Specific features of the I–V characteristics and high-efficiency electron-beam generation in a continuous open discharge

The main features of a continuous open discharge used to generate electron beams in medium-pressure gases are discussed. I – V characteristics have been investigated, current and energy efficiencies have been measured, and conditions for obtaining a high (comparable with the anode geometric transparency) energy efficiency of beam generation in helium at a pressure of 10–30 Torr and its mixtures with oxygen have been established. Fundamental differences between the investigated and anomalous discharges have been found. In particular, a Z-shaped I – V characteristic has been obtained and attributed to the modification of the role of main electron emission mechanisms with increasing voltage.