Recovery Strength Measurements in Arcs from Atmospheric Pressure to Vacuum

Measurements are reported for the recovery of electric strength following interruption of an arc drawn in nitrogen at pressures ranging from atmospheric to 0.02 torr. These data are compared with similar results obtained for vacuum arcs. Recovery strength measurements followed a single half-cycle of sinusoidal arc current with a peak of 400 amperes. For conditions of gap length and pressure described by the Paschen curve minimum, full recovery is reached in a time less than a few micro-seconds. The voltage corresponding to full recovery is essentially determined by contacts, their separation, and ambient gas pressure.