DESIGN OF A NOVEL SAPPHIRE BASED DIELECTRIC RESONATOR TO MEASURE THE SURFACE RESISTANCE OF HIGH TEMP SUPER CONDUCTORS
A sapphire dielectric resonator system has been used to measure the surface resistance of high temperature superconductors. The cavity is made up of a lower superconducting plate, a dielectric puck and a movable upper plate where the sample is placed. The temperature of the lower plate is kept at 4.2 K while the sample is heated independently attached to the end of a sapphire rod. The measurements are performed at TE01d mode. By moving the upper plate, the shift in resonance frequency and the corresponding change in the bandwidth are recorded. The overall system is designed to fit into a continuous flow helium cryostat. Real part of the surface impedance of the sample is related to the change in bandwidth, ?fb, and the imaginary part of the surface impedance is related to the change in resonant frequency, ?f0. Instead of absolute calibration of the chamber, a known oxygen free copper sample was used as the reference. The samples were Seeded Melt Grown (SMG) solid material. The measured surface resistance of the SMG YBCO high Tc materials was comparable to that of the best thin HTS films grown by other techniques.
School:University of Cincinnati
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:htsc dielectric resonator surface resistance ovalue temode
Date of Publication:01/01/2003