Study on Electron Optics System for 670 GHz Travelling Wave Tube

The electron optics system (EOS) includes electron gun, focusing system and collecting pole, which is the key part of the traveling wave tube (TWT). In this paper, the EOS suitable for 0.67 THz TWT is studied, and the design process of the electron gun and focusing system are reported. Through theoretical analysis and simulation, some key parameters and electrostatic simulation of the electron gun are preliminarily obtained. To reduce the size and weight of the TWT, the periodic closed magnetic (PCM) focusing field structure is used to further obtain the simulation situation of the electron gun with the additional magnetic field. The results show that under the conditions of operating voltage 23.8 kV, current intensity 23.7 mA and radius of electron beam channel 0.07 mm, the electron beam can be transmitted stably for more than 30 mm, and the pass rate was over 99%.