极紫外波段A r光谱分析在EAST偏滤器杂质屏蔽效应研究中的应用

摘要

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 Ⅹ Ⅳ‐Ⅹ Ⅵ ,are being identified .Ar Ⅹ Ⅵ 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 .%在托卡马克偏滤器区域充入杂质气体是检验偏滤器杂质屏蔽效应的重要手段。利用快速极紫外EUV光谱仪对EAST托克马克装置上开展的偏滤器Ar杂质注入实验进行观测。结合NIST 原子光谱数据库对2～50 nm范围内不同电离态A r的线光谱进行了谱线识别，识别出A r Ⅳ，A r Ⅸ‐Ⅺ，A r ⅩⅣ‐ⅩⅥ等若干个电离态的谱线。为了同时观测等离子体不同区域的Ar杂质行为，在杂质注入实验时重点监测Ar ⅩⅥ35.39 nm （A r ⅩⅥ电离能918.4 eV ，主要分布在等离子体芯部）和A r Ⅳ44.22 nm （A r Ⅳ电离能9.6 eV ，主要分布在等离子体边界）这两条谱线。利用该两条谱线强度随时间演化的结果初步分析了偏滤器杂质屏蔽效应。在同一充气口不同等离子体位形下的实验结果表明偏滤器对于从偏滤器区域注入Ar杂质的屏蔽效果优于从主等离子体区域注入，并且下偏滤器及内冷泵的综合粒子排除能力优于上偏滤器。