A Novel 270 $^{\circ}$ Bent-Axial-Type Electron Gun and Positioning of Its Electron Beam Spot on the Target

In this paper, we propose and evaluate the performance of a practical 270° 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° bent-transverse-type electron guns.