Study on the Radial-Sheet-Beam Electron Optical System
A new kind of radial-sheet-beam electron optical systems in W-band radial-sheet-beam traveling-wave tubes was described in this paper. A cylindrical cathode with an arc emitting surface was adopted to produce a 2-kV 2-A radial sheet electron beam. The effects of cathode size and anode size on the space-charge-limited current were studied. The electron-beam formation and transmission were discussed under the condition of the space-charge-limited current, and the radial Brillouin focusing magnetic field was obtained. This kind of electron optical systems was simulated by the particle-in-cell method to check up the design. The simulation results presented in this paper show that the beam transmission attained 100% over a distance of 35 mm with a fill factor of ~ 0.55.