Bulk Breakdown in Rexolite for Non-Uniform Field Geometries and Single Polarity Pulses < 10 μs /sup */

Although there is much written in regards to voltage breakdown of polymeric insulators under AC and DC conditions, much less is written involving Rexolite©(1422), non-uniform field geometries, and impulse conditions. Yet, in order to design optimized pulsed power systems with some desired degree of reliability, understanding the behavior of this type of insulating system is needed. Specifically, Sandia National Laboratory\´s ZR project, which will use anode plugs in the vacuum stack (thus increasing the electrical stress in the Rexolite insulators), needs to be able to estimate the reliability of these vacuum stack insulators. In an effort to estimate the insulator\´s lifetime small scale testing is in progress. Nine samples have been tested so far and at least ten more will be tested. Results from the current testing suggest that the Rexolite "ages" from pulse to pulse, that there is some volume dependence on breakdown strength, and that the electrode-vacuum- insulator interface has an affect on the insulator lifetime.