Scaling of up-down asymmetric turbulent momentum flux with poloidal shaping mode number in tokamaks
Scaling of up-down asymmetric turbulent momentum flux with poloidal shaping mode number in tokamaks
复制标题
托卡马克中上下不对称湍流动量通量与极向整形模数的缩放
DOI：
10.1088/0741-3335/58/5/055016
复制
发表时间：
2016
影响因子：
2.2
通讯作者：
Ball J
中科院分区：
文献类型：
--
作者：
Ball J
打破托卡马克的上下对称性，消除了限制本征动量输运的约束，从而使环向旋转变得很小。利用回转动力学理论，研究了不同上下非对称流面形状对动量湍流输运的影响。这是通过在大通量表面整形模数下微扰展开陀螺动力学方程来实现的。结果表明，缺乏镜面对称性(必然是上下不对称)的整形所产生的动量通量与整形模数成幂函数关系。然而，镜面对称磁通面整形(即使是上下不对称)产生的动量通量随着整形模数的增加呈指数衰减。这些标度与非线性局部陀螺动力学模拟是一致的，并表明低模数整形效应(如伸长、三角性)对于产生旋转是最佳的。此外，它还表明，打破磁通面的镜面对称性可能会产生明显更多的环向旋转。
Breaking the up–down symmetry of tokamaks removes a constraint limiting intrinsic momentum transport, and hence toroidal rotation, to be small. Using gyrokinetic theory, we study the effect of different up–down asymmetric flux surface shapes on the turbulent transport of momentum. This is done by perturbatively expanding the gyrokinetic equation in large flux surface shaping mode number. It is found that the momentum flux generated by shaping that lacks mirror symmetry (which is necessarily up–down asymmetric) has a power law scaling with the shaping mode number. However, the momentum flux generated by mirror symmetric flux surface shaping (even if it is up–down asymmetric) decays exponentially with large shaping mode number. These scalings are consistent with nonlinear local gyrokinetic simulations and indicate that low mode number shaping effects (eg elongation, triangularity) are optimal for creating rotation. Additionally it suggests that breaking the mirror symmetry of flux surfaces may generate significantly more toroidal rotation.