平面反射镜对激光诱导等离子体光谱的增强作用  

Enhancement on laser-induced plasma spectroscopy with a flat-mir ror

作　　者：陈金忠[1] 陈振玉[1] 孙江[1] 李旭[1] 郭树青[1] 

机构地区：[1]河北大学物理科学与技术学院,河北保定071002

出　　处：《光电子．激光》2013年第9期1838-1843,共6页Journal of Optoelectronics·Laser

基　　金：国家自然科学基金(10804025);河北省自然科学基金(A2006000951)资助项目

摘　　要：为了获得高质量的激光诱导等离子体发射谱,在激光诱导等离子体附近放置平面反射镜,通过改变平面反射镜与等离子体中心轴线之间的距离,观测反射镜对土壤等离子体辐射强度的影响;利用Boltzmann图法和光谱线Stark展宽法测量了等离子体的电子温度Te和电子密度Ne,并解释了辐射增强的机理。实验结果表明,平面反射镜对等离子体辐射有一定程度的增强作用,当平面反射镜与等离子体中心轴线的间距为3 mm时,样品元素Cr、Fe和Ca的光谱线强度比无反射镜时的分别提高了49.3、50.1和75.9%,光谱信噪比(SNR)分别提高了56.8、47.5和65.5%,Te升高了1250K,Ne增加了0.62×1015 cm-3;随着反射镜与等离子体中心轴线之间距离的增大,等离子体辐射强度逐渐减弱。To obtain the higher quality of the lase%induced breakdown spectroscopy （LIBS） and improve the detection capability of the LIBS technique on soil samples, the effect of flat mirror on the radiation of the lase〉induced plasma is investigated by changing the distance between the fiat mirror and the axis of the plasma center. And, the plasma parameters, the electron temperature and electron density of plasmas,are measured by the Bohzmann graph method and Stark broadening to explain the mechanism of the radiation enhancement obtained with the flat mirror. The experimental results indicate that the plasma radiation intensity is significantly enhanced with the mirror, and the plasma radiation intensity is gradual- ly weakened as the distance increasing. The calculated results show that the spectral line intensities of elements Cr,Fe and Ca with the distance between the mirror and the axis of the plasma center of 3 mm are enhanced by about 49.3 %,50. 1 %, and 75.9 %, respectively than those without mirror, tbe spectral signal tcynoise ratios are increased by about 56.8% ,47.5% ,and 65.5% ,respectively while the electronic temperature and electronic density of plasmas are enhanced by 1 250 K and 0.62× 10^16 cm ^-3 ,respec tively. It is an effective method to obtain the higb quality laser spectrum.

关 键 词：激光诱导等离子体 平面反射镜 光谱强度 信噪比（SNR） 电子温度 电子密度 

分 类 号：O433.2[机械工程—光学工程]