激光等离子体X射线特征谱轮廓诊断  

X-ray line profile measurements in laser produced plasma

作　　者：王瑞荣[1] 王伟[1] 

机构地区：[1]上海激光等离子体研究所,上海201800

出　　处：《光学精密工程》2014年第7期1737-1742,共6页Optics and Precision Engineering

基　　金：国家自然科学基金资助项目(No.11175167)

摘　　要：开展了利用X射线特征谱轮廓诊断激光等离子体状态参数的研究。在"神光II"激光装置上,将0.35μm频谱激光束聚焦于真空室内固体氯(Cl)元素靶上产生激光氯等离子体,利用高分辨X射线椭圆弯晶谱仪获取高能谱分辨激光氯等离子体辐射的X射线精细结构能谱。用类氢(1s-3p)和类氦(1s2-1s3p)氯离子能级跃迁光谱线的光强度比率计算了激光等离子体的电子温度;然后在假定光性为薄的情况下,利用X射线谱线Lyman-线形轮廓的Stark效应所产生的谱线展宽测量了等离子体的电子密度。实验获得的激光等离子体日冕区内体平均电子温度约为450eV,电子密度约为7.5×1022 cm-3。文中还简单分析了能谱线的半高全宽度(FWHM)值以及诊断过程引入的诊断误差,初步预估诊断误差可控制在25%以内。该项工作为X射线特征谱轮廓法进一步应用于激光聚变靶丸压缩度精度测量等工作提供了参考。This paper explores the parameter measurement in laser produced plasma by X-ray line profile spectrscopy.The experiment was conducted on the SG-II laser facility.A 0.35μm laser beam was focused on a solid chlorine（Cl）target in a vacuum chamber to produce a laser chlorine plasma and the high resolution X-ray elliptical bent crystal spectrograph was used to obtain the X-ray fine structure energy spectrum of the chlorine plasma radiation.The line integrated intensity ratio between H-like Cl（1s-3p）（Lyman-）and He-like Cl（1s2-1s3p）（He-）transitions was used for calculation of the electron temperature.By assuming optically thin,the Lyman-stark broadened profile was utilized to measure the electron density.Obtained experimental results show that the volume averaged electron temperature of Te is about 450eV and the electron density of Ne is approximately 7.5×1022 cm-3.In addition,the line Full Width at Half Maximum（FWHM）was analyzed.The uncertainty in Ne due to uncertainties in the temperature and the assumed background level was also simply discussed and it is estimated to be within 25%.As a result,the experimental spectroscopic method may become a reference for diagnosing future higher-compression implosions.

关 键 词：X射线能谱 谱线轮廓 激光等离子体诊断 电子密度 X射线谱仪 

分 类 号：O433.3[机械工程—光学工程] TL653[理学—光学]