多碱光电阴极饱和机理研究  

Study on the saturation mechanism of multi-alkali photocathode

作　　者：谢运涛 孙晓泉 王玺[1] 张玉钧 XIE Yuntao;SUN Xiaoquan;WANG Xi;ZHANG Yujun(State Key Laboratory of Pulsed Power Laser Technology,National University of Defense Technology,Hefei 230037,China)

机构地区：[1]国防科技大学脉冲功率激光技术国家重点实验室,安徽合肥230037

出　　处：《国防科技大学学报》2018年第4期28-34,共7页Journal of National University of Defense Technology

基　　金：国家杰出青年科学基金资助项目(41605015);脉冲功率激光技术国家重点实验室主任基金资助项目(SKL2016ZR06)

摘　　要：多碱光电阴极饱和机理的研究对于提高阴极电子发射能力具有重要意义。依据光电阴极三步电子发射理论,采用蒙特卡洛法研究了多碱光电阴极的电子发射过程。研究结果与相关文献中的实验数据进行了对比分析,光子能量临近光电阴极响应阈值附近时,得到的量子效率曲线以及电子能量分布曲线与实验数据吻合良好。基于上述模型,研究了光压效应和空间电荷效应对多碱光电阴极电子发射特性的影响。结果表明,多碱光电阴极在光压效应限制下的阈值饱和激光能量密度约为8μJ/cm^2,在空间电荷效应限制下的阈值饱和激光能量密度约为2. 23μJ/cm^2。开展了266 nm激光辐照多碱光电阴极实验,经测量,多碱光电阴极的阈值饱和激光能量密度约为2μJ/cm^2,这表明空间电荷效应是限制其光电子发射能力的主要因素。The study of the saturation mechanism of multialkali photocathode is of great significance for improving its electron emission performance.According to the threestep electron emission model,the electron emission process of a multi-alkali photocathode was studied by Monte-Carlo method.Simulation results were compared with the experimental data in the related literatures,which shows that when the photon energy is near the photoemission threshold of the photocathode,the obtained quantum efficiency curves and electron energy distribution curves were in good agreement with experimental data.Based on the above model,the photo-voltage effect and the space charge effect on the electron emission characteristics of multialkali photocathode were studied.Results show that the threshold laser energy density of the photocathode is about 8μJ/cm2under the photovoltage effect,and 2.23μJ/cm2 under the space charge effect.An experimental investigation of the saturation effect of multi-alkali photocathode irradiated with 266 nm laser is conducted,and the saturation threshold laser energy density is about 2μJ/cm2,which indicates that the space charge effect is the main factor limiting its photoelectron emission capability.

关 键 词：多碱光电阴极 蒙特卡洛法 量子效率 能量分布 饱和 

分 类 号：O462.3[理学—电子物理学]