磁场对脉冲展宽分幅相机空间电荷效应的影响  

Influence of Magnetic Field on Space Charge Effect in Pulse-Dilation Framing Camera

作　　者：白雁力 宋明诚 朱望纯[1] Bai Yanli;Song Mingcheng;Zhu Wangchun(School of Electronic Engineering and Automation,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

出　　处：《光学学报》2024年第5期281-287,共7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);广西图像图形与智能处理重点实验室(桂林电子科技大学)开放基金(GIIP2210)。

摘　　要：基于磁聚焦成像的脉冲展宽分幅相机是具有超快时间分辨的诊断设备,空间电荷效应是制约其时空性能向更高量级提升的主要因素。为研究脉冲展宽分幅相机中的空间电荷效应,基于电子脉冲电势分布和电场力方程建立研究模型,将电子脉冲动态特性融入模型分析。研究结果显示,由成像磁场引起的电子脉冲动态半径对空间电荷效应时空弥散影响显著,当轴上磁场强度为4.585×10^(-3)T时,随着离轴位置增加至15 mm,磁场强度提高到4.763×10^(-3)T;由于离轴电子脉冲散焦使动态半径较大,因此在降低电子密度的同时,使空间电荷效应的时间弥散由2.94 ps减小至483 fs,空间弥散由668μm减小至22μm;当轴上磁场强度由4.585×10^(-3)T降低至3.359×10^(-3)T时,与最优空间分辨性能相似,空间电荷效应时空弥散在磁场3.4×10^(-3)~3.5×10^(-3)T区域内达到最小,此时离轴15 mm内的时间弥散范围为256~392 fs,空间弥散范围为3.1~15.4μm。研究结论为分析磁场对脉冲展宽分幅相机空间电荷效应的影响提供一定的理论参考。Objective In the inertial confinement fusion(ICF)experiment,the microchannel plate(MCP)framing camera is an important two-dimensional ultrafast diagnostic device that is used to acquire the duration and dynamic image of plasma at the stage of implosion compression.However,due to limitations of the electronic transmission time and its dispersion in the channel of the MCP,the temporal resolution is restricted to 60?100 ps for a long time.In order to further improve temporal resolution,a pulse-dilation framing camera(PDFC)is developed,which couples the MCP framing camera with the temporal dilation technique of the electron beam.With an ultrafast temporal resolution of better than 10 ps,it is easier to meet the detection requirements of the shorter duration states in the ICF.Therefore,the relevant ways and techniques of the PDFC are gradually focused on the field of ultrafast diagnosis.The PDFC is a new kind of framing camera with a long drift region using the imaging of magnetic focusing technique.Due to its similar structure to the streak camera,the improvement of its spatio-temporal performance to a higher order is restricted by the space charge effect(SCE).Moreover,the temporal width and radius of the electronic pulses(EPs)are dynamically changed by the dilating pulse and magnetic focusing in the PDFC.Therefore,building the model of the SCE that meets the dynamic parameters of the EPs and analyzing the influence of the dynamic radius caused by magnetic focusing on the spatio-temporal dispersions will be an important theoretical significance for systemically studying the SCE of the PDFC.Methods In the research,to analyze the influence of magnetic field on the spatio-temporal dispersions of the SCE,first of all,the model of the PDFC using magnetic focusing is built,and the dynamic characteristics of EPs during transmission are analyzed by the working principle of the PDFC.Then,the spatio-temporal dispersion model of the SCE is deduced by solving the equation of the electric field force based on the two-dimensional

关 键 词：超快光学 超快诊断技术 脉冲展宽分幅相机 空间电荷效应 成像磁场 时空弥散 

分 类 号：TN143[电子电信—物理电子学]