通过测量由等离子体临界面移动造成的反射激光的频移,研究了有质动力对超短脉冲激光与固体等离子体相互作用的影响.实验表明,当激光强度达到1017W/cm2时,有质动力将明显地降低等离子体热膨胀速度,造成极陡的密度分布,使得等离子体中的主导吸收机制,由共振吸收转换为真空吸收.

The influence of the ponderomotive force on interaction of the ultrashort pulse laser with the solid plasma was studied by measuring the frequency shift induced by the movement of plasma critical surface. When laser intensity reache 10 17 W/cm 2, the ponderomotive force reduced the thermal expanding velocity of laser induced plasma, and produced a very steep density profile. In this case, the vacuum heating becomes the dominant absorption mechanism instead of the resonant absorption.