Features of the Formation of a Focused Electron Beam by a Forevacuum-Pressure Plasma-Cathode Source With Single Emission Channel

Abstract

We have explored the formation processes of a focused electron beam generated by a forevacuum plasma-cathode electron source with a single emission channel in the higher-pressure range (5–10 Pa). Appropriate design of the beam formation system geometry together with decrease in working gas pressure and increase in beam accelerating voltage leads to a decrease in the convergence angle of the electron beam. The convergence angle decreases with decreasing diameter of the emission channel aperture and of the extractor, as well as with increasing accelerating gap length. In this case, the dependence of the beam cross-sectional diameter at crossover (focus) on the beam accelerating field has a non-monotonic form. With optimized discharge gap geometry, the minimum convergence angle of the electron beam was 0.1° and its brightness <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 10^{6}$ </tex-math></inline-formula> A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot \text{m}^{-2} \cdot $ </tex-math></inline-formula> sr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> .