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arXiv 1806.03093physics.plasm-ph
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双流体MHD的电阻漂移波不稳定性

Two-fluid MHD Regime of Resistive Drift-Wave Instability

Shangchuan Yang, Ping Zhu, Jinlin Xie, Wandong Liu

摘要:

漂移不稳定性有助于边缘湍流和纬向流的形成,从而导致托卡马克中的异常输运。实验经常发现微尺度湍流与大尺度磁流体动力学(MHD)过程强烈耦合,而一直缺乏一个通用的框架,可以涵盖这两个制度,特别是,他们的耦合。本文采用全双流体MHD模型研究了线性电阻漂移波不稳定性,并在NIMROD程序中进行了数值模拟。分析和数值分析揭示了宏观尺度的全球漂移波本征模耦合MHD动力学和说明一个非单调的色散关系,相对于垂直和平行波数。NIMROD结果还揭示了径向模式结构中的边缘局部化行为,随着方位角模式数的增加,这意味着由于密度分布的不均匀性,2流体效应的依赖性。边缘局域化引入了有效垂直波数对垂直模数的非平凡依赖性,这可以解释全局色散关系与传统局部理论的局部近似之间的定量差异。

英文摘要:

Drift instabilities contribute to the formation of edge turbulence and zonal flows, and thus the anomalous transport in tokamaks. Experiments often found micro-scale tur- bulence strongly coupled with large-scale magnetohydrodynamic (MHD) processes, whereas a general framework has been lacking that can cover both regimes, in partic- ular, their coupling. In this paper, the linear resistive drift wave instability (DWI) is investigated using a full 2-fluid MHD model, as well as its numerical implementation in NIMROD code. Both analytical and numerical analyses reveal a macro-scale global drift wave eigenmode coupled with MHD dynamics and illustrate a non-monotonic dispersion relation with respect to both perpendicular and parallel wavenumbers. NIMROD results also reveal an edge-localized behavior in the radial mode structure as the azimuthal mode number increases, implying the dependence of the 2-fluid ef- fects due to the inhomogeneous density profile. The edge-localization introduces a non-trivial dependence of the effective perpendicular wavenumber to the perpendicular mode number, which may explain the quantitative difference between the global dispersion relation and its local approximation from the conventional local theory.

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