Anode modes in vacuum arcs: Update

This paper discusses the seven different anode discharge modes which can occur in a vacuum arc. These modes are diffuse arc (low current, with or without anode sputtering), footpoint and plume (intermediate current), plus anode spot (two types), and intense arc (high current). The plume and Type 2 anode spot modes may occur just for certain materials, since they have been seen only with CuCr electrodes. Descriptions of the various spot modes are presented, based primarily on experimental results. The effects of external magnetic fields on anode modes are briefly stated. Arc column modes are also discussed, but only as they correspond to anode modes.