使用二维粒子模拟程序研究了电子弓形波注入机制中激光脉冲形状对电子俘获效果的影响。研究结果表明,激光脉冲时间上升沿陡峭的正扭曲脉冲激发的尾波场强度高,加速区域分布广,并且有利于电子获得更高的初速度,从而推动更多的电子进入尾波场加速相位。在其他条件相同的情况下,正扭曲脉冲的电子俘获数目远高于激光脉冲时间分别为高斯形和负扭曲分布的情形,使得电子束的品质得到改善。研究结果对于理解尾波场加速中电子注入过程以及获得大电荷量高能电子束具有积极意义。
Effects of pulse temporal profile on electron injection and trapping in the electron bow-wave injection regime are investigated by two-dimensional particle-in-cell simulations. It is found that a positive skew pulse can enhance the wake-field amplitude, extends the accelerating aera, and improves the initial velocity of electrons injected into the bubble. Thus more energetic electrons are driven into the bubble accelerating phase. The total injection number for a positive skew pulse is higher than those of negative skew and usual Gaussian pulses in the same conditions, and the quality of electron beam is also improved. The obtained result is very important and beneficial for the future experimental investigation of the laser wake-field acceleration to obtain an energetic electron beam with a large charge quantity.