Use of a glow discharge in a magnetic field for production of broad ion beams for technological applications

Abstract

The results of investigations of the conditions of existence and ion-emission properties of a plasma of the high-current variety of a low-pressure glow discharge with a hollow cathode in a magnetic field are given. It has been shown that an applied weak magnetic field (∼10–3 T) not only reduces the minimum threshold gas pressure, but also makes the radial distribution of the plasma density more uniform (∼10%). A decrease in statistical straggling of the delay time to breakdown (∼102 times) and in discharge formative time (∼10 times) with increasing pulse repetition rate has been revealed to occur as a result of the transition to multielectron discharge initiation. The mass constitution of the discharge and the charge state of ions have been investigated and ways of lowering the content of the basic types of impurities have been determined. The influence of the parameters of the space charge cathode layer on the beam formation by electrostatic ion optics was investigated. The design of a source of gas ions possessing an increased lifetime and high reliability is described. The source is capable of producing an ion beam of cross section ∼100 cm2 with an energy of ions of up to 40 keV at an average current density of up to 1 mA/cm2.