Microwave power handling capability of HTS superconducting thin films: weak links and thermal effects induced limitation

Microwave power-handling capabilities of YBCO thin superconducting films, u p to 150 W of the input power, have been investigated using a 14 GHz shield ed dielectric cavity. The YBCO films were deposited by the thermal reactive co-evaporation and the de sputtering method on LaAlO3, NdGaO3, and Al2O3 s ubstrates. A simple nonlinear R(P)-L(P)-C equivalent circuit model was used to simulate a nonlinear cavity response. The correlation of nonlinearity w ith global and local heating is discussed. The analysis of experimental dat a confirms, that for all films, the heating of weak links switched to norma l state is one of the rf power handling capability major limitations.