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The azimuthal magnetorotational instability (AMRI)
Author(s) -
Rüdiger G.,
Hollerbach R.,
Gellert M.,
Schultz M.
Publication year - 2007
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.200710852
Subject(s) - magnetorotational instability , physics , toroid , instability , rotational symmetry , mechanics , magnetic field , inverse , magnetohydrodynamics , classical mechanics , plasma , geometry , mathematics , quantum mechanics
We consider the flow of an electrically conducting fluid between differentially rotating cylinders, in the presence of an externally imposed current‐free toroidal field B 0 ( R in / R ) ê ϕ . It is known that the classical, axisymmetric magnetorotational instability does not exist for such a purely toroidal imposed field.We show here that a nonaxisymmetric magnetorotational instability does exist, having properties very similar to the axisymmetric magnetorotational instability in the presence of an axial field. In the nonlinear regime the magnetic energy of the perturbances is shifted (in the sense of an inverse cascade) to the axisymmetric mode rather than to the modes with m > 1. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)