A technique for high-power microwave diagnostics of large-area homogeneous HTS films

A new technique and measuring equipment for determination of the dependence of HTS surface resistance on a microwave magnetic field amplitude, R/sub s/(H), were developed. The measuring system was an open 36 GHz resonator formed between a spherical metal surface and a flat HTS film. The microwave scheme included a high-power pumping wave circuit and a spectrally separated low-power diagnostic signal circuit. The H structure inhomogeneity on the HTS surface was taken into account. Measurements of the averaged surface resistance have shown it to be related with R/sub s/(H) by the integral equation. The technique for solution of the integral equation based on the Tikhonov method extended from the theory of incorrect inverse problems was applied. Some results of R/sub s/(H) measurements for large-area (>35 mm) YBCO films deposited onto NdGaO/sub 3/, LaAlO/sub 3/ substrates are presented and discussed.