Dynamic model of thermal cathode spot in initial stage of its formation

Abstract

The formation of a cathode spot (CS) as evolution of instability of emission-ionization process in CS is considered. The equations for the analysis of instability have been found for certain approximations. It has been shown that the point of a position of process equilibrium is an unstable point of a `saddle' type. An increment of instability evolution and some other dynamic parameters of CS have been calculated for the copper cathode. The possibility of using the results obtained to calculate a rate constant of a new CS formation by existing CS has been considered. The use of stricter approximations to construct initial equations is discussed. It has been shown that taking into account the decrease in the number of neutral particles because of ionization process results in the appearance of the second stable point of an equilibrium position.