ALFVÉN WAVES IN A PARTIALLY IONIZED TWO-FLUID PLASMA

Alfven waves are a particular class of magnetohydrodynamic waves relevant in many astrophysical and laboratory plasmas. In partially ionized plasmas the dynamics of Alfven waves is affected by the interaction between ionized and neutral species. Here we study Alfven waves in a partially ionized plas...

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Bibliographic Details
Published inThe Astrophysical journal Vol. 767; no. 2; pp. 1 - 14
Main Authors Soler, R, Carbonell, M, Ballester, J L, TERRADAS, J
Format Journal Article
LanguageEnglish
Published United States 20.04.2013
Subjects
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Attenuation
COLLISIONS
DISTURBANCES
Evolution
Fluid dynamics
Fluid flow
FLUIDS
Flux
HYDROMAGNETIC WAVES
Ionization
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
NORMAL-MODE ANALYSIS
OSCILLATIONS
PARTICLES
Perturbation methods
PERTURBATION THEORY
PLASMA
STANDING WAVES
TIME DEPENDENCE
WAVELENGTHS
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Summary:Alfven waves are a particular class of magnetohydrodynamic waves relevant in many astrophysical and laboratory plasmas. In partially ionized plasmas the dynamics of Alfven waves is affected by the interaction between ionized and neutral species. Here we study Alfven waves in a partially ionized plasma from the theoretical point of view using the two-fluid description. We consider that the plasma is composed of an ion-electron fluid and a neutral fluid, which interact by means of particle collisions. To keep our investigation as general as possible, we take the neutral-ion collision frequency and the ionization degree as free parameters. First, we perform a normal mode analysis. We find the modification due to neutral-ion collisions of the wave frequencies and study the temporal and spatial attenuation of the waves. In addition, we discuss the presence of cutoff values of the wavelength that constrain the existence of oscillatory standing waves in weakly ionized plasmas. Later, we go beyond the normal mode approach and solve the initial-value problem in order to study the time-dependent evolution of the wave perturbations in the two fluids. An application to Alfven waves in the low solar atmospheric plasma is performed and the implication of partial ionization for the energy flux is discussed.
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ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/767/2/171