can deliver average beam power as high as 250 kW. We can reach up to 1 MW by combining several modules. Compact and light enough to mount on mobile platforms, our machine will enable applications such as treating contaminants in water, innovative pavement construction, and X-ray medical device sterilization.
	Slides THIXA07 [3.113 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Investigation of Plasma Processing for Coaxial Resonators

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 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

Cite •

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

THIXA02

Plasma Cleaning at FNAL: LCLS-II HE vCM Results and Ongoing Studies on Spoke Resonators

P. Berrutti
Fermilab, Batavia, Illinois, USA

Funding: Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Plasma cleaning has been proven effective in eliminating multipacting and in preserving the field emission free performance of the LCLS-II HE vCM. Using high order modes (HOMs) for plasma ignition allows overcoming limitations imposed by weakly coupled fundamental modes. HOMs ignition can be applied to different SRF cavities making plasma processing potentially possible for any cavity geometry, including spoke resonators like the SSR1 for PIP-II. The results of plasma processing of LCLS-II HE cavities in vCM are presented, along with the summary of the plasma cleaning operations in the CM test cave. The preliminary results of plasma cleaning tests of SSR1 cavities and future plans are discussed.

Slides THIXA02 [7.045 MB]

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.

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)

THIXA04

Development of a Prototype Superconducting Radio-Frequency Cavity for Conduction-Cooled Accelerators

G. Ciovati, S. Balachandran, G. Cheng, E.F. Daly, P. Dhakal, K.A. Harding, F. Marhauser, T. Powers, U. Pudasaini, R.A. Rimmer, H. Vennekate
JLab, Newport News, Virginia, USA
J.P. Anderson, B.R.L. Coriton, L.D. Holland, K.R. McLaughlin, D.A. Packard, D.M. Vollmer
GA, San Diego, California, USA
A.V. Gurevich
ODU, Norfolk, Virginia, USA
J. Rathke
TechSource, Los Alamos, New Mexico, USA
T. Schultheiss
TJS Technologies, Commack, New York, USA

Funding: Work supported by the U.S. DOE, ARDAP Office, under contract No. DE-AC05-06OR23177. SB¿s microscopy work at the NHMFL was partly supported by the U.S. DOE, HEP Office under Award No. DE-SC0009960.
Recent progress in the development of high-quality Nb₃Sn film coatings along with the availability of cryocoolers with high cooling capacity at 4 K makes it feasible to operate SRF cavities cooled by thermal conduction at relevant accelerating gradients for use in accelerators. We have developed a prototype single-cell cavity to prove the feasibility of operation up to the accelerating gradient required for 1 MeV energy gain, cooled by conduction with cryocoolers. The cavity has a ~3 ¿m thick Nb₃Sn film on the inner surface, deposited on a ~4 mm thick bulk Nb substrate and a bulk ~7 mm thick Cu outer shell with three Cu attachment tabs. The cavity was tested up to a peak surface magnetic field of 53 mT in liquid He at 4.3 K. A horizontal test cryostat was designed and built to test the cavity cooled with three cryocoolers. The rf tests of the conduction-cooled cavity achieved a peak surface magnetic field of 50 mT and stable operation was possible with up to 18.5 W of rf heat load. The peak frequency shift due to microphonics was 23 Hz. These results represent the highest peak surface magnetic field achieved in a conduction-cooled SRF cavity to date

Slides THIXA04 [3.906 MB]

Cite •

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

THIXA05

Conduction-Cooled SRF Cavities: Opportunities and Challenges

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 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)

THIXA06

Dark Matter and Gravitational Waves Experiments with SRF Cavities

B. Giaccone, A. Grassellino, S. Posen, A.S. Romanenko
Fermilab, Batavia, Illinois, USA

Funding: This material is based upon work supported by the U.S. DOE, SC, National QIS Research Centers, Superconducting Quantum Materials and Systems Center (SQMS) under contract n. DE-AC02-07CH11359
Recent efforts have shown that the SRF technology developed for accelerators can be successfully applied to new applications, including quantum computing, dark matter searches and beyond the standard model physics. The ultra-high quality factor of SRF cavities can allow to achieve unprecedented sensitivity in fields outside of the usual accelerator applications, for examples in dark photon and axion searches (both as dark matter candidates and lab-produced particles). Applications of SRF cavities for gravitational waves searches are also being investigated. The SQMS Physics and Sensing thrust is leveraging SRF cavities and QIS to search for new particles and BSM physics. This talk will highlight experiments where SRF cavities have already set experimental bounds on new physics.

Slides THIXA06 [5.984 MB]

Cite •

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

THIXA07

Compact, High-Power Superconducting Electron Linear Accelerators for Environmental and Industrial Applications: Projects and Status

J.C.T. Thangaraj, R. Dhuley, C.J. Edwards, I.V. Gonin, S. Kazakov, T.N. Khabiboulline, T.K. Kroc, T.H. Nicol, W. Pellico, A. Saini, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

We have developed and demonstrated a novel superconducting accelerator technology ¿ conduction cooling - that eliminates the need for liquid Helium, thus dramatically simplifying the infrastructure needed to access SRF technology for industrial applications. Our machine combines R&D breakthroughs in high-temperature SRF cavities (Nb₃Sn), cost-effective radio-frequency sources, modern technology cryo-coolers, and high-average current electron guns. We will describe currently active conduction-cooled accelerator projects at 650 MHz and 1.3 GHz. We will also present the experimental results on the conduction cooling of SRF cavities and briefly discuss results from other labs. Our compact linac is designed to generate electron beam energies up to 10 MeV in continuous-wave operation. Our detailed thermal, RF, and beam transport simulations show that a single accelerator module can deliver average beam power as high as 250 kW. We can reach up to 1 MW by combining several modules. Compact and light enough to mount on mobile platforms, our machine will enable applications such as treating contaminants in water, innovative pavement construction, and X-ray medical device sterilization.

Slides THIXA07 [3.113 MB]

Cite •

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