Study of a cold cathode electron gun for THz traveling wave tube

Based on the field emission test results of the single wall carbon nanotubes (SWCNTs) cold cathode, a cold cathode electron gun for terahertz (THz) traveling wave tube (TWT) was studied. The simulation results showed that the radius of the electron beam could be well confined within 0.05 mm when the peak value of the axial magnetic field (Br) of the periodic permanent magnet (PPM) focusing system was set as 0.8 Tesla (T). The beam waist radius was about 0.014mm, and the area compression ratio was 13. The designed cold cathode electron gun could be used in some miniaturized THz TWTs.