为研究激光脉冲能量对激光诱导等离子体辐射特性和膨胀过程的影响, 采用ICCD相机对不同激光脉冲能量激发的铝合金等离子体进行快速成像, 并利用Boltzmann斜线法和Stark展宽法分析等离子体的电子温度和电子数密度随激光脉冲能量的演化规律.实验结果表明, 激光诱导等离子体呈现明显的分层结构, 等离子体的激发阈值约为3 mJ, 等离子体不同区域的面积随激光脉冲能量变化呈现不同的特征.当激光脉冲能量低于10 mJ时, 等离子体的分层结构不显著.激光脉冲能量从10 mJ增加到100 mJ过程中, 等离子体电子温度从4 980 K升高到7 221 K, 等离子体的电子数密度在1017 cm－3量级并随激光能量增加而增大且趋于饱和.

In order to investigate the influences of laser pulse energy on the radiation characteristics and the expansion process of laser-induced plasma, the fast images of laser-induced aluminum alloy plasma were obtained by ICCD camera under different laser pulse energy, and the electron temperature and electron number density with different laser pulse energy were also determined by using the Boltzmann plot method and Stark broadening of line, respectively. The results show that the plasma presents an obvious hierarchical structure, and the excitation threshold of the plasma is approximate 3 mJ. The areas of different regions in plasma present different characteristics with different laser pulse energy. There is no significant hierarchical structure when the laser pulse energy is under 10 mJ. The electron temperature increases from 4 980 K to 7 221 K, and the electron number density which is of the order of 1017 cm－3 increases firstly and then trends to saturation when the laser pulse energy increases from 10 mJ to 100 mJ.