Transient modeling and simulation of high current vacuum arc under different conditions

In this paper, based on a two-dimensional (2D) transient magneto-hydrodynamic (MHD) model, HCVA under different interruption conditions was simulated and analyzed. The simulation results of power-frequency current show that the simulation results of the transient model are the same as those of the steady-state model, as the varying time of current is much longer than the relaxation time of plasma. This verified the correctness of previous conclusions of simulating power-frequency vacuum arc by steady-state model. For fast current drop process in DC interruption, simulation results show that higher frequency makes current drops faster and ion number density larger, besides, the density of residual plasma between electrodes at current-zero moment is higher, and interruption becomes more difficult. Finally, transient characteristics of high-frequency HCVA also was simulated and analyzed. Simulation results showed that plasma between electrodes was too slow to spread in the high-frequency condition, and the change of ion number density lagged behind the current change; the higher ion number density in the second 1/4 cycle weakens the Hall Effect, and leading to a more uniform distribution of current density.