Nonlocal properties of gyrokinetic turbulence and the role of E×B flow shear
Nonlocal properties of gyrokinetic turbulence and the role of E×B flow shear
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DOI：
10.1063/1.2750647
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发表时间：
2007-07
影响因子：
2.2
通讯作者：
Weixing Wang;T. Hahm;W. Lee;G. Rewoldt;J. Manickam;W. Tang
中科院分区：
文献类型：
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作者：
Weixing Wang;T. Hahm;W. Lee;G. Rewoldt;J. Manickam;W. Tang
利用具有真实参数的整体回旋动力学模拟研究了成形托卡马克等离子体中与湍流输运相关的非局域物理。本文研究了湍流通过以平衡E×B剪切层为特征的输运障碍的传播。结果表明，E×B剪切层的剪切速率与实验值相当，它可以通过减小湍流扩散的范围和速度，显著地减小甚至阻断湍流扩散。该特征代表了传输屏障动力学的一个新方面。在这个过程中的关键量被确定为局部最大剪切速率，而不是径向电场的幅度。这些模拟研究还延伸到径向局部物理相对于饱和的离子温度梯度（ITG）不稳定性，并表明，非线性环形耦合是占主导地位的k-空间活动的ITG动力学，这导致能量转移到较长的波长阻尼模…
The nonlocal physics associated with turbulent transport is investigated using global gyrokinetic simulations with realistic parameters in shaped tokamak plasmas. This study focuses on the turbulence spreading through a transport barrier characterized by an equilibrium E×B shear layer. It is found that an E×B shear layer with an experimentally relevant level of the shearing rate can significantly reduce, and sometimes even block, turbulence spreading by reducing the spreading extent and speed. This feature represents a new aspect of transport barrier dynamics. The key quantity in this process is identified as the local maximum shearing rate ∣ωEmax∣, rather than the amplitude of the radial electric field. These simulation studies also extend to radially local physics with respect to the saturation of the ion temperature gradient (ITG) instability, and show that the nonlinear toroidal couplings are the dominant k-space activity in the ITG dynamics, which cause energy transfer to longer wavelength damped mod...