Design of electron optical system of millimeter electrostatically focused traveling wave tube

This paper introduced the particular advantages of electrostatic focusing style in millimeter traveling wave tube and analyzed the methods to establish periodic electrostatic field. Based on a Ka band traveling wave tube, first we designed an intense current density electron gun and selected a comb-like shape as slow wave circuit. Then a numerical simulation on the electron optical system made up of an electron gun and a slow wave circuit was carried out. Finally we summarized tolerance for key sizes of the slow wave circuit. The results showed that one hundred-percent beam passed slow wave structure smoothly. The good static beam pass was a foundation stone for subsequent sufficient beam-wave interaction and it was proven that a large current density beam in millimeter traveling wave tube could be focused commendably by electrostatic field. Simultaneously, the summary for the tolerance could provide a reference for the design of the electron optical system of millimeter electrostatically focused traveling wave tube.