Electron-Optic System With High Compression of a Multiple Elliptic Electron Beam for a Miniaturized THz-Band Vacuum Electron Device

Electron-optic systems (EOSs) with high compression are required for THz-band vacuum-tube electron devices to reduce the cathode load, which is necessary to increase lifetime and enable operation in a continuous-wave (CW) mode. However, it is difficult to achieve high compression of multiple electron beams. In this article, we present the design and simulation of EOS with triple elliptic electron beam for a 0.2-THz traveling-wave tube. The triode electron gun with planar electrodes provides $3\times 0.06$ -A electron beam with compression factor of 16. At the cathode, the current density is 26.31 A/cm2 while in the beam tunnel it is higher than 400 A/cm2. The magnetic focusing system with 1.34-T axial magnetic field consisting of Nd–Fe–B permanent magnets and pole pieces is also designed. The numerical simulation predicts stable beam transmission at 25-mm distance.