Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712, USA.
Phys Rev Lett. 2014 Mar 7;112(9):095002. doi: 10.1103/PhysRevLett.112.095002. Epub 2014 Mar 4.
From numerical solutions of a gyrokinetic model for ion temperature gradient turbulence it is shown that nonlinear coupling is dominated by three-wave interactions that include spectral components of the zonal flow and damped subdominant modes. Zonal flows dissipate very little energy injected by the instability, but facilitate its transfer from the unstable mode to dissipative subdominant modes, in part due to the small frequency sum of such triplets. Although energy is transferred to higher wave numbers, consistent with shearing, a large fraction is transferred to damped subdominant modes within the instability range. This is a new aspect of regulation of turbulence by zonal flows.
从离子温度梯度湍流的回旋动理学模型的数值解可以看出，非线性耦合主要由包括主流和阻尼次主导模的谱分量的三波相互作用所控制。主流几乎不耗散不稳定性注入的能量，但有利于将其从不稳定模式传递到耗散的次主导模式，部分原因是这种三重态的小频率和。尽管能量被转移到更高的波数，符合剪切，但大部分能量在不稳定性范围内被转移到阻尼的次主导模式。这是主流对湍流的调节的一个新方面。
