Removal of Oxide Layer on Metal Surface by Vacuum Arc

The interesting properties of cathode spots were investigated in the removal of an oxide layer on metal surface by a vacuum arc. The cathode spots attack the oxides selectively and remove them by evaporation. The observed removal rate of the oxide layer increases in proportion to the arc current and in inverse proportion to the thickness of the oxide layer. Considering the energy balance at the cathode spot, the authors have developed a simplified model to predict the removal rate. The theoretical results agree with the experimental ones qualitatively. The modeling reveals that there exists a critical current density below which the removal of oxides does not occur.