Two-dimensional kinetic simulation of plasma dynamics in the post-arc stage of vacuum circuit breakers

Abstract

In this paper, the plasma decay process is simulated with a two-dimensional kinetic model. The charged particles including electrons and singly charged copper ions are processed with the particle-in-cell method, and the electric field is solved in cylindrically symmetric coordinates. When the residual magnetic field is not taken into consideration, electrons react to the transient recovery voltage instantaneously, leaving an ion sheath in the vicinity of the postarc cathode where the electric field is significantly enhanced. The sheath expanding velocity increases as the overall plasma density decreases. Charged particles move not only along the axial direction but also toward the shield of the arc chamber. When the shield is at postarc cathode potential, the radial expansion of electrons is reduced, while that of ions is facilitated. In addition, postarc current is higher than that in simulation with the shield at postarc anode potential. These results are consistent with those in previously published works. When the axial magnetic field is applied, electrons rotate around the magnetic lines and instabilities develop, resulting in density fluctuations. Besides that, the postarc current is higher than those in the case without the magnetic field.