Alfven resonance' reconsidered: Exact equations for wave propagation across a cold inhomogeneous plasma

Journal Article · Tue Nov 01 04:00:00 EST 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870888· OSTI ID:6970522

Bellan, P M ^[1]

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1. California Institute of Technology, Pasadena, California 91125 (United States)

Previous discussions of Alfven wave propagation across an inhomogeneous plasma predicted that shear Alfven waves become singular (resonant) at the [omega]=[ital k][sub [ital zv]][sub [ital 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 Alfven resonance' (incompressible magnetohydrodynamics, compressible magnetohydrodynamics, and two-fluid) are re-examined and shown to have errors and be mutually inconsistent. [ital 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 Alfven layer so that there is no wave absorption or localized heating. These equations also show that the real shear' Alfven 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]=[ital k][sub [ital zv]][sub [ital A]] layer, is actually a quasielectrostatic resonance cone mode. For [omega][much lt][omega][sub [ital ci]] and [ital k][sub [ital y]]=0, the [omega]=[ital k][sub [ital zv]][sub [ital A]] layer turns out to be a cutoff (reflecting) layer for [ital both] the shear' and compressional modes (and not a resonance layer). For finite [omega]/[omega][sub [ital ci]] and [ital k][sub [ital y]]=0 this layer becomes a region of wave inaccessibility. For [omega][much lt][omega][sub [ital ci]] and finite [ital k][sub [ital y]] there is strong coupling between shear and compressional modes, but still no resonance.

• DOE Contract Number: FG03-86ER53232
• OSTI ID: 6970522
• Journal Information: Physics of Plasmas; (United States), Journal Name: Physics of Plasmas; (United States) Vol. 1:11; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700340* -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
ALFVEN WAVES
COLD PLASMA
FLUID MECHANICS
HEATING
HYDRODYNAMICS
HYDROMAGNETIC WAVES
INHOMOGENEOUS PLASMA
MAGNETOHYDRODYNAMICS
MECHANICS
PLASMA
PLASMA FLUID EQUATIONS
PLASMA HEATING
RESONANCE
WAVE PROPAGATION