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arXiv 2303.10596physics.plasm-ph
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ASDEX升级底座上的turbulence结构复杂

Complex structure of turbulence across the ASDEX Upgrade pedestal

L. A. Leppin, T. Görler, M. Cavedon, M. G. Dunne, E. Wolfrum, F. Jenko, the ASDEX Upgrade Team

摘要:

H模湍流输运机制的理论研究是一个巨大的科学和数值挑战。在这项研究中,我们解决了这一挑战的全球性,非线性gyrokinetic模拟的一个完整的基座的分界线,支持gyrokinetic不稳定性的详细表征,从里面的基座顶部基座中心和脚。我们目前ASDEX升级基座模拟使用的gyrokinetic,欧拉,delta-f代码基因(genecode.org),使稳定的全球模拟实验等离子体β值的升级版本。湍流传输被发现表现出多通道,多尺度字符整个基座与占主导地位的贡献过渡从离子尺度的陷阱电子模式(TEM)/微撕裂模式(MTM)在基座顶部的电子尺度电子温度梯度模式(ETG)在陡峭的梯度区域。因此,湍流电子热通量的变化从离子到电子尺度和离子热通量减少到几乎新古典的值在基座中心。ExB剪切被发现在所有通道(电子,离子,静电,电磁)和磁剪切和压力梯度的相互作用强烈降低热通量水平被发现局部稳定离子尺度不稳定性。

英文摘要:

The theoretical investigation of relevant turbulent transport mechanisms in H-mode pedestals is a great scientific and numerical challenge. In this study, we address this challenge by global, nonlinear gyrokinetic simulations of a full pedestal up to the separatrix, supported by a detailed characterisation of gyrokinetic instabilities from just inside the pedestal top to pedestal centre and foot. We present ASDEX Upgrade pedestal simulations using an upgraded version of the gyrokinetic, Eulerian, delta-f code GENE (genecode.org) that enables stable global simulations at experimental plasma beta values. The turbulent transport is found to exhibit a multi-channel, multi-scale character throughout the pedestal with the dominant contribution transitioning from ion scale Trapped Electron Modes (TEMs)/Micro Tearing Modes (MTMs) at the pedestal top to electron scale Electron Temperature Gradient modes (ETG) in the steep gradient region. Consequently, the turbulent electron heat flux changes from ion to electron scales and the ion heat flux reduces to almost neoclassic values in the pedestal centre. ExB shear is found to strongly reduce heat flux levels in all channels (electron, ion, electrostatic, electromagnetic) and the interplay of magnetic shear and pressure gradient is found to locally stabilise ion scale instabilities.

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