S-N TRANSITION OF HIGH-T(C) SUPERCONDUCTING RING CAUSED BY INDUCED CURRENT

The experimental investigation results of superconducting-normal state transitions in a high-T(c) superconducting ring with induced current are presented. A transformer device is used, where the superconducting ring forms a secondary winding of a transformer. Using the analysis m ethod based on an equivalent circuit of the transformer, the voltage a nd current in the ring vs time are obtained from oscilloscope traces o f the voltage and current in the primary winding of the device. The dy namic voltage-current characteristic of the ring is found to have a hy steresis. This hysteresis is explained by the inertia of thermal proce sses and propagation of a resistive zone in the ring.