The effect of the impurity seeding into the closed divertor on plasma detachment in the HL-2A tokamak
The effect of the impurity seeding into the closed divertor on plasma detachment in the HL-2A tokamak
复制标题
HL-2A托卡马克封闭偏滤器中注入杂质对等离子体脱离的影响
DOI：
10.1088/1741-4326/acaf2f
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发表时间：
2023
期刊：
影响因子：
3.3
通讯作者：
Min Xu
中科院分区：
文献类型：
--
作者：
Jinming Gao;Cai Laizhong;Chengzhi Cao;Huicong Ma;Rui Ke;Na Wu;Yi Hu;Xiaoyan Gao;Chenghe Cui;Zhihui Huang;Lin Nie;Liang Liu;Zengchen Yang;Xin Yu;Yonggao Li;Min Jiang;Guanqun Xue;Wulyu Zhong;Ting Wu;Zhongbing Shi;Longwen Yan;Xiao Quan Ji;Min Xu
抽象。HL-2A中非常封闭的偏滤器几何结构使人们对分离偏滤器物理学的理解取得了新的进展。将非本征杂质注入偏滤器外室，观察到偏滤器中性压力增加和偏滤器体积能量损失增加。同时，主室中性压力略有下降，偏滤器与主室之间的中性压力大幅增加。这导致偏滤器分离，上游等离子体线平均电子密度较低（~0.5n_GW）。在H模中，芯约束略有退化，表现为等离子体储能和基座压强的降低以及边缘局域模（ELM）频率的增加，但H模仍能保持较好的稳定性（H98>1）。在剥离过程中，基座密度波动增加，这意味着增强的基座输运可能是负责的退化。在偏滤器分离阶段，偏滤器中的杂质得到了很好的控制，在X点区域附近没有强辐射，主等离子体密度没有增加，而是略有下降，这可能是非常封闭的偏滤器几何结构的好处。实验结果表明，非常封闭的偏滤器几何结构具有体积能量损失、气体泵送和偏滤器内杂质控制等优点，而对等离子体约束没有明显影响，从而为偏滤器分离提供了更宽的操作窗口。
Abstract. Recent progress towards an increased understanding of the detached divertor physics has been made with the very closed divertor geometry in HL-2A. Non-intrinsic impurities were injected into the outer divertor chamber, and increased divertor neutral pressure and enhanced volumetric energy loss in the divertor were observed. Meanwhile the neutral pressure in the main chamber decreased slightly, and neutral compression between divertor and main chamber increased largely. This led to divertor detachment with a low level of upstream plasma line-averaged electron density (~0.5n_GW). In H-mode, a little degradation of the core confinement, characterized by decrease of plasma stored energy and pedestal pressure, and increase of edge localized mode (ELM) frequency, was observed, but the H-mode was still sustained well with H98>1. The pedestal density fluctuation was increased during detachment, implying that the enhanced pedestal transport might be responsible for the degradation. During divertor detachment phase, the impurities were well controlled in the divertor without strong radiation near X-point region, and the main plasma density did not increase but decreases slightly, this could be beneficial from the very closed divertor geometry. The experimental results suggest that, the very closed divertor geometry has the advantages of volumetric energy loss, gas pumping and impurity control in the divertor without significant effects on the plasma confinement, thus gives a wider operation window for the divertor detachment.