Mechanism of Cathode Microcrater Formation Under Vacuum Arc Based on Smoothed Particle Hydrodynamics Method

In this article, an improved smoothed particle hydrodynamics (SPHs) method is proposed to study the mechanism of cathode microcrater formation on electrode surface under vacuum arc. First, the improved SPH method is proposed by introducing the free-surface detection algorithm, the surface tension model, and the current continuity equation. Then, the dynamic processes of cathode microcrater formation are simulated based on the improved SPH method. Furthermore, the mechanism and characteristics of microcraters formation are analyzed. In addition, the effects of external parameters such as plasma pressure and energy flux density on the characteristics of microcraters are quantitatively studied and discussed. The simulation results show that the local cathode material would melt under the plasma pressure and energy flux density of vacuum arc and hence forming a liquid metal pool on the cathode surface. The molten metal would sputter under the action of high pressure and thus form a microcrater on the cathode surface. Besides, the liquid metal jet could break and form droplets under some circumstances. The results of this article may provide a new approach for further studying the formation mechanism of cathode microcrater and electrode surface erosion under the vacuum arc.