热阴极光热方法分析模型研究  

Research on Photothermal Method Analysis Model of Thermionic Cathodes

作　　者：董成坤 樊鹤红[1] 龚雪[1] 梁田 胡文景 孙小菡[1] DONG Cheng-kun;FAN He-hong;GONG Xue;LIANG Tian;HU Wen-jing;SUN Xiao-han(Electronic Devices and System Reliability Center,Southeast University,Nanjing 211189,China;Nanjing Sanle Group Co.Ltd.,Nanjing 210000,China)

机构地区：[1]东南大学电子器件与系统可靠性中心,江苏南京211189 [2]南京三乐集团有限公司,江苏南京210000

出　　处：《真空电子技术》2020年第6期35-40,共6页Vacuum Electronics

基　　金：国家自然科学基金项目(61701113)。

摘　　要：热阴极具有发射电流密度大、稳定性高、寿命长等优点,一直是真空电子器件的首选电子源。利用激光照射热阴极可以进一步提升热阴极的发射性能。本文针对热阴极在激光照射情况下的热状态分析方法进行了研究,基于真空绝热边界条件研究建立了考虑光透射深度,并综合考虑光热效应、冷却效应、热扩散和热辐射效应的热阴极光热过程动态仿真分析模型,并且给出了一种“快启动-保持”热阴极光热加热方案。利用该模型对不同吸收光强度下不同厚度阴极的温度变化进行了仿真模拟,仿真表明:阴极随吸收光强大小的不同存在不同的饱和温度,该饱和温度与阴极厚度无关,给出了升温拐点时间、饱和温度及启动时间与吸收光强和阴极厚度之间的关系;吸收光强越大,阴极厚度越薄,阴极启动时间越短,1 mm厚的钨阴极吸收连续光光强为0.4 kW/cm 2时,启动时间为1.88 s,当吸收光强为10 kW/cm 2时,则启动时间可以达到0.066 s。Thermionic cathodes have the advantages of high emission current density,high stability,long life,etc.,and have always been the preferred electron sources for vacuum electronic devices.Illuminating the thermionic cathodes with laser can further improve their emission performance.In this paper,the thermal state analysis method of thermionic cathodes under laser illumination is studied.A dynamic simulation analysis model for photothermal process of thermionic cathodes is established based on vacuum adiabatic boundary conditions,which takes into consideration of light transmission depth,photo-thermal effect,cooling effect,thermal diffusion,and heat radiation effect.And a quick start&maintaining photothermal heating scheme is given for illustration.The model is used to simulate temperature changes of different absorbed optical power density on cathodes with different thicknesses.Simulations show that the cathodes have different saturation temperature with different intensity of the absorbed light,while the temperature is independent of the thickness of the cathode.The relationship between the heating knee point time,the saturation temperature,the start-up time and the absorbed light intensity and the thickness of the cathode is given;The greater the absorption intensity and/or the thinner the cathode thickness,the shorter the cathode start-up time.When a 1 mm thick tungsten cathode absorbs continuous light intensity of 0.4 kW/cm 2,the start-up time is 1.88 s;and when the absorbed light intensity is 10 kW/cm 2,the startup time can be as short as 0.066 s.

关 键 词：热阴极 光热效应 冷却效应 启动时间 热辐射效应 

分 类 号：TN105[电子电信—物理电子学]