Total ion current fraction in a hot refractory anode vacuum arc

The total ion current in the radially expanded plasma of a hot refractory anode vacuum arc (HRAVA) was found to be larger than that measured in the conventional cathodic vacuum arc. The total ion current fraction $fi$ increased during the transition from the initial cathode spot stage to the HRAVA stage. While the $fi$ is independent of arc current in the range of $150–350A$ and other arcing conditions in conventional arcs, the fraction increased with arc current in this current range in the HRAVA. The ion current fraction was found to be 50% larger for a $350A$ HRAVA than the maximal value obtained previously in conventional cathodic arcs.