Secondary gap plasma: origin and resulting effects

Substantiation is given to the statement that the steady burning of a high-current vacuum arc (HCVA) calls for the presence of a sufficiently high concentration of the secondary plasma (SP) in the interelectrode gap (as distinct from the primary plasma of cathode jets). The efficiency of possible SP sources is analyzed. The basic SP source is shown to be the anode that emits atoms under the action of high-speed primary ions. A dynamic HCVA model that incorporates the SP generation is proposed and substantiated. The cause of the loss of stability and the anode spot formation in a freely burning HCVA is shown to be the lateral loss of high-speed ions and corresponding lowering of the SP generation efficiency. The consideration is based on the analysis of experimental studies of HCVA.