Flux jumps under time-dependent external conditions

The authors investigate the influence of the time-dependent external conditions on the stability criterion of the critical state in a hard superconductor with respect to flux jumps. It has been shown that the existence of a non-linear region in the current-voltage characteristic can result in a significant delay of the onset of the instability. The methods developed by the authors make it possible to define the dependence of the stability criterion on the rate of change of the external parameters (magnetic field, temperature etc). The total theoretical results have been compared with the experimental data.