Comparing the Effectiveness of Low Temperature Bake in EP and BCP Cavities

Conference · Mon Sep 25 04:00:00 EDT 2023 · JACoW

DOI:https://doi.org/10.18429/JACoW-SRF2023-MOPMB040· OSTI ID:2279063

Hu, Hannah ^[1]; Bafia, Daniel ^[2]; Kim, Young-Kee ^[1]

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1. Chicago U.
2. Fermilab

Electropolishing (EP) and buffered chemical polishing (BCP) are conventional surface preparation techniques for superconducting radiofrequency (SRF) cavities. Both EP and BCP treated SRF cavities display high field Q-slope (HFQS) which degrades performance at high gradients. While high gradient performance in EP cavities can be improved by introducing oxygen via a low temperature bake (LTB) of 120^{°}C by 48 hours, LTB does not consistently remove HFQS in BCP cavities. There is no consensus as to why LTB is not effective on BCP prepared cavities. We examine quench in EP, BCP, EP+LTB, and BCP+LTB treated 1.3 GHz single-cell Nb cavities by studying the heating behavior with field using a temperature mapping system. Cavity performance is correlated to characterizations of surface impurity profile obtained via time of flight secondary ion mass spectrometry studies. We observe a difference in near surface hydrogen concentration following BCP compared to EP that may suggest that the causes of quench in EP and BCP cavities are different.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• DOE Contract Number: AC02-07CH11359
• OSTI ID: 2279063
• Report Number(s): FERMILAB-CONF-23-785-SQMS; oai:inspirehep.net:2723488
• Conference Information: Journal Name: JACoW Journal Volume: SRF2023
• Country of Publication: United States
• Language: English

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