The Brunt-Vaisala frequency of rotating tokamak plasmas

TitleThe Brunt-Vaisala frequency of rotating tokamak plasmas
Publication TypeJournal Article
Year of Publication2012
AuthorsJ.W Haverkort, H.J de Blank, B. Koren
JournalJournal of Computational Physics
Volume231
Issue3
Pagination981-1001
Date PublishedFeb
Type of ArticleArticle
ISBN Number0021-9991
KeywordsACCRETION DISKS, Analytical solutions, AXISYMMETRICAL MHD EQUILIBRIA, COMPUTATION, Continuous spectrum, CONTINUOUS-SPECTRUM, Convective effect, EQUATION, Grad-Shafranov equation, HYDROMAGNETIC STABILITY, IDEAL MAGNETOHYDRODYNAMIC EQUILIBRIA, IDEAL MAGNETOHYDRODYNAMICS, INCOMPRESSIBLE FLOWS, plasma flow, RESISTIVE MHD, TOROIDAL MASS-FLOW, TOROIDAL ROTATION
Abstract

The continuous spectrum of analytical toroidally rotating magnetically confined plasma equilibria is investigated analytically and numerically. In the presence of purely toroidal flow, the ideal magnetohydrodynamic equations leave the freedom to specify which thermodynamic quantity is constant on the magnetic surfaces. Introducing a general parametrization of this quantity, analytical equilibrium solutions are derived that still posses this freedom. These equilibria and their spectral properties are shown to be ideally suited for testing numerical equilibrium and stability codes including toroidal rotation. Analytical expressions are derived for the low-frequency continuous Alfven spectrum. These expressions still allow one to choose which quantity is constant on the magnetic surfaces of the equilibrium, thereby generalizing previous results. The centrifugal convective effect is shown to modify the lowest Alfven continuum branch to a buoyancy frequency, or Brunt-Vaisala frequency. A comparison with numerical results for the case that the specific entropy, the temperature, or the density is constant on the magnetic surfaces yields excellent agreement, showing the usefulness of the derived expressions for the validation of numerical codes. (C) 2011 Elsevier Inc. All rights reserved.

URLhttp://homepages.cwi.nl/~haverkor/publications/12_JCP_JWHaverkort.pdf
DOI10.1016/j.jcp.2011.03.016
Division

FP

Department

CPP-HT

PID

e5149a320943e83ffbfd7e483a30712e

Alternate TitleJ. Comput. Phys.

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