Formation of emission plasma in a pulsed forevacuum-pressure plasma-cathode electron source based on a cathodic arc with redistributing electrode

Abstract

The paper describes the investigations of the influence of a redistributing electrode on the formation of emission plasma near the electron extraction region in a pulsed forevacuum-pressure plasma-cathode electron source utilizing a cathodic arc for generation of emission plasma. The authors show that the use of the redistributing electrode with optimal geometry in the discharge gap of the source provides a fairly uniform emission plasma density distribution. For the used discharge gap and pulse duration up to 5 ms, the use of the spherical stainless-steel redistributing electrode with radius of 6 mm provides rather uniform plasma density distribution near electron extraction region in the investigated gas pressure range 3–15 Pa. A model simulating the formation of plasma in the forevacuum pressure range has been developed. The model considers the scattering of ions of the arc plasma by gas atoms and the formation of gas ions by ionization of the operating gas by high-energy electrons. The calculated distributions of emission plasma density are consistent with the experimental data for different sizes of the redistributing electrode and for different gas pressures. The model and experiment show that the plasma density near the anode mesh increases with increasing gas pressure, for example, increase in gas pressure from 5 to 10 Pa leads to an 80% increase in density of emission plasma.