激光诱导Al等离子体温度随激光能量变化特性研究

Laser-produced Al Plasmas Temperature at Different Laser Energy

利用ＹＡＧ激光（波长１．０６ μｍ，脉宽为１０ｎｓ）烧蚀Ａｌ靶产生的三条 ＡｌⅢ等离子体谱线 （４５．９２ｎｍ； ４５１．２５ｎｍ； ４１５．０１ｎｍ）；在局部热力学平衡近似下，利用玻尔兹曼图，测定了等离子体电子温度在不 同激光能量下的变化特性．随着激光能量的增加，电子温度从１４８００Ｋ近似单调的上升到２００００Ｋ；随后反而有所 下降．在电子温度达最高时，连续辐射谱强度并未达最大值．同时还观测到，Ａｌ的原子谱线和离子谱线强度随激光 能量有不同的变化特点．利用玻尔兹曼图的最小二乘方拟合，测得Ａｌ Ⅲ谱线４４７．９９ ｎｍ（４ｆ２Ｆ７／２－５ｇ２Ｇ９／２） 跃迁的几率约为（１０．４±０．８）ｘ１０８

The temperature of laser-produced Al plasmas (LPP) have been measured at different laser energy by using the model of local thermodynamic equilibrium (LTE). The electron temperature changed from 14800 K to 20000 K when the laser energy increased from 30 mJ/pulse to 45 mJ/pulse, then, the temperature had some decrease along the laser energy increasing. The intensities of Al I spectra lines have shown similar variant property, but differetnt from other Al ions spectra lines. Meanwhile, the transition probability of 447.99 um line of Al Ⅲ was measured by the Boltzmann plots was about (9-10) x 108 s-1.