Formation of narrow-focused electron beams generated by a source with a plasma cathode in the forevacuum pressure range

Results are presented from experimental studies of the formation of focused electron beams produced by extracting electrons from the plasma of a steady-state discharge with a hollow cathode in the forevacuum pressure range. Based on the measurements of the energy spectrum and diameter of the electron beam, as well as of the emission parameters of the plasma produced in the course of beam-gas interaction, a conclusion is drawn about the excitation of a beam-plasma discharge that deteriorates the beam focusing conditions. The threshold beam current density for the excitation of a beam-plasma discharge is found to increase with accelerating voltage and gas pressure.