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Assessment of laser induced breakdown spectroscopy accuracy for determination of hydrogen accumulation in tungsten
Nuclear Materials and Energy ( IF 2.6 ) Pub Date : 2021-05-24 , DOI: 10.1016/j.nme.2021.101029
E.D. Marenkov , I.P. Tsygvintsev , Yu.M. Gasparyan , A.A. Stepanenko

Laser-induced breakdown spectroscopy (LIBS) is an in situ method of determining hydrogen (H) content in plasma-facing materials in tokamak fusion reactors. Observing radiation from the plasma plume produced by a powerful laser pulse during the target exposition characterizes the sample composition. This is typically accomplished using the Saha-Boltzmann (SB) plot technique under local thermodynamic equilibrium (LTE) conditions. Despite many experimental studies dedicated to applying LIBS to determine H isotope retention in fusion reactor materials, the current understanding of this method’s intrinsic accuracy remains inadequate. In this report, we use numerical calculations to estimate the relative error of determining H content in a sample using LIBS. As an example. we consider LIBS to study a W sample loaded with H in a vacuum. Under typical LIBS pulse parameters (109 W/cm2 and 12 ns duration), the error can be quite large, approximately 70%. We demonstrate that the error tends to decrease as the laser pulse intensity increases. Various factors contributing to the relative error are examined and their dependence on the LIBS plasma parameters is discussed. The SB plot remains a straight line even when LTE conditions are violated, making it difficult to anticipate the experimental results’ error.



中文翻译:

评估激光诱导击穿光谱法测定钨中氢积累的准确性

激光诱导击穿光谱 (LIBS) 是一种原位测定托卡马克聚变反应堆面向等离子体材料中氢 (H) 含量的方法。在目标暴露期间观察由强大激光脉冲产生的等离子体羽流的辐射表征样品成分。这通常是在局部热力学平衡 (LTE) 条件下使用 Saha-Boltzmann (SB) 绘图技术完成的。尽管许多实验研究致力于应用 LIBS 来确定聚变反应堆材料中的 H 同位素保留,但目前对该方法固有准确性的理解仍然不足。在本报告中,我们使用数值计算来估计使用LIBS测定样品中H含量的相对误差。举个例子。我们考虑 LIBS 来研究在真空中加载了 H 的 W 样本。9 W/cm 2和 12 ns 持续时间),误差可能非常大,约为 70%。我们证明了误差会随着激光脉冲强度的增加而减少。检查了导致相对误差的各种因素,并讨论了它们对 LIBS 等离子体参数的依赖性。即使违反 LTE 条件,SB 图仍保持直线,因此很难预测实验结果的误差。

更新日期:2021-05-30
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