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Through Cerenkov interactions, a low-frequency electrostatic dust acoustic waves (DAWs) have been driven to instabilities by negatively charged dust grains comprised in a plasma cylinder, where a Gyrating ion beam having velocity (v ⊥ θ ⌢ + v b 0 Z ^) has been propagating. For the typically existing parameters of dusty plasma, numerical calculations of phase velocity, unstable wave frequency and growth rate have been performed. With relative density δ (= n 0 i n 0 e ) of negatively charged dust grains, an enhancement in the unstable wave frequency and in the growth rate have been noticed. This is due to the fact that adding of dust into plasma increased the instability, so our growth rate will grow up. Consequently, with the beam density, an increment in the growth rate of unstable dust acoustic wave mode has been reported. It is scaled as 1/3rd of the beam density. Additionally, with the beam energy, an enhancement in the real part frequency of the unstable mode has also been reported. It is scaled as 1/2nd power of beam energy. In research laboratory as well as in astrophysical plasmas, the outcome of this work shall find useful applications. [ABSTRACT FROM AUTHOR]

Most power plants used in Iraq are gas power stations, and one of the most critical factors that affect the efficiency of the gas turbine is the inlet air quality thus due to the dusty weather most of the year, especially in the summer season where it's a problem in terms of limiting electricity production. The available filtration systems to filter undesired particles used in the inlet air unit are Conventional filters, including inertial separators and media-type filters; they usually are replaced when they become dirty. Particulate emissions from industrial operations such as boilers, furnaces, and the like may be controlled by an electrostatic precipitator (ESP). In this work, A novel technique is used, Presenting ESP in the purification of inlet air of gas turbine unit to enhance the air quality in dusty surroundings avoiding the loss of power production. A sectional electrostatic precipitator with cubic dimensions of 1m was established to remove Particles Matter (PM) from the air as a pre-stage filtration system. The airflow was channelled over through the corona discharge field, which was laden with PM, and then the charged particles were attracted to the grounded plates and accumulated there, where the efficiency of this electrostatic precipitator system is about 98%, with the benefits of extending the interval between filter changes from four months to six to eight months, in addition to upgrading the air intake system from having only the pressure difference reading to reading the flow rate, temperature and the density of fine particles of air in the intake air unit. [ABSTRACT FROM AUTHOR]

The propagation of nonlinear dust ion acoustic (DIA) solitary wave (SW) in dusty plasma consisting of positive and negative ions, nonthermally distributed electrons and positrons is studied in presence of magnetic field effect. The three-dimensional Zakarov-Kuznetsov (Z-K) equation is derived, using reductive perturbation technique and the solution is obtained using tan-hyperbolic method. It is observed that the bifurcation point (the point where two streams of nonlinear waves split) for compressive and rarefactive solitary waves are found to be on opposite sides of each other. Also, it is seen that at a certain value of nonthermal electrons in plasma, the transition from compressive to rarefactive solitary wave is observed. [ABSTRACT FROM AUTHOR]

The propagation of small amplitude dust ion acoustic (DIA) solitary waves (SW) in four component relativistic plasma with nonthermal electrons, mobile positively charged ions and positrons, and negatively charged massive dust particles is discussed in this paper. The Korteweg-de-Vries (K-dV) nonlinear wave equation is numerically derived using the reductive perturbation approach. The role of streaming positron beam on the characteristic features of solitary waves are observed and the possible region of the formation of ion acoustic (IA) SW is analysed. The findings of this work will help in the understanding of the Earth's upper atmosphere (Ionosphere's Aurora region) as well as the space plasmas. [ABSTRACT FROM AUTHOR]

The environmental impact of construction industries is obvious as they deplete the natural resources by overconsumption and polluting the environment by emitting greenhouse gases. Emerging thoughts of sustainable construction lead to experiments on the ways to solve the issues related to these. Reuse of wastes as construction and building materials will, certainly help in achieving the sustainability goals. In this study an approach of utilizing the Sugarcane Bagasse Ash (SBA), a non-biodegradable waste generated by burning Sugarcane Bagasse for the energy production in sugar industries, for manufacturing of unburnt brick in place of clay, along with Lime powder and Quarry dust. Compressive strength and other physical properties have been correlated and discussed the benefits of usage of SBA in brick manufacturing [ABSTRACT FROM AUTHOR]

A full-scale test experiment has been carried out to study the operational characteristics of a multi-helix screw pile in dusty-clay soil under static compressive and pull-out loads. On the basis of this experiment, a numerical simulation of the stress-strain state of the base of the multi-helix screw pile was performed using the Plaxis 3D software package, and the results obtained were compared with the results of full-scale testing. [ABSTRACT FROM AUTHOR]

In the frame of latest requirements to improve the renewable energy harvesting, the wind turbines get more and more used. Due to the propeller sizes, the blades' materials must comply with high resistance and weight requirements. As consequence, composite materials with dedicated structures are used. These materials are designed for long life and, as consequence, are potential pollution factors for the environment, after turbine working life is ended. Beside the methods to destroy the blades and give other use to the material, the optimization of the maintenance and repair procedures stand as valuable way to reduce both the turbines cost and the environment contamination. Taking into account the working conditions of blades such as the presence of the abrasive particles (sand or dust) and the high rotational speeds that can be reached, following the wind speed, the assessment of wear resistance of blades in abrasive conditions stands as valuable information for both designing and repairing procedures. In the present work, an industrial blade composite material is analyzed and subjected to abrasive wear with sand particles flowing in air stream, simulating the wind effect. A dedicated test rig is used, allowing to change the wear process parameters. After the abrasive tests, the damage evolution was observed by optical microscopy to identify the most affected areas of the blade, which provides important information for establishing of repairing procedures. [ABSTRACT FROM AUTHOR]

Mathematical modeling of the process of dedusting the air with foam for the operating conditions of belt conveyors (sand dust and crushed stone dust) has been carried out. The dependences of the efficiency of dust suppression by foam on the parameters characterizing the properties of dust aerosol, foam and air flow, as well as the peculiarities of their interaction, taking into account the conditions of foam destruction, have been established. On the basis of a mathematical model, it is possible to develop recommendations for the selection of optimal operating parameters for dust collection, dust cleaning and dust dispersion by a foam method, taking into account the peculiarities of production conditions, which provide a significant reduction in dust content in the working area to concentrations close to the maximum permissible concentrations. [ABSTRACT FROM AUTHOR]

A study of stability of stratified incompressible rheological dusty plasma arranged in horizontal strata with quantum pressure in a porous medium in magneto hydrodynamics (MHD). The rheology of the plasma is described by the Walters'(model B') model. The coupled non-linear partial differential equations defining the physical system pervaded by a uniform vertical magnetic field are reduced to linear ordinary differential equations by using the perturbation method, linear theory and normal mode technique. Stratifications in fluid density, coefficient of viscosity and viscoelasticity, pressure of quantum plasma and intensity of magnetic field are assumed to vary exponentially along the vertical, the exact solutions satisfying the boundary conditions are obtained. The dispersion relation so obtained is computed numerically to investigate the role that the various variables play on the growth rates of the unstable perturbed mode on the considered physical system. Impact of the embedded dust particles density is to raise, whereas quantum pressure, the magnetic field and the viscoelasticity damp the frequency of the most unstable perturbed mode thereby increasing the stability region for certain range of wave number for growth rate of Rayleigh Taylor Instability thereby suppressing this instability. This research work finds applications in diverse fields viz. laser technology, astrophysics, petroleum oil additives, manufacturer of aeronautical devices. [ABSTRACT FROM AUTHOR]

Dust ion acoustic rogue waves (DIARWs) have been investigated in an unmagnetized, collisionless plasma comprising Maxwellian electrons, Maxwellian negative ions, and cold mobile positive ions and negatively charged stationary dust particles. To study DIARWs in our system, a nonlinear Schrodinger equation (NLSE) is derived by using reductive perturbation technique. In investigating the modulational stability/instability region, the variation of the coefficient of nonlinearity is plotted against wave number k for different values of the physical parameters. The critical wavenumber threshold kc at which modulational instability sets in, is raised by the increasing value of dust particle density and electron to-negative ion temperature ratio. Further, in the modulational instability region, the coefficient of nonlinearity increases (decreases) with the increase of dust particle density (electron-to-negative ion temperature ratio). Our present investigation may be helpful for basic characteristic study of DIARWs in the laboratory and astrophysical plasmas. [ABSTRACT FROM AUTHOR]

The analytical investigation of the effect of collisions on the Jeans instability in dusty plasma is carried out to observe the effect of the simultaneous presence of polarization force and charge gradient force on the dust particles. The dispersion relation, the instability growth rate and the graphical analysis shows that the combined effect of the charge gradient force, dust polarization force and collisions moves the system towards stabilization. [ABSTRACT FROM AUTHOR]

The characteristics of self-organized vortices, namely, Great Red Spot (GRS) and White Ovals of Jupiter's atmosphere, are analyzed using a 2D hydrodynamic model. The model considers an electrostatically bound charged dust cloud in an unbound streaming plasma as the prototype setup for various driven-dissipative complex flow systems. This physical picture is consistent with Jupiter's vortices where the zonal jets stream through the giant vortices. The simulation results fairly predict the characteristic features of the steadily driven dust circulation in laboratory experiments and the vortices in Jupiter's atmosphere. The continuous structural changes of GRS and the persistence of high-speed collar rings around the quiescent interiors of the vortices are demon- strated as a result of changes in internal properties governed by the kinematic viscosity. This analysis brings out the effect of the driving field, boundaries, and dynamical parameters on the circulation and drifts of the vortices in Jupiter's atmosphere. [ABSTRACT FROM AUTHOR]

This work presents a comparative study of homogeneous and inhomogeneous plasmas for the effect of different plasma parameters on the phase velocity of dust acoustic wave. For the inhomogeneous plasma the growth rate of the dust acoustic wave is intensely studied and the role of components of plasma i.e. inertialess isothermal electrons, inertialess ions at two temperature and massive dust grains with heavy charge is observed on the phase velocity. The general dispersion relation is the guiding factor for the detailed study of dust acoustic wave which is obtained using normal mode analysis. [ABSTRACT FROM AUTHOR]

The quantum mechanical effects has wide applications in quantum plasma echoes, quantum plasma instabilities and microelectronics devices.Quantum effects may become important when the electron number density of the order of 1030 m−3 andsmall temperatures of a few thousand Kelvin. A dusty plasma is a three-component plasma consisting of electrons,ions, and a solid grains.We use the quantum hydrodynamic model to derive the plasma dispersion equation to study the growth rate of electron drift waves in quantum dusty plasmas. The growth shows depends on the electron temperature, electron density, electron drift velocity and wave number, ions and dust mass. The results may be useful to understand the physics of dense astrophysical objects. Different approximations are tried to solve the dispersion equation. [ABSTRACT FROM AUTHOR]

A theoretical model for self-trapping of Gaussian electromagnetic beam has been developed in dusty plasma. This model comprise of balancing of charge, number density, and energy exchange between plasma components having charge neutrality. Ionization of neutrals, recombination, emission and sticking of electrons to the dust particles, and the collisions between the constituents are considered herein. For numerical appreciation, curves have been drawn for variation of electron density with time and beam waist parameter with the dimensionless length of propagation for different number density and sizes of dust grains. This formulation is helpful for explaining the results of dusty plasma in space and laboratories. [ABSTRACT FROM AUTHOR]

The effects of dust polarization force and charge gradient have been investigated on low frequency strongly coupled dust acoustic modes. We have taken the massive dust particulates as polarized and degenerate electrons and distribution of ions are assumed as Maxwellian. The general dispersion relation has been obtained by employing the normal mode method and generalized hydrodynamic model. The obtained general dispersion relation is further studied for a characteristic timescale which gives two different frequency regimes hydrodynamic and kinetic regimes. The numerical results have been presented by plotting the graphs between frequency and wave number which show the effect of different parameters on dust acoustic modes. [ABSTRACT FROM AUTHOR]

In the present work, the dust acoustic modes of strongly coupled quantum plasma have been examined considering the dust polarization force with degenerate electron and ion species. We have incorporated the statistical and diffraction effects of all the three plasma species i.e. electron, ion and dust grains. The normal mode analysis technique is used to obtain the general dispersion relation. Further, the general dispersion relation is discussed analytically as well as numerically for hydrodynamic and kinetic regimes. The numerical results for the strongly coupled degenerate plasma have been shown to see the effect of polarization force on dust acoustic modes. [ABSTRACT FROM AUTHOR]

The polarization force and the charge-gradient force effects in strongly coupled dusty plasma along with the effects of viscosity are studied using theoretical techniques. The strongly coupled dusty medium is suitably described by the simplified phenomenological fluid model. The plasma model is considered to compose of Maxwellian distribution of ions and radiative electrons along with comparatively massive dust grains. With the Generalized Hydrodynamic (GHD) fluid model, the dispersion relation is deduced and the collective properties of the medium are discussed. The viscoelastic and low frequency modes of the waves derived from the dispersion relation and the instabilities of the plasma are inspected in detail to understand the hydrodynamic mode of propagation and the kinetic mode of propagation. [ABSTRACT FROM AUTHOR]

The wave modes and the stability of a magnetized viscous self-gravitating plasma system with Maxwellian distribution of ions and radiative effect of electrons, charge gradient force and polarization force is theoretically analysed. The investigation is carried out with a theoretical model dealing with ions, electrons and dust grains to bring forth a dispersion relation defining the characteristics of the plasma by the normal mode analysis method. The dispersion relation is examined to understand the wave modes propagating longitudinally and transversely (along the direction of the magnetic field) with their significance. Numerical calculations and graphical interpretations are also included to support the results. Applications based on the interstellar clouds can utilize the result from the study. [ABSTRACT FROM AUTHOR]

In present paper, the propagation of dust acoustic shocks are investigated in viscous dusty plasma including the effect of polarization force. The considered three fluid model is dealing with electrons, ions and negatively charged dust grains. In the governing model equations, the non-thermal ions distribution, Maxwell Boltzmann electrons and dust polarization force modified by the presence of nonthermal ion population are considered. Using the reductive perturbation method, Burger equation is obtained to study the characteristics of modified dust acoustic shocks analytically and graphically. The viscous and nonthermal polarization force significantly affects the propagation of dust acoustic shocks. [ABSTRACT FROM AUTHOR]

Characteristics ofthe nonlinear dust ion acoustic solitary waves in dusty plasma with weak relativistic effect are examined. We consider the weakly relativistic effect of electron species, the ion species with nonthermal distribution and charged dust grains. The nonlinear Korteweg-de Vries equation is derived from the governing normalized basic set of equations. The numerical calculations show the influence of non-thermal ion population on the width and amplitude of dust ion acoustic solitary waves. Space plasma and interstellar medium are the areas where the results of the work can be applied. [ABSTRACT FROM AUTHOR]

We have, present work on kinetic Alfven waves instability in dusty plasma. The expression for the dispersion relation, growth rate and growth length of the kinetic Alfven waves are derived using the particle aspect analysis in auroral acceleration region. Our purpose in this paper is to be investigating the effect of kappa distribution function with dusty plasma on kinetic Alfven waves. The results of the work are consistent for Alfven wave in dusty plasma are applicable of the magnetospheric and astrophysical in auroral acceleration region. [ABSTRACT FROM AUTHOR]

The influence of Photoelectron current and rotation of dusty plasma is studied with the inclusion of Quantum effect. The fluid model of dusty (complex) plasma is considered with the dynamics of charged dust along with the Boltzmann distributed ions. The General dispersion relation is derived analytically using the plane wave solution. The Joint effect of Photoelectron current (depends upon irradiated frequency) and rotation is examined on the modified Jeans instability. The Growth rate of the system is analysed with graphical presentation. It is observed that Photoelectron current has destabilizing influence while rotation has stabilizing influence on the growth rate of instability. [ABSTRACT FROM AUTHOR]

In the present paper we derive the plasma dispersion equation under the effect of ionization rate in a dust plasma to investigate the electrostatic ion cyclotron instability, where dust charge fluctuation is absent. It has one of the lowest threshold drift velocities among all the current-driven instabilities in isothermal plasma. The Electrostatic ion cyclotron instability in a dusty plasma containing electrons, light ions, and massive negatively charged dust grains which can be investigated both experimentally and theoretically. [ABSTRACT FROM AUTHOR]

It has been shown that rotation has to play a predominant important role in the formation of many astrophysical objects and the stability of molecular clouds. In this paper the theoretical investigation of the presence of rotation in the magnetized dusty plasma. The general dispersion relation is obtained normal mode analysis technique, and we found the Alfven mode is modified due to the presence of rotation and magnetic field. The graphical presentation shows that rotation and Alfven wave velocity have a stabilizing in the system. [ABSTRACT FROM AUTHOR]

A description is given of the Magnetized Dusty Plasma Experiment (MDPX) at Auburn University that was designed to study the physics of highly magnetized low temperature plasmas and magnetized dusty plasmas. The central components of the MDPX are a superconducting solenoid capable of operation at magnetic fields up to 4 T, and a parallel plate RF discharge plasma. Results from some of the initial experiments will be presented. [ABSTRACT FROM AUTHOR]

The influence of nanoparticle growth on the plasma characteristics is studied by analyzing the spatiotemporal evolution of several argon lines. It appears that some lines are promoted in dusty areas while other ones have an enhanced emission in dustfree regions like the void. This effect is related to the spatial dependence of the electron energy distribution: the particularly small electron energy in dust-free regions of a dusty plasma results in enhanced excitation of certain argon energy levels from metastable atoms. [ABSTRACT FROM AUTHOR]

The paper presents an analysis of the causes of a formation of spatial ordered grain structures in a smoky plasma. We are modeling the process of melting (crystallization) of a condensed phase in this environment taking into account the screened electrostatic interaction and the diffusion-drift force. We discuss an influence of the charge on the melting temperatures. [ABSTRACT FROM AUTHOR]

In this paper, the effect of ion-neutral collision type on the ion cloud formation around a dust particle immersed in plasma in the presence of an external electric field is considered. It is shown that elastic ion-neutral collisions in low-temperature low-density plasma lead to the persistence of directed velocity compared to the resonant charge exchange collisions, where ions lose almost their energy. Thus the ion drift velocity is larger for the case of elastic collisions than for resonant charge exchange collisions. With the increase of an external electric field strength, the charge of dust particle increases faster for the elastic case than for resonant case. The dipole moment of the ion cloud-dust particle system is also appeared to have higher values for the case of elastic collisions. [ABSTRACT FROM AUTHOR]

The paper presents a study of the coupling parameter, Γ of ordered structures in the dusty plasma and its dependence on the structural parameter κ. Investigations revealed that this dependence differs in different ranges of κ. If κ < 0.85, a strong interaction of dust grains was observed, whereas it is significantly weaker for κ > 1.4. [ABSTRACT FROM AUTHOR]

Dust clouds are often formed in many dusty plasma experiments, when micron size dust particles introduced in the plasma are confined by spatial non-uniformities of the potential. These formations show self-organized patterns like vortex or circulation flows. Steady-state equilibrium dynamics of such dust clouds is analyzed by 2D hydrodynamics for varying Reynolds number, Re, when the cloud is confined in an azimuthally symmetric cylindrical setup by an effective potential and is in a dynamic equilibrium with an unbounded sheared plasma flow. The nonconservative forcing due to ion flow shear generates finite vorticity in the confined dust clouds. In the linear limit (Re ⪡ 1), the collective flow is characterized by a single symmetric and elongated vortex with scales correlating with the driving field and those generated by friction with the boundaries. However in the high Re limit, (Re ≥ 1), the nonlinear inertial transport (u · ▿u) is effective and the vortex structure is characterized by an asymmetric equilibrium and emergence of a circular core region with uniform vorticity, over which the viscous stress is negligible. The core domain is surrounded by a virtual boundary of highly convective flow followed by thin shear layers filled with low-velocity coand counter-rotating vortices, enabling the smooth matching with external boundary conditions. In linear regime, the effective boundary layer thickness is recovered to scale with the dust kinematic viscosity as Δr≈ μ1/3 and is modified as Δr ≈ (μL‖/u)1/2 in the nonlinear regime through a critical kinematic viscosity μ* that signifies a structural bifurcation of the flow field solutions. The flow characteristics recovered are relevant to many microscopic biological processes at lower Re, as well as gigantic vortex flows such as Jovian great red spot and white ovals at higher Re. [ABSTRACT FROM AUTHOR]

The formation of elongated dust particles in a spherical dc glow discharge in ethanol was observed for the first time. Dust particles were formed in the process of coagulation of ethanol dissociation products in the plasma of gas discharge. During the process the particles were captured into clouds in the electric potential wells of strong striations of spherical discharge. The size and the shape of dust particles are easily detected by naked eye after the illumination of the laser sheet. The description of the experimental setup and conditions, the analysis of size, shape and composition of the particles, the explanation of spatial ordering and orientation of these particles are presented. [ABSTRACT FROM AUTHOR]

The methane decomposition in a planar RF discharge (13.56 MHz) leads both to a dust-particle generation in the plasma bulk and to a coating growth on the electrodes. Growing dust-particles fall onto the grounded electrode when they are too heavy. Thus, at the end of the experiment, the grounded electrode is covered by a coating and by fallen dustparticles. During the dust-particle growth, the negative DC self-bias voltage (VDC) increases because fewer electrons reach the RF electrode, leading to a more resistive plasma and to changes in the plasma chemical composition. In this paper, the cleanliness influence of the RF electrode on the dust-particle growth, on the plasma characteristics and composition is investigated. A cleanliness electrode is an electrode without coating and dust-particles on its surface at the beginning of the experiment. [ABSTRACT FROM AUTHOR]

We describe experimental observations of nonlinear wave structures excited by a supersonic mass flow of dust particles over an electrostatic potential hill in a dusty plasma medium. The experiments have been carried out in a Π-shaped experimental (DPEx) device in which micron sized Kaolin particles are embedded in a DC glow discharge Argon plasma. An equilibrium dust cloud is formed by maintaining the pumping speed and gas flow rate and the dust flow is induced either by suddenly reducing the height of a potential hill or by suddenly reducing the gas flow rate. For a supersonic flow of the dust fluid precursor solitons are seen to propagate in the upstream direction while wake structures propagate in the downstream direction. For flow speeds with a Mach number greater than 2 the dust particles flowing over the potential hill give rise to dispersive dust acoustic shock waves. The experimental results compare favorably with model theories based on forced K-dV and K-dV Burger's equations. [ABSTRACT FROM AUTHOR]

An investigation of the characteristics of freak waves in dusty plasma containing two temperatures ions is presented. The reductive perturbation method is used to obtain the Kadomstev-Petviashvili (KP) equation. Further, on modulating KP equation, the nonlinear Schrödinger equation (NLSE) is derived. Under the influence of various parameters (e.g., superthermality of cold and hot ions, a number density ratio of cold ions to dust and a temperature ratio of cold to hot ions), the characteristics of freak wave structures are studied. [ABSTRACT FROM AUTHOR]

In this investigation, the effect of polarization force on dust acoustic solitary waves (DASWs) has been presented in a dusty plasma composed of Maxwellian electrons, vortex-like (trapped) ions, and negatively charged mobile dust grains. It has been found that from the Maxwellian ions distribution to a vortex-like one, the dynamics of small but finite amplitude DA solitary waves is governed by a nonlinear equation of modified Korteweg-de Vries (mKdV) type instead of KdV. The combined effect of trapped ions and polarization force strongly influence the characteristics of DASWs. Only rarefactive solitary structures are formed under the influence of ions trapping and polarization force. The implications of our results are useful in real astrophysical situations of space and laboratory dusty plasmas. [ABSTRACT FROM AUTHOR]

An SPH (Smoothed Particle Hydrodynamics) simulation code is developed to reproduce our findings on behavior of dust particles, which were obtained in our previous experiments (Phys. Plasmas, 23, 013709 (2016) and Abst. 18th Intern. Cong. Plasma Phys. (Kaohsiung, 2016)). Usually, in an SPH simulation, a smoothed particle is interpreted as a discretized fluid element. Here we regard the particles as dust particles because it is known that behavior of dust particles in complex plasmas can be described using fluid dynamics equations in many cases. Various rotation velocities that are difficult to achieve in the experiment are given to particles at boundaries in the newly developed simulation and motion of particles is investigated. Preliminary results obtained by the simulation are shown. [ABSTRACT FROM AUTHOR]

At present, there are several theoretical assumptions that the rotation of the plasma-dust structures in the striation in a magnetic field can be caused by the presence of a number of irregularities. In this paper one of the irregularities, such as the influence of the edge effect at the ends of the solenoids on the rotational motion of plasma-dust structures in the stratum of the glow discharge, was experimentally investigated. [ABSTRACT FROM AUTHOR]

The velocity distribution function of dust particles immersed in a plasma was investigated under microgravity conditions. A three-dimensional (3D) cloud of polymer microspheres was suspended in a neon plasma, in the PK-4 instrument onboard the International Space Station (ISS). These dust particles were tracked using video microscopy in a cross section of the 3D dust cloud. The velocity distribution function (VDF) is found to have a non-Maxwellian shape with high-energy tails; it is fit well by a combination of low-energy Maxwellian core and a high-energy non-Gaussian Kappa-distribution halo. Similar non-Maxwellian VDFs are typically observed in space plasmas. [ABSTRACT FROM AUTHOR]

The role of dust in the space environment is of increasing interest in recent years and also the fast development of fusion devices with a magnetic confinement brought new issues in the plasma-surface interaction. Among other processes, secondary electron emission plays an important role for dust charging in interplanetary space and its importance increases at and above the surfaces of airless bodies like planets, moons, comets or asteroids. A similar situation can be found in many industrial applications where the dust is a final product or an unintentional impurity. The present paper reviews the progress in laboratory investigations of the secondary emission process as well as an evolution of the modeling of the interaction of energetic electrons with dust grains of different materials and sizes. The results of the model are discussed in view of latest laboratory simulations and they are finally applied on the estimation of an interaction of the solar wind and magnetospheric plasmas with the dust attached to or levitating above the lunar surface. [ABSTRACT FROM AUTHOR]

Dust grains play a key role in dusty plasma since they interact with the plasma we can use them to study plasma itself. The grains are illuminated by visible light (e.g., a laser sheet) and the situation is captured with camera. Despite of simplicity, light scattering on similar-to-wavelength sized grains is complex phenomenon. Interaction of the electromagnetic wave with material has to be computed with respect to Maxwell equations -- analytic solution is nowadays available only for several selected shapes like sphere, coated sphere, or infinite cylinder. Moreover, material constants needed for computations are usually unknown. For computation result verification and material constant determination, we designed and developed a device directly measuring light scattering profiles. Single dust grains are trapped in the ultrasonic field (so called "acoustic levitation") and illuminated by the laser beam. Scattered light is then measured by a photodiode mounted on rotating platform. Synchronous detection is employed for a noise reduction. This setup brings several benefits against conventional methods: (1) it works in the free air, (2) the measured grain is captured for a long time, and (3) the grain could be of arbitrary shape. [ABSTRACT FROM AUTHOR]

We study the electric and dust environment near a complex surface structure on the moon: a vertical hole. In order to model an electric field structure near the surface, we performed the particle-in-cell simulations. The simulations provide electric field and plasma current density profiles in three-dimensional space above the complex lunar surface topography. Subsequently, we applied the obtained electric field and plasma current density data to the test-particle simulation on the dynamics of submicronsized charged dust grains. We focus on an effect of a stochastic charging process of such small dust grains. Because of their small surface areas, the dusts will get/lose one elementary charge infrequently. The preliminary simulation results show an evidence of dust mobilization across the sunlight-shadow interface formed inside the lunar hole. [ABSTRACT FROM AUTHOR]

The propagation properties of ion acoustic nonlinear periodic waves is studied in unmagnetized collisionless plasma consisting of fluid ions, immobile negatively charged dust particulates and nonthermal electrons. By employing reductive perturbation technique (RPT), the nonlinear Korteweg-de Vries equation is derived. Further, energy balance equation is derived by applying the Sagdeev potential approach, which gives the solutions having cnoidal ellipitical functions. The combined effects of dust concentration and nonthermality of electrons on the propagation properties of periodic wave structures, have been discussed in detail. Both compressive and rarefactive cnoidal wave structures are formed. It is observed that nonthermality of electrons significantly influence the structures of periodic waves. The present investigation could be useful in space and astrophysical plasma environments. [ABSTRACT FROM AUTHOR]

Modulation instability of dust acoustic waves (DAWs) is investigated in a collisionless, unmagnetized one dimensional plasma, containing two temperature ions and electrons featuring hybrid nonthermal distribution. Using the multiple scale perturbation technique, a nonlinear Schrodinger equation (NLSE) which governs the modulation instability of the DAWs is derived. Valid range of plasma parameters has been fixed and their effects on the modulational instability are discussed in detail. Different types of envelope (bright/dark) solitons are observed. Both dispersion and nonlinearity coefficients of the NLSE are explicit functions of relevant physical parameters that change the critical wave number at which modulational instability sets in. The characteristics of DASWs are modified by varying different physical parameters. The findings of this investigation may useful to understand the nonlinear excitations in space and astrophysical environments where dust, two temperature ions and non-Maxwellian electrons are present. [ABSTRACT FROM AUTHOR]

Theoretical investigation of dielectric response function of a magnetized dusty plasma has been considered for dust acoustic (DA) modes in the presence of strong interaction between dust grains employing the generalized hydrodynamic (GHD) fluid model. This dielectric response function can be used for analyzing of the behavior of the complex plasma and also wake potential in magnetic field. [ABSTRACT FROM AUTHOR]

Shock wave properties generated by impulse mechanical loading and base state structure of dusty plasma system versus the change of dusty particle charges with height were investigated in the framework of the molecular dynamics method. Spherically symmetric electrostatic confinement was used as the boundary conditions. Interactions between dusty particles were described using Debye-Huckel potential. Particle charges decreased linearly with the increase of height. Shape of dusty plasma crystals with taking into account a variable particle charge was simulated. [ABSTRACT FROM AUTHOR]

The dynamics of a van der Pol-Mathieu (vdPM) equation with time delay is considered. The vdPM model can be realized as the governing equation for dust density in a simplified model of dusty plasma. The dynamics of the time-delayed equation is analyzed by separating the timescales of the system assuming that the fundamental simple harmonic oscillator is at least an O(ε ) dominating other terms of the oscillator including time-delay, where ε ≪ 1. Our analytic prediction of the slow-flow system correctly represents the dynamics of the original system, showing periodic creation and annihilation of multi-periodic limit cycles. The original system is then analyzed using the DDE-Biftool [1] bifurcation analysis tool. We show that for large time-delay, the system undergoes a double-Hopf bifurcation, whereas for small delay, it undergoes a Bogdanov-Takens bifurcation. [ABSTRACT FROM AUTHOR]

In strongly coupled limit the general hydrodynamic (GH) model shows that the dusty plasma, acquiring significant rigidity, is able to support the " shear " like mode [P. K. Kaw and A. Sen, Phys. Plasmas 5, 3552 (1998)]. In presence of velocity shear, this shear like mode is coupled with the dust acoustic mode which is generated by the compressibility effect of the dust fluid due to the finite temperature of the dust, electron and ion fluids. Local dispersion shows the velocity shear is also responsible for the instabilities of the shear mode, acoustic mode, as well as the shearacoustic coupled mode. The present work, carried out in GH visco-elastic formalism, also gives the clear insight of the instabilities of the coupled mode in non local regime with a hyperbolic tangent velocity shear profile over a finite width. [ABSTRACT FROM AUTHOR]

Dust cluster is a stable structure of negatively charged dust particles formed in complex plasmas. This paper briefly describes the dynamics of these objects. Dust clusters are confined by external applied and or self consistent electrostatic plasma fields. Dust cluster may be regarded as energy storage device which stores plasma thermal energy in the electrostatic fields of cluster. This energy is recovered when the cluster explodes upon removal of the confining potential. In this paper a model for the dust cluster explosion in the afterglow phase of a complex plasma discharge is described. The model is tested by MD simulations of dust particles in a confining potential. The nature of the explosion (caused by switching off the discharge) and the concomitant dust acceleration is found to depend critically on the pressure of the back ground neutral gas. At low gas pressure, the explosion is due to unshielded Coulomb repulsion between dust particles and yields maximum acceleration while in the high pressure regime it is due to shielded Yukawa repulsion and yields much feebler acceleration. These results are in agreement with recent experimental findings. The simulations also confirm a recently proposed electrostatic (ES) isothermal scaling relation, PE ∝ Vd-2 (where PE is the ES is pressure of the dust particles and Vd is the confining volume). [ABSTRACT FROM AUTHOR]