Electrode erosion by particle ejection in low-current arcs

Abstract

Examination of the electrode damage due to various types of low-current (< 5 A) atmospheric pressure arcs has led to the conclusion that a similar contact erosion mechanism exists for each. These arcs have included high-voltage-gas-breakdown arcs, resistive-make arcs, and both resistive-and inductive-break arcs. Material transfer is considered to result from the ejection of molten metal out of the electrode craters by the recoil force, which follows the abrupt cessation of ion bombardment. In the so-called ``cathode arcs'', i.e., arcs burning predominantly in cathode material, metal droplets have been observed on the anode. In ``anode'' arcs, i.e., arcs burning predominantly in anode material, droplets have been observed on the cathode, an observation that is consistent with the above model using electron instead of ion bombardment.