The influence of cathode surface microstructure on DC vacuum arcs

Abstract

The experimental results of the arc lifetime, the arc voltage, the cathode spot velocity and the erosion structure influenced by the cathode surface microstructure for low-current DC vacuum arcs are presented. The correlation between the arc voltage instability peak and the discontinuity in the cathode erosion trace has been shown when applying a transversal magnetic field. With increasing cathode surface roughness, an increase (of about a factor of 100) in the arc lifetime and a 30% decrease in arc voltage at the most, has been found for a drawn arc. The increase of the cathode spot velocity of the retrograde motion by cathode roughness is significant (a hundred times different at most) for triggered arcs. The mechanism of the cathode surface microstructure influence on the DC arc stability is discussed.