Gas Temperatures in Impulse Discharge Channels at Low-Pressure Air

Abstract

Two types of glow-to-arc transition processes, following constricted and transitional glows, in a nonuniform field gap between a point anode and a protrusion on a plane cathode in low-pressure air under impulse voltage are investigated, observing the spatiotemporal variation of emission intensity of the discharges by means of an image converter camera. At the same time, the distribution of gas temperature along the gap axis is measured spectroscopically with high resolution in time. The results show that the gas temperature is raised to a considerably high, though not extreme level. Along the positive column, the gas temperature rise is higher in the constricted region, especially at two parts near the respective tips of the point anode and the cathode protrusion. The transition mechanisms from the glow to the arc are discussed.