激光诱导铅等离子体的自吸收时空分辨特性研究

SPATIO-TEMPORAL EVALUATION OF SELF-ABSORPTION OF A LASER INDUCED LEAD PLASMA

利用一价铅离子谱线和原子谱线,在延迟时间0-360 ns内对铅等离子体自吸收的时空特性进行了研究.通过改变靶材距离及观察不同的延迟时间,发现铅等离子体不同的特征谱线的自吸收行为存在很大不同.从实验图像中可明显的看出,等离子体形成初期,铅离子和铅原子表现出不同的线型的变化.铅离子（220.26nm）出现了红移,而铅原子（280.20 nm）出现了蓝移.靶材距离焦点位置不同时,不同的特征谱线,不仅自吸收持续时间不同,而且自蚀最强点出现的时间点也不一样.所以在利用某特征谱线进行定量分析时,若选择合适的延迟时间和靶材位置,可有效地减小或削弱自吸收的影响.笔者还对铅等离子体不同特征谱线自吸收行为进行了解释.

The spatio-temporal spectra of self-absorption of laser induced lead plasma were investigated by using monovalent ion and atomic spectra within the delay time of 0-360 ns.There are distinct differences between the self-absorption behavior of the characteristics of spectral lines when we change the target position and the delay time.It is obvious that the spectral linetype of lead ion and atom put up different tendency in the early stage of the plasma.The lead ion spectrum has a red shift,in contrast,the lead atomic spectrum a appears blue shift.When we changed the distance between the focus and target,we found that not only the duration of self-absorption is various,but also the time of the maximum erosion is different for the different spectral lines.So if we choose the appropriate delay time and target position,the effect of self-absorption can be reduced or weaken effectively.