2D continuous spectrum of shear Alfvén waves in the presence of a magnetic Island

Alessandro Biancalani, Liu Chen, Francesco Pegoraro, Fulvio Zonca

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Abstract

The radial structure of the continuous spectrum of shear Alfvén modes is calculated in the presence of a magnetic island in tokamak plasmas. Modes with the same helicity as the magnetic island are considered in a slab model approximation. In this framework, with an appropriate rotation of the coordinates the problem reduces to two dimensions. Geometrical effects due to the shape of the flux surface's cross-section are retained to all orders. On the other hand, we neglect toroidal couplings but fully take into account curvature effects responsible for the beta-induced gap in the low-frequency part of the continuous spectrum. New continuum accumulation points are found at the O-point of the magnetic island. The beta-induced Alfvén eigenmodes (BAE) continuum accumulation point is found to be positioned at the separatrix flux surface. The most remarkable result is the modification of the BAE continuum accumulation point frequency, due to the presence of the magnetic island. © 2011 IOP Publishing Ltd.
Original languageEnglish
Article number025009
Pages (from-to)-
JournalPlasma Physics and Controlled Fusion
Volume53
Issue number2
DOIs
Publication statusPublished - Feb 2011
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

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