Time Domain Simulation And Analysis For Noise Performance Of Electron Gun

Traveling-wave tube(TWT)is an important kind of microwave vacuum power amplifier,with the advantages of wide bandwidth,high gain,high efficiency,and long life etc.TWT is widely used in national defence engineering and military electronic equipment,such as in radar,communication,navigation and electromagnetic countermeasure systems,and is called the "heart" of weapon.Noise performance is a major factor to be considered when TWT is used in situations with high quality communication requirements such as in satellite and radar communication systems.With simulation and calculation ability of computers increasing continuously,using computer simulations to design the stracture and functionality of TWT has become an important design method.Software with noise simulation capability is still yet to be seen.To solve this problem,time-domain simulation model for simulation of TWT electron gun noise performance,analytical method for the noise performance based on simulations,and their applications,were studied in this article.The main contents of the study includes:Basing on the existing electron gun noise performance simulation software modules(EGunNoiseSim 1.0,without time-domain simulation capability),we proposed and established an electron gun noise performance time-domain simulation software modules(EGunNoiseSim 2.0),which consists of noise source module with angular randomness simulation capability for simulation of initial velocity of emitted particles,electron gun modeling module,initial electromagnetic field solver module,electromagnetic field updating module based on FDTD,boundary solver module,particle trajectory solver module and spatial current density field updating module;What's more,we also developed a noise parameter solver module for electron gun,which could be used to calculate noise parameters such as:noise current/voltage power spectral density,noise power,and noise wave impedance,based on simulation results,which can provide valuable parameter references for study of electron gun noise performance.Electron beam trajectory of an electron gun given in a previous paper was simulated using EGunNoiseSim 2.0,with the simulation results compared with the simulation&experimental results given in that paper,and the simulation results of CST,which verified,to some degree,the functionality and correctness of our program.Furthermore,we explored the impact of the operational parameters and stractual parameters of electron gun on the noise performance of electron gun by using the programs we developed.Simulations and analyses show that:noise current power/power spectral density increases with the increase of temperature,while the relationship between noise voltage power/power spectral density and tempetature is not obvious;noise voltage power/power spectral density increases with the increase of focusing electrode angle;and noise current power/power spectral density increases with the increase of focusing electrode angle firstly,then decreases;with the increase of cathode radius of curvature,noise voltage/current power/power spectral density increases firstly,then decreases;with the increase of anode pore radius,noise cuttent power/power spectral density decrases and noise voltage power/power spectral density increases.Work in this article provides a relatively more efficient analytical method for the analysis of the noise performance of TWT electron gun.