Q disease on 350-MHZ superconducting spoke cavities
- Tsuyoshi
- Randall L.
- Frank L.
- Dale L.
- Alan H.
Q disease, i.e., an increase of RF surface resistance due to hydride precipitation, has been investigated with 350-MHz spoke cavities. This phenomenon was studied extensively in early 1990s with cavities at frequencies >1 GHz. This is possibly due to the fact that the lower-frequency cavities were believed to show insignificant effect. However, early 500-MHz KEK elliptical cavities and JAERI 130-MHz quarter wave resonators have shown significant Q degradation, suggesting that this disease can be a serious problem with lower-frequency cavities as well. Since there were no quantitative data with 350-MHz cavities, we decided to measure our two spoke cavities. Our spoke cavities were made of RRR{approx}250 niobium and were chemically polished {approx}150 microns. A few series of systematic tests have shown that our spoke cavities do not show any Q{sub 0} degradation up to {approx}24 hours of holding the cavity at 100 K. However it starts showing degradation if it is held for a longer time and the additional loss due to the Q disease increases linearly. It was also found that our spoke cavity recovers from Q disease if it is warmed up to 150 K or higher for 12 hours.
- Research Organization:
- Los Alamos National Laboratory
- Sponsoring Organization:
- DOE
- OSTI ID:
- 976655
- Report Number(s):
- LA-UR-03-3149
- Country of Publication:
- United States
- Language:
- English
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