LATERAL SPREAD OF SHORT GLOW-DISCHARGES

A weakly abnormal glow discharge, started at one end of a pair of long coaxial electrodes, spreads laterally over the whole length of anode and cathode. In helium and neon at 10 Torr and for short interelectrode distances, the lateral velocity is independent of position and gas pressure when the applied voltage is kept constant. When the voltage approaches the normal cathode fall, the speed tends to zero and it rises with voltage in excess of the normal cathode fall. The spreading mechanism is assumed due to positive ions emerging from the boundary between cathode fall or negative glow and the virgin gas. Discharge expansion rate calculations are based on a model representing the boundary by an edge normal to the cathode.