Magnetized Dusty Plasma Research Articles

Nonlinear dust acoustic waves in a nonuniform magnetized complex plasma with nonthermal ions and dust charge variation

Propagations of nonlinear dust acoustic (DA) solitary waves and shock waves in a nonuniform magnetized dusty plasma are investigated. The incorporation of the combined effects of nonthermally distributed ions, nonadiabatic dust charge fluctuation, and the inhomogeneity caused by nonuniform equilibrium values of particle density, charging variable, and particle potential on the waves leads to a significant modification to the nature of nonlinear DA solitary waves. The nonlinear wave evolution is governed by a modified Zakhavov-Kusnetsov-Burgers (MZKB) equation, whose coefficients are space dependent. Using a generalized expansion method, new solutions for the MZKB equation are obtained. The form of solutions consists of two parts; one of them is the amplitude factor and the other is a superposition of bell-shaped and kink-type shock waves. New solutions are classified into three categories. A type of the solution is determined depending on the nonthermal parameter. Findings in this investigation should be useful for understanding the ion acceleration mechanisms close to the Moon and also enhancing our knowledge on pickup ions around unmagnetized bodies, such as comets, Mars, and Venus, including medium inhomogeneities with nonadiabatic dust charging processes.

Observation of Vortex Patterns in aMagnetized Dusty Plasma System

Vortex patterns of dust particles have been observed in a magnetizeddusty plasma system. The formation mechanism of two-dimensional (2D)vortex patterns has been investigated by analysing the forces actingon dust particles and molecular dynamics (MD) simulations in a 2Dconfined magnetized dusty plasma. It has been found that with a weakconfining electric field and a strong magnetic field, the particles'trajectories will form a vortex shape. The simulation results agreewith our experimental observations. In our experiments, vortexpatterns can be induced via circular rotation of particles bychanging the rf (radio-frequency) power in a magnetized dustyplasma.

Instability of Waves in Magnetized Vortex-Like IonDistribution Dusty Plasmas

A modified Zakharov–Kuznetsov equation for small but finiteamplitude dust acoustic waves in a magnetized votex-like iondistribution dusty plasma is obtained in this paper. Itseems that there are instability for a soliton under higher-ordertransverse perturbations in this system. There is a certaincritical value 4λ0. If the ratio of the wave length ofthe higher-order perturbations to the width of the soliton islarger than this critical value, the solitary wave is unstable,otherwise it is stable.

Dust ion acoustic solitary waves in a magnetized dusty plasma with anisotropic ion pressure

Abstract The influence of anisotropic ion pressure on the dust ion acoustic solitary wave (DIASW) and the double layer (DL) obliquely propagating to a magnetic field are investigated by using the Sagdeev potential. The anisotropic ion pressure is defined by applying the Chew–Goldberger–Low (CGL) theory, p ⊥ = p ⊥ 0 n and p ∥ = p ∥ 0 n 3 , where n is the normalized ion density. The solutions of DIASWs and DLs obliquely propagating to an external magnetic field are obtained in the small amplitude limit. It is found that the perpendicular component of anisotropic ion pressure works differently from that of the parallel component on the DIASWs in a magnetized dusty plasma, deviating from a straight extension of the isotropic pressure effect.

Pair Annihilation Effects on Lower Hybrid Oscillation in Semi-Bounded Magnetized Dusty Pair Plasmas

The electron-positron pair annihilation effects on the electrostatic hybrid resonance oscillation are investigated in semi-bounded magnetized dusty pair plasmas. The surface wave dispersion relation is obtained by the plasma dielectric function with the specular reflection condition. The result shows the existence lower hybrid resonance oscillation modes in semi-bounded dusty pair plasmas. It is found that the electron-positron annihilation events enhance the lower hybrid resonance oscillation frequency. It is also found that the lower hybrid resonance frequency decreases with increasing the ratio of the positron density to the electron density. In addition, the lower hybrid resonance frequency decreases with increasing the strength of the magnetic field

Zakharov–Kuznetsov–Burgers equation for dust ion acoustic waves

The nonlinear wave structures of small, but finite amplitude dust ion acoustic waves in a magnetized dusty plasma consisting of cold positive ions, isothermal electrons and variable charged stationary dust particles are investigated using reductive perturbation theory. The basic set of fluid equations is reduced to Zakharov–Kuznetsov–Burgers (ZKB) equation. The presence of charging process give rise to three cases. The first case arises when the charging process lead to originate anomalous dissipation, which makes possible existence of a new kind of shocks related to this dissipation. Case two, in the absence of dissipation (or if the dissipation is weak) the balance is then between nonlinear and dispersion effects, which can result in the formation of a symmetrical solitary waves. Case three considers the dissipation and dispersion at the same footing, i.e. we cannot neglect either dissipation or dispersion. Exact solution of the ZKB equation is obtained, for the first time, using a improved modified extended tanh-function method. Then, all possible cases of ZKB equation are covered.

Non-Thermal and Dust Charge Effects on Surface Ion Waves in Semi-Bound Lorentzian Plasmas

The non-thermal and dust charge effects on a surface electrostatic ion plasma wave are investigated in a semi-bound magnetized dusty Lorentzian plasma. The results show that the phase velocity of the surface wave with negatively charged dust grains is greater than that with positively charged dust grains or that with neutral dust grains. It is also found that the phase velocity increases with increasing the spectral index of the plasma. For the long wavelength domain, however, the phase velocity of the surface wave is found to be almost independent of the spectral index.

Effects of two-temperature ions, magnetic field, and higher-order nonlinearity on the existence and stability of dust-acoustic solitary waves in Saturn’s F ring

Nonlinear propagation of dust-acoustic solitary waves (DASWs) in a strong magnetized dusty plasma comprising warm adiabatic variable-charged dust particles, isothermal electrons, and two-temperature ions is investigated. Applying a reductive perturbation theory, a nonlinear Zakharov-Kuznetsov (ZK) equation for the first-order perturbed potential and a linear inhomogeneous ZK-type equation for the second-order perturbed potential are derived. However, at a certain value of high-temperature ion density, the coefficient of the nonlinear terms of both ZK and ZK-type equations vanishes. Therefore, a new set of expansion physical parameters and stretched coordinates are then used to derive a modified Zakharov-Kuznetsov (mZK) equation for the first-order perturbed potential and a mZK-type equation for the second-order perturbed potential. Stationary solutions of these equations are obtained using a renormalization method. A condition for two-temperature ions assumption is examined for various cosmic dust-laden plasma systems. It is found that this condition is satisfied for Saturn’s F ring. The effects of two-temperature ions, magnetic field, and higher-order nonlinearity on the behavior of the DASWs are discussed. To obtain the stability condition of the waves, a method based on energy consideration is used and the condition for stable solitons is derived.

Publisher’s Note: “Three-dimensional nonlinear Schrödinger equation for dust-acoustic waves and its stability in magnetized dusty plasma with two-temperature nonthermal ions and dust charge variation” [Phys. Plasmas 13, 022304 (2006)

Publisher’s Note: “Three-dimensional nonlinear Schrödinger equation for dust-acoustic waves and its stability in magnetized dusty plasma with two-temperature nonthermal ions and dust charge variation” [Phys. Plasmas 13, 022304 (2006)

Dust-acoustic solitary waves in an inhomogeneous magnetized hot dusty plasma with dust charge fluctuations

Using a standard reductive perturbation theory, a Zakharov-Kuznnetsov (ZK) equation is derived in an inhomogeneous dusty plasma comprised of negatively charged dust grains of equal radii, Boltzmann distributed electrons and positive ions. The effects of dust thermal pressure, dust charge variation, dust-neutral collision, and the external magnetic field are taken into account. Either compressive or rarefective solitons are shown to exist depending on the critical value of the phase velocity which in turn, depends on the dust temperature and pressure. An analytic soliton solution is obtained and discussed. The behaviors of the soliton amplitude, width, and the Mach number are investigated numerically for different plasma parameters.

Interaction of solitary waves in magnetized warm dusty plasmas with dust charging effects

In consideration of adiabatic dust charge variation, the combined effect of the external magnetized field and the dust temperature on head-on collision of the three-dimensional dust acoustic solitary waves is investigated. By using the extended Poincare–Lighthill–Kuo method, the phase shifts and the trajectories of two solitons after the collision are obtained. The effects of the magnitude and the obliqueness of the external magnetic field and the dust temperature on the solitary wave collisions are discussed in detail.

Three-dimensional nonlinear Schrödinger equation for dust-acoustic waves and its stability in magnetized dusty plasma with two-temperature nonthermal ions and dust charge variation

The effect of two-temperature nonthermal ions and variable dust charge on small-amplitude nonlinear dust-acoustic waves (DAW) is investigated. By using the reductive perturbation technique, the three-dimensional nonlinear Schrödinger equation (3D-NLSE) is first derived. The modulational instability of DAW in the magnetized dusty plasma is investigated as well. Meanwhile, some new and important stability regions are given. The effect of the nonthermal parameter a is shown to play a significant role in the determination of the normalized dust charge. Further, setting this parameter to zero degenerates the system into one in the magnetized dusty plasma consisting of the isothermal ions.

Backward branch of surface dust cyclotron wave in a semi-bounded magnetized dusty plasma

The surface dust cyclotron waves are investigated in semi-bounded magnetized dusty plasmas. The dispersion relation is obtained by the plasma dielectric function with the specular reflection boundary condition. The result shows the existence of the low-frequency backward wave branch in the surface dust cyclotron wave. The frequency of the wave is found to be decreased with the dust Debye wave number. It is also found that there is a minimum position of the scaled group velocity in the small-wave-number region. It is interesting to note that the group velocity increases below the minimum position and, however, decreases above the minimum position with increasing the dust Debye wave number.

Dust-lower-hybrid instability in a streaming magnetized dusty plasma

Instabilities for the excitation of the dusty plasma modes, namely the dust-acoustic and dust-lower-hybrid waves, due to the free streaming of ion/dust particles in uniformly magnetized dusty plasmas have been examined analytically. Expressions for growth rates and threshold have been presented for different conditions of free streaming beams of either ions, dust grains, or two contrastreaming dust particle beams. The relevance of the present investigation has been pointed out for laboratory as well as space dusty plasmas.

Electrostatic hybrid resonance modes in semi-bounded magnetized dusty plasmas

Electrostatic hybrid resonance oscillation modes are investigated in semi-bounded magnetized dusty plasmas. The surface wave dispersion relations are obtained for the orientation of the magnetic field using the specular reflection boundary condition with the plasma dielectric function. The result shows the existence of upper- and lower-hybrid resonance oscillation modes in semi-bounded magnetized dusty plasmas. It is found that the frequencies for the electrostatic upper- and lower-hybrid resonance oscillations are independent of the orientation of the applied magnetic field. In addition, the hybrid resonance frequencies are found to decrease as we increase the ratio of the electron plasma frequency to the electron cyclotron frequency.

Parametric instabilities and localization of nonlinearly coupled electromagnetic modes in astrophysical dusty plasmas

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.

Nonlinearly coupled whistlers and dust-acoustic perturbations in dusty plasmas

The nonlinear interaction between magnetic-field-aligned coherent whistlers and dust-acoustic perturbations (DAPs) in a magnetized dusty plasma is considered. The interaction is governed by a pair of equations consisting of a nonlinear Schrödinger equation for the modulated whistler wave packet and an equation for the nonresonant DAPs in the presence of the ponderomotive force generated by the whistlers. The coupled equations are employed to investigate the occurrence of modulational instability, in addition to the formation of whistler envelope solitons. This investigation is relevant to amplitude modulated electron whistlers in magnetized space dusty plasmas.

Dust-ion-acoustic solitons in a strong magnetic field

The ionization source model is considered, for the first time, to investigate the propagation of small, but finite amplitude dust-ion-acoustic solitons in a strong magnetized dusty plasma. Soliton properties and formation conditions are clearly explained. The relevancy of this investigation to supernovae shells and Saturn's F-ring is pointed out.

The instability of electrostatic wave in a magnetized dusty plasma with nonadiabatic dust charge fluctuation

The effects of external magnetized field and nonadiabatic dust charge fluctuation on instability of wave incorporating the nonthermally distributed ions and the temperatures of ion and dust in dusty plasmas are investigated. A linear dispersion relation is obtained. The numerical results show that the external magnetized field, fast ions and nonadiabatic dust charge fluctuation have strong influence on the frequency and the damping of wave.

Mode coupling of low frequency electromagnetic waves in magnetized dusty plasmas

A kinetic description is used to analyze wave propagation in dusty plasmas, taking into account the fluctuation of the charge of the dust particles due to inelastic collisions with electrons and ions. The case of propagation of waves exactly parallel to the external magnetic field and Maxwellian distributions for the electrons and ions in the equilibrium is considered, and a parametric analysis of the dispersion relation is performed. The investigation emphasizes particularly the effects of dust density, radius of dust particles, ion temperature, ratio between electron and ion temperatures, ion density, and ambient magnetic field, on the solutions of the dispersion relation. The analysis shows the possibility of occurrence of coupling between waves in the whistler branch and waves in the branch of circularly polarized waves, in the presence of the dust particles.