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arXiv 1302.0611physics.plasm-ph
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共振磁扰动对带状模、漂移波Turbulence和L-H转变阈值的影响

Impact of Resonant Magnetic Perturbations on Zonal Modes, Drift-Wave Turbulence and the L-H Transition Threshold

M. Leconte, P. H. Diamond, Y. Xu

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30 pages, IAEA-based article
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摘要：

本文在电阻漂移波湍流的框架下研究了共振磁扰动对湍流、流动和约束的影响。这项工作的动机，部分，在国际原子能机构2010年会议上报告的实验[Y。Xu { \it等人}，Nucl. Fusion \textbf{51}，062030]，其显示在RMP应用期间长程相关性降低。本文导出并应用了一个耦合漂移波带模系统的零维捕食模型[M。Leconte和P.H. Diamond，Phys. Plasmas \textbf{19}，055903]中的方法来计算平均量的演化。该模型以密度梯度驱动和RMP振幅作为控制参数，预测了在RMP存在下的一种新型输运分岔。该模型允许描述完整的L-H转变与RMP的演变，包括平均剪切流的演变。主要成果如下：i）L-I和I-H功率阈值\emph{both}随着RMP幅度$|\bx|$而增加，L-I阈值的相对增加按$ΔP_{\rm LI} \propto |\bx|^2 ν_*^{-2} \gyro^{-2}$缩放，其中$ν_*$是边缘碰撞性，而$\gyro$是声音回转半径。ii）预测RMP以\emph{decrease}前向转变与后向转变之间的滞后。iii）考虑到平均密度演变，与没有RMP的参考情况相比，由粒子源维持的密度分布具有增加的湍流扩散，这为\emph{density pump-out}效应提供了一种可能的解释。

英文摘要：

We study the effects of Resonant Magnetic Perturbations (RMPs) on turbulence, flows and confinement in the framework of resistive drift-wave turbulence. This work was motivated, in parts, by experiments reported at the IAEA 2010 conference [Y. Xu {\it et al}, Nucl. Fusion \textbf{51}, 062030] which showed a decrease of long-range correlations during the application of RMPs. We derive and apply a zero-dimensional predator-prey model coupling the Drift-Wave Zonal Mode system [M. Leconte and P.H. Diamond, Phys. Plasmas \textbf{19}, 055903] to the evolution of mean quantities. This model has both density gradient drive and RMP amplitude as control parameters and predicts a novel type of transport bifurcation in the presence of RMPs. This model allows a description of the full L-H transition evolution with RMPs, including the mean sheared flow evolution. The key results are: i) The L-I and I-H power thresholds \emph{both} increase with RMP amplitude $|\bx|$, the relative increase of the L-I threshold scales as $ΔP_{\rm LI} \propto |\bx|^2 ν_*^{-2} \gyro^{-2}$, where $ν_*$ is edge collisionality and $\gyro$ is the sound gyroradius. ii) RMPs are predicted to \emph{decrease} the hysteresis between the forward and back-transition. iii) Taking into account the mean density evolution, the density profile - sustained by the particle source - has an increased turbulent diffusion compared with the reference case without RMPs which provides one possible explanation for the \emph{density pump-out} effect.

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