Design of a High Compression Ratio Carbon-based Cold Cathode Electron Gun for Terahertz TWTs

Carbon-based cold cathode electron gun attracts many attentions due to its low response time, room temperature operation, simple processing and assembly. In order to produce minuteness electron beams for Terahertz (THz) vacuum devices, carbon-based cold cathode electron guns are required to have a good laminar flow as well as a high compression ratio. In this paper, a carbon-based cold cathode electron gun model is presented to solve this problem. The CST simulation result shows that under the working voltage of 11.5kV, a 12.48mA beam has been extracted from 0.8mm radius carbon nanotubes cathode. Passing three focusing anodes the emitted electrons has been compressed to a 0.149mm radius minuteness beam and the area compression ratio reaches 28.8 under this electron optical system.