Wang Shuzhong

The Design of Elliptical Sheet Beam Electron Gun

Sheet beam klystrons, like multi-beam klystrons, have many advantages such as decreased beam voltage, reduced power densities, lower voltage gradients and increased bandwidth (Basten and Booske, 1999). As a function of frequency, the power output of a sheet beam klystron falls only linearly with wavelength, making it more suitable for high frequency applications (Scheitrum, 2005; and Read et al., 2005). The generating, forming and focusing of electron beam is one of the key technologies of the sheet beam klystrons. Elliptical sheet beams are easy to focusing than rectangular sheet beams. The paper describes the considerations of designing elliptical sheet beam electron gun.

Design of a large compression ratio electron gun and uniform field focusing system for Ka-band exended interaction klystron

This paper presents an electron gun which have a voltage of 13kV, current of 0.7A and large compression ratio of 80 . The maximum emitted current density is only 2.2A/cm2.Uniform field focusing system is also designed to keep the trajectories in a good shape while passing through a 40 mm-long channel.

Analysis and Simulation of Multi-Beam Interaction

The result obtained from beam-beam interaction of multi-beam klystron using analytic theory has a difference with simulation result using a PIC code. The difference was affected by beam radius. New analytic theory need to be provided to tackle the problem

Simulation on suppression of virtual cathode effects in collector of L-band multibeams klystron

Virtual cathode in collector of multibeam klystron (MBK) is formed when the electron beam current exceeds the space charge limited current. Then the electron-beams return the drift tubes of output cavity causing device performance deterioration as stated in W. Jiang et al. (2005). A number of collector designs have been developed in this paper to eliminate this nuisance. Virtual cathode effects were simulated with PIC (Particle in Cell) software. The results show that setting bottleneck and thin slot structures at the port of a collector are beneficial to restrain the formation of virtual cathode.

Electron gun simulation using MAFIA

The paper describes the work of 2D/3D electron gun simulation using MAFIA. The results obtained by EGUN and by MAFIA are almost alike for 2D model. For 3D model, the current and perveance are 5-10% lower than those of EGUN. Multi-beam guns have also been developed.