Study of spectral features and depth distributions of boron layers on tungsten substrates by ps-LIBS in a vacuum environment

IF 2.3 2区物理与天体物理 Q1 NUCLEAR SCIENCE & TECHNOLOGY

Nuclear Materials and Energy Pub Date : 2024-11-12 DOI:10.1016/j.nme.2024.101812

Huace Wu , Rongxing Yi , Anne Houben , Sebastijan Brezinsek , Marcin Rasinski , Cong Li , Gennady Sergienko , Yunfeng Liang , Timo Dittmar , Hongbin Ding

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引用次数: 0

Abstract

Boronization is used in present-devices as wall condition technique due to its effectiveness in reducing oxygen and other impurities in the vessel as well as improving plasma performance. The technique is also currently under consideration as wall conditioning method for the proposed full-tungsten (W) wall of the International Thermonuclear Experimental Reactor (ITER). However, the impact of the deposited Boron (B) layer thickness, and its homogeneity after the boronization process is uncertain as well as knowledge about the layer lifetime and improved conditions. In this study, an approach of the picosecond-laser-induced breakdown spectroscopy (ps-LIBS) is investigated to analyze the depth distribution of B-films on W-substrates by using three optical spectrometers in a vacuum environment. The depth distribution of two types of B-films on W-substrates with the thicknesses of 130 nm and 260 nm were sequentially measured under different laser spot sizes (varying the laser fluence). The B-films on the W-substrates were made by magnetron sputtering to simulate the thin B layers during the boronization. The measured average ablation rate of ps-LIBS shows a notable decrease with increasing laser spot size. Additionally, the spectral lines of B and W exhibit distinct intensity distributions under different spot sizes due to the different excitation thresholds of the B-films and the W-substrates. The interface between B-films and W-substrates, as well as the thickness of the B-films, were determined using the normalized intensity and intensity ratio method, respectively. The results from ps-LIBS measurements regarding the depth are in good agreement with those obtained through the Focused Ion Beam combined with Scanning Electron Microscopy (FIB-SEM) and Energy Dispersive X-ray Spectroscopy (EDS). These initial findings verify the feasibility to characterize the thickness and uniformity of thin B films in the order of 100 nm and below on W-substrates using ps-LIBS.

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在真空环境中利用 ps-LIBS 研究钨基板上硼层的光谱特征和深度分布

由于硼化技术能有效减少容器中的氧气和其他杂质，并能提高等离子体的性能，因此在目前的设备中被用作器壁调节技术。目前，国际热核聚变实验堆（ITER）正在考虑将这种技术作为拟建的全钨（W）壁的壁调节方法。然而，硼化过程后沉积硼（B）层厚度及其均匀性的影响，以及有关硼层寿命和改进条件的知识都是不确定的。本研究采用皮秒激光诱导击穿光谱（ps-LIBS）方法，在真空环境中使用三台光学光谱仪分析 W 基板上硼膜的深度分布。在不同激光光斑尺寸（改变激光能量）条件下，依次测量了 W 基片上厚度分别为 130 nm 和 260 nm 的两种 B 膜的深度分布。W 基片上的 B 膜是通过磁控溅射制造的，以模拟硼化过程中的薄 B 层。测得的 ps-LIBS 平均烧蚀率随着激光光斑尺寸的增大而明显下降。此外，由于硼薄膜和 W 基质的激发阈值不同，在不同光斑尺寸下，硼和 W 的光谱线呈现出不同的强度分布。利用归一化强度和强度比方法分别确定了 B 膜和 W 基底之间的界面以及 B 膜的厚度。ps-LIBS的深度测量结果与聚焦离子束结合扫描电子显微镜（FIB-SEM）和能量色散 X 射线光谱（EDS）获得的结果十分吻合。这些初步发现验证了利用 ps-LIBS 测定 W 基底上 100 纳米及以下 B 薄膜厚度和均匀性的可行性。

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来源期刊

Nuclear Materials and Energy Materials Science-Materials Science (miscellaneous)

CiteScore

3.70

自引率

15.40%

发文量

175

审稿时长

20 weeks

期刊介绍： The open-access journal Nuclear Materials and Energy is devoted to the growing field of research for material application in the production of nuclear energy. Nuclear Materials and Energy publishes original research articles of up to 6 pages in length.