Cathode spot craters in pulse vacuum arc cleaning of a metal surface oxide layer

Cathode spot behavior during vacuum arc cleaning (VAC) of a metal surface covered with an oxide layer is investigated using a pulse discharge. During VAC, a bright spot is visible. A dot-like trace is marked on the cathode surface by the removed oxide layer. Detailed surface analyses show that the surface roughness is increased and that the oxide layer is stripped off almost uniformly in the trace. The cathode spot size adjustment is more precise than in our previous experiment. Spot characteristics change concomitantly with variation of the discharge electric power.