Electrode material release into a vacuum gap and mechanisms of electrical breakdown

Abstract
Two types of instabilities of electrodes of vacuum gaps, leading to the electrical breakdown, are analyzed in connection with newly published experimental results on the electrode material release into a gap. It is noted that the cathode material release, in correlation with short time delays of the breakdown, is in agreement with the widely accepted model of explosive emission of electrons, whereas the anode material release and long time delays cannot be expanded by the model of clump detachment of the anode material as it was supposed in the experimental study. An alternative explanation is proposed on the basis of the thermal anode instability.