Experimental study on metallic impurity behavior with boronization wall conditioning in EAST tokamak

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

Nuclear Materials and Energy Pub Date : 2024-09-21 DOI:10.1016/j.nme.2024.101744

Yunxin Cheng , Ling Zhang , Ailan Hu , Shigeru Morita , Wenmin Zhang , Chengxi Zhou , Darío Mitnik , Fengling Zhang , Jiuyang Ma , Zhengwei Li , Yiming Cao , Haiqing Liu

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Abstract

Operation of EAST tokamak with full metal wall without any wall conditioning are attempted in 2023 and 2024 experimental campaign to address the issues related to ITER tungsten wall operation. It is found that H-mode plasma could be sustained even with a substantial increase in metallic impurity content caused by strong plasma-wall interaction under uncoated metal wall. Boronization wall conditioning is therefore performed to improve the plasma performance with higher injected power. This study aims to quantitatively assess the impact of boronization wall conditioning on metallic impurity concentration and behavior in the EAST tokamak. It is then proved to be an effective wall conditioning approach for significantly controlling high-Z impurity content. In this work, the impurity spectra at extreme ultraviolet (EUV) wavelength range measured by sets of fast-time-response and space-resolved EUV spectrometers are widely used in the data analysis. The variation in the boron content in plasma after boronization are investigated by monitoring the 2nd order of B V line at 48.59 Å. It is found that the persistence time of boron in EAST device after a boronization with 10 g of carborane (C₂B₁₀H₁₂) is about 2000 s (∼150 shots) of discharge duration. The impact of different wall conditions (uncoated metal wall and boron coated wall) on metallic impurity content are then quantitatively studied. After boronization, the concentration of tungsten (C_W) and molybdenum (C_Mo) dropped by 85 %, e. g., from 2.0 × 10^-4 to 4.1 × 10^-5 and from 4.6 × 10^-5 to 6.3 × 10^-6, respectively. While the concentration of copper (C_Cu) and iron (C_Fe) decreased by approximately 50 % and 65 %, respectively, e. g., from 4.3 × 10^-5 to 2.1 × 10^-5 and from 2.0 × 10^-4 to 6.9 × 10^-5. A comparison of the line emission profiles from tungsten ions of W²⁶⁺ − W³²⁺ and W⁴³⁺ before and after boronization reveals an overall reduction in the intensity while without obvious change in the profile shape, which suggests a reduction in metallic impurities source after boronization instead of altering impurity transport in core plasma significantly.

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EAST 托卡马克硼化壁调节金属杂质行为的实验研究

在2023年和2024年的实验活动中，EAST托卡马克在没有任何壁调节的情况下使用全金属壁运行，以解决与ITER钨壁运行相关的问题。实验发现，在无涂层金属壁下，由于等离子体与壁之间的强烈相互作用，即使金属杂质含量大幅增加，H 模式等离子体仍可持续。因此，需要进行硼化壁调节，以提高等离子体在更高注入功率下的性能。本研究旨在定量评估硼化壁调节对 EAST 托卡马克中金属杂质浓度和行为的影响。然后证明这是一种有效的壁调节方法，可显著控制高Z杂质含量。在这项工作中，数据分析广泛使用了由多套快速时间响应和空间分辨超紫外光谱仪测量的极紫外（EUV）波长范围内的杂质光谱。通过监测 48.59 Å 处 B V 线的二阶，研究了硼化后等离子体中硼含量的变化。研究发现，使用 10 g 碳硼烷（C2B10H12）进行硼化后，硼在 EAST 器件中的持续时间约为放电持续时间的 2000 s（150 次）。然后定量研究了不同壁条件（无涂层金属壁和硼涂层壁）对金属杂质含量的影响。硼化后，钨（CW）和钼（CMo）的浓度下降了 85%，例如分别从 2.0 × 10-4 降至 4.1 × 10-5 和从 4.6 × 10-5 降至 6.3 × 10-6。而铜（CCu）和铁（CFe）的浓度则分别下降了约 50% 和 65%，例如分别从 4.3 × 10-5 降至 2.1 × 10-5 和从 2.0 × 10-4 降至 6.9 × 10-5。通过比较硼化前后 W26+ - W32+ 和 W43+ 钨离子的线发射剖面，发现强度总体上有所降低，但剖面形状没有明显变化，这表明硼化后金属杂质源减少了，而不是核心等离子体中的杂质传输发生了重大改变。

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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.