Gaseous ion and plasma sources based on glow discharge with electron injection

Abstract

Summary form given only, as follows. High current density and simplicity of practical embodiment of the hollow cathode glow discharge favor its use in plasma and charged particle sources. Although, if operating pressure is lower than 10/sup -4/ Torr, the discharge voltage usually exceeds 1 kV. One of the possible ways of reducing the discharge voltage is to provide additional energetic electrons for the discharge plasma using auxiliary electron emitter. Since the electron fraction of the cathode current is low, the injection of electrons has a significant effect on the discharge parameters. Along with the discharge voltage reduction, the minimum operating pressure was decreased, as well as energy efficiency of ion beam generation was enhanced. Also the gas ion beam contamination by metal ions dropped due to lower sputtering. Uniformity and stability of plasma parameters of the hollow cathode glow discharge with external electron injection allow to produce high-quality ion beams with large cross-section. Operating pressure reduction by means of electron injection into the cathode cavity provides ion beam formation in a wide range of accelerating voltage without accelerating gap breakdown. The ion source based on the hollow cathode glow discharge with electron injection provides beams of gas ions (O, N, Ar, He) accelerated by voltage ranging from 100 V to 30 kV, with current of up to 20 mA (DC mode), and 2 A (pulsed mode). The gas plasma generator based on this principle produces uniform plasma with density of 371010 cm/sup -3/ over the vacuum vessel of volume 0.2 m/sup 3/, at operating gas pressure of 10/sup -3/ -10/sup -4/ Torr.