Inertial Dust Grains Research Articles

The impact of polarization force on the oblique propagation of dust-acoustic solitons in a superthermal complex magnetoplasma

This work aims to examine the (non)linear properties of the dust-acoustic waves (DAWs) in a polarized superthermal complex magnetoplasma. The existing plasma model consists of inertial dust grains and inertialess electrons and ions. The electrons in this model adhere to the Maxwell–Boltzmann distribution, while the ions conform to the superthermal distribution. It is postulated that the electrostatic waves propagate obliquely with the magnetic field. The Sagdeev potential approach is employed to reduce the basic model equations to an equivalent energy balance equation. It is shown how the existence domain and the properties of large amplitude obliquely propagating dust-acoustic solitary waves (DASWs) are affected via the characteristic relevant plasma parameters. The implication of the study is highlighted to the space dusty plasma.

Effect of Gurevich Polarization Force on Arbitrary Amplitude Dust-Acoustic Waves and Double-Layer Structures in a Collisionless Complex Plasma

In this article, we have investigated the effect of the Gurevich polarization force on both large-amplitude dust-acoustic (DA) solitary waves and double-layer (DL) structures in a collisionless complex plasma. To do this, we have redefined the 3-D Gurevich distribution, which describes the evolution of the adiabatically trapped ions in the plasma potential well and derived the associated density and polarization force expressions. As an application, we have reviewed, using the pseudo-potential approach, the nonlinear DA solitons in an unmagnetized polarized complex plasma containing inertial dust grains, Maxwellian electrons, and adiabatically trapped ions. We have shown that the spatial profile of DA solitary waves is drastically affected by the Gurevich polarization force. In particular, we have found that due to the presence of this polarization force, the potential pulse amplitude increases while its width decreases, thus making the DA structure more spiky. For the sake of completeness, we have also analyzed the effect of the polarization force on DA-DL structures. Our numerical results have shown that both amplitude and width of rarefactive (compressive) DL DA structure decrease (increase) in the presence of polarization force.

On the dynamics of nonlinear propagation and interaction of the modified KP solitons in multicomponent complex plasmas

Dust-acoustic waves (DAWs) are analyzed in the small amplitude limit in a collisionless unmagnetized dusty plasma whose constituents are inertial dust grains, massless ions expressed by the generalized (r,q) distribution and inertialess Maxwellian electrons using the fluid theory of plasmas. The modified Kadomtsev-Petviashvili (mKP) equation is derived at a critical plasma condition for which the quadratic nonlinearity vanishes. The propagation of single soliton and interaction of two solitons are analyzed for the mKP equation in the context of plasma physics by employing Hirota bilinear formalism. The effects of the flatness parameter r and tail parameter q of the ions on the frequency of the DAWs are studied and the comparison with Maxwellian and kappa distributions is drawn. Using the plasma parameters corresponding to the Saturn’s E-ring, the range of electric field amplitude for dust-acoustic solitary waves (DASWs) for different ion distributions is calculated and is shown to agree very well with the Cassini Wideband Receiver (WBR) observations. The interaction time of two DASWs for non-Maxwellian ion distributions is estimated and shown to be fastest for the (r,q) distributed ions. The interesting feature of the interaction between compressive solitons with their rarefactive counterparts is also discussed in detail.

Adapted instabilities excited in spherical magnetized viscoelastic astroclouds with extreme dust-fugacity moderations

We investigate the dynamics of the dust acoustic wave (DAW, low-fugacity) and the dust Coulomb wave (DCW, high-fugacity) in self-gravitating magnetized viscoelastic spherical dusty astroclouds. It consists of the inertial dust grains with variable charge alongside the nonthermal electrons and ions in a generalized hydrodynamic framework. A spherical wave analysis yields a unique generalized quadratic dispersion relation. The fluctuations are free from the viscoelasticity effects in the weakly coupled limit (WCL) against the strongly coupled limit (SCL). The electron concentration, dust charge, and magnetic field act as stabilizing and accelerating agencies. The ion density and nonthermality parameters show destabilizing and decelerating effects. The cloud size shows a unique stabilizing feature in the ultralow-frequency domain. Both the DAW and DCW are dispersive in the short-wavelength (acoustic) regime and nondispersive in the long-wavelength (gravitational) regime. The distinctive WCL–SCL scenarios are explicitly compared. The results show correlative consistencies in real astronomic circumstances sketchily. The dust acoustic wave (DAW) and the dust Coulomb wave (DCW) in self-gravitating magnetized viscoelastic spherical dusty astroclouds with extreme dust-fugacity moderations are explored. The spatiospectral profiles of (a) $$\Omega_{r}$$ and (b) $$\Omega_{i}$$ with $$K$$ and $$\xi$$ in the SCL (upper row) and in the WCL (lower row) of the HFR in the $$\kappa$$ -case are numerically portrayed.

Dust-acoustic envelope solitons in strongly coupled dusty plasmas

The propagation nature and the modulational instability (MI) criteria of low frequency amplitude modulated dust-acoustic envelope solitons are analyzed theoretically and numerically in an unmagnetized dusty plasma consisting of strongly coupled micron-sized inertial dust grains, Boltzmann distributed non-inertial electrons and ions. A hydrodynamical fluid model approach is used, based on [V. V. Yaroshenko, F. Verheest, H. M. Thomas and G.E. Morfill, New J. Phys. 11, 073013 (2009); V. V. Yaroshenko, V. Nosenko, and G. E. Morfill, Phys. Plasmas, 17, 103709 (2010)], where the strong coupling between dust grains for by an effective electrostatic pressure is accounted, which is in fact a dynamical function of the dust-density and the electrostatic potential. It is seen that the strong coupling between dust particles due to the effective electrostatic ``pressure” modifies the wavepacket stability and affects the occurrence of MI. A cubic nonlinear Schrodinger-type equation, which describes the evolution of the wavepacket’s envelope, is derived by adopting a multiscale technique for the amplitude dynamics. It is shown that long-wavelength dust-acoustic wavepackets are stable, while MI sets in beyond a carrier wavenumber threshold, which is evaluated in terms of intrinsic plasma parameters of relevance. On the other hand, the MI window is larger for higher ion density. The effect of the ion number density on MI is twofold, in that a higher ion density leads to a higher threshold (thus, the wave will be modulationally unstable for the larger values of the carrier wavenumber) but it also entails a wider instability window (hence, external perturbations must be of specific wavenumbers to trigger the instability). Numerical simulation confirms that the bright-type envelope soliton solution is stable beyond the carrier wavenumber threshold, i.e., in the modulationally unstable region, while the dark type envelope soliton is stable for wavenumbers below the threshold.

Study of Dust Acoustic Wave Propagation in a Lorentzian Dusty Plasma in Presence of Secondary Electron Emission

In this paper, we have investigated the effect of secondary electron emission on the propagation characteristics of linear dust acoustic waves in dusty plasmas consisting of suprathermal inertialess primary electrons, secondary electrons, Boltzmann distributed ions, and negatively charged inertial dust grains. The suprathermal electrons are assumed to follow kappa velocity distribution. We have derived the linear dispersion relation and shown that real and imaginary frequencies of the waves are influenced by the strength of secondary electron emission as well as suprathermal electron population.

The Maximum Amplitude of Dust-Acoustic Waves in Dusty Plasma with Vortex-Like Ions

Theoretical investigations are carried out for the properties of small amplitude dust-acoustic solitary waves in plasmas consisting of extremely massive, high negatively charged inertial dust grains, Boltzmann distributed electrons and trapped ions, for one-dimensional case and three-dimensional case. An energy integral equation involving the Sagdeev potential is derived. The dependence of the critical Mach number corresponding to maximum amplitude on other parameters is obtained. It is observed that the magnitude of the external magnetic field has no effect on the amplitude of the solitary waves.

Ion Nonthermality Induced Nonlinear Dust Acoustic Wave Propagation in a Complex Plasma in Presence of Weak Secondary Electron Emission from Dust Grains

In this paper we have investigated the effect of ion nonthermality on nonlinear dust acoustic wave propagation in a complex plasma in presence of weak secondary electron emission from dust grains. Equilibrium dust charge in this case is negative. Dusty plasma under our consideration consists of inertialess nonthermal ions, Boltzman distributed primary and secondary electrons and negatively charged inertial dust grains. Both adiabatic and nonadiabatic dust charge variations have been taken into account. Our analysis shows that in case of adiabatic dust charge variation, at a fixed non-zero ion nonthermality increasing secondary electron emission decreases amplitude and increases width of the rarefied dust acoustic soliton whereas for a fixed secondary electron yield increasing ion nonthermality increases amplitude and decreases width of such rarefied dust acoustic soliton. Thus shape of the soliton may be retained if strength of both the secondary electron yield and the ion nonthermality are increased. Nonadiabatic dust charge variation shows that, at fixed non-zero ion nonthermality, increasing secondary electron emission suppresses oscillation of oscillatory dust acoustic shock at weak nonadiabaticity and pronounces monotonicity of monotonic dust acoustic shock at strong nonadiabaticity. On the other hand at a fixed value of the secondary electron yield, increasing ion nonthermality enhances oscillation of oscillatory dust acoustic shock at weak nonadiabaticity and reduces monotonicity of monotonic dust acoustic shock at strong nonadiabaticity. Thus nature of dust acoustic shock may also remain unchanged if both secondary electron yield and ion nonthermality are increased.

Nonplanar electrostatic shock waves in an opposite polarity dust plasma with nonextensive electrons and ions

A rigorous theoretical investigation has been carried out on the propagation of nonplanar (cylindrical and spherical) dust-acoustic shock waves (DASHWs) in a collisionless four-component unmagnetized dusty plasma system containing massive, micron-sized, positively and negatively charged inertial dust grains along with q (nonextensive) distributed electrons and ions. The well-known reductive perturbation technique has been used to derive the modified Burgers equation (which describes the shock wave properties) and its numerical solution. It has been observed that the effects of charged dust grains of opposite polarity, nonextensivity of electrons and ions, and different dusty plasma parameters have significantly modified the fundamental properties (viz., polarity, amplitude, width, etc.) of the shock waves. The properties of DASHWs in nonplanar geometry are found to be significantly different from those in one-dimensional planar geometry. The findings of our results from this theoretical investigation may be useful in understanding the nonlinear features of localized electrostatic disturbances in both space and laboratory dusty plasmas.

Higher order nonlinear dust-acoustic waves in a dusty plasma with dust of opposite polarity

The nonlinear propagation of dust-acoustic (DA) waves in an unmagnetized dusty plasma (containing positive and negatively charged inertial dust grains and nonextensive distributed electrons and ions) have been investigated theoretically. Three different types of nonlinear dynamical equations, namely, Korteweg-de Vries (K-dV), modified K-dV (mK-dV) and Gardner equations have been derived by employing the reductive perturbation method. The basic features (viz., polarity, amplitude, width, etc.) of solitary waves have been also analyzed numerically. It has been observed that the effects of nonextensivity of electrons and ions, mass and charge of positive and negative dust, and different dusty plasma parameters have significantly modified the fundamental properties of the solitary waves.

Small-amplitude shock waves and double layers in dusty plasmas with opposite polarity charged dust grains

Theoretical investigation is carried out for understanding the properties of nonlinear dust-acoustic (DA) waves in an unmagnetized dusty plasma whose constituents are massive, micron-sized, positive and negatively charged inertial dust grains along with q (nonextensive) distributed electrons and ions. The reductive perturbation method is employed in order to derive two types of nonlinear dynamical equations, namely, Burgers equation and modified Gardner equation (Gardner equation with dissipative term). They are also numerically analyzed to investigate the basic features (viz., polarity, amplitude, width, etc.) of shock waves and double layers. It has been observed that the effects of nonextensivity, opposite polarity charged dust grains, and different dusty plasma parameters have significantly modified the fundamental properties of shock waves and double layers. The results of this investigation may be used for researches of the nonlinear wave propagation in laboratory and space plasmas.

Landau damping of dust acoustic waves in a dusty plasma

By using the Vlasov equation, Landau damping of dust acoustic waves is investigated by assuming Maxwell velocity distribution of dust grains for a three component, unmagnetized and collisionless dusty plasma consisting of extremely massive, high negatively charged inertial dust grains, inertialess Boltzmann distribution of ions and electrons with charge neutrality at equilibrium. It is observed that for long wave length, Landau damping is weak, while it is strong for short wave length. Landau damping in a dusty plasma is also explained.

Effects of nonthermal ions of distinct temperatures on dust acoustic shock waves in a dusty plasma

The nonlinear propagation of dust acoustic (DA) waves in an unmagnetized dusty plasma system consisting of negatively charged mobile dust fluid, Boltzmann distributed electrons, and two-temperature nonthermally distributed ions, is rigorously investigated. The reductive perturbation method has been employed to derive the Burgers equation. The hydrodynamic equation for inertial dust grains has been used to derive the Burgers equation. The effects of two temperature nonthermally distributed ions and dust kinematic viscosity, which are found to significantly modify the basic features of DA shock waves, are briefly discussed. Our present investigation can be effectively utilized in many astrophysical situations (e.g. satellite or spacecraft observations, Saturn’s E ring, etc.), which are discussed briefly in this analysis.

Effect of secondary electron emission on Jean's instability in a complex plasma in the presence of nonthermal ions

In this paper, we have investigated the role of secondary electron emission on Jean's instability in a complex plasma in the presence of nonthermal ions. The equilibrium dust surface potential has been considered negative and hence primary and secondary electron temperatures are equal. Such plasma consists of three components: Boltzman distributed electrons, nonthermal ions and negatively charged inertial dust grains. From the linear dispersion relation, we have calculated the real frequency and growth rate of Jean's instability. Numerically, we have shown that for strong ion nonthermality Jean's mode is unstable. Growth of the instability reduces and the real part of the wave frequency increases with increasing secondary electron emission from dust grains. Hence, strong secondary electron emission suppresses Jean's instability in a complex plasma even when ion nonthermality is strong and equilibrium dust charge is negative.

Lagrangian description of nonlinear dust-ion acoustic waves in dusty plasmas

An analytical model is presented for the description of nonlinear dust-ion-acoustic waves propagating in an unmagnetized, collisionless, three component plasma composed of electrons, ions and inertial dust grains. The formulation relies on a Lagrangean approach of the plasma fluid model. The modulational stability of the wave amplitude is investigated. Different types of localized envelope electrostatic excitations are shown to exist.

New resonance and cut-off for low-frequency electromagnetic waves in dusty magnetoplasmas

The dispersion properties of low-frequency (in comparison with the ion gyrofrequency) dust-electromagnetic waves in a four-component magnetized dusty plasma have been investigated. It has been shown that the simultaneous presence of positive and negative inertial dust grains introduces new resonance and cut-off for dust-electromagnetic waves, and a sharp forbidden- frequency-band in between the two branches of the propagating dust-electromagnetic waves. The two wave branches have been found to have frequencies of the order of negative and positive dust gyrofrequencies, respectively. The effects of space and laboratory dusty plasma parameters on these newly found resonance and cut-off and on the dispersion properties of the dust-electromagnetic wave branches have also been examined.

Large Amplitude Solitons and Double Layers in Multicomponent Dusty Plasmas

Supposing that the constituents of dusty plasmas are inertialess electrons, inertialess ions, and an admixture of negatively and positively charged inertial dust grains, and employing the nonlinear multi-fluid dusty plasma equations and Poisson's equation, we have derived dynamical equations for small amplitude nonlinear dust-acoustic waves, as well as the energy integral of a classical particle with a modified Sagdeev potential for large amplitude disturbances. The energy integral is analyzed both analytically and numerically to demonstrate the existence of rarefactive and compressive electrostatic potentials which travel faster than the effective dust-acoustic velocity. Compressive dust-acoustic potential exist only when there is a significant fraction of positively charged dust grains. Furthermore, the four-fluid dusty plasma system also admit double layers.