Temporal and spatial dynamics of optical emission from laser ablation of the first wall materials of fusion device
Temporal and spatial dynamics of optical emission from laser ablation of the first wall materials of fusion device
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聚变装置第一壁材料激光烧蚀光发射的时空动力学
DOI：
10.1088/2058-6272/aa96a0
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发表时间：
2018
影响因子：
1.7
通讯作者：
Ding HB
中科院分区：
文献类型：
--
作者：
Zhao Dongye;Li Cong;Wang Yong;Wang Zhiwei;Gao Liang;Ding Hongbin;Hu Zhenhua;Wu Jing;Luo Guang-Nan;Ding HB
利用激光诱导击穿光谱（LIBS）对EAST托卡马克第一壁的化学成分进行了原位诊断。然而，在真空激光等离子体中，对钨、钼和石墨等关键等离子体材料的光学发射动力学还没有研究。本文利用ICCD光谱仪研究了光发射的时空动态。采用脉冲持续时间为6 ns的Nd: YAG激光器（1064 nm）产生等离子体。结果表明，LPP的典型寿命小于1.4 μs，离子的寿命小于原子，为~ 10−6 mbar。光发射的时间特征表明，光谱采集的最佳延迟时间为100 ~ 400 ns，这取决于对应的物种。在空间分布上，等离子体羽流的最大LIBS光谱强度出现在离样品表面1.5 ~ 3.0 mm的区域。此外，我们还测量了多组分系统中涉及不同物质的等离子体膨胀速度，以获得最大发射强度的适当定时（栅极延迟时间和栅极宽度），并了解等离子体膨胀机制。不同物种膨胀速度的顺序为
Laser-induced breakdown spectroscopy (LIBS) has been developed to in situ diagnose the chemical compositions of the first wall in the EAST tokamak. However, the dynamics of optical emission of the key plasma-facing materials, such as tungsten, molybdenum and graphite have not been investigated in a laser produced plasma (LPP) under vacuum. In this work, the temporal and spatial dynamics of optical emission were investigated using the spectrometer with ICCD. Plasma was produced by an Nd: YAG laser (1064 nm) with pulse duration of 6 ns. The results showed that the typical lifetime of LPP is less than 1.4 μs, and the lifetime of ions is shorter than atoms at∼ 10− 6 mbar. Temporal features of optical emission showed that the optimized delay times for collecting spectra are from 100 to 400 ns which depended on the corresponding species. For spatial distribution, the maximum LIBS spectral intensity in plasma plume is obtained in the region from 1.5 to 3.0 mm above the sample surface. Moreover, the plasma expansion velocity involving the different species in a multicomponent system was measured for obtaining the proper timing (gate delay time and gate width) of the maximum emission intensity and for understanding the plasma expansion mechanism. The order of expansion velocities for various species is