强激光与等离子体相互作用中低频电磁场孤子波的产生及其捕获

用二维粒子模拟程序研究了超短脉冲强激光与等离子体相互作用中局域低频电磁场的产生现象.这种低频电磁场在超短脉冲激光激发尾波场、脉冲后沿产生频率下移的过程中形成.通常它们的振荡频率接近于或低于电子等离子体振荡频率，因而被捕获在等离子体中(即传播速度接近于零).在演化过程中，通常它们以孤子场的形式出现.这种孤子波的形成及其演化与离子运动有极大关系.用相对论强激光脉冲可以产生达到相对论振幅的电磁场孤子波，后者可以把离子加速到非常高的能量.研究还表明，在二维几何位形下，孤子波产生与入射光的偏振态有很大关系.

Generation of low frequency electromagnetic solitons in plasmas near the critical density with ultrashort intense laser pulses

Generation of low frequency electromagnetic solitons in plasmas near the critical density by use of an ultrashort intense laser pulse has been studied with a two-dimensional (2D) particle-in-cell simulation code. They are formed while the ultrashort laser pulse is exciting a wake field, with its trailing edge experiencing strong frequency down-shift and part of its energy trapped in the plasmas. The formed solitons are usually found to move with small velocity, which results in the formation of plasma cavities and the acceleration of ions to high energy. It is also found that the soliton formation in 2D simulation geometry depends heavily on the polarization state of the incident pulse.