Dusty Magnetoplasma Research Articles

On the nonlinear dynamics of large scale dust-acoustic solitary waves in a superthermal bi-ion dusty ionospheric magnetoplasma

The purpose of this study is to examine the properties of the dust-acoustic solitary waves in a complex magnetoplasma made up of negatively charged moving dust grains in the lower ionospheric region and inertialess electrons and ions obeying Maxwell and kappa distributions, respectively. In this context, the reductive perturbation technique is carried out to obtain the Zakharov–Kuznetsov (ZK) equation within the given framework. The obtained evolution equation, i.e., ZK equation is transformed to a planar dynamical system for studying the qualitative behavior of the solitary waves. The impact of important physical parameters, such as the dust number density, ion concentration, ion temperature, superthermality, and the background magnetic field, on the profile of the nonlinear structures is numerically investigated. The findings may be utilized to comprehend the low-frequency irregularities that are detected in the lower ionosphere.

Excitation of kinetic Alfvén waves by streaming ions in a dusty magnetoplasma with generalized (r, q) distribution function

AbstractWe investigate the parallel streaming effects on the dispersion characteristics of a kinetic Alfvén wave (KAW) in a low β dusty magnetoplasma. To analyse the influence of streaming ions obeying generalized (r, q) distribution function, hot and magnetized electrons, and mobile charged dust, a theoretical approach has been used for the instability analysis by employing two potential theories. A linear kinetic dispersion relation of Alfvén waves is derived, whose solutions are used to interpret the numerical and analytical results. The solutions of dispersion relation indicate that the characteristics of KAWs are transformed when generalized (r, q) distribution function is employed instead of its Maxwellian counterpart. We also found that the unstable modes have a strong dependence on spectral indices r and q, dust parameters, and plasma β. For the excitation of KAWs, the streaming velocity has been observed to be within the sub‐Alfvén range, whereas when it extends to the super‐Alfvén range, the growth rates are significantly suppressed. The observations further show that an ambient magnetic field and superthermal particles inhibit the growth of an electromagnetic wave to a significant degree and have a stabilizing effect on the wave mode, whereas an increasing concentration of low‐energy particles contributes to enhancing growth rates.

Dynamic charging effect on electromagnetic wave in low $\beta $ plasmas

Low beta plasma system is chosen for the study of low frequency electromagnetic Shear Alfven waves exhibiting dynamical charging of micron/sub micron size dust particles. A semi classical Quantum Hydrodynamic Model (QHD) is employed which includes the quantum effects for plasma electrons in the terms of statistical degenerate pressure, Landau quantization, exchange-correlation potential, and tunneling potential. The low beta plasma characteristics provides the opportunity for the usage of two potential theory in order to derive a complex equation of dispersion of the shear Alfven wave in quantum dusty magneto plasmas. Analytical simplification of dispersion equation provides the damping rate of the Shear Alfven wave which is verified graphically for a typical set of parameters. It is noticed that the damping rate depends upon the quantum properties of Landau quantization, exchange-correlation, and tunneling potential in addition to the dust radius which modifies the floating potential of the dust particles. This work may seek its applications in the astrophysical objects in general, and in the semiconductor laboratory plasmas for particular dust size and magnetic field.

Low-frequency plasma waves in a radiative dusty magnetoplasma

The impact of electromagnetic (thermal) radiation on the dispersive low-frequency waves is examined in a radiative dusty magnetoplasma. For this purpose, a magneto-hydrodynamic model along with the Maxwell equations is employed to describe the three-component radiative dusty plasma that contains inertialess electrons, dynamical positive ions and negatively charged static dust particulates. The behavior of the electrostatic and electromagnetic waves significantly changes in a plasma medium when a radiation pressure is taken into consideration, as compared to the waves in vacuum. After seeking a plane wave solution, a general dispersion relation is obtained to investigate different limiting cases of the low-frequency modes propagating parallel, perpendicular and oblique to the external magnetic field direction both analytically and numerically. The calculations reveal that the usual thermal and acoustic speeds (cT, ca) do not remain constant even if the temperature is kept constant, because of the radiation pressure which strongly depends on the equilibrium number density as well. The present results may prove a useful understanding for the new features of the dispersive dust-ion-acoustic and compressional Alfven waves in astrophysical dusty magnetoplasmas.

Potential Distribution in a Strongly Coupled Dusty Magnetoplasma

The potential distribution around a test charge particle is studied in a strongly coupled dusty magnetoplasma. Special emphasis is given to study the combined influence of the strong interaction between the charged dust grains and the external magnetic field on the potential distribution. It is found that these effects significantly modify the potential profile. For example, an increase in the coupling parameter increases the potential amplitude and then can change the polarity of the response potential. The present results may be useful in laboratories as applications of wave–particle interactions [i.e., inertial confinement fusion (ICF) scheme, particle acceleration, and heavy-ion pumped X-ray lasers], as well as in space plasmas (i.e., dust coagulation in space).

Multidimensional freak waves in electron depleted dusty magnetoplasmas having superthermal ion with two temperatures

The three-dimensional modulational instability (MI) and the associated electrostatic freak waves in electron depleted dusty magnetoplasmas having two temperature ions obeying Kappa distribution with transverse plane perturbations are investigated. For this purpose, the three-dimensional (3D) nonlinear Schrodinger equation (NLSE) is derived using the multi-scale perturbation technique. The regions of stable and unstable structures are determined precisely depending on a new criterium different from that of the one-dimensional (1D) NLSE. In the unstable regions the first- and second-order rogue waves are examined. The dependence of MI and freak waves on the relevant plasma parameters, namely, modulational obliqueness, cold ion concentration, cold-to-hot ion temperature ratio, dust gyrofrequency, and the spectral indices of the cold and hot ions are investigated. The present investigation is useful in space and laboratory magnetoplasmas, for instance, Geotail spacecraft observations seen in Earth’s magnetotail, solar wind, interstellar medium, and in the magnetosphere of Jupiter.

Arbitrary Amplitude Oblique Electrostatic Solitary Waves in a Degenerate Cold Dusty Magnetoplasma

Linear and nonlinear properties of obliquely propagating waves are studied in a degenerate dense cold magnetoplasma, comprising of Thomas–Fermi distributed electrons and ions as well as non-degenerate negatively charged dust particulates. By using the plane wave approximation, a linear dispersion relation for the dust-cyclotron (DC) and dust-acoustic (DA) waves is derived and analyzed numerically. For fully nonlinear waves, a Sagdeev pseudopotential theory is employed to derive an energy-balance equation and the soliton existence domain depending upon the dust concentration $(h)$ , obliqueness $(L_{z})$ , and Mach number $(M)$ . Numerical analysis reveals that the parameter $h$ enhances the domain for allowed Mach numbers, i.e., $M_{1} and therefore favoring the solitary excitations, where $M_{1}$ and $M_{2}$ are the lower and upper Mach numbers, respectively. In addition, the dust concentration significantly reduces the amplitude and the profile sharpness of the solitary pulses. Similarly, variations in the obliqueness parameter and the Mach numbers modify the wave characteristics. This paper is important for understanding the nonlinear properties of electrostatic excitations in degenerate dusty magnetoplasma, relevant to white dwarfs (WDs), namely $GD56,\,\,GD29-38,\,\,GD362$ , and $WD2115-560$ , being termed as the DUSTY DAZ WDs.

Electrostatic Solitary Pulses in a Dusty Electronegative Magnetoplasma

The nonlinear characteristics of dust-electron-acoustic (DEA) waves in a dusty electronegative magnetoplasma system consisting of nonextensive hot electrons, inertial cold electrons, positively charged static ions, and negatively charged immobile dust grains has been investigated. In this observation, the well-known reductive perturbation technique is employed to determine different types of nonlinear dynamical equations, namely, magnetized Korteweg–de Vries (KdV), magnetized modified KdV (mKdV), and magnetized Gardner equations. The stationary solitary wave and double layer solution of these three equations, which describe the characteristics of solitary waves and double layers of DEA waves, are obtained and numerically analyzed. It is noticed that various plasma parameters (viz., hot electron nonextensivity, positive ion-to-cold electron number density ratio, dust-to-cold electron number density ratio, etc.) significantly affect the basic properties of DEA solitary waves (DEASWs) and Gardner solitons (GSs). The prodigious results found from this theoretical investigation may be useful for researchers to investigate the nonlinear structures in various space and laboratory plasmas.

On the dielectric response function and dispersion relation in strongly coupled magnetized dusty plasmas

Using the generalized viscoelastic fluid model, we derive the dielectric response function in a strongly coupled dusty magnetoplasma which reveals two different dust acoustic (DA) wave modes in the hydrodynamic and kinetic limits. The effects of the strong interaction of dust grains and the external magnetic on these DA modes, as well as on the shear wave are examined. It is found that both the real and imaginary parts of DA waves are significantly modified in strongly coupled dusty magnetoplasmas. The implications of our results to space and laboratory dusty plasmas are briefly discussed.

Modified Jeans instability of collisional dusty magnetoplasma in presence of radiative cooling and dust charge fluctuation

We have investigated the modifications in the self-gravitational instability of magnetized collisional dusty plasma, arising from the radiative effects of electrons and ions, and charge fluctuation of dust. The electron and ion dynamics are described by their radiative effects and considering the full dynamics of dust and neutrals, the general dispersion relation is derived. The properties of the general dispersion relation are discussed in the absence and presence of dust charge fluctuation. The results of these two cases are further reduced for parallel and perpendicular modes of propagation. The consequences of magnetic field, collisions, dust charge fluctuation, and radiative condensation on the growth rate of self-gravitational instability are discussed analytically and graphically. We found that the radiative effects and dust charge variation increase the growth rate of self-gravitational instability while the presence of magnetic field and collisions shows the stabilizing behavior. The findings are discussed in context of the structure formation in interstellar clouds.

Nonlinear beat excitation of low frequency wave in degenerate plasmas

The beat phenomenon due to the coupling of two signals at slightly different frequencies that generates the low frequency signal is studied. The linear dispersive properties of the pump and sideband are analyzed. The modified nonlinear dispersion relation through the field coupling of linear modes against the beat frequency is derived in the homogeneous quantum dusty magnetoplasmas. The dispersion relation is used to derive the modified growth rate of three wave parametric instability. Moreover, significant quantum effects of electrons through the exchange-correlation potential, the Bohm potential, and the Fermi pressure evolved in macroscopic three wave interaction are presented. The analytical results are interpreted graphically describing the significance of the work. The applications of this study are pointed out at the end of introduction.

Streaming Jeans-Alfvén Instability in Quantum Magnetoplasmas

Abstract The physical mechanism of magnetosonic perturbations which modifies the Jeans instability in streaming quantum dusty magnetoplasmas is examined. These perturbations are low frequency and electromagnetic in nature that propagate with Alfvén speed. The fluid model consisting of momentum balance equations for quantum plasmas, Poisson’s equation for gravitational potential, and Maxwell’s equations for magnetosonic perturbations is used for the coupled solution. The numerical analysis of the dispersion relation elaborates the significant contribution of streaming speed of plasma species at equilibrium v 0, uniform external magnetic field B 0, electron number density at equilibrium n 0e, and variable dust mass m d over the Jeans instability. This study helps to understand the possible mechanism responsible for the formation of astrophysical objects.

The Exchange-Correlation Field Effect over the Magnetoacoustic-Gravitational Instability in Plasmas

Abstract Jeans instability with magnetosonic perturbations is discussed in quantum dusty magnetoplasmas. The quantum and smaller thermal effects are associated only with electrons. The quantum characteristics include exchange-correlation potential, recoil effect, and Fermi degenerate pressure. The multifluid model of plasmas is used for the analytical study of this problem. The significant contribution of electron exchange is noticed on the threshold value of wave vector and Jeans instability. The presence of electron exchange and correlation effects reduce the time to stabilise the phenomenon of self-gravitational collapse of massive species. The results of Jeans instability by magnetosonic perturbations at quantum scale help to disclose the details of the self-gravitating dusty magnetoplasma systems.

Backward propagating branch of surface waves in a semi-bounded streaming plasma system

The influence of wake and magnetic field on the surface ion-cyclotron wave is kinetically investigated in a semi-bounded streaming dusty magnetoplasma in the presence of the ion wake-field. The analytic expressions of the frequency and the group velocity are derived by the plasma dielectric function with the spectral reflection condition. The result shows that the ion wake-field enhances the wave frequency and the group velocity of the surface ion-cyclotron wave in a semi-bounded dusty plasma. It is found that the frequency and the group velocity of the surface electrostatic-ion-cyclotron wave increase with an increase of the strength of the magnetic field. It is interesting to find out that the group velocity without the ion flow has the backward propagation mode in a semi-bounded dusty plasma. The variations due to the frequency and the group velocity of the surface ion-cyclotron wave are also discussed.

Drift vortices in inhomogeneous collisional dusty magnetoplasma**Project supported by the National Natural Science Foundation of China (Grant Nos. 11365017, 11465015, 11405110, 11305031, and 11404214) and the Technology Landing Project of the Education Department of Jiangxi Province of China (Grant No. KJLD13086).

For the sake of investigating the drift coherent vortex structure in an inhomogeneous dense dusty magnetoplasma, using the quantum hydrodynamic model a nonlinear controlling equation is deduced when the collision effect is considered. New vortex solutions of the electrostatic potential are obtained by a special transformation method, and three evolutive cases of monopolar vortex chains with spatial and temporal distribution are analyzed by representative parameters. It is found that the collision frequency, particle density, drift velocity, dust charge number, electron Fermi wavelength, quantum correction, and quantum parameter are all influencing factors of the vortex evolution. Compared to the uniform dusty system, the vortex solutions of the inhomogeneous system present richer spatial evolution and physical meaning. These results may explain corresponding vortex phenomena and support beneficial references for the dense dusty plasma atmosphere.

Ion-Temperature-Gradient-Driven Modes with Nonthermal Electron Distributions in Bi-ion Dusty Magnetoplasma

The effect of nonthermal distributions of electrons on ion-temperature-gradient (ITG)-driven drift modes in the presence of tiny dust particles for bi-ion magneto plasmas is investigated. The dynamics of bi-ions and dust particles is considered for the study of low-frequency (less than the gyrofrequencies of dust and ions) ITG mode. A new dispersion relation is derived and analyzed numerically as well as analytically. Three different distributions for nonthermal electrons (Kappa, q, and Cairns distribution) are used. It is found that the presence of nonthermal electrons in bi-ion dusty magnetoplasma reduces the growth rate of the ITG instability. These results should be useful for laboratory and space plasmas where nonthermal electrons and dust is always present.

Jeans-Alfvén instability in quantum dusty magnetoplasmas

The Jeans instability is examined in quantum dusty magnetoplasmas due to low-frequency magnetosonic perturbations. The fluid model consisting of the momentum balance equation for quantum plasmas, Poisson’s equation for the gravitational potential and Maxwell’s equations for electromagnetic magnetosonic perturbations is solved. The numerical analysis elaborates the significant contribution of magnetic field, electron number density and variable dust mass to the Jeans instability.

Low frequency modes and instability analysis in non-thermal dusty magnetoplasma considering dust charge fluctuation and polarization force

The effect of non-thermal ion population on self-gravitational instability of magnetized dusty plasma considering electrons are in Maxwell-Boltzmann distribution has been investigated. The dust dynamics is described including polarization force, thermal velocity, and charge fluctuation dust. The modified general dispersion relation has been derived including non-thermal ion population, polarization force, and dust charge fluctuation for self-gravitating dusty plasma system, using the normal mode analysis method. The obtained general dispersion relation is discussed in parallel and perpendicular modes of propagation. The population of non-thermal ion, polarization force and dust charge fluctuation affect the self-gravitational instability criteria in both the modes of propagation while the magnetic field affects the instability criterion only in perpendicular mode of propagation. The domains of instability has been discussed analytically to signify the importance of considered parameters. The stability of the self-gravitating dusty plasma system has been analyzed using Routh-Hurwitz stability criterion. Numerical calculations have been performed to analyze the effects of non-thermal ion population, polarization force, and dust charge fluctuation on the growth rate of self-gravitational instability. The results of the present work can be useful in self-gravitating dusty plasma found in space and the interstellar medium such as the interstellar molecular clouds where non-thermally distributed ions are the species of the plasma matter.

Dust acoustic waves in collisional uniform dense magnetoplasma**Project supported by the National Natural Science Foundation of China (Grant Nos. 11365017, 11465015, 11305031, 11405110, and 11275123) and the Technology Landing Project of the Education Department of Jiangxi Province of China (Grant No. KJLD13086).

In order to study the characteristics of dust acoustic waves in a uniform dense dusty magnetoplasma system, a nonlinear dynamical equation is deduced using the quantum hydrodynamic model to account for dust–neutral collisions. The linear dispersion relation indicates that the scale lengths of the system are revised by the quantum parameter, and that the wave motion decays gradually leading the system to a stable state eventually. The variations of the dispersion frequency with the dust concentration, collision frequency, and magnetic field strength are discussed. For the coherent nonlinear dust acoustic waves, new analytic solutions are obtained, and it is found that big shock waves and wide explosive waves may be easily produced in the background of high dusty density, strong magnetic field, and weak collision. The relevance of the obtained results is referred to dense dusty astrophysical circumstances.

Electromagnetic waves and instabilities in a non-degenerate quantum dusty plasma

In this paper, we have investigated the effects of Bohm potential on the low frequency wave propagation in a dense non-degenerate dusty magnetoplasma. We have employed two potential theory to study the quantum modification of kinetic Alfvén wave on a dust acoustic velocity branch. The linear dispersion relation and growth rate of instability of dust kinetic Alfvén wave are obtained by incorporating Bohm quantum potential in the linearized Vlasov model. It is found that unlike in classical plasma, the presence of CQ which arises through the Bohm potential, tends to enhance the dispersion of the particles, while the growth rates are suppressed. The importance and relevance to compact astrophysical objects and space dusty plasma environments is also pointed out.