Cathode spot phenomena in titanium vacuum arcs

Abstract
Investigations of cathode spot behavior on a titaniumcathode in the presence of a variable magnetic field are presented. The cathode spot velocity as a function of magnetic field strength, arc current, and gas pressure has been determined using an optical technique, and the results have been compared with a number of available theories. The cathode spots have been investigated using a magnetic probe coil, and using both high‐speed and conventional photography. The observations show that the motion of the spots is consistent with the presence of a positive space charge at the spot.