Study of vacuum arc behavior under anode spot and anode plume modes.

Anode spot (AS) and anode plume (AP) phenomena are widely observed in vacuum arc experiments and are related to anode melting and evaporation under strong heating from the arc column. Anode vapor will then strongly influence the arc column through ionization-recombination and energy exchange among atoms, ions, and electrons. This work investigated the characteristics of the vacuum arc with AS or AP using the two-dimensional magnetohydro dynamic model. Formation of the AS and AP modes was studied and analyzed using numerical simulation. Friction forces between ions and atoms were also taken into account. Simulation results show that anode vapor expansion depends on the pressure balance between the anode jet and cathode plasma. Higher anode temperature produces a larger neutral atom vapor area (NAVA), which was dominated by neutral atoms. Inside the NAVA, ion and electron temperatures were low in the AS and AP mode due to ionization and energy exchange. Electric conductivity in this area was also so low that the location of the maximal current density was near the edge of the anode instead of the anode center. The asymmetric appearance of an AP was mainly caused by the asymmetric anode temperature distribution with respect to the AS center. Qualitative comparisons show that the simulation results are consistent with the experimental results. [ABSTRACT FROM AUTHOR]