Physics of Spotless Mode of Current Transfer to Cathodes of Metal Vapor Arcs

A fresh attempt is made to clarify the physics of the diffuse, or spotless, mode of current transfer that may occur on cathodes of vacuum arcs if the average cathode surface temperature is high enough, about 2000 K. It is shown that in the case of chromium cathode the usual mechanism of current transfer to arc cathodes cannot sustain current densities of the order of 105-106 A · m-2 observed in th...