用电光采样法测量相对论电子束团长度

 介绍了电光采样法测量电子束束团长度的实验原理和装置，理论分析并模拟计算了被测电子束团库仑场分布、ZnTe晶体的电光效应与束团电场的关系，并利用琼斯矩阵法分析了探测光通过电光晶体时在束团电场作用下的偏振变化、测量信号与束团长度的关系等。分析表明：测量中应使束团库仑场垂直于ZnTe的［001］方向，探测光偏振方向与ZnTe晶体y″轴成45°或者135°夹角，1/4波片快轴与探测光偏振方向夹角应取45°，这时平衡探测器输出信号与束团库仑场Eb成正比。1/4波片的作用是将电光晶体的工作点从非线性段移到线性段，平衡探测的作用是简化信号与Eb的关系，并提高信噪比。为实际测量应用提供参考。

Measurement of relativistic electron beam bunch length by electro-optic sampling method

Electro-optic sampling measurement of relativistic electron pulses is promising. In this paper the theory and the experiment setup of the measurement are introduced. The coulomb field of electron bunch is analyzed and simulated. The relation of this field with the electro-optic effect of ZnTe crystal is studied.The polarization change of the probe light and the relation of the electron bunch length and the detected signal are calculated by Jones calculus. The results show that the coulomb field of electron bunch should be perpendicular to the ［001］ axis of ZnTe crystal, the initial polarization of probe light should lie at an angle of 45° or 135° with y″ axis of ZnTe crystal and the fast axis of 1/4 wave plate should lie at an angle of 45° with z″ axis of ZnTe crystal. In such situa