On the anode potential fall in a vacuum arc: PIC simulation

The interaction of plasma generated by a vacuum arc with the anode surface was numerically simulated by using a particle-in-cell (PIC) method. It has been found that the anode potential fall remains negative even at high electron drift velocities. The plasma–anode-surface interaction has been analyzed for a ‘steady-state’ regime and for a ‘turbulent’ regime with microinstabilities developing in the plasma. For the steady-state regime, approximate formulas for the anode potential fall and energy flux have been derived from the simulation results. For the turbulent regime, naturally associated with high electron drift velocities, the negative anode fall voltage and the effective plasma electron temperature have been found to be larger than that for the steady-state regime.