Failure analysis of high temperature superconducting films at high microwave power using microsecond time domain measurements

摘要

A generic characteristic of resonators can be exploited to determine whether thermal or magnetic mechanisms dominate the failure of high quality, high temperature superconducting thin films at high microwave power. We demonstrate that a transient response can be superimposed on a pulse wave form with a frequency equal to the difference between the driving frequency and the resonant frequency of the resonator. When a thermal failure mechanism dominates, the resonant frequency depends on the temporal separation between pulses. This is in marked contrast to a magnetic failure mechanism, which is insensitive to the pulse separation. For poor quality films the technique cannot differentiate between vortices in weak links and local heating at weak links that happen on a short time scale. We discuss the application of the technique to noncontact microwave bolometry.