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Title: Quench-Induced Degradation of the Quality Factor in Superconducting Resonators

Journal Article · · Physical Review Applied
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Quench of superconducting radio-frequency cavities frequently leads to the lowered quality factor Q0, which had been attributed to the additional trapped magnetic flux. Here we demonstrate that the origin of this magnetic flux is purely extrinsic to the cavity by showing no extra dissipation (unchanged Q0) after quenching in zero magnetic field, which allows us to rule out intrinsic mechanisms of flux trapping such as generation of thermal currents or trapping of the rf field. We also show the clear relation of dissipation introduced by quenching to the orientation of the applied magnetic field and the possibility to fully recover the quality factor by requenching in the compensated field. We discover that for larger values of the ambient field, the Q-factor degradation may become irreversible by this technique, likely due to the outward flux migration beyond the normal zone opening during quench. Lastly, our findings are of special practical importance for accelerators based on low- and medium-beta accelerating structures residing close to focusing magnets, as well as for all high-Q cavity-based accelerators.

Research Organization:
Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC), High Energy Physics (HEP)
Grant/Contract Number:
AC02-07CH11359
OSTI ID:
1249801
Alternate ID(s):
OSTI ID: 1254145
Report Number(s):
arXiv:1605.00272; FERMILAB-PUB-16-087-TD; PRAHB2; 044019
Journal Information:
Physical Review Applied, Journal Name: Physical Review Applied Vol. 5 Journal Issue: 4; ISSN 2331-7019
Publisher:
American Physical SocietyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 11 works
Citation information provided by
Web of Science

References (13)

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Probing dynamics and pinning of single vortices in superconductors at nanometer scales journal January 2015
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Effect of vortex hotspots on the radio-frequency surface resistance of superconductors journal February 2013
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Flux-Flow Resistance in Type-II Superconductors journal August 1965

Cited By (1)

Theory of RF superconductivity for resonant cavities journal January 2017

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