Saturation and nonlinear electromagnetic stabilization of ITG turbulence
Saturation and nonlinear electromagnetic stabilization of ITG turbulence
复制标题
ITG 湍流的饱和和非线性电磁稳定
DOI：
10.1063/1.5096252
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发表时间：
2019
影响因子：
2.2
通讯作者：
H. Doerk
中科院分区：
文献类型：
--
作者：
G. G. Whelan;M. Pueschel;P. Terry;J. Citrin;I. McKinney;W. Guttenfelder;H. Doerk
本文研究了离子温度梯度驱动的湍流中的能量传递及其在模拟输运中的作用。分析表明，与零β情况一样，有限β ITG湍流通过非线性能量转移到由纬向流介导的稳定模式而饱和。电磁效应可靠地增加了稳定模式的振幅，但影响热通量只有在0.5%的水平。随着β的增加，最重要的变化是不稳定模式、稳定模式和带状流的三重态相互作用的相关时间增加，从而提供了提高的非线性能量传递效率，这使得不稳定性在较低的振幅下饱和。热通量与非线性电磁稳定性有关，其中通量随β下降的现象比准线性输运模型预测的下降更明显。准线性模型中包含的三重态相关时间捕获了本文研究的配置的大部分非线性增强稳定性。针对有限的归一化等离子体压力β，研究了离子温度梯度驱动（ITG）湍流中的能量传递及其在建模输运中的作用。许多测试案例和实验放电。分析表明，与零β情况一样，有限β ITG湍流通过非线性能量转移到由纬向流介导的稳定模式而饱和。电磁效应可靠地增加了稳定模式的振幅，但影响热通量只有在0.5%的水平。随着β的增加，最重要的变化是不稳定模式、稳定模式和带状流的三重态相互作用的相关时间增加，从而提供了提高的非线性能量传递效率，这使得不稳定性在较低的振幅下饱和。热通量与非线性电磁稳定性有关，其中通量随β下降的现象比准线性输运模型预测的下降更明显。三重态相关时间的列入…
Energy transfer in ion-temperature-gradient-driven (ITG) turbulence and its role in modeling transport are examined for finite normalized plasma pressure β for a number of test cases and experimental discharges. The analysis shows that like the zero-β case, finite-β ITG turbulence saturates by nonlinear energy transfer to stable modes mediated by a zonal flow. Electromagnetic effects reliably increase stable mode amplitudes but affect heat fluxes only at the ≈5% level. The most important change with increased β is an increase in the correlation time of the triplet interaction of the unstable mode, stable mode, and zonal flow, thus providing a heightened nonlinear energy transfer efficiency, which allows the instability to saturate at lower amplitude. The heat flux is examined in connection with nonlinear electromagnetic stabilization, the phenomenon where the flux falloff with β is more pronounced than the falloff predicted by quasilinear transport models. The inclusion of the triplet correlation time in the quasilinear model captures most of the nonlinearly enhanced stabilization for the configurations studied here.Energy transfer in ion-temperature-gradient-driven (ITG) turbulence and its role in modeling transport are examined for finite normalized plasma pressure β for a number of test cases and experimental discharges. The analysis shows that like the zero-β case, finite-β ITG turbulence saturates by nonlinear energy transfer to stable modes mediated by a zonal flow. Electromagnetic effects reliably increase stable mode amplitudes but affect heat fluxes only at the ≈5% level. The most important change with increased β is an increase in the correlation time of the triplet interaction of the unstable mode, stable mode, and zonal flow, thus providing a heightened nonlinear energy transfer efficiency, which allows the instability to saturate at lower amplitude. The heat flux is examined in connection with nonlinear electromagnetic stabilization, the phenomenon where the flux falloff with β is more pronounced than the falloff predicted by quasilinear transport models. The inclusion of the triplet correlation time in ...