A Novel 270 Bent-Axial-Type Electron Gun and Positioning of Its Electron Beam Spot on the Target

摘要

In this paper, we propose and evaluate the performance of a practical 270 $^{circ}$ bent-axial-type electron gun, in which focusing is bidirectional through an axial magnetic field. Such an electron gun has two advantages: 1) a high-voltage cathode assembly placed in a geometrical shadow region of the emerging vapor and 2) a compact electron beam (e-beam) spot with circular symmetry that results in high power density. It is also shown that the position of the e-beam spot on the target is controllable along any direction without compromising the compactness and circular symmetry of the e-beam spot just like a straight-axial-type electron gun, but not typically possible for conventional 270 $^{circ}$ bent-transverse-type electron guns.