Experimental Studies of the Microwave Properties of 8.6 GHz Superconducting Niobium, Niobium-Tantalum, and Tantalum Cavities.
STANFORD UNIV CALIF HIGH ENERGY PHYSICS LAB
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In this dissertation measurements on the surface impedance of superconducting niobium, tantalum, and a 30 at niobium-70 at tantalum alloy are reported. The measurements were made on X-band mode cavities at a nominal frequency of 8.6 GHz. The surface resistance and the change of surface reactance for the three materials were measured from 1.3 K up to their respective transition temperatures. These data were compared to computer calculations based on the Mattis-Bardeen expressions for the surface resistance and reactance of superconductors. Evidence is also presented concerning the effect of thermal expansion of niobium on the resonant frequency of an X-band cavity as a function of temperature below 2K. The influence of trapped magnetic flux on the microwave surface resistance and reactance of niobium is also reported. Modified author abstract
- Solid State Physics