Presence Of Polarization Force Research Articles

Dust magnetoacoustic waves in an inhomogeneous cylindrical four-component dusty plasma in the presence of polarization force

Abstract Dust magnetoacoustic waves have been examined in an inhomogeneous, bounded, cylindrical dusty plasma containing oppositely polarized dust particles. Considering polarization force, dust dynamics in r − θ plane is studied in the presence of inhomogeneous external magnetic field along z axis. At equilibrium, the dusty plasma components are supposed to follow Gaussian density distribution. Using reductive perturbation method (RPM), a variable coefficient cylindrical Kadomtsev–Petviashvili (VCCKP) equation has been derived. For weak azimuthal perturbation, an analytical solution, obtained by Zhang (“Exact solutions of a kdv equation with variable coefficients via exp-function method,” Nonlinear Dynam., vol. 52, nos. 1–2, pp. 11–17, 2008) using Exp-function method, is chosen. Phase velocity of dust magnetoacoustic wave is found to be modified by the density inhomogeneities, polarization force, dust charge state ratio and ion-to-electron temperature ratio. Spatio-temporal evolution of the dust number densities has been noticed. Existence of the compressive electromagnetic solitary waves is observed numerically for the chosen dusty plasma parameter range. The impacts of the inhomogeneity, polarization force, dust charge state ratio and ion-to-electron temperature ratio on the relative amplitude of the dust magnetoacoustic wave are also discussed.

Application of Adomian decomposition method to study collision effect in dusty plasma in the presence of polarization force

Application of Adomian decomposition method to study collision effect in dusty plasma in the presence of polarization force

Test charge driven response of a dusty plasma with polarization force

By using the framework of kinetic model, the test charge driven response of a dusty plasma is evaluated in the presence of polarization force. The plasma containing electrons, singly ionized positive ions, and highly charged negative dust particulates is known as a dusty plasma, which can be perturbed by a test particle of charge qT moving with velocity vT along the z-axis. The polarization force purely comes from the high charging state of micron-sized dust particles, causing a deformation of shielding length due to density gradient and modifying the collective motion and particulates’ acceleration. The application of Fourier transformation technique to the set of dynamical equations may result in the shielded potential for a test charge with a modified dielectric constant. Several possibilities have been explored to evaluate the shielded potentials by imposing different conditions on the test charge speed in comparison with the thermal speeds of plasma species. It is found that the profiles of wakefield, Debye-Hückel and farfield (FF) potentials are strongly modified by the polarization force coefficient via the dust charging state and dust concentration. The present findings are useful in the study of strongly coupled dusty plasma, where micron-sized negatively charged dust grains are characterized by a high charging state.

Two-dimensional dust acoustic solitary waves in a dusty plasma in the presence of polarization force with a nonextensive ion distribution

Two-dimensional dust acoustic solitary waves in a dusty plasma in the presence of polarization force with a nonextensive ion distribution

Arbitrary amplitude dust kinetic Alfvén solitary waves in the presence of polarization force

In this investigation, the effect of polarization force on dust kinetic Alfvén solitary waves (DKASWs) in a magnetized dusty plasma consisting of dust fluid, electrons, and positively charged ions is studied. By incorporating density non-uniformity and polarization force in the fluid model equations, the energy balance equation is derived, and from the expression for Sagdeev pseudopotential, the existence conditions for solitary structures in terms of Mach number are determined. From the numerical analysis of Sagdeev pseudopotential, compressive and rarefactive DKASWs at sub- and super-Alfvénic speeds are observed. These waves are significantly affected by varying polarization force, angle of propagation, plasma beta, and Mach number.

Modified gravitational instability of degenerate and non-degenerate dusty plasma

The gravitational instability of strongly coupled dusty plasma (SCDP) is studied considering degenerate and non-degenerate dusty plasma situations. The SCDP system is assumed to be composed of the electrons, ions, neutrals, and strongly coupled dust grains. First, in the high density regime, due to small interparticle distance, the electrons are considered degenerate, whereas the neutrals, dust grains, and ions are treated non-degenerate. In this case, the dynamics of inertialess electrons are managed by Fermi pressure and Bohm potential, while the inertialess ions are by only thermal pressure. Second, in the non-degenerate regime, both the electrons and ions are governed by the thermal pressure. The generalized hydrodynamic model and the normal mode analysis technique are employed to examine the low frequency waves and gravitational instability in both degenerate and non-degenerate cases. The general dispersion relation is discussed for a characteristic timescale which provides two regimes of frequency, i.e., hydrodynamic regime and kinetic regime. Analytical solutions reveal that the collisions reduce the growth rate and have a strong impact on structure formation in both degenerate and non-degenerate circumstances. Numerical estimation on the basis of observed parameters for the degenerate and non-degenerate cases is presented to show the effects of dust-neutral collisions and dust effective velocity in the presence of polarization force. The values of Jeans length and Jeans mass have been estimated for degenerate white dwarfs as Jeans length LJ=1.3×105 cm and Jeans mass MJ=0.75×10−3M⊙ and for non-degenerate laboratory plasma Jeans length LJ=6.86×1016 cm and Jeans mass MJ=0.68×1010M⊙. The stability of the SCDP system is discussed using the Routh-Hurwitz criterion.

Effect of Fermi Pressure and Bohm Potential on Jeans Instability of Quantum Dusty Plasma in Presence of Polarization Force

The quantum hydrodynamic model is considered to investigate the Jeans instability of three species ultracold inhomogeneous dusty plasma. The formulation of this paper is based on the assumption that the electron and ion inertial force is negligible in comparison with the electron and ion pressure and force associated with the electron and ion correlations at the quantum scale. The gravitational force acting on the negatively charged dust grains is considered in the presence of both the electrostatic and polarization forces taking into account the quantum diffraction and statistical contributions of dust particles. The modified dispersion relation is derived and analyzed to obtain the instability criterion by including the dust polarization force and the quantum corrections. Numerical results are presented to show the effect of these modifications on the growth rate of Jeans instability. The present investigation is relevant to the collapse of ultracold astrophysical objects like the inner core of white dwarf and neutron star.

The effect of positive dust mass on instability in four-component magnetodustyplasma in the presence of polarization force

A theoretical investigation has been carried out on the growth rate of instability of the low-frequency electrostatic waves in a partially ionized four-component magnetodustyplasma in the presence of polarization force. Utilizing the method of linear mode analysis, the results of investigation have been presented. The findings of the investigation reveal that the polarization force, the external magnetic field and the dust temperature have a tendency to destabilize the the system by increasing the growth rate of instability. On the other hand, the positive dust mass causes the instability growth rate to decrease, thereby stabilizing the system.

Modified Jeans instability of strongly coupled inhomogeneous magneto dusty plasma in the presence of polarization force

In the present work, the influence of the magnetic field and dust polarization force on the Jeans instability of self-gravitating strongly coupled inhomogeneous dusty plasma has been investigated. The dusty plasma containing strongly correlated negatively charged dust grains and weakly correlated Maxwellian electrons and ions which are embedded in a uniform magnetic field is considered. The construction of the equations is done by employing the generalized hydrodynamic (GH) model for magnetized strongly coupled dusty plasma. In deriving a dispersion relation, the plane-wave solutions are used on the linearized perturbation equations. The analysis is done by normal mode analysis theory. The dispersion relation is analyzed to obtain the Jeans criterion of instability. Numerical results are presented to show the effect of the polarization parameter, the magnetic field and the strong correlation effect of dust. The growth rates are further compared in the kinetic and hydrodynamic regime of propagation. It is observed that the decay in the growth rate is faster in the kinetic mode of propagation in comparison to the hydrodynamic mode.

Observing the effects of the polarization force in strongly coupled dusty plasmas with suprathermal electrons

Our objective here is to investigate a strongly coupled dusty plasma system with the presence of polarization force (PF). This plasma consists of superthermal electrons, Maxwellian ions, and negatively charged dust grains. The nonlinear propagation of dust-acoustic (DA) waves in such dusty plasma system has been theoretically investigated by employing the reductive perturbation method. The Burgers’ and K-dV equations have been derived to and numerically analyzed. It has been found that the dust-acoustic shock and solitary waves exist associated with a negative potential only, and that the effect of the dust fluid temperature significantly modifies the basic properties (amplitude and width) of such nonlinear waves’ potential structures. We hope that the results of our present investigation should help us in understanding the localized electrostatic disturbances in space and laboratory strongly coupled dusty plasmas with superthermal electrons and polarization force.

Roles of polarization force and nonthermal electron on dust-acoustic waves in an inhomogeneous dusty plasma with positively charged dust

The influence of polarization force (PF) (arises due to dust density inhomogeneity), nonthermal electrons, and dust density inhomogeneity associated with positively charged dust on linear dust-acoustic (DA) waves in an inhomogeneous unmagnetized dusty plasma are investigated. By taking the normal mode analysis, the dispersion relation in such a non-Maxwellian inhomogeneous plasma is obtained, and that the dispersion properties of the DA waves are significantly modified by the presence of PF and nonthermal electrons. The PF is increased with the increase of nonthermal electrons. It is found that the phase speed of the DA waves is significantly decreased with the presence of PF and nonthermal electrons. The potential associated with the DA waves is de-enhanced with the increase of equilibrium dust number density. The role of positive dust number density on dispersion properties is also shown. The present findings relevant to different scenarios in laboratory and space dusty plasma, such as Martian ionosphere, solar flares, TEXTOR-94 tokamak plasmas, rf excited argon magnetoplasma, etc., can be useful to understand the properties of localized electrostatic disturbances in those dusty plasma system, are also briefly addressed.

Dust-acoustic waves in a nonuniform adiabatic dusty plasma in the presence of polarization force

The linear propagation of the dust-acoustic (DA) waves in a nonuniform adiabatic dusty plasma, which consists of inertialess adiabatic electrons, inertialess adiabatic ions, and inertial negatively charged dust by taking into account the effects of polarization force, is theoretically investigated. It is found that the linear dispersion properties of the DA waves are significantly modified by the dust density nonuniformity, adiabaticity of electrons and ions, and the effects of the polarization force. It is shown that the phase speed of the DA waves is increased with the increase of adiabaticity of electrons and ions but decreased with the increase of the effects of polarization force. It is also shown that the dust density is enhanced with the increase of adiabatic index but depleted with the increase of polarization force. The scenarios relevant to dust-ion plasma in space environments are briefly addressed.

Effects of polarization force and fast electrons on DA shock waves in a strongly coupled dusty plasma

AbstractA strongly coupled dusty plasma system consisting of non-thermal electrons, Maxwellian ions, and negatively charged dust in presence of polarization force has been considered. The nonlinear propagation of dust-acoustic shock waves in such a dusty plasma system has been theoretically investigated by employing the reductive perturbation method. The effects of the polarization force and non-thermal electrons, on the properties of these dust-acoustic shock waves are briefly discussed. It is shown that the strong correlation among the charged dust grains is a source of dissipation, and is responsible for the formation of the dust-acoustic shock waves. It has been found that the effects of polarization force and non-thermal electrons significantly modify the basic features of such shock waves. It has been proposed to design a new laboratory experiment, which will be able to identify the basic features of the dust-acoustic shock waves predicted in this present investigation.

Dust-acoustic waves in nonuniform dusty plasma in presence of polarization force

The effects of the dust density nonuniformity and the polarization force on linear propagation of the dust-acoustic waves in a nonuniform dusty plasma (consisting of electrons, ions, and arbitrarily charged dust particles) have been theoretically investigated. It has been shown that the linear dispersion properties of the dust-acoustic (DA) waves have been significantly modified by the dust density nonuniformity, dust polarity, and the polarization force. It is also found here that the phase speed of the DA waves is decreased by the effects of polarization force, and that their amplitude increases with the decrease of equilibrium dust number density. The different situations, which are relevant to different space and laboratory dusty plasmas, have been briefly discussed.

Dust-acoustic solitary waves in a strongly coupled inhomogeneous dusty plasma in the presence of polarization force and effective dust-temperature

The nonlinear propagation of the dust-acoustic waves is studied in a strongly coupled inhomogeneous dusty plasma which consists of the strongly correlated negatively charged dust grains and weakly correlated electrons and ions. The Korteweg-de Vries equation with variable coefficients and an additional term due to the density gradient is deduced, and its solution is found by appropriate transformations. The propagation of two possible modes (fast and slow) and their evolution are investigated. Only the fast rarefactive solitary waves are found to propagate in such plasma with parameter ranges corresponding to the experimental conditions. It is shown that the special patterns of nonlinear DA waves (e.g., amplitude and width) are significantly modified in a way that depends upon the effects of polarization force (which arises due to the interaction between thermal ions and highly negatively charged dust grains), effective dust-temperature (which arises from the electrostatic interactions among highly negatively charged dust and from the dust thermal pressure), equilibrium electron density, and ion temperature. The amplitude of solitary waves also decreases as the wave propagates in the direction of increasing dust concentration.