Investigation of breakdown in porous ceramics initiated by nanosecond pulses

Abstract

Breakdown delay times are measured and velocities of forming a conductive channel in aluminum oxide based porous ceramic materials impregnated with transformer oil are determined for pulsed electrical breakdown initiated by nanosecond pulses at a voltage of 140 kV. The breakdown delay times are also measured in monolithic aluminum oxide ceramics and leuco-sapphire single crystals. It is demonstrated that in porous ceramics, the average velocity of breakdown channel propagation decreases with increasing volume of the sample occupied by the liquid dielectric in comparison with single crystal and monolythic ceramics; it makes 50% of the velocity of breakdown channel propagation in leuco-sapphire and exceeds 3 times the corresponding value in transformer oil measured at the same voltage and pulse duration. © 2012 Springer Science+Business Media, Inc.