Postarc phenomena in a diffuse self-commutating DC vacuum arc

Measurements were made of the postarc chopping current of a self-commutating DC vacuum arc. Cathode current, anode current, and arc voltage, as well as ion current, to a grounded shield were monitored. A qualitative description of conditions in the gap is proposed, explaining the apparent current reversal observed. A significant feature of the postarc current is a slight increase in cathode current, accompanied by an increase in ion current to the shield. The anode current simultaneously appears to reverse direction. These transient features all appear to occur after the extinction of the last cathode spot emission site