Bellan, P. M. (1994) Alfvén 'resonance' reconsidered: Exact equations for wave propagation across a cold inhomogeneous plasma. Physics of Plasmas, 1 (11). pp. 3523-3541. ISSN 1070-664X http://resolver.caltech.edu/CaltechAUTHORS:BELpop94
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Previous discussions of Alfvén wave propagation across an inhomogeneous plasma predicted that shear Alfvén waves become singular (resonant) at the omega = k(z)v(A) layer and that there is a strong wave absorption at this layer giving localized ion heating. In this paper the three standard derivations of the Alfvén 'resonance' (incompressible magnetohydrodynamics, compressible magnetohydrodynamics, and two-fluid) are re-examined and shown to have errors and be mutually inconsistent. Exact two-fluid differential equations for waves propagating across a cold inhomogeneous plasma are derived; these show that waves in an ideal cold plasma do not become 'resonant' at the Alfvén layer so that there is no wave absorption or localized heating. These equations also show that the real 'shear' Alfvén wave differs in substance from both the ideal MHD and earlier two-fluid predictions and, in the low density, high field region away from the omega = k(z)v(A) layer, is actually a quasielectrostatic resonance cone mode. For omega much-lesser-than omega(ci) and k(y) = 0, the omega = k(z)v(A) layer turns out to be a cutoff (reflecting) layer for both the 'shear' and compressional modes (and not a resonance layer). For finite omega/omega(ci) and k(y) = 0 this layer becomes a region of wave inaccessibility. For omega much-lesser-than omega(ci) and finite k(y) there is strong coupling between shear and compressional modes, but still no resonance.
|Additional Information:||Copyright © 1994 American Institute of Physics. Received 10 March 1994; accepted 30 June 1994. This work has been supported by United States Department of Energy Grant No. DE-FG-04-86ER53232. P.M. Bellan, Response to Comments on "Alfvén 'resonance' reconsidered: Exact equations for wave propagation across a cold inhomogeneous plasma" [Phys. Plasmas 1, 3523 (1994)], Phys. Plasmas 2, 3552 (1995).|
|Subject Keywords:||ALFVEN WAVES; RESONANCE; MAGNETOHYDRODYNAMICS; PLASMA FLUID EQUATIONS; COLD PLASMA; INHOMOGENEOUS PLASMA; WAVE PROPAGATION; PLASMA HEATING|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||28 Feb 2006|
|Last Modified:||26 Dec 2012 08:46|
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