Investigating the effect of BT direction on W source-to-core pathways during the SAS-VW campaign on DIII-D

IF 2.3 2区物理与天体物理 Q1 NUCLEAR SCIENCE & TECHNOLOGY Nuclear Materials and Energy Pub Date : 2024-10-05 DOI:10.1016/j.nme.2024.101752

J.D. Mateja , S.A. Zamperini , T. Odstrcil , J.H. Nichols , T.E. Ray , A. Cacheris , T. Abrams , A.G. McLean , G. Sinclair , S.H. Messer , R. Maurizio , D.M. Thomas , D.C. Donovan

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Abstract

Experiments using the V-shaped closed slot tungsten (W) coated SAS-VW divertor in DIII-D studied the effects of the B_T direction on core contamination of eroded tungsten from a closed slot divertor configuration. Core W content is inferred using soft-X ray tomography (SXR) and vacuum ultraviolet spectroscopy (SPRED), while W divertor erosion is inferred from visible spectroscopy of W emission (400.9 nm) measured by in-slot filterscopes (filtered photo-multipliers). Post-mortem analysis from the campaign discovered tile misalignment leading to suspected pronounced leading-edge erosion in the unfavorable B_T direction (ion

\vec{B} \times \nabla \vec{B}

drift away from divertor) likely not captured by diagnostics. However, empirical findings show up to ∼ 2-3x larger core contamination in the favorable B_T direction even considering no additional W erosion from leading edges. A “source-to-core efficiency factor” is derived to estimate the effects of leading-edge erosion and compare W contamination for two pairs of H-mode discharges in opposite B_T directions. While having differing absolute parameters, similar core impurity density gradients suggest comparable core impurity transport. These results show that favorable B_T may have stronger source-to-core pathways for W impurities sourced from the outer divertor region. Possible explanations could include the effects of

\vec{E} \times \vec{B}

drifts on W transport in the scrape-off-layer (SOL) as well as previously determined fast SOL inner target directed flows in favorable B_T.

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在 DIII-D 上进行的 SAS-VW 活动期间，研究 BT 方向对 W 源到岩心路径的影响

在 DIII-D 中使用 V 形封闭槽钨 (W) 涂层 SAS-VW 分流器进行的实验研究了 BT 方向对封闭槽分流器配置侵蚀钨的堆芯污染的影响。通过软 X 射线断层扫描（SXR）和真空紫外光谱（SPRED）推断出堆芯中的钨含量，而通过槽内滤波器（滤波光电倍增管）测量的钨发射可见光谱（400.9 纳米）推断出钨分流器的侵蚀情况。活动结束后的分析发现，瓦片错位导致前缘在不利的 BT 方向（离子 B→×∇B→ 漂离偏转器）出现明显的侵蚀，而诊断仪很可能无法捕捉到这种侵蚀。然而，经验研究结果表明，即使不考虑来自前缘的额外 W 侵蚀，在有利的 BT 方向上，堆芯污染也会增加 2-3 倍。为了估算前缘侵蚀的影响，并比较 BT 方向相反的两对 H 模式放电的 W 污染情况，得出了一个 "源到堆芯效率系数"。虽然绝对参数不同，但相似的堆芯杂质密度梯度表明堆芯杂质传输具有可比性。这些结果表明，对于来自外侧分流器区域的 W 杂质来说，有利的 BT 可能具有更强的源到堆芯的路径。可能的解释包括 E→×B→ 漂移对 W 在刮离层（SOL）中的传输的影响，以及先前确定的在有利 BT 中快速 SOL 内靶定向流的影响。

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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.