Anode spot in a high-current vacuum arc

We have studied the anode region of a heavy-current vacuum arc in which an anode spot has formed. Special attention has been devoted to the layer of space charge near the anode. We show that the generation of ions in this layer plays an essential role. Depending on what role the pinch effect plays, arcs with an anode spot can be divided into relatively ''low current'' and relatively ''high current'' arcs. The boundary between these two types lies at a current of approx.10 kA. We have calculated the following chracterstics of the arc: the radius of the spot, the temperature of the anode, the drop in voltage in the Langmuir sheath and across the entire arc, and the rate of vapor erosion. Comparison with experimental quantities shows satisfactory agreement