Measurement of the high-voltage breakdown channel propagation velocity in crystalline and amorphous quartz on a subnanosecond time scale

Abstract

The formation time of a breakdown channel in 0.5- to 1.6-mm-thick crystalline and amorphous quartz samples is measured at a pulse voltage of 240 kV, and the effective velocity and direction of breakdown front propagation are determined. In the crystal, the velocity is more than 2.5 times higher than in amorphous SiO2. This may be associated with a higher mobility of free carriers and, consequently, with a quicker motion of the avalanche breakdown front owing to a higher effective velocity of nonequilibrium carriers responsible for the high-energy tail of the distribution function.