Argon needle discharge excited by 5-ns 20-kV voltage pulse

Summary form only given. A point-to-plane discharge in argon was created inside a reaction chamber. The pressure inside the chamber was varied from 100 torr up to 760 torr. The potential electrode through a 1-m high voltage RG cable was connected to a 20 kV, 5 ns pulser (FPG-30SM) with impedance of 50 Omega and pulse repetition rate up to 200 Hz. The electrode system consisted of a flat stainless steel anode and a point tungsten cathode. The distance between the electrodes varied in the range of 0.1 cm-1 cm. This operation could be performed without depressurization. The dependence of the peak current on the gap distance and visual patterns of the discharge are presented. The latter, together with the current and voltage measurements suggest that the discharge transited from streamer corona to spark at higher voltages. The experiments have shown that during one hundred nanoseconds after the end of the high- voltage pulse the gap conductivity was enough to support a 40-A current. The spectral measurements demonstrated that the gas temperature was approximately 1290 K. The experiments have also shown that small admixture of air had strong effect on the average electron energy in the discharge as was predicted.