空间约束对激光诱导等离子体演化和光谱的影响  

Effect of Spatial Confinement on Plasma Evolution and Spectrum in Laser-Induced Breakdown Spectroscopy

作　　者：蔡亚超 步扬 王远航 吴芳 阎晓娜[1] Cai Yachao;Bu Yang;Wang Yuanhang;Wu Fang;Yan Xiaona(Department of Physics,Shanghai University,Shanghai 2004,China;Laboratory of Information Optics and Optoelectronic Technology,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China)

机构地区：[1]上海大学物理系,上海200444 [2]中国科学院上海光学精密机械研究所信息光学与光电技术实验室,上海201800

出　　处：《光学学报》2023年第7期261-268,共8页Acta Optica Sinica

基　　金：上海市科委项目(18511104500)。

摘　　要：应用纳秒脉冲激光烧蚀铝的动力学模型分析了激光诱导等离子体的演化过程。通过设置有无空腔的不同情况,研究和讨论了空间约束对等离子体和光谱信号的影响,并得到了等离子体演化过程中的电子温度和电子数密度。基于局域热平衡的假设,计算了铝在396.15 nm波长处的谱线强度。与无空腔条件下产生的等离子体相比,有空腔时等离子体的电子温度和电子数密度都明显提高。随着空腔宽度的增加,增强效果减弱,光谱信号强度先升后降,在空腔宽度为1.4 cm处获得最大值。建立了实验装置,实验结果与仿真结果吻合得较好,在同一宽度下得到了最大的信号强度值。模拟和实验结果提供了膨胀过程中等离子体空间和时间分布的数值信息,并解释了空腔存在对等离子体演化产生影响的机制。Objective Laser-induced breakdown spectroscopy(LIBS)is a valuable element analysis method that has been widely applied in many fields including biomedical,industrial,and environmental analysis.It uses a pulsed laser beam to interact with the sample and produces a plasma plume above the sample surface.The emission spectra of the specific elements can be obtained from the plasma,and element compositions and contents of the sample can be gained by spectral analysis.The properties of plasma and sample analysis depend on the related parameters of the LIBS system,which includes the laser pulse and physical situation of the sample.Related works have been carried out to describe the effects of such conditions on laser-induced plasma through numerical simulation.Spatial confinement is an effective method to enhance LIBS signals.The plasma evolution,including its morphological characteristics,is affected by the presence of the cavity.The plasma confined by the cavity is physically modified,with its morphology changed,because of its interaction with the cavity walls.In this work,the effects of spatial confinement on plasma evolution and spectra in LIBS are investigated by the model.The laser-induced plasma plume of Al with or without the cavity is analyzed,and numerical information on the plasma particles is acquired during the expansion of plasma.In addition,the distributions of electron number density and electron temperature are studied.According to the plasma evolution data,the specific spectral signal intensities of the cases with different cavity widths are calculated.Under the same conditions as the simulation,experiments are performed to show the enhancement effect on signal intensity with the presence of the cavity and make a comparison with the simulation.Methods In this study,Al is employed as the sample material for the laser-induced plasma.Firstly,the initial conditions of the simulation process are determined,including relevant parameters of the incident laser,the spatial state of the sample(cavities with diff

关 键 词：光谱学 激光诱导击穿光谱 仿真分析 等离子体演化 空间约束 光谱信号强度 

分 类 号：O433[机械工程—光学工程]