Present state of the theory of vacuum arcs

The understanding of vacuum are processes including the cathode and anode phenomena with cold and hot electrodes as well as the processes in interelectrode plasma is presented. In the case of cold electrodes, the current continuity mechanism, the nature of mass loss, spot motion, plasma jet generation in the spots and the cathode potential drop are reviewed. The explosive and gasdynamical models of cathode spot operation are described. In the case of hot electrodes, the diffuse current continuity mechanism is analyzed. The present state of electrical and plasma characteristics of high current arcs in magnetic fields are discussed.