基于电子脉冲调制技术的飞秒条纹相机的研究

Owing to the excellent feature of ultrahigh temporal and spatial resolution, streak camera has been the indispensable scientific instrument with application in Inertial Confinement Fusion(ICF) and the Synchrotron Radiation Experiments. However, due to the restriction of temporal dispersion and scanning speed, it is difficult to break the temporal resolution of 100fs. Based on the electron pulse modulation technique, the key factors to improve temporal resolution better than 100fs have been analyzed theoretically. The principle and method of electron pulse wave front correction are studied, and the optimal slope of the pulse modulation voltage has been calculated numerically, which compensate the temporal dispersion, as well as slow down the speed of electrons in the drift region, and improve the deflection sensitivity. The space charge effects have been researched, and the quantitative relationship between the space charge effects and electron pulse broadening has been built. Then the compensation method has been given. On account of all the factors that may influence the performance, a streak camera has been optimally designed, which will supply an effective support on developing femtosecond streak camera with high temporal resolution.

基于条纹变像管的条纹相机是具备超高时间、空间分辨的超快诊断设备，是惯性约束聚变(ICF)、同步辐射实验等超快过程研究的核心技术手段。但受光电子时间弥散和扫描速度等因素的限制，其时间分辨率却一直很难突破100fs。本项目基于电子脉冲调制技术，开展时间分辨率优于100fs的高时间分辨率飞秒条纹相机的关键因素理论分析；研究电子脉冲调制技术对电子脉冲的波前矫正原理和实现方法，在提高栅极加速电压的同时如何补偿阴栅电极之间的时间弥散，以及降低电子在漂移区的速度，提高偏转板的偏转灵敏度，进而提高系统时间分辨率，并数值计算脉冲调制的最佳斜坡电压；研究条纹变像管空间电荷效应的计算方法，构建空间电荷效应与电子脉冲展宽的定量关系，并给出其补偿方法；优化设计条纹变像管的性能参数，完成时间分辨率优于100fs的飞秒条纹变像管电子光学设计，为研制高时间分辨率的条纹相机提供理论和技术支持。

基于时空映射测量的超快诊断条纹相机是实现皮秒至飞秒量级时间分辨的超快现象探测的重要测量仪器。但由于受光电子时间弥散和扫描速度等因素的限制，条纹相机的时间分辨率却一直很难突破100fs。本研究结合我国巨型工程——惯性约束核聚变，以及其它重大超快过程前沿科学对时空分辨率的更高需求，研究空间电荷效应在飞秒条纹变像管加速区域和自由漂移空间对电子脉冲宽度的影响，在条纹相机中引入电子脉冲调制技术，重点研究电子脉冲调制技术对电子脉冲的波前矫正原理和实现方法，提出空间电荷效应的补偿方法；同时设计了电压斜率大于10kV/ns的低晃动光导开关扫描电路和高偏转灵敏度的行波偏转器，从而提高了扫描速度，降低条纹变像管的技术时间弥散；设计研制磁聚焦系统和高精度电控位移台，并实验测试磁聚焦系统内部轴向磁场分布，实现磁场对电子束的有效聚焦作用，提高条纹变像管的空间分辨率和时间分辨率；完成飞秒条纹变像管性能参数的优化设计，仿真计算得到：飞秒条纹变像管的时间分辨率达到65.7fs，突破时间分辨率100fs的研究目标，为研制高性能的条纹相机提供理论和技术支持。