飞秒激光辐照铝靶产生快电子发射的实验和模拟研究

Experimental and simulative study for an emission of the fast electron beams from an Al target irradiated by intense femtosecond laser pulses

采用实验和数值模拟研究了飞秒激光辐照铝靶产生的快电子发射.实验中,在主脉冲前加上一个预脉冲产生预等离子体,然后主脉冲与预等离子体作用产生快电子.在激光反射方向附近,实验测量的快电子束发射与数值模拟的结果高度地一致;在靶背面,发射的快电子的数目小于数值模拟的结果,原因在于快电子在靶内输运受到电荷分离场和碰撞的影响;在数值模拟中未出现的,沿靶表面发射的快电子束,是由表面准静态电磁场的禁闭效应产生.

The emission of the fast electron beams in the interaction of femtosecond laser with Al target has been investigated by the experiment and PIC simulation. By adding a prepulse to generate preplasma, the fast electrons are produced from the preplasma irradiated by a main pulse in experiment. The fast electron beam emitted in the specular refection direction is highly consistent with our PIC simulation result. However, the number of fast electron at the rear target surface is less than that from simulation, which is due to the collision of electrons with target, and the charge separation field in the rear target surface. The fast electron beam emitted along the surface of target, which does not appear in the simulation, is formed due to the confinement of the target surface quasistatic electromagnetic fields.