发射度效应占主导线性电子注的临界半径研究  

Critical Radius of Emittance-Dominated Linear Electron Beams

作　　者：曾鹏[1,2] 王光强[1,2] 王建国[1,2,3] 李爽[1,2,3] 王东阳[1,2] 滕雁[1,2] ZENG Peng;WANG Guang-qiang;WANG Jian-guo;LI Shuang;WANG Dong-yang;TENG Yan(Northwest Institute of Ni^clear Technology, X i’an 710024,China;Science and Technology on High Power Microwave Laboratory, X i’ an 710024,China;School of Electronics and Information Engineering, X i, an Jiaotong University, X i’ an 710049, China)

机构地区：[1]西北核技术研究所,西安710024 [2]高功率微波技术重点实验室,西安710024 [3]西安交通大学电子与信息工程学院,西安710049

出　　处：《现代应用物理》2016年第2期33-37,共5页Modern Applied Physics

摘　　要：基于考虑发射度效应的线性电子注边缘电子受力平衡方程,获得了约束电子注所需磁感应强度,通过对比约束不同效应所需磁感应强度的大小,推导了发射度效应占主导电子注的临界半径公式。利用该公式分析了典型电子注的临界半径,分析表明在导流系数小于0.1μA·V^(-3/2)时,电子注发射度效应对电子注的影响随电子注半径减小到亚毫米量级后迅速增大。通过理论推导获得了热阴极发射的线性电子注临界半径下限公式,分析表明采用较大负载的阴极有利于获得较高质量的电子注,且在电子注半径小于0.05mm后,常规热阴极的发射能力已不足以保证电子注工作于空间电荷限制状态。此外,在用缩尺法设计电子枪时,若缩尺后的电子注半径小于临界半径,则缩尺法将失效。The force balance equation for an electron at the radial edge of the magnetic field confined electron beam with emittance effect is derived to define the magnetic induction of the confined electron beam.The critical radius is obtained by comparing the confined magnetic induction for space charge effect with the one for emittance effect.The critical radius of elec-tron beam in the typical electron gun is analyzed,and the result shows that the impact of emittance gets more pronounced and increases markedly as the radius of beam decreases to sub-millimeter,with perveance less than 0.1μA·V-3/2 .In addition,the lower limits of crit-ical radius for linear electron beams with thermionic cathodes are also derived,which show that the qualities of electron beams could be improved by high current density cathode.Mo-reover,beams with current thermionic cathodes could become emittance-dominated when the radius is less than 0.05 mm.Besides,the critical radius is also the lower limit for the ration-al design of electron guns with traditional scaling rules.

关 键 词：线性电子注 发射度效应 空间电荷效应 临界半径 

分 类 号：TN98[电子电信—信息与通信工程]