Dispersion relation of Alfven waves in multi-component magneto-plasma

2015 ◽  
Author(s):  
Vishnu P. Ahirwar ◽  
G. Ahirwar
Keyword(s):  
Dispersion Relation ◽  
Alfven Waves ◽  
Alfvén Waves

Drift-Alfvén waves at the arbitrary ion Larmor radius scale in dusty plasmas

2010 ◽  
Vol 76 (3-4) ◽  
pp. 553-557 ◽  
Author(s):  
O. G. ONISHCHENKO ◽  
O. A. POKHOTELOV ◽  
V. V. KRASNOSELSKIKH
Keyword(s):  
Nonlinear Dynamics ◽  
Fourier Transform ◽  
Dispersion Relation ◽  
Spatial Scales ◽  
Dusty Plasmas ◽  
Alfven Waves ◽  
Mhd Equations ◽  
Larmor Radius ◽  
Alfvén Waves ◽  
Linear Limit

AbstractA set of magneto-hydrodynamic (MHD) equations that govern the nonlinear dynamics of drift-Alfvén waves with arbitrary spatial scales in comparison with the ion Larmor radius is derived. It is shown that in the linear limit a Fourier transform of these equations yields the dispersion relation which in the so-called Padé approximation corresponds to the fully kinetic theory.

Unified theory of damping of linear surface Alfvén waves in inhomogeneous incompressible plasmas

1996 ◽  
Vol 56 (1) ◽  
pp. 107-125 ◽  
Author(s):  
M. S. Ruderman ◽  
M. Goossens
Keyword(s):  
Dispersion Relation ◽  
Resonant Absorption ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Dimensionless Number ◽  
Inhomogeneous Layer ◽  
Wide Range ◽  
Damping Rate ◽  
Nonmonotonic Variation ◽  
Incompressible Mhd

The viscous damping of surface Alfvén waves in a non-uniform plasma is studied in the context of linear and incompressible MHD. It is shown that damping due to resonant absorption and damping on a true discontinuity are two limiting cases of the continuous variation of the damping rate with respect to the dimensionless number Rg = Δλ2Re, where Δ is the relative variation of the local Alfvén velocity, λ is the ratio of the thickness of the inhomogeneous layer to the wavelength, and Re is the viscous Reynolds number. The analysis is restricted to waves with wavelengths that are long in comparison with the extent of the non-uniform layer (λ ≪ 1), and to Reynolds numbers that are sufficiently large that the waves are only slightly damped during one wave period. The dispersion relation is obtained and first investigated analytically for the limiting cases of very small (Rg ≪ 1) and very large (Rg ≫ 1) values of Rg, For very small values of Rg, the damping rate agrees with that found for a true discontinuity, while for very large values of Rg, it agrees with the damping rate due to resonant absorption. The dispersion relation is subsequently studied numerically over a wide range of values of Rg, revealing a continuous but nonmonotonic variation of the damping rate with respect to Rg.

Kinetic Alfvén waves in an inhomogeneous anisotropic magnetoplasma in the presence of an inhomogeneous electric field: particle aspect analysis

2000 ◽  
Vol 63 (4) ◽  
pp. 311-328 ◽  
Author(s):  
A. BARONIA ◽  
M. S. TIWARI
Keyword(s):  
Growth Rate ◽  
Dispersion Relation ◽  
Electric Field ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Larmor Radius ◽  
Alfvén Waves ◽  
Temperature Anisotropy ◽  
Inhomogeneous Electric Field ◽  
Kinetic Alfvén Waves

Kinetic Alfvén waves in the presence of an inhomogeneous electric field applied perpendicular to the ambient magnetic field in an anisotropic, inhomogeneous magnetoplasma are investigated. The particle aspect approach is adopted to investigate the trajectories of charged particles in the electromagnetic field of a kinetic Alfvén wave. Expressions are found for the field-aligned current, the perpendicular current, the dispersion relation and the particle energies. The growth rate of the wave is obtained by an energy- conservation method. It is predicted that plasma density inhomogeneity is the main source of instability, and an enhancement of the growth rate by electric field inhomogeneity and temperature anisotropy is found. The dispersion relation and growth rate involve the finite-Larmor-radius effect, electron inertia and the temperature anisotropy of the magnetoplasma. The applicability of the investigation to the auroral acceleration region is discussed.

scholarly journals Bending Waves on Current Sheets

1985 ◽  
Vol 107 ◽  
pp. 491-496
Author(s):  
G. Bertin ◽  
B. Coppi
Keyword(s):  
Solar Wind ◽  
Dispersion Relation ◽  
Alfven Waves ◽  
Magnetic Polarity ◽  
Alfvén Waves ◽  
Planetary Magnetospheres ◽  
Current Sheets ◽  
Bending Waves ◽  
Modified Surface

Current sheets are found to be subject to bending waves described by a dispersion relation indicating that these are, essentially, modified surface Alfvén waves. Applications to the observed magnetic polarity sectors in the solar wind and to other astrophysical environments, such as planetary magnetospheres, are suggested.

Effect of finite spectral width on the modulational instability of Alfvén waves

1992 ◽  
Vol 47 (3) ◽  
pp. 521-531 ◽  
Author(s):  
P. C. Roy ◽  
J. C. Bhakta
Keyword(s):  
Growth Rate ◽  
Dispersion Relation ◽  
Spectral Density ◽  
Transport Equation ◽  
Modulational Instability ◽  
Spectral Width ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Monochromatic Wave ◽  
Derivative Nonlinear Schrödinger Equation

The effect of finite spectral width on the modulational instability of Alfvén waves described by the derivative nonlinear Schrodinger equation is investigated using a method developed by Alber to derive a transport equation for the spectral density. The dispersion relation for a monochromatic wave is regained for a delta spectrum. It is shown that the growth rate and domain of modulational instability diminish as the spectral width increases for both the Gaussian and uniform spectrums.

scholarly journals Linear Waves in Force-Free Fibrils

1998 ◽  
Vol 167 ◽  
pp. 155-158
Author(s):  
Y.D. Zhugzhda
Keyword(s):  
Dispersion Relation ◽  
Magnetic Flux ◽  
Flux Tube ◽  
Temperature Fluctuations ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Flux Tubes ◽  
Linear Waves ◽  
Magnetic Flux Tubes ◽  
Wave Modes

AbstractThe advanced thin flux tube approximation for force-free thin magnetic flux tubes is used to derive a dispersion relation for linear waves. All wave modes appear to be coupled in a twisted flux tube. In the case of a weakly twisted flux tube, it has been found that torsional Alfvén waves have dispersion and produce pressure and temperature fluctuations. The effect of tube rotation is pointed out. These properties of linear waves have an impact on prominence oscillations.

scholarly journals Drift-Alfvén waves in space plasmas – theory and mode identification

2009 ◽  
Vol 27 (2) ◽  
pp. 639-644 ◽  
Author(s):  
O. G. Onishchenko ◽  
O. A. Pokhotelov ◽  
V. V. Krasnoselskikh ◽  
S. I. Shatalov
Keyword(s):  
Dispersion Relation ◽  
Spatial Scales ◽  
Wave Impedance ◽  
Alfven Waves ◽  
Larmor Radius ◽  
Space Plasmas ◽  
Alfvén Waves ◽  
Mode Identification ◽  
Density Perturbations ◽  
Theoretical Results

Abstract. The theory of drift-Alfvén waves with the spatial scales comparable to the ion Larmor radius is developed. The dispersion relation, the wave impedance and variations of the plasma density perturbations versus the wave frequency are investigated. The relevance of theoretical results obtained to the Cluster observations in the cusp and near a reconnection X line in the Earth's magnetopause is discussed.

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