Experimental study of plasma parameters in a vacuum arc with a hot refractory anode

The spatial distributions of plasma density, electron temperature, plasma potential and ion energy were measured during hot refractory anode vacuum arc (HRAVA) development as functions of arc current and inter-lectrode gap distance. Plasma density increased with arc time and saturated (≥1014 cm-3) in the developed HRAVA stage. While the ion energy in the anode plasma at the gap exit was relatively small, the ions were accelerated outside the gap in radially expanding plasma to ∼15 eV at 19 cm from the electrode axis. The electron temperature decreased during anode plume development and was ≥1 eV in the developed HRAVA stage. Measured plasma parameters agreed well with previously developed theory.