行波偏转器前置短磁聚焦条纹变像管理论设计与实验研究  

Design and evaluation of a pre-traveling wave deflector magnetic solenoid lens focused streak image tube

作　　者：刘蓉[1,2,3] 田进寿[1] 李昊[1,2] 王强强[1,2] 王超[1] 温文龙[1] 卢裕[1] 刘虎林[1] 曹希斌[1] 王俊锋[1] 徐向晏[1] 王兴[1] 

机构地区：[1]中国科学院西安光学精密机械研究所,瞬态光学与光子技术国家重点实验室,西安710119 [2]中国科学院大学,北京100049 [3]西安工业大学,西安710032

出　　处：《物理学报》2014年第5期432-439,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11274377;11304374);财政部重大科研仪器研制项目(高性能条纹相机的研制)资助的课题~~

摘　　要：条纹变像管因其超高时间分辨特性而成为实现皮秒至飞秒量级时间分辨的重要测量仪器.本文设计了一种同时兼顾高时空分辨的行波偏转器前置短磁聚焦条纹变像管.该管型通过减小电子渡越时间以抑制空间电荷效应、采用偏转器前置以及行波偏转方式提高偏转灵敏度,实现整管时空分辨率的大幅提升.利用CST微波工作室有限元法数值计算条纹变像管行波偏转器的通频带宽、偏转灵敏度,结果表明:本设计中的行波偏转器因其较高的通频带宽特性实现了偏转器上的电磁波相速度在很宽频率范围内与电子轴向群速度匹配,产生更有效偏转.利用CST粒子工作室模拟追踪光电子的运行轨迹,通过最佳像面上的时间调制传递函数和空间调制传递函数,计算得到其理论时间分辨率可达220 fs,空间分辨率高于100 lp/mm.同时根据像差定义给出追踪实际电子轨迹的像差计算方法,实现对变像管成像质量评价.最后利用紫外灯对其进行静态测试,获得静态空间分辨率优于35 lp/mm的结果.Owing to the excellent feature of ultrahigh temporal resolution, the streak image tube has been the indispensable scientific instrument for the application to measurement of ultrafast phenomena on subpicosecond time scale. In this paper, a new femtosecond streak image tube with both high temporal and spatial resolution is designed. To improve its integrated performance, a pair of traveling wave defiectors is located before a magnetic solenoid lens in the tube, which minimizes the electron transit time from anode to defiection plates and therefore reduces time dispersion and space charge efiects. Using CST microwave studio finite element method, bandwidth and defiection sensitivity of traveling wave defiector have been studied numerically. The result shows that the wide bandwidth of the traveling wave defiectors designed is beneficial to slow down the electrical defiecting pulse to match the beam velocity in a wide frequency range,which can improve the defiection sensitivity. After tracing the trajectory of electrons and calculating the modulation transform function, we get temporal resolution of 220 fs and spatial resolution above 100 lp/mm. Based on the aberration theory, the aberration formulas of electron trajectory are deduced, which systematically evaluate the imaging quality of streak image tube with modulation transfer function. Finally, static experiment is carried out, and the result shows that the static spatial resolution is better than 35 lp/mm.

关 键 词：条纹变像管 行波偏转器 磁聚焦 时间分辨率 

分 类 号：O439[机械工程—光学工程]