Threshold Currents of Vacuum Arcs With Tungsten and Copper Cathodes

ABSTRACT This paper presents the results of an experimental study aimed at determining the threshold current for triggering a vacuum arc discharge, the probability of arc ignition and the average arc operation time depending on the current for tungsten and copper electrodes. It has been shown that the cutoff current of a vacuum arc varies widely under constant experimental conditions. The threshold current for tungsten cathodes is higher than for copper ones. For both materials, there is a nonzero probability of arc ignition at currents significantly lower than the average threshold. At the same time, the exponential dependence of the average arc operation time on the current is preserved.