1. Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China 2. Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230031, China 3. General Atomics, P.O. Box 85608, San Diego, California 92186, USA
Abstract:Divertor impurity injection on Tokamak is the most important means to achieve divertor impurity screening efficiency. In this paper, a fast-response extreme-ultraviolet (EUV) spectrometer is used to monitor the Ar emission lines during the EAST(Experimental Advanced Superconducting Tokamak)divertor Ar injection experiment. Based on the NIST(National Institute of Standards and Technology)atomic spectrum database, the emission lines from different ionized Ar ions in 2~50 nm wavelength range, e.g. Ar Ⅳ, Ar Ⅳ-Ⅺ and Ar ⅩⅣ-ⅩⅥ, are being identified. Ar ⅩⅥ 35.39 nm and Ar Ⅳ 44.22 nm with the ionization energy of 918.4 and 59.6 eV respectively are being monitored during the experiment with Ar puffing to observe the behavior of Ar impurities in different regions in plasmasimultaneously. The preliminary analysis on divertor impurity screening efficiency is carried outwith the time evolution of intensities of two Ar emission lines. The results of experiment puffing from the same gas puffing inlet (e. g. from lower outer target inlet) and withdifferent plasma configurations (e. g. lower single null, upper single null) show that the screening effect on the impurity injected from the divertor region is better thanfrom the main plasma region; the screening effect of lower divertor and particle pumping by internal cryopump installed in lower divertor is stronger than upper divertor.
[1] Pitcher C S, Stangeby P C. Plasma Physics and Controlled Fusion, 1997, 39(6): 779. [2] McCracken G M, Granetz R S, Lipschultz B, et al. Journal of Nuclear Materials, 1997, 241: 777. [3] McCracken G M, Lipschultz B, LaBombard B, et al. Physics of Plasmas, 1997, 4(5): 1681. [4] Li J, Guo H Y, Wan B N, et al. Nature Physics, 2013, 9(12): 817. [5] Zhou Z, Yao D, Cao L. Journal of Fusion Energy, 2015, 34(1): 93. [6] HUANG Jian-feng, WU Zhen-wei, WANG Ling, et al(黄剑锋, 吴振伟, 王 玲, 等). Vacuum(真空), 2014, 3: 001. [7] WANG Wen-zhang, LUO Guang-nan, YANG Zhong-shi, et al(王文章, 罗广南, 杨钟时, 等). Nuclear Fusion and Plasma Physics(核聚变与等离子体物理), 2016, 36(1): 42. [8] ZHANG Wei, SHI Yue-jiang, WANG Qiu-ping, et al(张 伟, 石跃江, 王秋平, 等). Nuclear Science and Techniques(核技术), 2011(08): 613. [9] Kramida A, Ralchenko Yu, Reader J,et al. NIST Atomic Spectra Database (version 5.2), National Institute of Standards and Technology, Gaithersburg, MD, 2014. [10] Katai R, Morita S, Goto M. Journal of Quantitative Spectroscopy & Radiative Transfer, 2007, 107(1): 120. [11] Duan Y M, Hu L Q, Chen K Y, et al. Journal of Nuclear Materials, 2013, 438: S338.