We model electron acceleration using paraxial approximation (PA) and seventh order correction description (O7) of a laser field in vacuum in the presence of an axial magnetic field. The effect of initial momentum, laser intensity, spot size, and initial position of electron on optimum value of magnetic field and electron energy for linearly and circularly polarized laser pulse has been investigated. We show that PA fails to obtain correct values of optimum magnetic field and electron energy. The amplitude of oscillations of the electron increases with time in the presence of axial magnetic field and PA fails to correctly take into account focusing and defocusing of laser and obtain correct results.

中文翻译：

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在存在轴向磁场的情况下，在真空中通过激光脉冲模拟电子加速度的近轴近似的局限性

我们使用轴向磁场存在下的真空中的激光场的近轴近似（PA）和七阶校正描述（O7）对电子加速度进行建模。研究了线性和圆偏振激光脉冲的初始动量，激光强度，光斑尺寸和电子的初始位置对磁场和电子能量的最佳值的影响。我们表明，PA无法获得最佳磁场和电子能量的正确值。在存在轴向磁场的情况下，电子的振荡幅度会随时间增加，并且PA无法正确考虑激光的聚焦和散焦，而无法获得正确的结果。