对线极化、圆极化的超短超强激光脉冲与靶前有一段低密度预等离子体的固体靶的相互作用进行了理论和粒子模拟研究.激光通过有质动力加速机制加速预等离子体中的电子,研究了电子获得的最大能量随激光强度和预等离子体密度的变化.当激光脉冲与靶直接作用时,靶中的电子由于J×B机制而得到加速,所获得的能量比预等离子体中电子低.研究表明,在超短超强激光脉冲与固体靶相互作用中,预等离子体的存在有利于高能电子的产生.

The interaction between an ultra-short ultra-intense laser pulse and a solid target with a low density pre-plasma is examined. Both linear and circular polarizations of the laser are considered. The electrons in the pre-plasma are accelerated by the ponderomotive force of propagating laser pulse, and the dependences of the maximum electron energy on the laser intensity and the pre-plasma density are examined. The target electrons are accelerated by J×B mechanism, and the maximum energy achieved is much lower than that of the pre-plasma electrons. In this sense, the pre-plasma is advantageous for energetic electrons generation in the ultra-short ultra-intense laser-solid interaction.