Noise Performance Simulation And Analyses For TWT Electron Gun

In recent years,aiming for higher power, higher gain, wider bandwidth and smaller size, the systems impose higher and requirements on noise performance TWTs. So, noise performance simulation and analyses for TWT electron gun are studied in this paper as follows.First, noise types and according occurrence mechanisms, noise performance indexes, development of TWT and relevant simulation software for TWT are summarized.Based on existing TWT gun simulation model and procedures, this paper designed and implemented noise emission module; completed the process of cathode electron emission in condition of surface degradation due to ion bombardment; build TWT noise simulation and analysis model. Furthermore, we defined a 2D noise parameter for electron gun, i.e.distributed noise wave impedance. The model can be used for simulation of shot noise and velocity noise along with the cathode electron emission, and simulation of the cathode surface layer degradation and electron emission degradation caused by ion bombardment, where distributed noise wave impedances can be obtained for given output cross-section. The model has been used for noise performance simulation the effect of noise and ion bombardment, under conditions of different temperature and currents, to electron beam form, velocity distribution and output current fluctuations, velocity fluctuations, and distributed noise wave impedance.etc. have been analyzed. Compared with existing softwares, our codes showed better noise performance simulation and analysis capability.Finally, by comparing the simulation results for a given electron gun with a existing literature and CST, simulation results of electronic beam beam position are much more and more close to the experimental test results and the simulation results of electric beam radius more accurate than the results of directly using the electronic beam universal divergence curve,which further demonstrate the validity of the simulation model and applicability.Work in this paper provides an effective simulation method for impact analyses of the noise performance of TWT electron gun.