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Title: Thermal link design for conduction cooling of SRF cavities using cryocoolers

Abstract

Superconducting radio frequency (SRF) cavities with quality factors ~1010 near 4 K have potential to be cooled using re-generative-cycle cryocoolers. Contrary to using liquid helium, cry-ogen-free operation can be realized by conductively linking a cavity to a cryocooler. The cavity-cryocooler thermal link needs careful design for balancing cooling capacity of the cryocooler with the dissipation rate in the cavity. We present a thermal analysis of a conduction-cooled SRF cavity that identifies the link thermal con-ductance requirement. The analysis uses published or expected RF dissipation characteristics of an Nb3Sn coated niobium cavity and in-house measured cooling capacity of a commercial pulse tube cryocooler. We describe mechanical design of a link that is con-structed using commercial high-purity aluminum and facilitates bolted-connection to elliptical SRF cavities. The thermal perfor-mance of the link is assessed by finite element simulations, taking into account temperature dependent thermal conductivities and measured thermal contact resistance of aluminum and niobium. The link is shown to support operation at an accelerating gradient of 10 MV/m with the lowest-known ‘perfect’ Nb3Sn surface re-sistance (10 nΩ) and also under non-ideal cases that assume certain static heat leak into the system and non-perfect Nb3Sn coatings

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Fermilab
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP)
OSTI Identifier:
1487040
Report Number(s):
FERMILAB-PUB-18-491-DI-TD
1708486
DOE Contract Number:  
AC02-07CH11359
Resource Type:
Journal Article
Journal Name:
IEEE Trans.Appl.Supercond.
Additional Journal Information:
Journal Name: IEEE Trans.Appl.Supercond.
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS

Citation Formats

Dhuley, R. C., Kostin, Kostin,R., Prokofiev, O., Geelhoed, M. I., Nicol, T. H., Posen, S., Thangaraj, J. C.T., Kroc, T. K., and Kephart, R. D. Thermal link design for conduction cooling of SRF cavities using cryocoolers. United States: N. p., 2018. Web.
Dhuley, R. C., Kostin, Kostin,R., Prokofiev, O., Geelhoed, M. I., Nicol, T. H., Posen, S., Thangaraj, J. C.T., Kroc, T. K., & Kephart, R. D. Thermal link design for conduction cooling of SRF cavities using cryocoolers. United States.
Dhuley, R. C., Kostin, Kostin,R., Prokofiev, O., Geelhoed, M. I., Nicol, T. H., Posen, S., Thangaraj, J. C.T., Kroc, T. K., and Kephart, R. D. 2018. "Thermal link design for conduction cooling of SRF cavities using cryocoolers". United States. https://www.osti.gov/servlets/purl/1487040.
@article{osti_1487040,
title = {Thermal link design for conduction cooling of SRF cavities using cryocoolers},
author = {Dhuley, R. C. and Kostin, Kostin,R. and Prokofiev, O. and Geelhoed, M. I. and Nicol, T. H. and Posen, S. and Thangaraj, J. C.T. and Kroc, T. K. and Kephart, R. D.},
abstractNote = {Superconducting radio frequency (SRF) cavities with quality factors ~1010 near 4 K have potential to be cooled using re-generative-cycle cryocoolers. Contrary to using liquid helium, cry-ogen-free operation can be realized by conductively linking a cavity to a cryocooler. The cavity-cryocooler thermal link needs careful design for balancing cooling capacity of the cryocooler with the dissipation rate in the cavity. We present a thermal analysis of a conduction-cooled SRF cavity that identifies the link thermal con-ductance requirement. The analysis uses published or expected RF dissipation characteristics of an Nb3Sn coated niobium cavity and in-house measured cooling capacity of a commercial pulse tube cryocooler. We describe mechanical design of a link that is con-structed using commercial high-purity aluminum and facilitates bolted-connection to elliptical SRF cavities. The thermal perfor-mance of the link is assessed by finite element simulations, taking into account temperature dependent thermal conductivities and measured thermal contact resistance of aluminum and niobium. The link is shown to support operation at an accelerating gradient of 10 MV/m with the lowest-known ‘perfect’ Nb3Sn surface re-sistance (10 nΩ) and also under non-ideal cases that assume certain static heat leak into the system and non-perfect Nb3Sn coatings},
doi = {},
url = {https://www.osti.gov/biblio/1487040}, journal = {IEEE Trans.Appl.Supercond.},
number = ,
volume = ,
place = {United States},
year = {Tue Sep 18 00:00:00 EDT 2018},
month = {Tue Sep 18 00:00:00 EDT 2018}
}