环形阴极宏观场增强因子计算研究

Study on Macroscopic Field Enhancement Factor of Annulus Cathode

环形阴极是一种结构场增强型阴极,能有效提高电子发射性能,广泛应用于脉冲硬X射线负载、强流电子束装置及高功率微波系统中,对其宏观场增强效应计算研究具有重要意义。本文采用电荷等效法和镜像法相结合的方法,建立阴阳极间隙空间电场的理论计算模型,获得阴极表面电场分布及其宏观场增强因子,并拟合给出宏观场增强因子的经验估算公式。计算结果表明,当阴阳极间隙与阴极环宽之比(d/w)<5,环形阴极宏观场增强因子与d/w呈良好的线性关系,理论计算结果与Ansoft软件模拟结果基本一致。

Annulus cathodes with structural field enhancement which can improve the electron emission performance effectively have wide application in load of pulsed hard X-ray,preparation of strong electron beam and high-power microwave system.It’s of great significance to make investigation on structural field enhancement of annulus cathode.The charge equivalent method and mirror image method were applied to build the model for calculating the electric field distribution between cathode and anode.The electric field distribution of cathode surface and the macroscopic field enhancement factor were calculated with the theoretical model.The practical estimation formula of the macroscopic field enhancement factor was obtained.The calculated results show that when d/w(the ratio of distance between cathode and anode to the width of cathode ring)is less than five there is a good linear positive correlation between the macroscopic field enhancement factor and d/w,and the theoretical result is consistent with simulation result of Ansoft.