Experimental Study of the Effect of Gas Pressure on Arc Cathode Erosion and Redeposition in He, Ar, and SF6 from Vacuum to Atmospheric Pressure

Experimental data on the erosion rates of a copper cathode in He, Ar, and SF6 from 10-6 to 760 torr are presented. The work performed by the cathodic-erosion plasma expanding against the gas is found experimentally to be constant, the volume of the expanding plasma cloud being linked to the gas pressure by the relation R3p = constant. These data agree with a redeposition model based on condensation of the metallic vapor produced by the arc on the cathode surface. The redeposited mass on the cathode is found to be proportional to the cube root of the gas mass density.