Noise parameters of defects of the emitting surface of thermionic cathodes

Abstract

A noise model in which fluctuation noise of output current is determined by weakly emitting fragments of thermionic cathode working in the saturation regime (defects on the emitting surface) is proposed. The measured noise characteristics of the shot and flicker components of noise can be used to determine distribution of defects with respect to emission current densities and the noise parameters of defects. The relation of noise parameters and the degree of degradation of cathode is analyzed using the pulsed emission current at relatively long working times of dispenser cathodes with the W–Re sponge and Os coating. Preliminary results show that that proposed noise parameters can be used for the development of working methods for estimation of cathode quality.