Simulation of ECCD optimization for neoclassical tearing mode suppression in KSTAR
Simulation of ECCD optimization for neoclassical tearing mode suppression in KSTAR
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DOI：
10.1016/j.fusengdes.2007.12.016
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发表时间：
2008-04
影响因子：
1.7
通讯作者：
Y. S. Park;Y. Hwang
中科院分区：
文献类型：
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作者：
Y. S. Park;Y. Hwang
在KSTAR的高约束放电中，由螺旋扰动的局部自举电流引起的新经典撕裂模（NTMs）的出现将是不可避免的，并显著降低等离子体约束。为了抑制KSTAR中的NTM，将实施高功率、长脉冲170 GHz电子回旋电流驱动（ECCD）系统来补偿缺失的自举电流。使用TORAY-GA的射线跟踪分析进行EC波发射的位置优化和预测的电流驱动器的性能。从优化模拟中发现，发射位置应在中板下方− 30 cm处，以最大化轮廓品质因数，从而实现更有效的NTM抑制。在1 MWECCD单元功率的最佳剖面情况下，q=3/2和2/1谐振面上的剖面优值分别为13.5MA/rho ~ 2和14.0MA/rho ~ 2。110 GHz ECCD作为具有更高电流驱动效率的替代方法，显示出比170 GHz ECCD更大的驱动电流，但由于其更宽的轮廓，轮廓品质因数没有太大改善。
In high confinement discharges of KSTAR, onset of neoclassical tearing modes (NTMs) by helically perturbed local bootstrap current will be inevitable and significantly degrade plasma confinement. For the suppression of NTMs in KSTAR, high power, long pulse 170GHz electron cyclotron current drive (ECCD) system will be implemented to compensate the missing bootstrap current. A ray tracing analysis using TORAY-GA is performed to optimize the location of EC wave launch and to predict the performance of the current drive. From the optimization simulation, it is found that the launch location should be at −30cm below the midplane to maximize the profile figure of merit which enables more efficient NTM suppression in itself. The profile figure of merits on q=3/2 and 2/1 resonant surfaces are estimated to be about 13.5MA/rho2and 14.0MA/rho2, respectively, in the case of optimal profiles with 1MW ECCD unit power. The 110GHz ECCD as an alternative method with higher current drive efficiency shows larger driven currents than 170GHz ECCD, but the profile figure of merit is not much improved due to its broader profile.