Electrical Breakdown of Small Gaps in Vacuum

Abstract

The comparison of the characteristics of an electric arc breakdown in vacuum between two sil-ver or silver-nickel alloy convex electrodes, enabled us to show experimentally that the process initiating discharge invacuum is the electronic emission at the micrometer scale. Increased con-tent of nickel in the alloy improves the insulation and achieves high resistance to erosion for low power arcs. Heating in vacuum demonstrates the multiple layer structure of studied alloys. Secondary electron microscopy and energy dispersing spectroscopy of the electrode surfaces af-ter breakdown, as well as the measurements of fall and delay times, enabled us to evidence the origin of the electric arc. 1