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Magnetohydrodynamic stability spectrum with flow and a resistive wall.

机译:具有流动和电阻壁的磁流体动力学稳定性谱。

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摘要

Magnetically confined fusion plasmas are known to develop a variety of instabilities. Some of these instabilities can be understood with the ideal magnetohydrodynamic (MHD) model. A plasma in MHD equilibrium can be unstable to small perturbations, which are always present in experiments. One particular instability is the external kink mode. While this mode might be stabilized by a perfectly conducting wall, actual walls have some finite resistivity such that the kink still grows on the L/R time of the wall---it is a resistive wall mode (RWM).;In this dissertation, the RWM is studied with the ideal MHD equilibrium and stability equations that include equilibrium flow. The stability equation is a nonlinear eigenvalue problem, which is transformed by the use of an auxiliary variable into a set of linear eigenvalue equations. For a flowing cylindrical plasma, these equations are formulated as a matrix eigenvalue problem by expanding the radial dependence of the perturbations as finite elements. The perturbations at the edge of the plasma are coupled to the surrounding resistive wall by the use of a Green's function for the vacuum fields and by the introduction of an additional unknown that represents the induced current in the wall.;The matrix eigenvalue formulation of the RWM problem was solved numerically with a new finite element eigenvalue code. The code is benchmarked both analytically and numerically for the boundary conditions of a close fitting conducting wall, no wall, a perfectly conducting wall, and a resistive wall. The RWM is shown to be stabilized by flow for a window of wall positions, both with and without parallel viscosity, the latter requiring an extrapolation to a grid step size of zero in the region of resonance between the RWM and the sound continuum. Finally, flow shear is introduced, which reveals that the RWM does not move with the plasma at the resonance location, but rather with the plasma at a radial location which is independent of the value of the poloidal mode number.
机译:已知磁约束聚变等离子体会产生多种不稳定性。这些不稳定性中的某些可以通过理想的磁流体动力学(MHD)模型来理解。 MHD平衡状态下的血浆可能对小扰动不稳定,而小扰动在实验中始终存在。一种特殊的不稳定性是外部扭结模式。虽然此模式可以通过完美导电的墙来稳定,但实际的墙具有有限的电阻率,因此弯折仍会在墙的L / R时间上增长-这是电阻墙模式(RWM)。 ,使用理想的MHD平衡和包括平衡流的稳定性方程来研究RWM。稳定性方程是一个非线性特征值问题,可通过使用辅助变量将其转换为一组线性特征值方程。对于流动的圆柱等离子体,通过扩展微扰的径向依赖性作为有限元,将这些方程式表示为矩阵特征值问题。通过在真空场中使用格林函数,并通过引入表示壁中感应电流的其他未知数,将等离子体边缘处的扰动耦合到周围的电阻壁上。用新的有限元特征值代码对RWM问题进行了数值求解。该代码针对紧密贴合的导电墙,无墙,完美导电墙和电阻墙的边界条件进行了分析和数字基准测试。显示的RWM通过壁位置窗口的流动而稳定,无论是否具有平行粘度,后者都需要在RWM和声音连续体之间的共振区域外推至零的网格步长。最后,引入流动剪切,这表明RWM不会随等离子体在共振位置移动,而是随着等离子体在径向位置移动,而与径向模式数的值无关。

著录项

  • 作者

    Smith, Sterling Paul.;

  • 作者单位

    Princeton University.;

  • 授予单位 Princeton University.;
  • 学科 Physics Electricity and Magnetism.;Physics Fluid and Plasma.;Physics Theory.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 180 p.
  • 总页数 180
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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