Nonlinear interactions between gravitational radiation and modified Alfvén modes in astrophysical dusty plasmas (original) (raw)
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Alfvén waves in space and astrophysical dusty plasmas
Nonlinear Processes in Geophysics, 2014
In this paper, we present some results of previous works on Alfvén waves in a dusty plasma in different astrophysical and space regions by taking into account the effect of superthermal particles on the dispersive characteristics. We show that the presence of dust and superthermal particles sensibly modify the dispersion of Alfvén waves. The competition between different damping processes of kinetic Alfvén waves and Alfvén cyclotron waves is analyzed. The nonlinear evolution of Alfvén waves to chaos is reviewed. Finally, we discuss some applications of Alfvén waves in the auroral region of space plasmas, as well as stellar winds and star-forming regions of astrophysical plasmas.
Journal of Plasma Physics, 2006
The nonlinear coupling between the Alfvén-Rao (AR) and dust-Alfvén (DA) modes in a uniform magnetized dusty plasma is considered. For this purpose, multi-fluid equations (composed of the continuity and momentum equations), the laws of Faraday and Ampère and the quasi-neutrality condition are adopted to derive a set of equations, which show how the fields of the modes are nonlinearly coupled. The equations are then used to investigate decay and modulational instabilities in magnetized dusty plasmas. Stationary nonlinear solutions of the coupled AR and DA equations are presented. The relevance of the investigation to nonlinear phenomena (instabilities and localized structures) in interstellar molecular clouds is also discussed.
Exact nonlinear dust kinetic Alfvén waves in a dust–ion plasma
2003
The properties of nonlinear dust kinetic Alfvén waves in a collisionless, low (but finite)-β, dust-ion plasma are investigated by employing the pseudo-potential approach, which is valid for arbitrary amplitude solitary waves. It is shown both analytically and numerically that a dusty plasma model can support solitary waves consisting of density humps or dips. Furthermore, the properties of these solitary waves are found to be significantly modified by the speed and obliqueness of the wave propagation. The findings of the present investigation should be useful in understanding the formation of coherent nonlinear soliton structures in space and astrophysical dusty plasmas, such as in planetary rings and cometary tails. References 10
Large-amplitude dust inertial Alfvén waves in an electron-depleted dusty plasma
Journal , 2021
The existence of the large-amplitude dust inertial Alfvén waves (DIAWs) has been presented in an electron-depleted, two-fluid dust-ion plasma. Linear analysis shows that the DIAWs travel slower than the dust Alfvén waves. DIAWs are the obliquely (with respect to the external magnetic field) propagating oscillations of dust density, having the characteristics of a solitary wave. In order to observe the nonlinear behaviour of the DIAWs, the Sagdeev pseudopotential method has been used to derive the energy balance equation and from the expression of the Sagdeev pseudopotential, the existence conditions for the DIAWs have also been determined. It is observed that density rarefactions travelling at sub-and super-Alfvénic speeds are associated with DIAWs.
Nonlinear scattering of Alfvén waves off low-frequency dust modes in a magnetized dusty plasma
Il Nuovo Cimento D, 1998
The three-wave nonlinear scattering of an electromagnetic Alfvén wave off a low-frequency dust mode, viz. dust-Bernstein mode in a homogeneous, magnetized, hot and collisionless dusty plasma, has been analytically investigated. The Vlasov equation in terms of gyrokinetic variables has been employed to find the nonlinear response of the plasma particles including the finite-Larmor-radius thermal kinetic effects. An approximate expression for the comparative growth rates of the three-wave parametric instability has been obtained. It is noted that for the usual dusty plasma parameters the parametric scattering of the electromagnetic Alfvén waves through the dust-Bernstein modes in the low-density limit is more efficient than that in the highdensity limit. PACS 52.35.Fp-Electrostatic waves and oscillations (e.g., ion-acoustic waves). PACS 52.25.Mq-Dielectric properties. PACS 52.35.Mw-Nonlinear waves and nonlinear wave propagation (including parametric effects, mode coupling, ponderomotive effects, etc.
Effects of dust-charge fluctuation on the damping of Alfvén waves in dusty plasmas
Physics of Plasmas, 2005
Using a completely kinetic description to analyze wave propagation in dusty plasmas, the case of propagation of waves exactly parallel to the external magnetic field and Maxwellian distributions for electrons and ions in the equilibrium is considered. A model for the charging process of dust particles which depends on the frequency of inelastic collisions between dust particles and electrons and ions is used. The dispersion relation and damping rates for Alfvén waves are obtained. For the numerical solutions, the average value of the inelastic collision frequency is used as an approximation. The results show that the presence of dust particles with variable charge in the plasma produces significant additional damping of the Alfvén wave. A novel process of mode coupling of low-frequency waves is demonstrated to occur due to the presence of dust particles.
The European Physical Journal D, 2010
The effective one-fluid adiabatic magnetohydrodynamic (MHD) equations for a multicomponent plasma comprising of electrons, ions, and dust are used to investigate the nonlinear coupling of dust Alfven and dust acoustic waves in the presence of radiation pressure as well as the Jean's term that arises in a selfgravitating plasma. In this context, the set of Zakharov equations are derived. The soliton solutions in the presence of radiation pressure and Jeans term are separately discussed. It is found that ordinary solitons are obtained in the absence of Jeans term whereas cusp solitons are found in the absence of radiation pressure. To the best of our knowledge, cusp solitons are obtained for the first time for a self-gravitating plasma with Jeans term for an electromagnetic wave in a dusty plasma. The modulational instability is also investigated in the presence of radiation pressure and Jeans term. It is found that the Jeans term drives the system modulationally unstable provided it dominates the dust acoustic and radiation pressure terms whereas the radiation pressure enhances the stability of the system. The relevance of the present investigation in the photodissociation region that separates the HII region from the dense molecular clouds is also pointed out.
Monthly Notices of the Royal Astronomical Society, 2021
Using a kinetic description of a homogeneous magnetized dusty plasma with Maxwellian distribution of electrons and protons and dust particles charged by inelastic collisions and by photoionization, we analyse the dispersion relation considering the case where waves and radiation propagate exactly parallel to the ambient magnetic field. The investigation emphasizes the changes that the photoionization process brings to the propagation and damping of the waves in a stellar wind environment, since Alfvén waves are believed to play a significant role in the heating and acceleration processes that take place in the wind. The results show that, in the presence of dust with negative equilibrium electrical charge, the Alfvén mode decouples into the whistler and ion cyclotron modes for all values of wavenumber, but when dust particles acquire neutral or positive values of electrical charge, these modes may couple for certain values of wavenumber. It is also seen that the whistler and ion cyc...
Dynamics of a magnetized gravitating dusty plasma
Journal of Plasma Physics, 1996
Linear stability of a magnetized dusty plasma is studied for the regime with ≈ 1 (where G is the universal gravitational constant, md is the grain mass and qd is the grain charge). We demonstrate that the magnetic force plays a stabilizing role and, together with electrostatic repulsion, counter gravitational condensation. The implications of this result for astrophysical situations are briefly discussed.