Simulation on Development of Cathode Spot Crater and the Emission Distribution on the Crater Surface in Vacuum Arc

In this article, the 2-D axisymmetric model of cathode crater has been used to study the influence of temperature and morphology on metal vapor evaporation and thermal-field (T-F) emission during cathode spot development. The effect of cathode deformation on the surface electric field strength is reflected by replacing the current density boundary in previous model with the voltage boundary. The simulation results show that the temperature distribution on the crater surface exhibits either a single peak at the metal jet head or a double peak at both the center of the crater and the jet head, depending on the external pressure relative to the heat. However, the electric field consistently exhibits a peak at the head of the metal jet. The emission characteristics of the cathode crater surface indicate that the peaks of metal vapor and T-F current density coincide at the jet head, suggesting that the new cathode spot's explosion center will appear at the metal jet tip of the preexisting crater.