This paper reviews the physical phenomena that accompany the emission of electrons and ions from plasma. The development of plasma emission electronics as an independent research field is closely associated with the name of its founder, Professor Kreindel Yu. E. The well-known advantages of plasma electron emitters (plasma cathodes) are the higher emission current density, the pulsed emission capability, and the wider range of residual gas pressures. A peculiar property of the plasma cathode is the possibility of extracting practically all electrons from plasma. The parameters of an ion and electron beam extracted from plasma carry information about the physical processes occurring in the plasma. This makes it possible to invoke emission methods to study the fundamental phenomena that take place in plasma of vacuum arc and low-pressures gas discharges.

High-current electron beams with a current density of up to 100 A/cm2 generated by a plasma-cathode gas-filled diode at low accelerating voltages are studied. Two types of gas discharges are used to produce plasma in the cathode. With glow and arc discharges, beam currents of up to 150 A and 400 A, respectively, have been obtained at an accelerating voltage of 16 kV and at a pressure of 1–3·10−2 Pa in the acceleration gap. The ions resulting from ionization of gas molecules by electrons of the beam neutralize the beam charge. The charge-neutralized electron beam almost without losses is transported over a distance of 30 cm in a drift channel which is in the axial magnetic field induced by Helmholtz coils. The results of calculations for the motion of electrons of the charge-neutralized beam with and without axial external field are presented and compared with those of experiments.

This article presents two types of a hollow-cathode plasma source based on an arc discharge where the electrons emitted either by a hot filament or by a surface-discharge-based trigger system initiate a gas arc discharge. The sources produce gas plasmas of densities 1010–1012 cm−3 in large volumes of up to 0.5 m3 at a discharge current of 100–200 A and at a pressure of 10−1–10−2 Pa. Consideration is given to some peculiarities of the operation of the plasma sources with various working gases (Ar, N2, O2). The erosion rate of the cold hollow cathode in the designed plasma sources is shown to be 10 times lower than that found in an ordinary one. The sources are employed for plasma-assisted surface modification of solids.