Turbulence simulations of blob formation and radial propagation in toroidally magnetized plasmas
Turbulence simulations of blob formation and radial propagation in toroidally magnetized plasmas
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DOI：
10.1088/0031-8949/2006/t122/013
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发表时间：
2006-02
期刊：
影响因子：
2.9
通讯作者：
Odd Erik Garcia;V. Naulin;A. Nielsen;J. J. Rasmussen-J.
中科院分区：
文献类型：
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作者：
Odd Erik Garcia;V. Naulin;A. Nielsen;J. J. Rasmussen-J.
二维数值流体湍流模拟证明的形成和径向传播的斑点结构的环形磁化等离子体的详细介绍和分析。该模型的一个显着特点是一个线性不稳定的边缘等离子体区域与局部源的粒子和热量，这是耦合到一个刮削层与线性阻尼项对应的所有因变量的运输沿着开放的磁场线。团状结构的形成与全球湍流水平的爆发引起的轮廓变化有关，这是由于等离子体层的自持差分旋转的动态调节。径向传播的斑点结构如下从垂直的电荷极化由于磁导向中心漂移的环形磁化等离子体。粒子密度，径向电漂移和径向湍流粒子通量的统计分析揭示了不对称的条件波形与一个陡峭的前和尾流和积极倾斜和平坦的概率分布，与最近的实验研究。粗粒化和光谱分析进一步表明颗粒密度波动存在长程相关性。最后，粒子通量的条件统计证明了湍流等离子体传输的不稳定性和由于在全球湍流水平的爆发的斑点结构的准周期外观。
Two-dimensional numerical fluid turbulence simulations demonstrating the formation and radial propagation of blob structures in toroidally magnetized plasmas are presented and analysed in detail. A salient feature of the model is a linearly unstable edge plasma region with localized sources of particles and heat, which is coupled to a scrape-off layer with linear damping terms for all dependent variables corresponding to transport along open magnetic field lines. The formation of blob structures is related to profile variations caused by bursting in the global turbulence level, which is due to a dynamical regulation by self-sustained differential rotation of the plasma layer. Radial propagation of the blob structures follows from a vertical charge polarization due to magnetic guiding centre drifts in the toroidally magnetized plasma. Statistical analysis of the particle density, radial electric drift and the radial turbulent particle flux reveals asymmetric conditional waveforms with a steep front and a trailing wake and positively skewed and flattened probability distributions, in agreement with recent experimental investigations. Coarse graining and spectral analysis further indicate the presence of long-range correlations in the particle density fluctuations. Finally, conditional statistics of the particle flux demonstrates the intermittency of the turbulent plasma transport and the quasi-periodic apparency of blob structures due to bursting in the global turbulence level.