The formation of accelerated electrons and their effect on the structure of nanosecond discharge with slot cathode

Experimental investigations are performed of the current-voltage characteristics and spatial distribution of optical radiation of plasma within the cathode cavity and in the discharge gap under conditions of transverse nanosecond electric discharge with a slot cathode. The investigations are performed in helium in the gas pressure range from 1 to 100 torr. It is demonstrated that the cathode layer is formed at the initial stage of discharge and that the electrons accelerated in the narrow cathode region pick up energy of the order of 1 keV. The efficiency of electron beam generation is estimated, and the mechanisms of generation of fast electrons are identified. The free paths of accelerated electrons in plasma under different initial conditions are determined, and the mechanisms of relaxation of energy of this group of electrons are analyzed. The correlation is established between the special features of relaxation of energy of fast electrons and the formation of the structure of beam-plasma discharge with a slot cathode.