Two-Sapphire-Rod-Resonator Method to Measure the Surface Resistance of High-T_c Superconductor Films

摘要

Precise designs are presented for sapphire rod resonators of three types, which have been proposed by the IEC/TC90/WG8 in the standard measurement method of the surface resistance R_s of high-T_c superconductor (HTS) films; an open-type, a cavity-type and a closed-type. In order to separate TE_(011) and TE_(013)modes, which are used in R_s measurements, from the other modes, appropriate dimensions for these three resonators are determined from mode charts calculated from a rigorous analysis based on the mode matching method, taking account of an uniaxial-anisotropic characteristic of sapphire. Comparison of the open-type resonator with the closed-type is performed. For the open-type, the unloaded g values of both the TE_(011) and TE_(013) modes are reduced by radiations of a leaky state TM_(310) mode. Finally, validity of the design and a two-sapphire-rod-resonator method will be verified by experiments.