From pulse measurements to the frequency current-voltagу characteristic of superconductors: step one

The results of measurements in liquid nitrogen of volt-ampere characteristics (VAC) of high-temperature superconductor tapes for a decreasing alternating current with a period of τ ~ 9 ms are presented. In the case when the initial amplitude is 4 times greater than the critical current, after the first period the temperature exceeds the critical one, and a normal state occurs. This state is maintained until the current amplitude decreases to the level of the critical current of the superconductor. The experiment demonstrates the possibility of determining the conditions for using superconductors in alternating current circuits.