THE EFFECT OF PULSE SHAPE AND STEPOUT IN THE THREE-STEP PHOTOIONIZATION

The laser pulse shape effect and mainly the stepout effect on the ionization are investigated numerically in this paper. About the pulse shape effect, the result shows that it would be better to use shorter Gaussian pulses on the condition of constant area. About the stepout problem, the calculation shows that a certain stepout between pulses will benefit the ionization. Some interesting phenomena caused by stepout among pulses are found and explained in population dynamics.     

微脉冲束团诊断系统的时间分辨性能研究

北京自由电子激光器(BFEL)加速器束团的主要特点是微脉冲宽度仅4ps,这对束团诊断系统的时间分辨性能提出了很高的要求。本文分析了一些影响系统分辨率的因素,其中首次考虑到了色散及斜置辐射体的影响,这些分析计算将主要用来对实验数据进行校正。     

北京正负电子对撞机同步辐射光脉冲形状的高分辨率测量

用国产BWS-5kII型皮秒扫描相机测量了北京正负电子对撞机(BEPC)上极端相对论性运动正负电子束团产生的同步辐射光脉冲的时间结构、光脉冲长度与电子束流强度以及射频源电压的关系.当负电子束流强度由2mA增加到30mA时,光脉冲长度由220ps增加到670ps;在20mA电子束流强度条件下,射频源电压由250kV增加到500kV时,光脉冲长度在500ps到700ps范围内变化.测量系统的时间分辨率为30ps;时间刻度误差±15%,触发晃动小于±200ps.