Theory on excitations of drift Alfvén waves by energetic particles. II. The general fishbone-like dispersion relation

2014 ◽  
Vol 21 (7) ◽  
pp. 072121 ◽  
Author(s):  
Fulvio Zonca ◽  
Liu Chen
Keyword(s):  
Dispersion Relation ◽  
Energetic Particles ◽  
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.

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