真空中同轴LIBS系统下铝锂合金等离子体时空演化行为研究  

Spatiotemporal Evolution of Aluminum-lithium Alloy Plasma Using a Coaxial LIBS System under Vacuum

作　　者：崔紫宵 武华策 吴鼎[1] 刘佳敏 胡晓涵 海然[1] 李聪[1] 丁洪斌[1] CUI Zixiao;WU Huace;WU Ding;LIU Jiamin;HU Xiaohan;HAI Ran;LI Cong;DING Hongbin(School of Physics,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学物理学院,大连116024

出　　处：《光子学报》2023年第9期110-120,共11页Acta Photonica Sinica

基　　金：国家自然科学基金(No.12005034);国家磁约束核聚变能发展研究专项(No.2022YFE03200100);中央高校基本科研业务费资助(No.DUT22RC(3)066)。

摘　　要：采用基于线性阵列光纤束的同轴光学结构,在真空环境下利用波长1064 nm、脉宽5 ns、功率密度6.3 GW/cm^(2)的脉冲激光烧蚀铝锂合金靶材,对铝锂合金等离子体发射光谱分别进行时空积分和时空分辨测量。评估了等离子体发光时间~1μs,发光区域大小~1 cm。进一步研究了激光烧蚀等离子体连续辐射、离子谱线和原子谱线的时空演化行为,给出了激光烧蚀等离子体不同辐射机制的辐射时间尺度。谱线的空间分辨测量发现,Al、Li元素对应原子及离子的空间分布均有所不同,即真空中激光烧蚀铝锂合金等离子体在横向扩张过程中发生了元素“空间分离”的现象。物种的横向扩张速度研究结果表明,同种元素的离子速度大于其原子速度(Al III>Al II>Al I,Li II>Li I)。此外,对同种电荷态不同元素的原子(离子)速度的差异进行了讨论,并归因于元素的“质量分离”效应和较快的离子复合效应。As an important technique for in-situ wall diagnostics in tokamaks,Laser-Induced Breakdown Spectroscopy(LIBS)has been demonstrated to effectively detect fuel retention and element distribution on the wall surface of the Experimental Advanced Superconducting Tokamak(EAST).However,despite its potential,the accurate quantitative analysis of wall surface elements remains a critical challenge for LIBS technology.One of the primary factors contributing to this challenge is the significant spatiotemporal nonuniformity exhibited by the laser-induced plasma under vacuum conditions.Therefore,investigating the spatiotemporal evolution of the plasma holds great significance for optimizing signal quality and enabling qualitative and quantitative analysis in wall diagnostics using LIBS.In this work,the researchers employed a coaxial optical structure based on a linear array of optical fibers,this setup enabled them to perform spatiotemporal integration and spatiotemporal resolution measurements of aluminum-lithium alloy plasma emission spectra generated by pulsed laser ablation at a wavelength of 1064 nm,a pulse width of 5 ns,and a power density of 6.3 GW/cm^(2)under vacuum conditions.The emission time of the plasma was evaluated to be~1μs,and the emission area size was~1 cm.The spatiotemporal evolution behavior of continuous radiation,ionic lines,and atomic lines were analyzed to determine the emission time scale of different radiative mechanisms of laser-ablated plasma.Spatially resolved measurements revealed that the spatial distributions of aluminum(Al)and lithium(Li)atoms and ions were distinct from each other,revealing an element“spatial separation”phenomenon that occurred during the lateral expansion of the laser-ablated aluminum-lithium alloy plasma in a vacuum environment.The results of the spatiotemporal evolution of the species′lateral expansion velocity showed that the ion velocity of the same element was greater than its atomic velocity(Al III>Al II>Al I,Li II>Li I),this discrepancy in velocities can potent

关 键 词：激光诱导击穿光谱 铝锂合金 时空演化 等离子体尺寸 扩张速度 

分 类 号：O433.1[机械工程—光学工程]