Quantification of erosion pattern using picosecond- LIBS on a vertical divertor target element exposed in W7-X
Quantification of erosion pattern using picosecond- LIBS on a vertical divertor target element exposed in W7-X
复制标题
使用皮秒 LIBS 对 W7-X 中暴露的垂直偏滤器目标元件进行侵蚀模式的量化
DOI：
10.1088/1741-4326/abc408
复制
发表时间：
2020
期刊：
影响因子：
3.3
通讯作者：
the W7-X team
中科院分区：
文献类型：
--
作者：
D. Zhao;R. Yi;A. Eksaeva;J.Oelmann;S. Brezinsek;G. Sergienko;M. Rasinski;Y. Gao;M. Mayer;C.P. Dhard;D. Naujoks;L. Cai;the W7-X team
在温德尔斯坦7-X（W7-X）中安装了一组专用的标记样品，包括作为基底的细颗粒石墨、用作标记的0.2-0.4 μm钼（Mo）夹层和顶部5-10 μm厚的碳（C）标记层，以局部地研究C的侵蚀和沉积。在这项研究中，一组五个单独的标记瓦片，安装在半模块50中的测试偏滤器单元的垂直偏滤器元件中，并在W7-X中偏滤器运行的第一年暴露于标准磁偏滤器配置中占主导地位的等离子体中约40分钟（OP 1. 2A），从血管中取出进行尸检分析。皮秒激光诱导击穿光谱（ps-LIBS）被施加在这些标记瓷砖，以确定局部腐蚀/沉积图案所造成的等离子体的影响。借助于由ps-LIBS产生的Mo线发射的深度分布，研究垂直靶元件上的一般腐蚀/沉积图案，其中在一个探测位置处施加激光脉冲的数量（355 nm，2.3 J cm-2，35 ps）。几个潜在的不对称因素，避免了一个完美的逐层烧蚀过程中的激光烧蚀提出和讨论时，一个粗糙的层状结构的样品与粗糙的表面进行了分析，由PS-LIBS技术。因此，一个仿真模型的发展，以纠正所施加的激光束的非完美的矩形轮廓的ps-LIBS方法所造成的测量误差。所应用的ps-LIBS系统的深度分辨率通过量化不同层和C衬底的激光烧蚀速率来确定，所述激光烧蚀速率是利用轮廓测定法测量的，并且与通过组合的聚焦离子束和扫描电子显微镜技术确定的C和Mo标记层的厚度进行交叉比较。首次利用PS-LIBS技术对垂直靶上的侵蚀/沉积模式进行了测绘和定量分析。一个相对较宽的净侵蚀区的极向延伸约200毫米，可以与主要粒子的相互作用区的主要应用的标准磁偏滤器配置的磁走向线。在腐蚀峰值处，由于等离子体燃料粒子（H，He）和杂质（O，C）离子的碰撞，不仅有7.6× 1019 C原子/cm 2被腐蚀，而且还有2× 1018 Mo原子/cm 2被腐蚀，由此可外推到15× 1019 C原子/cm 2。
A set of dedicated marker samples consisting of fine-grain graphite as substrate, an interlayer of 0.2–0.4 μm molybdenum (Mo) employed as marker, and a 5–10 μm thick carbon (C) marker layer on top were installed in Wendelstein 7-X (W7-X) to investigate locally the C erosion and deposition. In this study, a set of five individual marker tiles, installed in a vertical divertor element of the test divertor unit in half-module 50, and exposed to about 40 min of plasma predominant in the standard magnetic divertor configuration in the first year of divertor operation in W7-X (OP1. 2A), were retrieved from the vessel for post-mortem analysis. Picosecond laser induced breakdown spectroscopy (ps-LIBS) was applied on these marker tiles in order to determine the local erosion/deposition pattern caused by plasma impact. The general erosion/deposition pattern on the vertical target element was studied with the aid of depth-profiling by Mo line emission due to ps-LIBS with the number of applied laser pulses (355 nm, 2.3 J cm− 2, 35 ps) at one probing location. Several potential asymmetry factors which avoid a perfect layer-by-layer ablation process in the laser ablations are proposed and discussed when a rough layered structure sample with a rough surface is analysed by the ps-LIBS technique. Thereby, a simulation model was developed to correct the measurement error of the ps-LIBS method caused by the non-perfect rectangle profile of the applied laser beam. The depth resolution of the applied ps-LIBS system was determined by quantification of the laser ablation rates of the different layers and the C substrate which were measured utilising profilometry and cross comparison with the thicknesses of the C and Mo marker layers determined by a combined focused ion beam and scanning electron microscopy technique. For the first time, the erosion/deposition pattern on the vertical target was mapped and quantified by ps-LIBS technique. A relatively wide net erosion zone with a poloidal extend of about 200 mm was identified which can be correlated to the main particle interaction zone at the magnetic strike-line of the dominantly applied standard magnetic divertor configuration. At the position of peak erosion, not only 7.6× 10 19 C atoms/cm 2 but also 2× 10 18 Mo atoms/cm 2 which results can be extrapolated to total 15× 10 19 C atoms/cm 2, were eroded due to plasma fuel particle (H, He) and impurity (O, C) ion impact.