静电聚焦脉冲展宽分幅相机中的空间电荷效应  

Space Charge Effect in Electrostatic Focusing Pulse-Dilation Framing Camera

作　　者：白雁力 黄国纯 秦兴国 Bai Yanli;Huang Guochun;Qin Xingguo(School of Electronic Engineering and Automation,Guilin University of Electronic Technology,Guilin 541004,Guangxi,China;School of Computer Science and Information Security,Guilin University of Electronic Technology,Guilin 541004,Guangxi,China)

机构地区：[1]桂林电子科技大学电子工程与自动化学院,广西桂林541004 [2]桂林电子科技大学计算机与信息安全学院,广西桂林541004

出　　处：《光学学报》2024年第23期282-289,共8页Acta Optica Sinica

基　　金：国家自然科学基金(11865007);广西自然科学基金(2022GXNSFAA035561);广西自动检测技术与仪器重点实验室主任基金(YQ22101)。

摘　　要：静电聚焦脉冲展宽分幅相机是具有长漂移区、电子光学成像系统和超快时间分辨率的二维超快诊断设备,而空间电荷效应引起的时空弥散,是影响其性能提升的重要因素。为研究静电聚焦中的空间电荷效应,采用双静电透镜设计成像系统,分析成像电场中的电子脉冲动态特性;基于电子脉冲电势分布、电场力方程和平均场理论,推导动态空间电荷效应计算方法,分析不同成像电场分布对空间电荷效应时空弥散的影响,并采用与最大值的平均相对误差(MRE)进行量化评价。研究结果显示,由不同间距透镜构成的成像电场分布,不仅引起漂移过程中的电子脉冲发散和聚焦最佳位置变化,而且也对空间电荷效应时空弥散及其均匀性具有显著影响。随着透镜间距由70 mm增加至370 mm,电场分布均匀度逐渐提升,电子脉冲受到的发散和聚焦力逐渐均衡,动态半径变化逐渐平缓。当间距为370 mm时,离轴25 mm区域内的时空弥散在数值上最小,范围分别为0.28~0.45 ps(MRE为22.13%)和2.09~6.34μm(MRE为43.17%);而当间距为310mm时,时空弥散均匀性达到最优,范围分别为0.33~0.44ps(MRE为10.99%)和4.11~8.78μm(MRE为22.94%)。本研究为分析静电聚焦脉冲展宽分幅相机中的空间电荷效应时空弥散及其均匀性,提供了理论参考。Objective The pulse-dilation framing camera using electrostatic focusing serves as a two-dimensional diagnostic device characterized by a long drift area,an electron optical imaging system,and ultrafast temporal resolution.The spatiotemporal dispersion(STD)resulting from the space charge effect(SCE)is influenced by electrons with different initial states,which limits the improvement of spatio-temporal performance.The main parameters affecting the SCE include acceleration,drift time,number of electrons,time width,and radius of the electron pulse.The first three are static variables with a linear relationship to the STD,while the latter two are dynamic variables exhibiting a non linear relationship,influenced by the dilation pulse.Therefore,analyzing the SCE based on dynamic variables is challenging yet provides important reference values for further studies on STD in pulse-dilation framing cameras.Methods To investigate the dynamic SCE of the pulse-dilation framing camera,we first design the imaging system with double electrostatic lenses.We study the dynamic characteristics of electronic pulses in electrostatic focusing,including time width,transmission radius,and electron density,to analyze the pulse-dilation principle of the electron beam and simulate the trajectory of electron motion.Based on the potential distribution of the electronic pulse,we construct an analysis model of the SCE applicable to the dynamic time width and radius of the electronic pulse using the electric field force equation and mean field theory.Next,we study the characteristics of the imaging electric field distribution of the pulse-dilation framing camera by adjusting the spacing of the two electrostatic lenses.Finally,we analyze the time width and dynamic transmission radius of the electronic pulse under different electric field distributions,study the influence of electrostatic focusing on the STD of the SCE,and quantitatively evaluate using mean relative error(MRE)based on the maximum value.Results and Discussions Our research results

关 键 词：超快光学 超快诊断技术 脉冲展宽分幅相机 静电聚焦成像系统 空间电荷效应 

分 类 号：TN143[电子电信—物理电子学]