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Different kinds of waves and instabilities in the F-region of the ionosphere excited by the relative streaming of the dust beam to the background plasma are studied in the present paper. The dispersion relations of different waves are obtained on different time scales. It is found from our numerical results that there are both a stable upper hybrid wave on the electron vibration time scale and a stable dust ion cyclotron wave on the ion vibration time scale. However, the chaotic behaviour appears on the dust particles vibration time scale due to the relative streaming of the dust particles to the background plasma. Such instabilities may drive plasma irregularities that could affect radar backscatter from the clouds. [ABSTRACT FROM AUTHOR]

The head-on collision between two dust-acoustic solitary waves in a non-magnetized, collisionless and strongly coupled dust plasma has been studied. The application scope of the analytical solution of the head-on collision is given in the present paper by using the particle-in-cell simulation method. It is noted that the analytical results are valid if the amplitudes of both of the solitary waves are small enough. The effects of the coupling parameters on both the head-on collision and the waveform are also studied in the present paper. [ABSTRACT FROM AUTHOR]

Kelvin–Helmholtz (KH) instability plays a significant role in transport and mixing in various media such as hydrodynamic fluids, plasmas, geophysical flows and astrophysical situations. In this paper, we numerically explore this instability for a two-dimensional strongly coupled dusty plasma medium with rotational shear flows. We study this medium using a generalized hydrodynamic fluid model which treats it as a viscoelastic fluid. We consider the specific cases of rotating vorticity with abrupt radial profiles of rotation. In particular, single-circulation and multi-circulation vorticity shell profiles have been chosen. We observe the KH vortices at each circular interface between two relative rotating flows along with a pair of ingoing and outgoing wavefronts of transverse shear waves. Our studies show that due to the interplay between KH vortices and shear waves in the strongly coupled medium, the mixing and transport behaviour are much better than those of standard inviscid hydrodynamic fluids. In the interest of substantiating the mixing and transport behaviour, the generalized hydrodynamic fluid model is extended to include Lagrangian tracer particles. The numerical dispersion of these tracer particles in a flow provides an estimate of the diffusion in such a medium. We present the preliminary observations of tracer distribution (cluster formation) and diffusion (mean square displacement) across the medium. [ABSTRACT FROM AUTHOR]

Dust charge fluctuates even in steady-state uniform plasma due to the discrete nature of the charge carriers and can be described using standard Langevin equation. In this work, two possible approaches in order to introduce the memory effect in dust charging dynamics are proposed. The first part of the paper provides the generalization form of the fluctuation-dissipation relation for non-Markovian systems based on generalized Langevin equations to determine the amplitudes of the dust charge fluctuations for two different kinds of colored noises under the assumption that the fluctuation-dissipation relation is valid. In the second part of the paper, aiming for dusty plasma system out of equilibrium, the fractionalized Langevin equation is used to derive the temporal two-point correlation function of grain charge fluctuations which is shown to be non-stationary due to the dependence on both times and not the time difference. The correlation function is used to derive the amplitude of fluctuations for early transient time. [ABSTRACT FROM PUBLISHER]

Ambipolar electrostatic field in dusty plasma. This article was published with ORCIDs for two of the authors missing. These are Mika Holmberg: 0000-0003-2553-8395 Shenyi Ye: 0000-0002-3064-1082 The authors would also like to add the following funding acknowledgement 'S.Y.'s work was supported by NSFC grant 42074180 and STIC grant 20200925153725002' The funding acknowledgement has been added to the original paper. [Extracted from the article]

The Magnetized Dusty Plasma Experiment (MDPX) device is a newly constructed research instrument for the study of dusty (complex) plasmas. The MDPX device is envisioned as an experimental platform in which the dynamical behavior of all three charged plasma components, the electrons, ions, and charged microparticles (i.e., the ‘dust’) will be significantly influenced by the magnetic force. This brief paper will provide a short overview of the design, magnetic performance, and initial plasma measurements in the MDPX device. [ABSTRACT FROM PUBLISHER]

In a magnetized plasma containing charged dust whose motion is magnetized, one of the fundamental collective modes that could occur is the electrostatic dust cyclotron (EDC) wave with frequency near the dust cyclotron frequency. The EDC wave propagates nearly perpendicular to the magnetic field with a small parallel wave number, so that it can be driven unstable by ion flow along the magnetic field. Because unstable parallel wavelengths can be relatively large, this places constraints on the plasma device size. In this paper, we use linear kinetic theory to investigate the excitation of higher harmonic EDC waves that have wavelengths smaller than that of the fundamental mode. Collisions of charged particles with neutrals and Coulomb collisions including dust–dust collisions are taken into account. Constraints on possible parameter ranges arising from collisional effects or from requiring stability of other waves are discussed. Numerical results are presented for possible sets of laboratory dusty plasma parameters. [ABSTRACT FROM AUTHOR]

A simplified description of dynamical response of strongly coupled medium is desirable in many contexts of physics. The dusty plasma medium can play an important role in this regard due to its uniqueness, as its dynamical response typically falls within the perceptible grasp of human senses. Furthermore, even at room temperature and normal densities it can be easily prepared to be in a strongly coupled regime. A simplified phenomenological fluid model based on the visco - elastic behaviour of the medium is often invoked to represent the collective dynamical response of a strongly coupled dusty plasma medium. The manuscript reviews the role of this particular Generalized Hydrodynamic (GHD) fluid model in capturing the collective properties exhibited by the medium. In addition the paper also provides new insights on the collective behaviour predicted by the model for the medium, in terms of coherent structures, instabilities, transport and mixing properties. [ABSTRACT FROM PUBLISHER]

The dust acoustic wave (DAW), associated with longitudinal dust oscillations in dusty plasmas, can be self-excited from the free energy of ion streaming. It is not only a fundamental plasma wave but also a paradigm to understand the generic dynamical behaviors of self-excited nonlinear longitudinal density waves through optically monitoring particle motion and dust density evolutions over a large area. In this paper, the dynamical behaviors of the wave-particle interaction and wave breaking in ordered self-excited DAW with straight wave fronts, and the defect-mediated wave turbulence with fluctuating defects and chaotic low amplitude hole filaments along defect trajectories in the 2+1D space-time space, are briefly reviewed. The first experimental observation of acoustic vortices with helical waveforms in self-excited acoustic-type defect-mediated wave turbulence, and the dynamics of spontaneous pair generation, propagation, and pair annihilation of acoustic vortices, is demonstrated and discussed. [ABSTRACT FROM PUBLISHER]

The dust acoustic wave (DAW) was first discussed by P. K. Shukla in May of 1989 at the First Capri Workshop on Dusty Plasmas. In the past 25 years, the subsequent publication of the linear and nonlinear properties of the DAW (Rao, N. N., Shukla, P. K. and Yu, M. Y. 1990 Planet. Space Sci.38, 543) has generated and sustained a large body of theoretical and experimental research that has clarified the physics of collective effects in dusty plasmas. A unique feature of the DAW is that it can be observed (literally) using laser illumination and high-speed videography, revealing details of wave-particle interactions at an unprecedented single particle level. This paper attempts to review some of the contributions and extensions of dust acoustic wave physics, as well as identify recent findings that illustrate the potential importance of this dust wave in the agglomeration of dust particles. [ABSTRACT FROM PUBLISHER]

Charging of dust grains and related phenomena are fundamental problems in the physics of complex plasmas. The relative motion of grains and plasma breaks the symmetry in dust charging and gives rise to the wake in plasma density and potential, which can significantly influence the dynamics of other grains. This paper gives an overview of dust charging in two- and multi-component plasma flows and related wake effects, and presents recent results from self-consistent particle-in-cell (PIC) simulations. The role of wakefields is considered in the context of charging of downstream grains. [ABSTRACT FROM PUBLISHER]

Dust ion-acoustic solitary structures have been investigated in an unmagnetized non-thermal plasma consisting of negatively charged dust grains, adiabatic positive ions, and non-thermal electrons. Whenever the non-thermal parameter exceeds a critical value, the present system supports negative potential double layer solution. However, this double layer solution is unable to restrict the occurrence of negative potential solitary waves of the present system. As a result, the occurrence of one type of negative potential solitary wave is restricted by Mc < M < MD, whereas the second type of solitary wave exists for all M > MD, where Mc is the lower bound of the Mach number M and MD (> Mc) is the Mach number corresponding to a negative potential double layer. A finite jump between the amplitudes of negative potential solitary waves at M = MD − ϵ1 and M = MD + ϵ2 has been observed, where 0 < ϵ1 < MD − Mc and ϵ2 > 0. Depending on the analytical theory presented in this paper, a numerical scheme has been provided to find the value of the Mach number at which double layer solution exists, and also the amplitude of that double layer. Although the occurrence of coexistence of solitary structures of both polarities is restricted by Mc < M ≤ Mmax, only negative potential solitary wave still exists for all M > Mmax, where Mmax is the upper bound of M for the existence of positive potential solitary waves only. Qualitatively different compositional parameter spaces showing the nature of existing solitary structures of the energy integral have been found. These solution spaces are capable of producing new results and physical ideas for the formation of solitary structures whenever one can move the solution spaces through the family of curves parallel to the curve M = Mc. [ABSTRACT FROM PUBLISHER]

The paper presents experimental investigation of flow of dusty plasma medium formed by macroparticles in argon plasma. The dependences of the coefficient of shear viscosity of such liquid on the external force causing the flow of dusty plasma liquid and on the pressure of plasma-generating gas are studied. It is found that the viscosity of the dusty plasma medium decreases with increasing shear stress and increases with increasing pressure of buffer gas. An experimental investigation of the dynamics of macroparticles in an unperturbed liquid dusty plasma medium as a function of coupling parameter is performed; in so doing, formations of particles whose motion is correlated are observed in the region of high values of coupling parameter. It is assumed that the non-Newtonian pattern of dusty plasma liquid may be due to the emergence of crystal-like dusty plasma clusters in the 'liquid' phase. An experimental investigation of a crystalline dusty plasma structure under the effect of laser radiation is performed; in so doing, a macroscopic flow of the crystalline dusty plasma structure is observed under the effect of shear stress. The mechanism of formation and subsequent annihilation of edge misfit dislocations is observed and the threshold pattern of such flow is established; the threshold value of power of laser radiation is determined. [ABSTRACT FROM AUTHOR]

AbstractIn the present research paper, the characteristics of dust-acoustic solitary waves (DASWs) and double layers (DLs) are studied. Ions are treated as non-thermal and variable dust charge is considered. The Korteweg?de Vries equation is derived using a reductive perturbation method. It is noticed that compressive solitons are obtained up to a certain range of relative density ? (=ni0/ne0) beyond which rarefactive solitons are observed. The study is further extended to investigate the possibility of DLs. Only compressive DLs are permissible. Both DASWs and DLs are sensitive to variation of the non-thermal parameter. [ABSTRACT FROM AUTHOR]

An experimental study to investigate the effect of an external magnetic field on the propagation of ion-acoustic waves (IAWs) has been carried out in hydrogen plasma containing two-temperature electrons and dust grains. It is a first step in understanding the propagation properties of IAWs in such an environment. A low-pressure hot cathode discharge method is chosen for plasma production. The desired two-electron groups with distinct temperatures are achieved by inserting two magnetic cages with a cusp-shaped magnetic field of different surface field strengths in the same chamber. The dust grains are dropped into the plasma with the help of a dust dropper, which gain negative charges by interacting with the plasma. The IAWs are excited with the help of a mesh grid inserted into the plasma. A planar Langmuir probe is used as a detector to detect the IAWs. The time-of-flight technique has been applied to measure the phase velocity of the IAWs. The results suggest that in the presence of a magnetic field, the phase velocity of IAWs increases, whereas introducing the dust particles leads to the lower phase velocity. The magnetic field is believed to have a significant effect on the wave damping. This study will aid in utilising IAWs as a diagnostic tool to estimate plasma parameters in the presence of an external magnetic field. [ABSTRACT FROM AUTHOR]

Based on self-consistent modelling of the radio-frequency sheath parameters, such as the ion and electron densities and the ion velocity, the dust particle charging process in an RF sheath is investigated by employing the kappa $(\kappa)$ distribution for the electrons. It is shown that the charge number of the dust particle decreases near the sheath–wall interface while it shows the opposite tendency near the plasma-sheath edge, as the $\kappa$ value is decreased. The fluctuation of the dust particle charge modified by the $\kappa$ value depends on the dust particle radius. With an increases in the $\kappa$ value, the fluctuation of the dust particle charge has a slight increase for a small dust particle, and it shows a significant increase for a large dust particle. In addition, as the $\kappa$ value is decreased, the charge number of the dust particle obtained from the time-averaged plasma parameters deviates from the results obtained from the instantaneous plasma parameters. Moreover, a smaller deviation can be found for a large dust particle under the same $\kappa$ value conditions. [ABSTRACT FROM AUTHOR]

Using the Sagdeev pseudopotential method, the properties of negative dust-acoustic supersolitons are investigated in a plasma comprising cold negative dust and Boltzmann and Cairns non-thermal positive ions. Supersolitons have electric field profiles with additional wiggles on traditional bipolar structures, and their existence requires pseudopotentials having two sub-wells before a root is reached. Once the existence ranges are determined in parameter space, typical pseudopotential, supersoliton and electric field profiles can be easily generated. Their characteristics are very robust and yield dust and dust-ion-acoustic supersolitons in a wide range of compositional models and parameter ranges. [ABSTRACT FROM PUBLISHER]

Supersolitons are a form of soliton characterised, inter alia, by additional local extrema superimposed on the usual bipolar electric field signature. Previous studies of supersolitons supported by three-component plasmas have dealt with ion-acoustic structures. An analogous problem is now considered, namely, dust-acoustic supersolitons in a plasma composed of fluid negative dust grains and two kappa-distributed positive ion species. Calculations illustrating some supersoliton characteristics are presented. [ABSTRACT FROM AUTHOR]

Waves in a dusty plasma over the lunar dayside are considered. It is shown that the relative motion of the solar wind with respect to the photoelectrons over the lunar surface leads to the excitation of high-frequency oscillations with frequencies in the range of Langmuir and electromagnetic waves. The dust acoustic wave excitation is possible in the vicinity of the lunar terminator. [ABSTRACT FROM AUTHOR]

AbstractThe existence of magnetosonic solitons in dusty plasmas is investigated. The nonlinear magnetohydrodynamic equations for a warm dusty magnetoplasma are thus derived. A solution of the nonlinear equations is presented. It is shown that, owing to the presence of dust, static structures are allowed. This is in sharp contrast to the formation of the so-called shocklets in usual magnetoplasmas. A comparatively small number of dust particles can thus drastically alter the behavior of the nonlinear structures in magnetized plasmas. [ABSTRACT FROM AUTHOR]

We investigate the influence of charged dust on the incoherent scatter from the D-region ionosphere. Incoherent scatter is observed with high-power, large aperture radars and results from electromagnetic waves scattering at electrons that are coupled to other charged components through plasma oscillations. The influence of charged dust can hence be considered an effect of dusty plasma. The D-region contains meteoric smoke particles that are of nanometre size and form from incoming ablating meteors. Detection of such charged dust in the incoherent scatter spectrum from the D-region has previously been proposed and studied to some degree. We here present model calculations to investigate the influence of the charged dust component with a size distribution, instead of the one size dust components assumed in other works. The developed code to calculate the incoherent scatter spectrum from the D-region including dust particles with different sizes and different positive and negative charge states is made available (https://doi.org/10.18710/GHZIIY). We investigate how sizes, number density and charge state of the dust influence the spectrum during different ionospheric conditions. We consider the ionospheric parameters for the location of the EISCAT VHF radar during a year and find that conditions are most suitable for dust detection in winter below 80 km at times with increased electron densities. The prospects to derive dust parameters increase, when the incoherent scatter observations are combined with those of other instruments to provide independent information on electron density, neutral density and temperature. [ABSTRACT FROM AUTHOR]

The excitation of low frequency dust acoustic (or dust density) waves in a dusty plasma can be driven by the flow of ions relative to dust. We consider the nonlinear development of the ion–dust streaming instability in a highly collisional plasma, where the ion and dust collision frequencies are a significant fraction of their corresponding plasma frequencies. This collisional parameter regime may be relevant to dusty plasma experiments under microgravity or ground-based conditions with high gas pressure. One-dimensional particle-in-cell simulations are presented, which take into account collisions of ions and dust with neutrals, and a background electric field that drives the ion flow. Ion flow speeds of the order of a few times thermal are considered. Waveforms of the dust density are found to have broad troughs and sharp crests in the nonlinear phase. The results are compared with the nonlinear development of the ion–dust streaming instability in a plasma with low collisionality. [ABSTRACT FROM AUTHOR]

The magnetized dusty plasma experiment (MDPX) is a newly commissioned plasma device that started operations in late spring, 2014. The research activities of this device are focused on the study of the physics, highly magnetized plasmas, and magnetized dusty plasmas. The design of the MDPX device is centered on two main components: an open bore, superconducting magnet that is designed to produce, in a steady state, both uniform magnetic fields up to 4 Tesla and non-uniform magnetic fields with gradients of 1–2 T m−1 and a flexible, removable, octagonal vacuum chamber that provides substantial probe and optical access to the plasma. This paper will provide a review of the design criteria for the MDPX device, a description of the research objectives, and brief discussion of the research opportunities offered by this multi-institution, multi-user project. [ABSTRACT FROM PUBLISHER]

In this paper, we study the (3+1)-dimensional generalized Johnson model, which can be used to describe the dust-ion-acoustic waves in a cosmic unmagnetized dusty plasma, and its perturbed model, which can be found in an unmagnetized dusty plasma for the electron temperature below the Curie temperature. (I) For the original model: Bilinear form and soliton solutions are obtained. Amplitude of the one soliton reaches the maximum when the equilibrium electron (ne0) and ion (ni0) densities take certain values which correspond with ne0/ni0 = 2. Overtaking and head-on interactions between the two solitons are given. (II) For the perturbed model: Phase projections are given numerically. Via the spectral analysis, two kinds of chaotic motions, i.e., the weak and developed chaos, are investigated. Largest Lyapunov exponents and power spectra are investigated to corroborate that those motions are indeed chaotic. Dynamic behavior of such a perturbed model varying with the external perturbation is different when the nonlinear term changes. With the damped term considered, two kinds of periodic motions are studied, and spectra of those periodic motions are also given. Through the comparison between the chaotic motions and periodic ones, possible chaotic or periodic motions in the perturbed model can be predicted. [ABSTRACT FROM AUTHOR]

Radiative-magnetohydrodynamic (RMHD) equations along with a full set of Maxwell's equations are followed to formulate the charged surface waves at the interface of an incompressible, radiative, magnetized dusty plasma and vacuum, while assuming that the characteristic wave frequency is much smaller than the ion gyrofrequency, having an equilibrium background state. It is found that the separation of charges on the surface is followed by thermal motion, which further leads to a negative pressure gradient normal to the surface, hence the plasma–vacuum interface is under tension due to two different types of oppositely directed pressures. The dusty plasma RMHD set of equations admits a linear dispersion relation of surface Jeans instability of an incompressible dusty plasma, which exhibits a strong coupling between the electron surface charge and dust surface mass densities and we conclude that the surface densities of both electrons and dust as well as the dust inertia play major roles in the gravitational collapse of the surface of astrophysical objects such as stars, galaxies etc. Further, the growth rate of radiative surface waves is found to be function of both the temperature inhomogeneity, appearing due to thermal radiation heat flux, as well as the thermal radiation pressure. The present findings of charged surface waves may seek application at the astroscales. [ABSTRACT FROM AUTHOR]

A distribution of the electric potentials around a charged absorbing particle in a drifting weakly ionised collisional plasma with negative ions is calculated in the linear hydrodynamic approach. Coulomb-like asymptote of the electric potential around the absorbing particle deforms under the action of the negative ions' flow and exhibits a valley profile along the flow behind the particle. The presence of the flowing negative ions can be conducive to string formation in the dust structures at relatively large pressures. [ABSTRACT FROM AUTHOR]

The effects of the electron energy distribution function (EEDF) on the structure of a dusty plasma sheath are investigated. Here, it is assumed that the electrons obey a Druyvesteyn-type distribution with a parameter x controlling the shape of the EEDF. The Druyvesteyn-like distribution tends to a Maxwellian distribution as x varies from 2 to 1. Using the orbital motion limited theory, the incident electron current on the dust is evaluated for a given x. The results of numerical simulations are compared with those of a Maxwellian distribution. It was found that the sheath dynamics depends strongly on the magnitude of x. The sheath thickness increases monotonically with increasing x. However, the absolute dust charge decreases and, as a result, the accelerating ion drag force is weakened and thus the dust number density is enhanced. For a plasma with a Druyvesteyn-like distribution, the Bohm speed is a function of x and increases with increasing x. [ABSTRACT FROM AUTHOR]

The effect of the finite probe size in plasma fluctuation measurements is revisited for dusty plasmas, where it has been argued that dust leads to a significant low-frequency enhancement in the spectral densities of ion density fluctuations, which can constitute the physical basis of a dust diagnostic technique. Theoretical predictions for the spectral modifications are presented and the dust acoustic mode contribution is analysed. The finite probe size effect is treated within the volume average approach, which introduces geometry dependent form factors that are calculated for spherical and cylindrical probes. The volume average approach is compared with the typically employed cutoffwavenumber approximation for various dust and plasma parameters. The contribution of temperature fluctuations to the spectral density of current fluctuations is also evaluated. [ABSTRACT FROM AUTHOR]

A collective behavior of dust particles in a complex plasma with a magnetic field (up to 4 kG) is investigated. Dust particles form a dust disk which is rotating in a horizontal plane pushed by ions rotating with the E × B drift as a trigger force. The thickness of the disk is determined by controlling the experimental conditions. The disk rotates in a horizontal plane and forms a two-dimensional thin structure when the pressure pAr is relatively high. The dust particles are ejected from near the disk center and form a rotation in the vertical plane and, hence, forms a helical vortex when the disk is thick for relatively low pAr. The reason the dust disk has the different thickness is due to the neutral pressure. Under a higher (lower) neutral gas pressure, the disk becomes two (three) dimensional due to the influence of the neutral drag force. [ABSTRACT FROM PUBLISHER]

Using a fluid theory approach, this article provides a comparative study on the evolution of nonlinear waves in dusty plasmas, as well as other plasma environments, viz electron-ion, and electron-positron plasmas. Where applicable, relevance to satellite measurements is pointed out. A range of nonlinear waves from low frequency (ion acoustic and ion cyclotron waves), high frequency (electron acoustic and electron cyclotron waves) in electron-ion plasmas, ultra-low frequency (dust acoustic and dust cyclotron waves) in dusty plasmas and in electron-positron plasmas are discussed. Depending upon the plasma parameters, saw-tooth and bipolar structures are shown to evolve. [ABSTRACT FROM PUBLISHER]

The formation of carbon nanoparticles in low pressure magnetized H2/CH4 and H2/C2H2 plasmas is investigated using infrared quantum cascade laser absorption, mass spectrometry, and electrostatic probe measurements. Results showed that dust formation is correlated to the presence of a significant amount of large positively charged hydrocarbon ions. Large negative ions or neutral hydrocarbon were not observed. These results, along with a qualitative comparison of diffusion and reaction characteristic, suggest that a positive ion may contribute to the growth of nanoparticles in hydrocarbon magnetized plasmas. [ABSTRACT FROM PUBLISHER]

The Kelvin-Helmholtz (KH) instability is studied in a two dimensional strongly coupled dusty plasma medium using a fluid approach as well as through a molecular dynamic (MD) simulation. For the fluid description the generalized hydrodynamic (GH) model which treats the strongly coupled dusty plasma as a visco-elastic fluid is adopted. For the MD studies the ensemble of particles are assumed to interact through a Yukawa potential. Both the approaches predict a stabilization of the KH growth rate with an increase in the strong coupling parameter. The present study also delineates the temporal evolution and the interaction of transverse shear waves with the collective dynamics of the dusty plasma medium within the framework of both these approaches. [ABSTRACT FROM PUBLISHER]

A theoretical investigation is carried out to study the basic properties of dust-acoustic (DA) shock waves propagating in a magnetized non-thermal dusty plasma (containing cold viscous dust fluid, non-thermal ions, and non-thermal electrons). The reductive perturbation method is used to derive the Korteweg–de Vries–Burgers equation. It is found that the basic properties of DA shock waves are significantly modified by the combined effects of dust fluid viscosity, external magnetic field, and obliqueness (angle between external magnetic field and DA wave propagation direction). It is shown that the dust fluid viscosity acts as a source of dissipation, and is responsible for the formation of DA shock structures in the dusty plasma system under consideration. The implications of our results in some space and laboratory plasma situations are briefly discussed. [ABSTRACT FROM AUTHOR]

The nonlinear Zakharov–Kuznetsov and the modified Zakharov–Kuznetsov equations are derived for dust-acoustic solitary waves (DASWs) in a magnetized four-component dusty plasma system comprising negatively charged cold dust, non-extensive electrons, and two-temperature thermal ions using standard reductive perturbation method. The combined effects of electron non-extensivity, strength of magnetic field, and its obliqueness on the DASWs profile are analyzed. Different ranges of non-extensive q-parameter are considered. Our results show that solitary waves, that their amplitude and width of which depend sensitively on the q-non-extensive parameter, can exist. Due to electron non-extensivity, our dusty plasma model can admit positive potential as well as negative potential solitons. The strength of magnetic field has no effect on the amplitude of solitary waves, whereas its obliqueness affects both amplitude and width of the solitary waves structure. Results show that the amplitude of soliton increases with increasing the velocity of soltion. For any magnitude of q there is an extremum for the direction of the magnetic field at which the width of soliton is maximum. [ABSTRACT FROM AUTHOR]

A theoretical investigation has been made of obliquely propagating nonlinear electrostatic shock structures. The reductive perturbation method has been used to derive the Korteweg-de Vries-Burger (KdV-Burger) equation for dust acoustic shock waves in a homogeneous system of a magnetized collisionless plasma comprising a four-component dusty plasma with massive, micron-sized, positively, negatively dust grains and non-extensive electrons and ions. The effect of dust viscosity coefficients of charged dusty plasma of opposite polarity and the non-extensive parameters of electrons and ions have been studied. The behavior of the oscillatory and monotonic shock waves in dusty plasma has been investigated. It has been found that the presence of non-extensive parameters significantly modified the basic properties of shock structures in space environments. [ABSTRACT FROM PUBLISHER]

The relaxation of an electron-depleted electronegative dusty plasma with two-negative ions is investigated. When the ratio of canonical vorticities to corresponding flows of all the plasma species is the same and all inertial and non-inertial forces are present, the relaxed state appears as a double Beltrami magnetic field which is the superposition of two force-free relaxed states. The numerical results show that highly diamagnetic relaxed magnetic fields can be obtained by controlling the flow and vorticities through a single Beltrami parameter. The study is useful to investigate the creation of diamagnetic plasma configurations which are considered to be very important in the context of nuclear fusion. [ABSTRACT FROM AUTHOR]

Polarization force (acting on a dust grain) and its modification by polarity of dust, non-isothermal (viz. non-thermal and trapped) ions, adiabaticity of electrons and ions, etc. have been investigated theoretically. It has been found that the polarization force is significantly modified by these effects, i.e. the magnitude of the polarization force is significantly decreased by the presence of non-thermal ions and by the adiabaticity of electrons and ions. On the other hand, it is significantly increased by the presence of trapped ions. It has been also shown that the magnitude of the polarization force is increased (decreased) by electric potential in the case of positively (negatively) charged dust. The relevance of our investigation to some space and astrophysical plasma situations is discussed. [ABSTRACT FROM AUTHOR]

The excitation of drift waves by an electron current parallel to the magnetic field is investigated in a nonuniform plasma composed of electrons, positive ions, negative ions, and massive, negatively charged dust. Electrostatic drift waves with frequencies smaller than the ion gyrofrequencies and wavelengths larger than the ion gyroradii are considered. Linear kinetic theory is used, and collisions of charged particles with neutrals are taken into account. The present results may be relevant to laboratory collisional magnetoplasmas containing negative ions and dust. [ABSTRACT FROM AUTHOR]

Dust charging processes involving the collection of electrons and positive/negative ions in a non-equilibrium dusty plasma are revisited by employing the power-law kappa (κ)-distribution function. In this context, the current balance equation is solved to obtain dust grain surface potential in the presence of negative ions. Numerically, it is found that plasma parameters, such as the κ spectral index, the negative ion-to-electron temperature ratio (γ), the negative–positive ion number density ratio (α), and the negative ion streaming speed (U0) significantly modify the dust grain potential profiles. In particular, for large kappa values, the dust grain surface potential reduces to the Maxwellian case, and at lower kappa values the magnitude of the negative dust surface potential increases. An increase in γ and U0 leads to the enhancement of the magnitude of the dust grain surface potential, while α leads to an opposite effect. The relevance of present results to low-temperature laboratory plasmas is discussed. [ABSTRACT FROM AUTHOR]

The nonlinear propagation of small but finite-amplitude dust-acoustic solitary waves in an unmagnetized, collisionless dusty plasma has been investigated. The fluid model is a generalization to the model of Mamun and Shukla to a more realistic space dusty plasma in different regions of space, viz., cometary tails, mesosphere, and Jupiter's magnetosphere, by considering a four-component dusty plasma consisting of the charged dusty plasma of opposite polarity, isothermal electrons and vortex-like ion distributions in the ambient plasma. A reductive perturbation method was employed to obtain a modified Korteweg–de Vries equation for the first-order potential. The effect of the presence of a positively charged dust fluid, the specific charge ratio μ, the temperature of the positively charged dust fluid, the ratio of constant temperature of free hot ions and the constant temperature of trapped ions, and ion temperature on the soliton properties and dusty grains energy are discussed. [ABSTRACT FROM AUTHOR]

Nonlinear properties of magnetoacoustic waves are investigated in magnetized pair-ion plasmas with dust impurity. Three-fluid collisionless magneto-hydrodynamic model is considered and reductive perturbation method is employed to derive Korteweg-de Vries equation for magnetoacoustic solitary waves (MASWs). The effects of the charge number of dust particles, magnetic field intensity, and plasma number density are studied on MASWs. It is found that the variation of parameters causes significant changes in solitary structures. The present investigation may be useful to understand formation and propagation of MASW structures in dust pair-ion plasmas. [ABSTRACT FROM AUTHOR]

Experimental observations of supersonically flowing dusty plasmas and their interaction with an electrically biased circular cylinder are presented. Two methods for producing flowing dusty plasmas are described. The dusty plasma is produced in a DC anode glow discharge plasma. In Configuration I, a secondary dust cloud, initially formed near a biased grid, flowed away from the grid at supersonic speeds when the grid voltage was suddenly changed. In Configuration II, a pencil-like dust beam was produced using a nozzle-like (converging-diverging) electrostatic potential structure. Using Configuration I, the streaming dust encountered a biased cylinder (wire) whose axis was oriented transverse to the dust flow. The flowing dust particles were repelled by the electrostatic field of the negatively charged cylinder, and a dust void was formed around the cylinder. A detached electrohydrodynamic bow shock, akin to the Earth's magnetohydrodynamic bow shock, was formed on the upstream side of the cylinder, while an extended teardrop-shaped wake region was formed on the downstream side. Video imaging of the dust stream allowed for observations of the structure and evolution of the bow shock. Configuration II was used to produce a narrow beam of dust particles and observe how the beam was deflected around the biased cylinder. Three multimedia files (movies) of the observed phenomena are provided in the online Supplementary material. [ABSTRACT FROM AUTHOR]

The properties of non-planar (cylindrical and spherical) dust-acoustic solitary waves (DA SWs) and double layers (DLs) in an unmagnetised collisionless four-component dusty plasma, whose constituents are positively and negatively charged dust grains, super thermal electrons and Boltzmannian ions are investigated by deriving the modified Gardner (MG) equation. The well known reductive perturbation method is employed to derive the MG equation and solve it numerically to study the nonlinear features of the finite amplitude non-planar DA Gardner solitons (GSs) and DLs, which are shown to exist for κ around its critical value κc (where, κ is the super thermal parameter and κc is the value of κ corresponding to the vanishing of the nonlinear coefficient of the Korteweg-de Vries (K-dV) equation). It is seen that the properties of non-planar DA SWs and DLs are significantly differs in non-planar geometry from planar geometry. It is also found that the magnitude of the amplitude of positive and negative GSs decreases with κ and the width of positive and negative GSs increases with the increase of κ. [ABSTRACT FROM AUTHOR]

The nonlinear propagation of dust ion-acoustic (DIA) solitary waves (SWs) as well as double layers (DLs) in a dusty plasma containing warm adiabatic ions, non-extensive electrons, and arbitrarily (positively or negatively) charged immobile dust are studied. Based on the energy-like integral equation, a new relationship between the localized electrostatic disturbances and dust polarity in the non-extensive dusty plasma is derived. It is shown that the effect of electron non-extensivity, in contrast to the influence of extensive electrons, is destructive for the formation of the SWs and DLs. It is also found that the negative (positive) dust number density raises (reduces) the possibility for the formation of these localized states. [ABSTRACT FROM AUTHOR]

Using the reductive perturbation approach, dust–ion acoustic solitons and double layers (DLs) have been studied in a dust–electron–positron–ion (d-e-p-i) plasma composed of q-distributed electrons and positrons, warm fluid ions, and a fraction of immobile dust grains. Existence domains of either solitary waves or DLs are presented and their parametric dependence determined. It is found that particle non-extensivity, dust concentration and positron concentration may drastically affect these existence domains and may play a key role in defining the polarity of these localized structures. Our results should assist in interpreting the nonlinear structures that may occur in astrophysical environments. [ABSTRACT FROM AUTHOR]

Solitary waves are investigated in a charge-varying dusty plasma involving dust trapping. A potentially useful neuronal method that may handle a wide variety of non-analytic pseudo-potentials is used. This method could be advantageously exploited in rendering a cumbersome pseudo-potential analytically more tractable. Making use of the approximate Sagdeev pseudo-potential, our results show the possibility of development of localized dust structures in a dusty plasma with variable charge trapped dust grains. [ABSTRACT FROM AUTHOR]

The linear dust lattice waves propagating in a two-dimensional honeycomb configuration is investigated. The interaction between particles is considered up to distance 2a, i.e. the third-neighbor interactions. Longitudinal and transverse (in-plane) dispersion relations are derived for waves in arbitrary directions. The study of dispersion relations with more neighbor interactions shows that in some cases the results change physically. Also, the dispersion relation in the different direction displays anisotropy of the group velocity in the lattice. The results are compared with dispersion relations of the waves in the hexagonal lattice. [ABSTRACT FROM AUTHOR]

The propagation of dust ion-acoustic shock waves (DIASHWs) in an unmagnetized dissipative dusty plasma system consisting of inertial ions, non-inertial, non-extensive q-distributed electrons, and negatively charged stationary dust is investigated in bounded non-planar (cylindrical and spherical) geometry. A modified Burgers equation is derived and its numerical solution is obtained. It is found that the basic features of DIASHWs are significantly modified by the effects of electron non-extensivity and ion kinematic viscosity in bounded geometry. It is also shown that the propagation characteristics of non-planar DIASHWs in a non-extensive plasma are qualitatively different from those of planar ones. [ABSTRACT FROM AUTHOR]