1　引言　　由强度 I =1 0 1 6～ 1 0 1 9W/cm2的皮秒激光脉冲生成的激光等离子体 ,是唯一的 X射线辐射源和荷电粒子源 ,粒子的参数与这一脉冲在靶中的吸收过程没有直接的关系。在研究超短脉冲与固体靶相互作用的理论基础时 ,这种脉冲的吸收过程特别令人注意。而解释实验测得的 1 INTRODUCTION Laser plasma generated by a picosecond laser pulse with an intensity of I = 1 0 1 6 ~ 1 0 1 9 W / cm 2 is the only source of X-ray radiation and a source of charged particles. The absorption process is not directly related. The absorption process of such pulses is of particular interest when studying the theoretical basis for the interaction of ultrashort pulses with solid targets. Explain the experiment measured