A Sheet Beam Electron Gun Using Thermal Emission with Large Beam Current for 0.22 THz Traveling-Wave Tubes

In this paper, a sheet beam electron gun with large beam current based on thermal emission mechanism is designed and simulated for developing 0.22 THz traveling-wave tubes (TWTs). A pencil beam of the electron gun can be compressed into a sheet beam by utilizing a novel focusing electrode. The CST simulation results show that the beam current of the sheet beam electron gun is 137.9 mA at beam voltage 24.6 kV, and the emission beam current density is
$27.45 \mathbf{A}/\mathbf{cm}^{\mathbf{2}}$
. The distance between the beam waist position and the cathode emission surface is ~12 mm, and the size of sheet beam waist is
$\mathbf{0.42}\ \mathbf{mm} \times \mathbf{0.06} \mathbf{mm}$
. In addition, the sensitivity analysis for the sheet beam electron gun is investigated. The research work reported here lays a foundation for the development of 0.22 THz TWTs.