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Description
In this work, a two-dimensional (2D) particle-in-cell/Monte Carlo collisional (PIC/MCC) model is developed to simulate the plasma decay and re-breakdown in the post-arc stage of vacuum circuit breakers. The field distribution is obtained by solving the Poisson’s equation in 2D cylindrical coordinate and the positions of charged particles, which are traced as super particles to save the calculation time and computer memory, are given by Newton’s law. Various collisions between charged particles and neutrals including elastic scattering, impact excitation and ionization are treated with MCC method. The grid size and time step satisfy the constraints given by the Debye length and plasma frequency. Results show that the plasma residual from the arcing stage gradually expands under the transient recovery voltage in the post-arc stage. An ion sheath forms near the post-arc cathode where the field is significantly enhanced. When the residual metal vapor is considered in the simulation, the plasma propagation is lowered by the collisions between charged particles and metal neutrals. The residual plasma is restricted in the inter-electrode region. When the metal vapor density further increases, the electrons emitted from the post-arc cathode surface could lead to re-breakdown in the post-arc stage.
