Nanosecond surface discharge study by using Dust figure techniques

Abstract

The developing mechanisms of the positive and negative corona streamers on the insulation surface have been studied by using the Dust figure technique together with a line pulser. The present method has the advantage of measuring the velocity of corona discharge development and the discharge mechanism, because the distributions of the positive and negative charges in the discharge figure can be colorfully separated and recorded. By applying shorter time pulses from 10‐ to 920‐nsec duration to a needle point where a glass plate is sandwiched in between the needle and plate electrodes, the diameter of the recorded discharge and the charge quantities and their distributions against the pulse duration were obtained. The observed average velocities of the developing corona streamers at a voltage of 12.0 kV were 2.05×108 cm/sec in the positive and 0.63×108 cm/sec in the negative, respectively. Moreover, when the negative pulse voltage was applied to the needle point the formation time lag of the cathode fall was about 10 nsec and the resulting high densities of the positive and the negative charges induced a back discharge.