Parameters of cathode region of vacuum arc

The existing systems of equations describing steady processes in the cathode region of a vacuum arc are analyzed. It is shown that the region of existence of the cathode spot parameters for copper obtained by the diagram method or the method of limiting relations cannot be used, as has been believed hitherto in the literature, to distinguish the narrow range of values of the parameters and, hence, to determine these parameters with appropriate accuracy. The possibility of using an expression for the evaporation rate of the cathode metal in the system of equations of the arc cathode region and obtaining a steady-state solution of such a system for a tungsten cathode is discussed.