Prospects for Edge Current Density Determination Using Li beam on DIII-D
Prospects for Edge Current Density Determination Using Li beam on DIII-D
复制标题
DIII-D 上使用 Li 束测定边缘电流密度的前景
DOI：
10.1063/1.1319612
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
R. Snider
中科院分区：
文献类型：
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作者：
D. Thomas;A. Bozek;T. Carlstrom;D. Finkenthal;R. Jayakumar;Makowski;D. Nilson;T. Osborne;B. Rice;R. Snider
边缘电流剖面的具体尺寸和结构对许多先进托卡马克（AT）工作模式的MHD稳定性和极限性能有重要影响。对于可用于裁剪边缘剪切的自引导电流和外部驱动电流都是如此。没有直接的局部测量j(r)，最好的替代方法是确定极向场。在感兴趣的区域（{rho} = 0.9-1.1）很难测量解决稳定性和控制问题所需的精度（0.1-0.01{sup o}的磁螺距角和1-10 ms）。利用来自DIII-D LIBEAM的2S-2P锂共振线发射的塞曼偏振光谱，可以在这些研究感兴趣的区域精确测量各种场分量。由于相关原子能级的斯塔克混合可以忽略不计，这种确定j(r)的方法对通常在增强约束（h模）边缘中发现的大局部电场不敏感，从而避免了b的运动斯塔克效应（MSE）测量中常见的模糊性。利用这种技术的关键问题包括良好的光束质量，最佳的观察几何形状，以及合适的光学预滤波器来隔离极化发射线。将描述一种用于DIII-D AT程序的前瞻性诊断系统。
The specific size and structure of the edge current profile has important effects on the MHD stability and ultimate performance of many advanced tokamak (AT) operating modes. This is true for both bootstrap and externally driven currents that may be used to tailor the edge shear. Absent a direct local measurement of j(r), the best alternative is a determination of the poloidal field. Measurements of the precision (0.1-0.01{sup o} in magnetic pitch angle and 1-10 ms) necessary to address issues of stability and control and provide constraints for EFIT are difficult to do in the region of interest ({rho} = 0.9-1.1). Using Zeeman polarization spectroscopy of the 2S-2P lithium resonance line emission from the DIII-D LIBEAM, measurements of the various field components may be made to the necessary precision in exactly the region of interest to these studies. Because of the negligible Stark mixing of the relevant atomic levels, this method of determining j(r) is insensitive to the large local electric fields typically found in enhanced confinement (H-mode) edges, and thus avoids an ambiguity common to Motional Stark Effect (MSE) measurements of B. Key issues for utilizing this technique include good beam quality, an optimum viewing geometry, and a suitable optical pre-filter to isolate the polarized emission line. A prospective diagnostic system for the DIII-D AT program will be described.