激光诱导Ti等离子体光谱的时间演化特性研究

The time evolution research of laser induced Ti plasma spectra

利用Nd:YAG激光器产生的1064 nm、10 ns脉冲激光聚焦在空气中的Ti靶,观测了激光诱导Ti等离子体发射光谱.调节激光能量为45 mJ/pulse,分析了时间范围在0到4000 ns的时间分辨发射光谱和谱线轮廓以及展宽.在局部热力学平衡(LTE)条件下,利用Saha-boltzmann图法拟合电子温度,Saha方程计算电子密度,讨论了等离子体电子温度和电子密度随时间的演化规律.结果表明,在所讨论的时间范围内,谱线的强度在延时250 ns处达到最大,250 ns后随着延迟时间的增加减小,电子密度和电子温度在延时1000 ns内快速衰减,1000 ns后衰减速度变慢.

Using Nd. YAG laser （with wavelength of 1064 nm and pulse width of 10 ns ） ablated Titani um target in air to produce plasma. The time resolved spectra were observed in the time range of 0 ns to4000 ns, the line profile and broadening were analyzed at the 45mJ /pulse of laser energy. Under the model of local thermodynamic equilibrium, the electron temperature and density were calculated by Sahaboltzmann and Saha equation, respectively. Furthermore, the characteristics of time evolution for e lectron temperature and electron density were also analyzed. The experimental results show that in thetime range discussed, the intensity of line were the strongest at 250 ns, and decayed with the delay time after 250 ns. While the electron temperature and density decayed rapidly with the delay time in 1000 ns,and then changed slowly after 1000 ns.