Generation of Millisecond Low-Energy Large-Radius Electron Beam by a Forevacuum Plasma-Cathode Source

We describe our research on the generation and formation of low-energy (up to 11 keV) large-radius (up to 3.5 cm) electron beams with pulse duration up to 10 ms, in the forevacuum pressure range (4-25 Pa). The electron beam was formed by extraction from a cathodic arc plasma of millisecond pulse duration using a dc accelerating voltage. To increase the efficiency of electron emission from the plasma, the anode of the plasma source was divided into hollow and plane parts, and the current through the hollow part was limited. When using a redistributing electrode and limiting the current through the hollow part of the anode, the working gas and the gas pressure affect the arc discharge parameters. On the other hand, limiting the current through the hollow part of the anode yields increased efficiency of electron emission from the plasma and provided control of the electron extraction efficiency as well as maximum tolerable gas pressure at the selected beam current. We have generated the electron beam with current up to 23-25 A at pulse duration up to 10 ms in the forevacuum pressure range 4-25 Pa. The electron beam energy per pulse reaches 1800-2000 J.