Effect of Contamination on Arc Initiation on a Metal Surface Exposed to Plasma

Abstract

The initiation of arcs on a metal surface stained by contamination and exposed to a plasma has been studied experimentally and with the use of a calculation model. It is assumed in the calculation model that a negative voltage is applied to a metal specimen with respect to the plasma potential, arcs are initiated when the electric field strength due to the voltage drop produced in the contaminant layer is large enough to induce dielectric breakdown in the layer, and that the conditions for arc initiation in the gap between the plasma and the metal surface are fulfilled by the burst of vapor produced when dielectric breakdown occurs. The variation of the arc initiation voltage with the plasma density and the variation of the time lag before arc initiation with the applied voltage were obtained experimentally. These experimental results can be qualitatively explained by the results obtained from the calculation model.