Insulator degradation resulting from high current surface discharges
Three surface discharge switches were designed and constructed to measure insulator degradation for direct surface discharges approaching 10 Amperes (current density on the order of 10 A/cm). The degradation of insulators exposed to ringing arc currents of this magnitude was thought to be a good simulation for pulsed power machines where direct or vicinity arcs, on the order of 10 Amperes, take place. More specifically, this arrangement was felt to be a good simulation of "wall insulators" in typical electromagnetic launchers (EML's). The three switches, SDS I. SDS II, and SDS III, were capable of peak, stationary arc discharge currents of 160 kA, 250 kA, and 670 kA, respectively, at a pulse repetition rate up to 2 pulses per second. SDS III was retrofitted with rail electrodes to study the effects of moving arc discharges. Insulator degradations were predicted in terms of heat resistance and thermal shock resistance, and verified experimentally for advanced ceramics, high purity aluminas, polymers, and polylaminate Fiberglasses.