Implications of the measured BRDF for the ITER divertor impurity monitor

IF 1.9 3区工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY

Fusion Engineering and Design Pub Date : 2025-03-14 DOI:10.1016/j.fusengdes.2025.114926

Hiroki Natsume , Kunpei Nojiri , Shin Kajita , Hirohiko Tanaka , Tomohiro Yokozuka , Yoshihiko Nunoya

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引用次数: 0

Abstract

This study employed a goniophotometer to investigate the three-dimensional bidirectional reflectance distribution function (BRDF) of tungsten, a material utilized in the ITER divertor. The measured BRDFs were incorporated into ray-tracing simulations to assess the impact of reflected light on the divertor impurity monitor (DIM), a spectroscopic measurement for ITER. The results demonstrate that surface conditions, which are expected to be modified by the plasma-wall interaction, exert a considerable influence on the characteristics of reflected light. In comparison to mirror-polished surfaces, the sputtered and recrystallized surfaces exhibited broader reflection patterns. In addition, the presence of a fuzzy surface resulted in a notable reduction in reflected light, including multiple reflections. Furthermore, this study investigated the potential for errors to arise from the use of optical reflection models with a small number of free parameters. It was found that discrepancies in the BRDF at shallow angles result in errors in the reflected light observed in the DIM. However, these discrepancies became relatively small in DIM measurements when the surface exhibited low specular reflection, such as sputtered or fuzzy surfaces. These results indicate that while some discrepancy exists between the predicted and actual BRDFs, the impact on DIM diagnostics may not be as significant as the error in the BRDF itself.

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这项研究使用测角光度计来研究钨的三维双向反射分布函数（BRDF），钨是用于热核实验堆分流器的一种材料。测得的双向反射分布函数被纳入光线跟踪模拟，以评估反射光对热核实验堆的光谱测量--分流器杂质监测器（DIM）--的影响。结果表明，预计会因等离子体-壁相互作用而改变的表面条件对反射光的特性有相当大的影响。与镜面抛光表面相比，溅射和重结晶表面显示出更宽的反射模式。此外，模糊表面的存在明显减少了反射光，包括多重反射。此外，这项研究还调查了使用自由参数较少的光学反射模型可能产生的误差。研究发现，浅角度 BRDF 的差异会导致在 DIM 中观测到的反射光出现误差。然而，当表面（如溅射表面或模糊表面）表现出低镜面反射时，这些差异在 DIM 测量中变得相对较小。这些结果表明，虽然预测的 BRDF 与实际的 BRDF 之间存在一些差异，但对 DIM 诊断的影响可能没有 BRDF 本身的误差那么大。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Fusion Engineering and Design 工程技术-核科学技术

CiteScore

3.50

自引率

23.50%

发文量

275

审稿时长

3.8 months

期刊介绍： The journal accepts papers about experiments (both plasma and technology), theory, models, methods, and designs in areas relating to technology, engineering, and applied science aspects of magnetic and inertial fusion energy. Specific areas of interest include: MFE and IFE design studies for experiments and reactors; fusion nuclear technologies and materials, including blankets and shields; analysis of reactor plasmas; plasma heating, fuelling, and vacuum systems; drivers, targets, and special technologies for IFE, controls and diagnostics; fuel cycle analysis and tritium reprocessing and handling; operations and remote maintenance of reactors; safety, decommissioning, and waste management; economic and environmental analysis of components and systems.