Research of the interaction among different spatio-temporal scale turbulence and transport structure

不同时空尺度湍流与输运结构相互作用研究

基本信息

批准号：
15560721
负责人：
KISHIMOTO Yasuaki
金额：
$ 1.79万
依托单位：
Graduate School of Energy Science, Kyoto University (2004-2005)Japan Atomic Energy Agency (2003)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Based on the idea that various prominent structures in thermonuclear fusion plasmas like tokamak are established resulting from complex interaction among different spatio-temporal scale fluctuations, we studied fundamental principles of the interaction in turbulent transport process. The main results are as follows :1) Based on theory and simulation using gyro-fluid model, we clarified the dynamics of zonal flows and its structures produced by nonlinear interaction of micro-scale electron temperature gradient (ETG) turbulence. We investigated a "partition law" between turbulent fluctuation and zonal fluctuation and found that the partition is controlled by magnetic shear. Specifically, we found that in weak and/or reversed magnetic shear plasmas a large portion of fluctuation energy is efficiently transferred to zonal fluctuation in high pressure gradient regime and then anomalousness of turbulent transport disappears.2) We studied the effects of the micro-scale ETG-driven zonal flows … More observed in the above process (1) on macro-scale ion temperature gradient (ITG) turbulent transport and found that an intermittent behavior is exhibited in the heat diffusivity near the ITG critical gradient. This may results from complex interplay among ITG turbulence, ITG-driven zonal flow and also micro-scale ETG-driven zonal flow. The result indicates that treating key physical processes with different spatio-temporal scales in wide wave number and frequency space simultaneously is important.3) In order to clarify the relation between secondary generated large scale convective structure and structure of maternal turbulence, we developed a modulational instability analysis and found that the convective structure is significantly influenced by the structure of turbulence. Namely, zonal flows are preferentially excited from radially elongated turbulence structure, whereas streamers are produced from poloidally elongated turbulence structure. Thus, the secondary large scale structure is found to be controlled by the structure of maternal turbulence.4) In order to characterize the transport dynamics where the turbulent component and zonal component are mixed, we investigated statistical quantities such as probability distribution function (PDF), fractal dimension, wavelet spectrum, bi-coherence, etc. We found that the fractal dimension is significantly reduced in plasmas dominated by zonal flows, suggesting that the suppressed transport is sustained by rather coherent process. Less

基于这样的想法，即热融合等离子体中的各种突出结构（如Tokamak）是由于不同的时空尺度波动之间复杂的相互作用而建立的，我们研究了湍流传输过程中相互作用的基本原理。主要结果如下：1）基于使用陀螺仪模型的理论和仿真，我们阐明了微尺度电子温度梯度（ETG）湍流的非线性相互作用产生的区域流及其结构的动力学。我们调查了湍流波动和区域波动之间的“分区定律”，发现该分区由磁剪控制。具体而言，我们发现，在弱和/或反向的磁剪切等离子体中，大部分波动能有效地转移到高压梯度状态下的区域波动中，然后在高压梯度状态下转移到区域波动中，然后在湍流转运的异常中消失。2我们研究了微观尺度ETG驱动的Zonal Zonal流动的效果。间歇性行为暴露于ITG临界梯度附近的热差分中。这可能是由于ITG湍流，ITG驱动的区域流以及微尺度ETG驱动的区域流之间的复杂相互作用所致。结果表明，在较大波数和频率空间中以不同的空间周期尺度处理关键的物理过程很重要。3）为了阐明二级产生的大规模对流结构和产物湍流的结构之间的关系，我们开发了一种模量不稳定性分析，并发现对流结构受到湍流结构的重大影响。也就是说，优选地从根本上伸长的湍流结构激发了纬向流，而流媒体是由多延长的湍流结构产生的。因此，发现二级大规模结构是由孕产妇湍流的结构控制的。4）为了表征混合湍流组件和区域成分的传输动力学，我们研究了统计数量，我们研究了概率分布函数（PDF），例如，分形尺寸，小波谱，双层范围，我们发现了范围的范围。被抑制的运输是通过相当连贯的过程来维持的。较少的