The analytical capabilities of laser-induced breakdown spectroscopy (LIBS) for in situ elemental analysis of nuclear materials at elevated temperatures were estimated. A certified molybdenum–tungsten alloy (Mo 70 wt% and W 30 wt%) was chosen as a replacement for the high Z impurities deposited on plasma facing components (PFCs) in tokamak. The influence of sample temperature (T_s) on the optical emission of the laser-induced molybdenum–tungsten plasma was investigated with a nanosecond infrared (1064 nm) laser pulse. LIBS experiments were carried out in a wide temperature range from 20 to 410 °C. Surface morphology and depth profiling measurements of the ablated crater for the different temperature conditions were performed. A noticeable dependence of signal emission intensity on T_s has been found. An increase in T_s leads to an increase in the spectral line emissions. In the laser ablation process, the ablation rate, plasma temperature and electron density increase significantly with T_s. In addition, the reflectivity of the alloy surface drops dramatically once oxidation occurs. The decrease of surface reflectivity leads to a greater laser energy coupled to the target and a higher LIBS signal. These results will help improve the LIBS quantitative analysis of high Z impurities in the tokamak device.

中文翻译：

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样品温度对钼钨合金激光击穿光谱的影响

估计了激光诱导击穿光谱法（LIBS）在高温下对核材料进行原位元素分析的分析能力。选择了经过认证的钼钨合金（Mo 70 wt％和W 30 wt％）来替代在托卡马克中沉积在等离子体部件（PFC）上的高Z杂质。样品温度（T _{s）的影响}）用纳秒级红外（1064 nm）激光脉冲研究了激光诱导的钼-钨等离子体的光发射。LIBS实验是在20至410°C的较宽温度范围内进行的。对不同温度条件下的烧蚀坑进行了表面形貌和深度轮廓测量。已经发现信号发射强度对T _s有明显的依赖性。在增加Ť_小号导致的增加谱线排放。在激光烧蚀过程中，烧蚀速率，等离子体温度和电子密度随T _s显着增加_。。另外，一旦发生氧化，合金表面的反射率急剧下降。表面反射率的降低导致耦合到目标的激光能量更大，LIBS信号更高。这些结果将有助于改善托卡马克装置中高Z杂质的LIBS定量分析。