Characteristics of a high-current transient glow discharge in dryair

Abstract

The transition of a high-current glow to an arc and the energydissipation during the glow phase have been investigated in dry air by staticbreakdown. The measurements have been made for uniform-field gaps up to 2 cmat gas pressures of 1-20 Torr. A low-inductance capacitor of 1.89 µF and a discharge circuit with a coaxial system were used to produce atransient glow discharge with a current in excess of 400 A. The experimentalresults showed that the high-current glow discharge occurred at a cathodecurrent density of 3.2 A cm-2, which is almost two orderslarger than the value deduced from the formula for Cu-air normal glow;jn = 240×10-6p2, where jn and p are the current density and gaspressure, respectively. The transition from the glow to an arc starts todevelop in the discharge region near the cathode. The energies dissipated inthe discharge or in the cathode fall region during the glow phase depend onthe gas pressure and/or the electrode separation. However, the dissipatedenergy density in the cathode fall region during the glow phase is independentof the gas pressure and the electrode separation, and is approximately0.035 J cm-3 in the present experiment.