Cathode Erosion in Vacuum Arcs and Unipolar Arcs

The cathode spots from vacuum arcs on 316 stainless steel are compared with the tracks found on the same material after exposure to the plasma of the tokamak TFR 600. Further the erosion yields of vacuum arc cathodes of 316 stainless steel and titanium are determined from experiments and the measured values are compared with theoretical estimates. The velocity of the arc is investigated as a function of the applied magnetic cross-field. The scatter of both, the velocity data and the erosion yields is substantial. Improved experiments are planned.