HIGH SPEED PARALLEL COMPUTATION OF THREE-DIMENSIONAL EQUILIBRIUM AND STABILITY FOR NONAXISYMMETRIC TORUS PLASMAS

非轴对称环面等离子体三维平衡和稳定性的高速并行计算

• 批准号: 05680403
• 负责人: HAYASHI Takaya
• 金额: $ 0.45万
• 依托单位: NATIONAL INSTITUTE FOR FUSION SCIENCE
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05680403/
• 关键词: Nonaxisymmetric Torus Plasma; Equilibrium and Stability of Plasma; Parallel Computer; Three-dimensional Equilibrium; Computer Simulation of Plasma; Magnetohydrodynamics; Pressre Driven Instability; Nonlinear Time Evolution

1. Equilibrium ptoperties of several typical configurations of helical plasmas, namely, heliotron/torsatron, Helias, and Heliac, were studied by using the 3D equilibrium code HINT,which we have developed. We found (1) in some configurations, a self-healing' of pressure driven islands can occur, (2) it occurs even in an unstable plasma configuration, (3) therefore global effects of plasma currents are proved to be important as a physical mechanism of island formation, and (4) in some cases, excitation of nonresonant type instability modifies structure of helical equilibria significantly.2. A new nonlinrear simulation code for nonaxisymmetric torus plasmas were successfully developed with a motivation to clarify whether or not self-organization of a plasma which is induced by pressure-driven instabilities can occur. The main characteristics of the developed code are that time development of the full MHD equations are solved in a full three dimensional geometry. Such a nonlinear simulation has seldom been attempted so far. We have executed simulations and found that while behavior of instabilities in an initial phase of the development agrees well with predictions of linear analyzes, strong mode coupling is eventually excited as the nonlinear development of instabilities, which results in a transition to a strongly turbulent state. It's interesting to note that in a later stage, the plasma pressure profile is broadened and the plasma spontaneously becomes quiet.3. Efficiency of the developed codes on a parallel computer was investigated. Algorithm that keeps the form of the physics principle of action through medium was found to be effective. Several practical methods which enable large scale simulation codes to use CPUs efficiently were found.

1.利用我们开发的三维平衡程序HINT，研究了几种典型的螺旋等离子体构型，即氦加速器/力矩管、氦原子和氦原子的平衡性质。我们发现：(1)在某些构型中，可以发生压力驱动孤岛的自愈；(2)即使在不稳定的等离子体构型中也可以发生自愈；(3)因此，等离子体电流的整体效应被证明是形成孤岛的一个重要的物理机制；为了阐明由压力驱动不稳定性引起的等离子体是否会发生自组织，开发了一个新的非轴对称环面等离子体非线性后方模拟程序。所开发的程序的主要特点是在全三维几何中求解全MHD方程的时间发展。到目前为止，很少有人尝试这样的非线性模拟。我们进行了模拟，发现虽然不稳定性在发展的初始阶段的行为与线性分析的预测很好地一致，但随着不稳定性的非线性发展，强模式耦合最终被激发，导致向强湍动状态的转变。有趣的是，在后来的阶段，等离子体压力分布被加宽，等离子体自发变得平静。在一台并行机上对所开发的程序进行了效率测试。通过介质保持物理作用原理形式的算法被发现是有效的。找到了使大规模仿真代码高效使用CPU的几种实用方法。

项目成果

J.Nuhrenberg: "Overview on Wendelstein 7-X Theory" Fusion Technology. 22. (1995)

J.Nuhrenberg：《Wendelstein 7-X 理论概述》聚变技术。

T.Hayashi: "Behavior of magnetic islands in 3D MHD equilibria of helical devices" Plasma Physics and Controlled Nuclear Fusion Research. (1995)

T.Hayashi：“螺旋装置 3D MHD 平衡中磁岛的行为”等离子体物理和受控核聚变研究。

B.D.Blackwell: "First Experimental Results and Recent MHD Studies for the H-1 Heliac" Plasma Physics and Controlled Nuclear Fusion Research. (1995)

B.D.Blackwell：“H-1 Heliac 的首次实验结果和最近的 MHD 研究”等离子体物理和受控核聚变研究。

T.Hayashi: "Nonlinear Simulations of Deformation and Destruction of Magnetic Surfaces in Helical Devices" Fusion Technology. 22. (1995)

T.Hayashi：“螺旋装置中磁性表面变形和破坏的非线​​性模拟”融合技术。

T.Hayashi: "3D MHD Study of Helias and Heliotron" Plasma Physics and Controlled Nuclear Fusion Research. 2. 29-34 (1993)

T.Hayashi：“Helias 和 Heliotron 的 3D MHD 研究”等离子体物理和受控核聚变研究。