强激光与稠密等离子体作用引起的冲击波加速离子的研究

Ion acceleration by shock wave induced by laser plasma interaction

用二维PIC(Particle-in-Cell)程序模拟研究了强激光与稠密等离子体靶作用产生的无碰撞静电冲击波的结构和这种冲击波对离子的加速过程.研究发现由于冲击波前沿附近的双极电场的作用,具有一定初速度的离子能被该双极场俘获并获得加速,最终能够被加速到两倍冲击波速度.冲击波加速可以得到准单能的离子能谱,叠加在通过鞘层加速机理产生的宽带离子能谱上.还对不同激光强度和不同等离子体密度情况下形成的冲击波进行了比较.研究表明,强度相对较低的激光在高密度等离子体中可以产生以一定速度传播的静电孤波结构,后者只能加速位于等离子体靶后鞘层处的离子.

The structure of the collisionless electrostatic shockwave（CES） and the process of the ion acceleration by shock wave are investigated with a series of two dimensional particle-in-cell（PIC） simulations.It is found that only ions satisfying some criteria can be accelerated due to the bipolar electric field in the shock wave front.A comparative investigation of the ion acceleration process by shock wave and solitary wave has been made.Only ions located in the sheath can be accelerated by the solitary wave.We also compare the shock wave for different laser intensities and different plasma densities.The ion energy spectrum of the shock wave has a platform.It can be used to ignite as the ignition material.