3D Simulation of Multi-cathode Spot Jets in Vacuum Arc

On the cathode surface, many cathode spots produce all of the plasma in the vacuum arc. Every cathode spot will generate a supersonic plasma jet, and the interactions among the jets of cathode spots are very important in vacuum arcs. In this paper, a steady three-dimensional Magneto-Hydro-Dynamic (MHD) model is developed to study how jets of multi-cathode spots mix and interact with each other. The simulation results of different distributions (triangle-type and line-type) of copper cathode spots on the cathode surface are presented. The results show that the line-type distribution is not conducive to the mixing of jets, and the emission and diffusion of the middle jet are limited by jets on both sides. The simulation results of copper cathode spots with different cathode spot radii show that as the radius decreases, the density of the ion number in the centre of xoy plane decreases, the maximum temperature area is farther away from the cathode surface, and the radial diffusion velocity at the edge is faster.