Effect of lithium coating on long pulse high performance plasma discharges in EAST

作者：Wei Xu, Jiansheng Hu, Zhen Sun, R. Maingi, L. Zhang, Y. W. Yu, C.L. Li, Guizhong Zuo, Y. Z. Qian, M. Huang, Xiancai Meng, W. Gao, Yanmin Duan, Y J Chen, Kehuan Wang, Xin Lin, Xiang Gao · 发表于：Plasma Physics and Controlled Fusion · 年份：2020 · DOI：10.1088/1361-6587/ab9b3a · 被引用次数：23 · 研究领域：Magnetic confinement fusion research、Fusion materials and technologies、Plasma Diagnostics and Applications

Abstract Control of impurities, fuel recycling and hydrogen content by lithium evaporative coatings and real-time lithium powder injection (LPI) in EAST are studied for high performance H-mode discharges of up to ∼100 s. The results show that the lithium evaporative coatings significantly reduced both the low-Z impurity carbon and high-Z impurity tungsten as well as molybdenum concentration in the plasmas, and the impurities concentration significantly reduced with the accumulated lithium coatings and maintained well afterwards. Specifically the high-Z tungsten core impurity concentration was maintained between 3 ppm–15 ppm during the 101 s H-mode discharge, which is acceptable for the long pulse operation. In addition, real-time wall conditioning via LPI successfully reduced the core high-Z metal impurities by 50% during ∼35 s long pulse H-mode discharge, exhibiting strong compatibility between real-time LPI with long pulse discharges. In addition, evaporative lithium coatings demonstrated fuel recycling control, with fuel recycling obviously reducing with lithium coatings and maintaining well afterwards. Also, the lithium evaporative coatings reduced the hydrogen minority species content, represented by the density ratio H/(H + D), from ∼50% down to ∼5% with accumulated lithium coatings; low hydrogen fraction improved the ICRF minority heating efficiency. Finally the real-time LPI reduced the recycling coefficient R global from 0.95 to 0.82. With these wall conditionings he...