Formation of a Focused High-Current Quasi-Continuous Electron Beam by a Forevacuum Plasma-Cathode Source Based on Cathodic Arc

In this paper, we present the research results of the generation of a focused high-current quasi-continuous electron beam by the forevacuum (3-30 Pa) plasma-cathode electron source. To realize such operating mode, the cathodic arc with millisecond pulse duration was used to generate the emission plasma. To prevent a high voltage breakdown of the accelerating gap, the electrons were initially extracted from the relatively large emission area and then compressed by the magnetic field. The used electrode configuration of the source and two focusing coils arranged sequentially and coaxially provided seven-fold compression of the quasi-continuous electron beam in comparison with the beam diameter near to the extractor. With the acceleration voltage of 10-11 kV, the beam current of 20 A and pulse duration of 5 ms, the current density of the focused millisecond electron beam reached 14-15 A/cm(2).