Abstract
An electron beam gun has been continuously operated at ambient pressure up to 5 Torr in helium and 0.5 Torr in argon using narrow gap electrodes and a plasma cathode. Contrary to a hollow cathode electron gun, this device is such that electron beam energy and current are independently controlled without current loss even in the low energy region. A maximum electron energy up to 2 keV and current density of 0.6 A·cm-2 are obtained by means of graphite perforated plate electrodes.