Three-dimensional hybrid simulation of vacuum arc extinction considering dynamic behavior of cathode spots

Abstract

Vacuum arc extinction directly determines the plasma distribution at the current zero point, which affects the post-arc insulation recovery. In that regard, studying the extinction process to improve the post-arc insulation recovery ability is of great significance. In the extinction process, as the current decreases, cathode spots are extinguished and their distribution exhibits apparent discreteness and asymmetry, while the plasma density decays drastically. On the one hand, the discreteness of cathode spots makes the simulation setup regarding the whole cathode surface as a continuous emission source no longer applicable. On the other hand, the drastic decay of plasma density requires a simulation tool that can balance the computational efficiency and accuracy of the extinction process. To deal with these problems, the dynamic behavior of cathode spots is considered in this paper, and a three-dimensional hybrid plasma model is established. In order to simulate a more realistic situation, two applied axial magnetic field configurations for practical applications—bell-shaped and saddle-shaped configurations—are introduced. Both configurations are used to compare the position distribution and extinguishing sequence of cathode spots, as well as the evolution of plasma. More importantly, the method applied in this study can be employed to evaluate the effect of different magnetic field conditions on vacuum interruption, which would enable one to simulate the extinction process in a realistic manner.