带轴向引导磁场自由电子激光器中的电子轨迹与稳定性

在对中国工程物理研究院电子学研究所和中国科学院上海光学精密机械研究所所做带引导磁场喇曼型自由电子激光实验进行数值模拟的基础上,本文研究了轴向引导磁场和摇摆磁场联合作用的单电子轨迹,对电子的平衡轨道和一阶微扰轨道进行了仔细分析,揭示了在引导磁场存在的情况下,摇摆磁场横向变化引起的电子感应回旋运动的重要性,推导了带引导磁场情况下的电子感应回旋运动方程,给出了电子感应回旋运动的周期,X方向、Y方向之间的关系。同时,用数值模拟方法研究了电子的运动,两者结果符合很好。 关键词：

ELECTRON TRAJECTORIES AND STABILITY IN FEL WITH AN AXIAL GUIDE MAGNETIC FIELD

The single-particle trajectories of relativistic electrons are studied in a magnetic field con-figuration consisting of a uniform axial guide field and a helical periodic wiggler field. The steady-state trajectories and the first order perturbed trajectories are analysed carefully. Based on the numerical simulations about the experiments which have been made at Shanghai Institute of Optics and Fine Mechanics, the effect of the betatron oscillations due to the transverse varing of wiggler field is first shown in the case that there is a axial guide field. In this case the betatron oscillations equations are drived. Its period and the relation between phase in X dirction and in Y dirction are obtioned. Further more, numerical simulations are made. The results of analytical calculation are in good agreement with the numerical simulations.