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用粒子模拟方法 ,研究激光脉冲的横向宽度有限时对产生激光尾波场和电子加热的影响 .在纵向和横向有质动力的作用下 ,电子密度的空间分布形成“马蹄型”的低密度区 ,这些低密度区好像运动的透镜 ,使长脉冲激光自聚焦 ,而且随着激光的传播 ,“马蹄型”的曲率越来越大 ,直到产生横向波破 .横向波破一方面使得波破时静电场极值远小于波破极限 ,另一方面将更多的电子推入加速相位 ,静电场“俘获”的电子数目大大增加 ,但最大电子动能明显减小 .
The effects of the laser transverse pulse width on the wake field and the electron heating are studied by means of the particle simulation method. The spatial distribution of electron density forms a “horseshoe” low density region , These low-density areas appear to be moving lenses that self-focus long pulsed lasers, and as the laser propagates, the curvature of the “horseshoe” becomes larger and larger until a lateral wave is broken. The extreme value of the electrostatic field is much smaller than the wave-breaking limit. On the other hand, more electrons are pushed into the accelerating phase. The number of electrons trapped in the electrostatic field greatly increases, but the maximum electron kinetic energy is obviously reduced.