Simulation of metal vapor breakdown after interrupting a vacuum arc

A breakdown after interrupting a vacuum arc current indicates the interruption limit of a vacuum circuit breaker (VCB). The objective of this paper is to study breakdowns in copper vapor at a density of interruption limit employing Particle in Cell-Monte Carlo Collision (PIC-MCC) method. A model with one dimension in physical space and three dimensions in velocity space was developed with a gap length of 10 mm between the contacts. The model took into account ionization, excitation, elastic collision and secondary emission. We obtained the boundary of instantaneous breakdown region of a VCB through the simulation. The results show that a higher neutral metal vapor density can accelerate the electron avalanche process but the influence was limited when the density exceeded a certain level. Moreover, a higher voltage can also accelerate the avalanche process.