Three-dimensional simulations of edge impurity flow obtained by the vacuum ultraviolet emission diagnostics in the Large Helical Device with EMC3-EIRENE
Three-dimensional simulations of edge impurity flow obtained by the vacuum ultraviolet emission diagnostics in the Large Helical Device with EMC3-EIRENE
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DOI：
10.1088/1741-4326/aace69
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发表时间：
2018-07
期刊：
影响因子：
3.3
通讯作者：
S. Dai;T. Oishi;G. Kawamura;M. Kobayashi;S. Morita;Y. Feng;D.Z. Wang
中科院分区：
文献类型：
--
作者：
S. Dai;T. Oishi;G. Kawamura;M. Kobayashi;S. Morita;Y. Feng;D.Z. Wang
利用三维边缘输运程序EMC 3-EIRENE研究了大螺旋装置（LHD）随机层中的边缘碳杂质流动。EMC 3-EIRENE模拟的C3+杂质流场分布与CIV（1548.20 × 2 μ m）多普勒频移谱的真空紫外（VUV）测量结果吻合较好。在随机层的顶部和底部边缘处，相同的水平向外的C3+杂质流由3D磁场结构和平行的C3+杂质流速度决定。观察到的上下不对称结构的C3+杂质流的顶部和底部的边缘是由垂直位移的真空紫外光谱仪从中平面。磁轴位置从3.6到3.9 m的水平向外移位导致在顶部和底部边缘处的C3+杂质流动方向的改变。对于高的上游等离子体密度，C3+杂质流的输运主要由背景平行等离子体流决定，而对于低的上游等离子体密度，由于热力主导区域的膨胀，获得反向C3+杂质流。增强的热力导致杂质屏蔽效应的抑制。
Edge carbon impurity flow in the stochastic layer of the Large Helical Device (LHD) has been investigated with the three-dimensional (3D) edge transport code EMC3-EIRENE. The simulated synthetic C3+ impurity flow profile from EMC3-EIRENE shows a reasonable agreement with the vacuum ultraviolet (VUV) measurements according to the CIV (1548.20 × 2 Å) Doppler- shift spectrum. The same horizontally outward C3+ impurity flows at the top and bottom edges of the stochastic layer are determined by the 3D magnetic field structure and the parallel C3+ impurity flow velocity. The observed up-down asymmetric structure of the C3+ impurity flow at the top and bottom edges is caused by the vertical displacement of the VUV spectrometer from the midplane. The horizontally outward shift of the magnetic axis position from 3.6 to 3.9 m leads to a change of the C3+ impurity flow direction at the top and bottom edges. For a high upstream plasma density, the transport of the C3+ impurity flow is mainly determined by the background parallel plasma flow, while a reversed C3+ impurity flow is obtained for a low upstream plasma density, due to the expansion of the thermal force dominant regions. The enhanced thermal force leads to a suppression of the impurity screening effect.