激光烧蚀Cu靶产生等离子体紫外段发射光谱的研究

Ultraviolet spectroscopic study of laser-induced Cu plasmas

利用波长532nm,脉宽15ns的Nd:YAG激光作用于Cu靶上,研究了产生等离子体的紫外段(180nm～300nm)发射光谱.在局部热力学平衡条件下,采用Boltzmann图表法估算了等离子体的电子温度,得到了电子温度随时间和空间的变化,以及电子温度随激光能量密度的变化.结果显示,随着激光能量的变化,电子温度有一个极大值.随着时间的发展,电子温度先减小,而后增大,接着缓慢减小.随着距靶面距离的增加,电子温度呈下降趋势.

Ultraviolet （180 nm^300 nm） spectra of laser-induced Cu plasmas is studied using 532 nm, 15 ns pulses from a Nd： YAG laser. Boltzmann diagram method is used to calculate the electron temperature by assuming LTE conditions. The relations between electron temperature and laser fluence is acquired. Also space- and time-resolved measurements of electron temperature have been carried out using emission lines of copper plasma. The result shows that the temperature has a maximum value as laser fluence varies. Time evolutions of temperature are found to decay at early times, then a rise appears. After the rise, the temperature decreases at a slow speed. Spatial variation of temperature shows a flat drop as distances from the target surface increases.