Abstract
The continuous spectrum of linear ideal MHD is determined analytically in 2D magnetostatic models for coronal loops and arcades by means of a perturbation expansion. Poloidal mode coupling, induced by non-circularity of the cross-sections of the magnetic surfaces and/or variation of the plasma density along the magnetic field lines, is shown to occur in first order. The coupling is most pronounced on and near rational surfaces for particular poloidal and toroidal mode numbers and produces gaps in the continuous spectrum of ideal MHD.
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Poedts, S., Goossens, M. On poloidal mode coupling in the continuous spectrum of 2D equilibria. Sol Phys 133, 281–311 (1991). https://doi.org/10.1007/BF00149891
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DOI: https://doi.org/10.1007/BF00149891