Observation of Impurity Accumulation After Hydrogen Multi-Pellet Injection in Large Helical Device  

作　　者：董春凤 Shigeru MORITA Motoshi GOTO 王二辉 Gen MOTOJIAMA Izumi MURAKAMI Ryuichi SAKAMOTO Norimasa YAMAMOTO 

机构地区：[1]National Institute for Fusion Science [2]Department of Fusion Science,Graduate University for Advanced Studies [3]Center of Applied Superconductivity & Sustainable Energy Research,Chubu University

出　　处：《Plasma Science and Technology》2013年第3期230-234,共5页等离子体科学和技术（英文版）

基　　金：support by LHD project (NIFS11ULPP010);partly supported by the JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics

摘　　要：Impurity accumulation is studied for neutral beam-heated discharges after hydrogen multi-pellet injection in Large Helical Device （LHD）. Iron density profiles are derived from radial profiles of EUV line emissions of FeXV-XXIV with the help of the collisional-radiative model. A peaked density profile of Fe2a＋ is simulated by using one-dimensional impurity transport code. The result indicates a large inward velocity of -6 m/s at the impurity accumulation phase. However, the discharge is not entirely affected by the impurity accumulation, since the concentration of iron impurity, estimated to be 3.3x10-5 to the electron density, is considerably small. On the other hand, a flat profile is observed for the carbon density of C6＋, which is derived from the Zeff profile, indicating a small inward velocity of -1 m/s. These results suggest atomic number dependence in the impurity accumulation of LHD, which is similar to the tokamak result.Impurity accumulation is studied for neutral beam-heated discharges after hydrogen multi-pellet injection in Large Helical Device （LHD）. Iron density profiles are derived from radial profiles of EUV line emissions of FeXV-XXIV with the help of the collisional-radiative model. A peaked density profile of Fe2a＋ is simulated by using one-dimensional impurity transport code. The result indicates a large inward velocity of -6 m/s at the impurity accumulation phase. However, the discharge is not entirely affected by the impurity accumulation, since the concentration of iron impurity, estimated to be 3.3x10-5 to the electron density, is considerably small. On the other hand, a flat profile is observed for the carbon density of C6＋, which is derived from the Zeff profile, indicating a small inward velocity of -1 m/s. These results suggest atomic number dependence in the impurity accumulation of LHD, which is similar to the tokamak result.

关 键 词：impurity accumulation EUV spectrometer inward velocity 

分 类 号：TL629.1[核科学技术—核技术及应用] TQ136.11[化学工程—无机化工]