Stabilization and prevention of the 2/1 neoclassical tearing mode for improved performance in DIII-D
Stabilization and prevention of the 2/1 neoclassical tearing mode for improved performance in DIII-D
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DOI：
10.1088/0029-5515/47/5/001
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发表时间：
2007-05
期刊：
影响因子：
3.3
通讯作者：
R. Prater;R. L. La Haye;T. Luce;C. Petty;E. Strait;J. Ferron;D. Humphreys;A. Isayama;J. Lohr-J
中科院分区：
文献类型：
--
作者：
R. Prater;R. L. La Haye;T. Luce;C. Petty;E. Strait;J. Ferron;D. Humphreys;A. Isayama;J. Lohr-J
已经观察到m=2/n=1的新古典主义撕裂模强烈地降低了禁闭，并且如果允许生长到大尺寸，常常会导致高β放电的中断。通过在岛状位置应用高度局域化的电子回旋电流驱动(ECCD)来稳定生长的NTM，导致在更高的等离子体压力下运行，直到无壁扭结极限。在NTM被ECCD稳定后，使用来自实时平衡重建的信息来维持当前驱动器的正确位置，其中包括来自运动斯塔克效应诊断的测量。同样的工艺可以交替使用，以防止模式不断增长，从而在β高于4%的高性能混合放电中实现压力极限下的性能。用修正的卢瑟福方程模拟表明，所需的功率与防止2/1 NTM的实验阈值非常一致。
The m = 2/n = 1 neoclassical tearing mode (NTM) has been observed to strongly degrade confinement and frequently lead to a disruption in high β discharges in DIII-D if allowed to grow to a large size. Stabilization of grown NTMs by the application of a highly localized electron cyclotron current drive (ECCD) at the island location has led to operation at an increased plasma pressure, up to the no-wall kink limit. After the NTM is stabilized by the ECCD, the correct location for the current drive is maintained using information from real-time equilibrium reconstructions which include measurements from the motional Stark effect diagnostic. This same process is used alternatively to prevent the mode from ever growing, leading to performance at the pressure limit in high performance hybrid discharges with β above 4%. Modelling using the modified Rutherford equation shows that the required power is in close agreement with the experimental threshold for the prevention of the 2/1 NTM.