Models to assess thermal state of an anode of vacuum arc

Three nonstationary models for analysis of thermal state of the anode and its relation to discharge operation are considered: (1) heating of the anode as a semi-infinite body with variable heat flux from the near-anode region; (2) model of melting and liquid metal film formation; and (3) model of anode evaporation. The first model can be applied for specifying some poorly defined parameters of the near anode region using experimental data on high current vacuum arcs. The second model helps to verify an idea of anode melting as a criterion of anode spot formation. The third (evaporation) model is applicable to a very heavy mode of current interrupter operation.