High pulsed current and voltage measurements on sintered BiPbSrCaCuO ceramics superconductors

High pulsed currents attaining 3300 A with a duration varying from 1.25 to 20 milliseconds have been applied at 77 K to sintered Bi1.8Pb0.4Sr2Ca2.2Cu3O10.3+xlong bars. Measurements of voltage versus applied current determine the critical current Ic = 60 A, and the conditions for superconductivity recovery. Two types of behaviour are observed: (i) When the mean temperature T raises up to T < 95 K a critical current is recovered at the end of the pulse. (ii) When the temperature goes beyond 95 K, Ic goes to zero after the pulse. The temperature increases up to 43 K for a 20 ms pulse. No deterioration in the sample is observed and experiments can be reproducibly repeated. Voltages as high as 90 V have been measured, corresponding to an electrical field of 1100 V/m. The maximum instantaneous power applied to the material is 180 GW/m3and the maximum energy per unit volume transmitted to the sample after a 20 ms pulse is 75 MJ/m3.