Effect of low temperature baking in nitrogen on the performance of a niobium superconducting radio frequency cavity

被引:32
作者
Dhakal, Pashupati [1 ]
Chetri, Santosh [2 ]
Balachandran, Shreyas [2 ]
Lee, Peter J. [2 ]
Ciovati, Gianluigi [1 ]
机构
[1] Thomas Jefferson Natl Accelerator Facil, Newport News, VA 23606 USA
[2] Natl High Magnet Field Lab, Appl Superconduct Ctr, Tallahassee, FL 32310 USA
关键词
HYDROGEN; OXYGEN;
D O I
10.1103/PhysRevAccelBeams.21.032001
中图分类号
O57 [原子核物理学、高能物理学];
学科分类号
070202 ;
摘要
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 degrees C with a nitrogen partial pressure of similar to 25 m Torr. 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 N-2-treated at 120 degrees C and at 140 degrees C showed no degradation in accelerating gradient, however the accelerating gradient was reduced by similar to 25% with a 160 degrees C N-2 treatment, compared to the baseline tests after electropolishing. 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 Nb2O5, 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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收藏
页数:10
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