Criteria of numerical simulation design for electron gun in TWT

This paper presents the criteria to judge the quality of electron-beam in designing the TWT’s electron gun by numerical simulation: uniform current density of cathode surface emission, good laminar flow property of the electron beam, uniform radial distribution of the beam near the beam waist and smooth of envelope which contain certain percent electrons. Designing the electron gun of a TWT by the code we have compiled code, judging and comparing the quality of beams of different structures, the better e-gun structure can be obtained.