We report on our work directed towards increasing the power density of the focused electron beam produced by a forevacuum-pressure plasma-cathode electron beam source at a pressure of 10-30 Pa. We have optimized the geometry of the plasma discharge system, emission channel and acceleration gap, and simultaneously increased the beam acceleration voltage. The beam power density achieved was 10 6 W cm −2 , an order of magnitude greater than that typical of forevacuum plasma electron sources, and is quite sufficient to allow the use of these beams for the treatment of high-temperature bulk dielectrics.
We describe a plasma-cathode electron beam source based on a hollow-cathode discharge that is capable of generating a 9 kW dc electron beam at an accelerating voltage of 20 kV, with helium as a working gas at a pressure of 30 Pa. A test run of ∼50 operational hours did not indicate any significant degradation of the electron source extraction system or other structural components, and we estimate the operational lifetime of the source at about 100–120 h.
We have investigated electron beam transport at an elevated forevacuum pressure of tens of Pascals of helium. The continuous electron beam (6–14 keV, 300 mA) is generated by a forevacuum-pressure plasma-cathode electron source utilizing a hollow-cathode discharge. A beam-plasma discharge is generated in the beam transport zone, which is characterized by increased plasma density in the region of the most intense beam-plasma interaction. We find that the location and distribution of the beam-plasma discharge depend on the electron beam energy and current density. Under certain conditions, we observe that the beam plasma is stratified, with a periodic variation of plasma density and luminosity along the direction of electron beam propagation.
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