在联立电子直线加速器中粒子运动方程的基础上,建立了一种计算束流横向发散度的方法,将束流划分为若干个等电荷的同心环,追踪它们的代表粒子在注入器中的运动,依照所有粒子的γ、P_r和方位角θ值,计算出束流的均方根发散度。在实例计算中给出了粒子的运动轨迹和相位会聚图象以及注入器出口处粒子的相图,计算了束流的均方根发散度,并对阴极磁场和轴向聚焦磁场对横向发散度的影响作了讨论。 Based on the equations of particle motion in the tandem electron accelerator, a method of calculating the lateral divergence of the beam is established. The beam is divided into several isoelectric concentric rings to track their representative particles in the injector According to the γ, P_r and azimuth θ values ​​of all the particles, the root mean square divergence of the beam is calculated. The particle trajectory, phase convergent image and particle phase diagram at the exit of the injector were given in the example calculation. The root mean square divergence of the beam current was calculated and the influence of the cathode magnetic field and the axial focusing magnetic field on the lateral divergence The impact of the discussion was discussed.