Generation of Electron Beam with Millisecond Pulse Duration by Plasma-Cathode Source Based on the Arc Discharge in the Fore-vacuum Pressure Range

The paper describes investigation of the possibility of generation of relatively high current (up to 25 A) large-radius electron beam with pulse duration of 4.2 ms by plasma-cathode source based on an arc discharge in the fore-vacuum pressure range. We research arc discharge features, electron emission from the discharge plasma, the threshold parameters (maximal working gas pressure and maximal emission current) of plasma-cathode source and propagation of electron beam with millisecond pulse duration in the fore-vacuum pressure range 3-28 Pa. It is shown, that for the arc with 4.2 ms pulse duration operating in the fore-vacuum plasma source a decrease of the arc current leads to an increase of discharge voltage, and the arc threshold (minimal) current is about 6-7 A. The sort of working gas and its pressure influence on the electron emission and the threshold parameters of plasma-cathode electron source. We obtained the electron beam generated in the pressure range 3-28 Pa with a pulse duration of 4.2 ms and an emission current of up to 25 A. The features of propagation of a millisecond electron beam are studied. Cross-sectional energy density distribution of electron beam for different distances and emission currents are presented. The obtained beam parameters provide to use 4.2 ms electron beam for the surface treatment of various materials by few (1-10) beam pulses.