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arXiv · 1711.03991

Effect of Low Temperature Baking in Nitrogen on the Performance of a Niobium Superconducting Radio Frequency Cavity

Pashupati Dhakal·Santosh Chetri·Shreyas Balachandran·Peter J. Lee·Gianluigi Ciovati
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Abstract

We report the rf performance of a single-cell superconducting radiofrequency cavity after low temperature baking in a nitrogen environment. A significant increase in quality factor has been observed when the cavity was heat treated in the temperature range of 120-160 {\deg}C with a nitrogen partial pressure of ~25 mTorr. This increase in quality factor as well as the Q-rise phenomenon (anti-Q-slope) is similar to those previously obtained with high temperature nitrogen doping as well as titanium doping. In this study, a cavity N2-treated at 120 {\deg}C and at140 {\deg}C, showed no degradation in accelerating gradient, however the accelerating gradient was degraded by 25 with a 160 {\deg}C N2 treatment. Sample coupons treated in the same conditions as the cavity were analyzed by scanning electron microscope, x-ray photoelectron spectroscopy and secondary ion mass spectroscopy revealed a complex surface composition of Nb_2O5, NbO and NbN(1-x)Ox within the rf penetration depth. Furthermore, magnetization measurements showed no significant change on bulk superconducting properties.

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Pashupati Dhakal, Santosh Chetri, Shreyas Balachandran, Peter J. Lee, Gianluigi Ciovati. 2017-11-10. Effect of Low Temperature Baking in Nitrogen on the Performance of a Niobium Superconducting Radio Frequency Cavity. https://doi.org/10.1103/physrevaccelbeams.21.032001

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