Numerical Simulation of Micro-Explosion of Cathode Micro-Protrusion Based on Smoothed Particle Magnetohydrodynamics

In this article, an improved smoothed particle magnetohydrodynamics (SPMHDs) method is proposed to study micro-explosion phenomena of cathode micro-protrusion under high-density electron emission. First, the improved SPMHD method is established by introducing the coupling effect of the heat conduction effect and Joule heating effect into the basic SPMHD method. Furthermore, the latent heat of phase transition is processed and the equations of state for different phase states are introduced into the basic SPMHD method. Then, the dynamic characteristics of the micro-protrusion during the micro-explosion, such as the temperature rise, the phase transition, the surface destruction, and the diffusion of the metal vapor, are quantitatively obtained and discussed based on the improved SPMHD method. The results show that the high-density electron emission could cause the significant temperature increase of the micro-protrusion and hence a micro-explosion. The action of the pressure exerted by the micro-explosion could lead to the formation of a crater on the cathode surface. The metal vapor produced by the micro-explosion would propagate into the surrounding vacuum gap at a high velocity, which may lead to the failure of the vacuum insulation. The results of this article may provide some useful information to further understand the mechanism of vacuum breakdown initiated by the electron emission.