Towards a Unified Magnetohydrodynamic Theory Describing the Formation of Energy-Transport Barriers in Plasma Turbulence

建立描述等离子体湍流中能量传输势垒形成的统一磁流体动力学理论

基本信息

批准号：
11680496
负责人：
YOKOI Nobumitsu
金额：
$ 2.37万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

In this study we clarified that plasma rotation, helicity, cross helicity, and electric field are closely related to the magnetic-field generation and the suppression of turbulent transports in magnetohydrodynamic plasmas. The findings are summarized as follows :(1) It was shown that large-scale magnetic structures can be generated and sustained in turbulence by a combination of plasma-rotation and cross-helicity (velocity/magnetic-field correlation) effects. This is a manifestation of the turbulent dynamo and suppression of turbulent transport.A turbulence model that can describe the field-generation and turbulence-suppression was constructed.(2) The magnetohydrodynamic mechanism of electric-field transport suppression, with special reference to tokamak's reversed-shear confinement, was presented. The mechanism of plasmarotation generation due to the combination of electric-field-curvature and cross-helicity effects was also presented for the first time theoretically. The validity of the mechanisms was confirmed through a numerical simulation of a cylindrical plasma.(3) Generation and sustainment mechanisms or dynamos of global magnetic field in plasma turbulence were presented with special emphasis of the combination of the helicity (an index representing helcal properties of velocity and magnetic-field structures) and cross-helicity effects. These dynamos were applied to phenomena such as the geomagnetism, solar polarity reversal, and collimation of astrophysical jets, and shown to successfully describe characteristics of these phenomena.(4) Turbulence theories and modeling of fluids and plasmas were reviewed from the viewpoint of inhomogeneities of fields and plasma parameters. The similarity and dissimilarity between the theoretical methods analysing fluid and plasma turbulence were shown.

在这项研究中，我们阐明了等离子体旋转、螺旋度、交叉螺旋度和电场与磁流体动力学等离子体中磁场的产生和湍流传输的抑制密切相关。研究结果概括如下：（1）研究表明，通过等离子体旋转和交叉螺旋（速度/磁场相关）效应的结合，可以在湍流中产生并维持大规模的磁结构。这是湍流发电机和湍流输运抑制的体现。构建了能够描述场产生和湍流抑制的湍流模型。(2)抑制电场输运的磁流体动力学机制，特别参考托卡马克的逆流模型。提出了剪切约束。还首次从理论上提出了电场曲率和交叉螺旋效应相结合产生等离子体旋转的机制。通过对圆柱等离子体的数值模拟，证实了该机制的有效性。(3)提出了等离子体湍流中全局磁场的产生和维持机制或发电机，特别强调了螺旋度(代表螺旋性质的指数)的组合。速度和磁场结构）和交叉螺旋效应。这些发电机被应用于地磁、太阳极性反转和天体物理喷流准直等现象，并被证明可以成功地描述这些现象的特征。(4)从流体和等离子体的不均匀性角度回顾了流体和等离子体的湍流理论和建模。场和等离子体参数。展示了分析流体和等离子体湍流的理论方法之间的相似性和不同点。