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

Abstract

Microwave power-handling capabilities of YBCO thin superconducting films, up to 150 W of the input power, have been investigated using a 14 GHz shielded dielectric cavity. The YBCO films were deposited by the thermal reactive co-evaporation and the dc sputtering method on LaAlO/sub 3/, NdGaO/sub 3/, and Al/sub 2/O/sub 3/ substrates. A simple nonlinear R(P)-L(P)-equivalent circuit model was used to simulate a nonlinear cavity response. The correlation of nonlinearity with global and local heating is discussed. The analysis of experimental data confirms, that for all films, the heating of weak links switched to normal state is one of the rf power handling capability major limitations.