Showing papers on "Dusty plasma published in 2018"

Dispersive solitary wave solutions of nonlinear further modified Korteweg–de Vries dynamical equation in an unmagnetized dusty plasma

Abstract: In this work, we consider the propagation of one-dimensional nonlinear unmagnetized dusty plasma, by using the reductive perturbation technique to formulate the nonlinear mathematical model which i...

Solitary wave solution and dynamic transition of dust ion acoustic waves in a collisional nonextensive dusty plasma with ionization effect

Abstract: The solitary wave solution and dynamic transition of dust ion acoustic waves (DIAWs) are studied in an unmagnetized collisional dusty plasma, which consists of negatively charged dust fluid, positively charged ions, q -nonextensive electrons, and background neutral particles, considering the ionization effect, ion loss, ion–neutral, ion–dust, and dust–neutral collisions. Using reductive perturbation technique (RPT) the damped Korteweg–de Vries (DKdV) equation and the damped modified Korteweg–de Vries (DMKdV) equation are derived. Using momentum conservation law, dust ion acoustic solitary wave solutions (DIASWSs) are obtained for the DKdV and MDKdV equations. Effects of nonextensive parameter ( q ) and ion–dust collisional frequency ( ν i d ) are presented on the DIASWSs. Effects of ion–dust collisional frequency ( ν i d ), ion–neutral collisional frequency ( ν i n ) and ion loss rate ( ν l ) on DIAWs are investigated considering an external periodic perturbation through three-dimensional phase portrait and time-series analysis. It is found that ν i d , ν i n and ν l significantly affect on the dynamics of the perturbed DIAWs and play a pivotal role in the transition from quasiperiodic and chaotic motions to periodic motion.

Strongly coupled plasmas obey the fluctuation theorem for entropy production

Abstract: Particles in strongly coupled plasmas behave collectively as in liquids, with additional long-range collisions. Experimental evidence is provided that fluctuation theorems obeyed by liquid are also valid for strongly coupled dusty plasmas. Fluctuation theorems1,2,3,4 describe nonequilibrium stochastic behaviour in small systems. Whilst experiments have shown that fluctuation theorems are obeyed by single particles in liquids5 and several other physical systems6,7,8,9,10, it has not been shown if that is the case in strongly coupled plasmas. Plasmas are said to be strongly coupled when interparticle potential energies are large compared to kinetic energies. Charged particles in such plasmas can behave collectively like liquids11,12, but with essential differences, such as long-range collisions13. It remains unexplored whether, despite these differences, the stochastic behaviour of strongly coupled plasmas will obey fluctuation theorems. Here we demonstrate experimentally that a strongly coupled dusty plasma obeys the fluctuation theorem of Evans, Cohen, and Morriss (ECM)14, which was developed for a simple liquid in a nonequilibrium steady state. This fluctuation theorem describes the entropy production arising from collisions in a steady laminar shear flow.

Effect of polarization force on head-on collision between multi-solitons in dusty plasma

Abstract: Head-on collision among dust acoustic (DA) multi-solitons in a dusty plasma with ions featuring non-Maxwellian hybrid distribution under the effect of the polarization force is investigated. The presence of the non-Maxwellian ions leads to eloquent modifications in the polarization force. Specifically, an increase in the superthermality index of ions (via κi) and nonthermal parameter (via α) diminishes the polarization parameter. By employing the extended Poincare-Lighthill-Kuo method, two sided KdV equations are derived. The Hirota direct method is used to obtain multi-soliton solutions for each KdV equation, and all of them move along the same direction where the fastest moving soliton eventually overtakes the others. The expressions for collisional phase shifts after head-on collision of two, four, and six-(DA) solitons are derived under the influence of polarization force. It is found that the effect of polarization force and the presence of non-Maxwellian ions have an emphatic influence on the phase ...

Bifurcation Analysis for Dust-Acoustic Waves in a Four-Component Plasma Including Warm Ions

Abstract: Investigation of linear dust-acoustic (DA) waves was analyzed in a system of collisionless, dissipative, and unmagnetized four-component dusty plasma consisting of cold positively and negatively charged particles of dust, with ions and electrons are of the Boltzmann distribution. The compatibility condition is obtained by using the normal mode analysis. The Korteweg de Vries–Burgers (KdV–Burgers) equation is obtained when the plasma system is nonlinearly analyzed by the reductive perturbation method. To study the nonlinear waves, we obtain some interesting physical solutions. These solutions are in the form of soliton, a combination between a shock and a soliton, and finally monotonic and oscillatory shock waves. Graphical illustration for these solutions was presented. The characteristics of the DA solitary and shock waves are significantly modified by the presence of positive and negative dust ions, the ratio of the ion to electron temperatures, and it is also found that the basic features are affected by the dust kinematic viscosity. The planar dynamical systems bifurcation theory, which was used to establish the existence of solitary wave solutions and periodic traveling wave solutions, has been established. Accordingly, the phase portrait topology and the potential diagram are illustrated for the KdV–Burgers equation. As a result of different phase orbits, there is an advantage to predict different classes of traveling wave solutions. The electric field is determined. Generalization of the obtained results in this paper can be used to investigate the nature of plasma waves in both laboratory and space.

Effect of polarization force on dust-acoustic cnoidal waves in dusty plasma

Abstract: A theoretical investigation has been presented to study the effect of polarization force on nonlinear dust acoustic (DA) cnoidal waves in dusty plasma composed of negatively charged dust fluid, Maxwellian electrons and superthermally distributed ions. The effect of polarization force is significantly modified due to the presence of the superthermal ions. In particular, an increase in superthermality index of ions leads to a decrease in polarization parameter. By employing reductive perturbation method, the nonlinear Korteweg–de Vries (KdV) equation is derived for the study of DA cnoidal waves. Further, the Sagdeev potential approach is employed to find the solution of KdV equation to analyze the characteristics of DA cnoidal waves. Only negative potential DA cnoidal waves are observed. Furthermore, the combined effects of polarization force and superthermality of ions on the characteristics of negative potential DA cnoidal waves have been studied in detail. It is emphasized that the real implementation of our present results is in laboratory experiments as well as in different regions of space and astrophysical environments especially in Saturn’s magnetosphere, comet tails, etc.

Scattering characteristics of electromagnetic waves in time and space inhomogeneous weakly ionized dusty plasma sheath

Abstract: The dielectric coefficient of a weakly ionised dusty plasma is used to establish a three-dimensional time and space inhomogeneous dusty plasma sheath. The effects of scattering on electromagnetic (EM) waves in this dusty plasma sheath are investigated using the auxiliary differential equation finite-difference time-domain method. Backward radar cross-sectional values of various parameters, including the dust particle radius, charging frequency of dust particles, dust particle concentration, effective collision frequency, rate of the electron density variation with time, angle of EM wave incidence, and plasma frequency, are analysed within the time and space inhomogeneous plasma sheath. The results show the noticeable effects of dusty plasma parameters on EM waves.

Nonplanar dust-acoustic waves and chaotic motions in Thomas Fermi dusty plasmas

Abstract: The properties of linear and nonlinear nonplanar dust acoustic (DA) solitary waves and chaotic behavior are investigated in an unmagnetized Thomas Fermi dusty plasma, whose components are degenerate electrons, ions, and negatively charged inertial cold dust grains. A linear dispersion relation is obtained and solved numerically. It has been observed that linear excitation characteristics are influenced by radial distance r, geometric term ν, and ion-to-electron Fermi temperature ratio σi. We have also noted that the addition of a geometrical term in dispersion relation gives damping along the radial axis. A modified Korteweg-de Vries (KdV) equation is derived by employing the reductive perturbation technique, and its numerical solutions are obtained. The modified KdV equation is discussed for cold dust grains in planar and nonplanar frameworks. Upon the introduction of external periodic perturbation, the perturbed modified KdV equation is studied in planar geometry via some qualitative and quantitative approaches. The perturbed KdV equation can give rise to the periodic, quasiperiodic, and chaotic motions for DA waves. The strength of the external perturbation and dust concentration h play the major role of the switching parameter in the transition of dynamic motion. The developed chaos can be weakened with the variation of dust concentration h. It has been observed that the dust concentration affects the dynamics of DA waves in planar geometry which is an important observation in this study.

Propagation characteristics of electromagnetic waves in dusty plasma with full ionization

Abstract: This study investigates the propagation characteristics of electromagnetic (EM) waves in fully ionized dusty plasmas The propagation characteristics of fully ionized plasma with and without dust under the Fokker–Planck–Landau (FPL) and Bhatnagar–Gross–Krook (BGK) models are compared to those of weakly ionized plasmas by using the propagation matrix method It is shown that the FPL model is suitable for the analysis of the propagation characteristics of weakly collisional and fully ionized dusty plasmas, as is the BGK model The influence of varying the dust parameters on the propagation properties of EM waves in the fully ionized dusty plasma was analyzed using the FPL model The simulation results indicated that the densities and average radii of dust grains influence the reflection and transmission coefficients of fully ionized dusty plasma slabs These results may be utilized to analyze the effects of interaction between EM waves and dusty plasmas, such as those associated with hypersonic vehicles

Dust acoustic shock waves in magnetized dusty plasma

Abstract: We have presented a theoretical study of the dust acoustic (DA) shock structures in a magnetized, electron depleted dusty plasma in the presence of two temperature superthermal ions. By deriving a Korteweg–de Vries–Burgers equation and studying its shock solution, we aim to highlight the effects of magnetic field and obliqueness on various properties of the DA shock structures in the presence of kappa-distributed two temperature ion population. The present model is motivated by the observations of Geotail spacecraft in the Earthʼs magnetotail and it is seen that the different physical parameters such as superthermality of the cold and hot ions, the cold to hot ion temperature ratio, the magnetic field strength, obliqueness and the dust kinematic viscosity greatly influence the dynamics of the shock structures so formed. The results suggest that the variation of superthermalities of the cold and hot ions have contrasting effects on both positive and negative polarity shock structures. Moreover, it is noted that the presence of the ambient magnetic field affects the dispersive properties of the medium and tends to make the shock structures less wide and more abrupt. The findings of present investigation may be useful in understanding the dynamics of shock waves in dusty plasma environments containing two temperature ions where the electrons are significantly depleted.

Experimental observation of a dusty plasma crystal in the cathode sheath of a DC glow discharge plasma

Abstract: Dusty plasma crystals have traditionally been observed and studied in radio frequency discharge plasmas, and their formation in a DC glow discharge plasma remains experimentally challenging. We report the first ever observation of a stable dusty plasma Coulomb crystal in the cathode sheath region of a DC glow discharge plasma. The observations are made in the dusty plasma experimental (DPEx) device where crystals of mono-disperse melamine formaldehyde grains are produced in the background of an Argon plasma. The crystalline nature of the structure is confirmed through a host of characteristic parameter estimations which includes the radial pair correlation function, Voronoi diagram, Delaunay Triangulation, the structural order parameter, the dust temperature, and the Coulomb coupling parameter. The special features of the DPEx device which permit such a crystal formation are delineated, and some principal physical features of the crystal are discussed.

Structures and diffusion of two-dimensional dusty plasmas on one-dimensional periodic substrates

Abstract: Using numerical simulations, we examine the structure and diffusion of a two-dimensional dusty plasma (2DDP) in the presence of a one-dimensional periodic substrate (1DPS) as a function of increasing substrate strength. Both the pair correlation function perpendicular to the substrate modulation and the mean-squared displacement (MSD) of dust particles are calculated. It is found that both the structure and dynamics of 2DDP exhibit strong anisotropic effects, due to the applied 1DPS. As the substrate strength increases from zero, the structure order of dusty plasma along each potential well of 1DPS increases first probably due to the competition between the interparticle interactions and the particle-substrate interactions, and then decreases gradually, which may be due to the reduced dimensionality and the enhanced fluctuations. The obtained MSD along potential wells of 1DPS clearly shows three processes of diffusion in our studied 2DDP. Between the initial ballistic and finally diffusive motion, there is the intermediate subdiffusion discovered here, which may result from the substrate-induced distortion of the caging dynamics.

Magnetic field effects and waves in complex plasmas

Abstract: Magnetic fields can modify the physical properties of a complex plasma in various different ways. Weak magnetic fields in the mT range affect only the electrons while strong fields in the Tesla regime also magnetize the ions. In a rotating dusty plasma, the Coriolis force substitutes the Lorentz force and can be used to create an effective magnetization for the strongly coupled dust particles while leaving electrons and ions unaffected. Here, we present a summary of our recent experimental and theoretical work on magnetized complex plasmas. We discuss the dynamics of dust particles in magnetized discharges, the wave spectra of strongly coupled plasmas, and the excitations in confined plasmas.

Methods for the characterization of imposed, ordered structures in MDPX

Abstract: Dusty plasmas have been studied in argon, radio frequency (rf) glow discharge plasmas with magnetic fields up to 1.5 T. Plasmas were formed between a powered bottom electrode and a grounded top electrode in which an aluminum wire mesh is fixed in the center. This work will examine the experimental conditions at which imposed, ordered structures form within the dusty plasma. These imposed, ordered structures, as reported in earlier works, are characterized by the alignment of dust particles to the spatial structure of the wire mesh in the top electrode and occur at high magnetic fields (B ≥ 1 T) and low neutral pressure (P ≤ 100 mTorr). A pair of parameters will be established to characterize the degree to which the dust particles are affected by these imposed ordered structures on both long and short time scales. Using these parameters, it will be shown that a correlation exists between the onset of imposed, ordered structures and the magnetization of ions within the plasma.Dusty plasmas have been studied in argon, radio frequency (rf) glow discharge plasmas with magnetic fields up to 1.5 T. Plasmas were formed between a powered bottom electrode and a grounded top electrode in which an aluminum wire mesh is fixed in the center. This work will examine the experimental conditions at which imposed, ordered structures form within the dusty plasma. These imposed, ordered structures, as reported in earlier works, are characterized by the alignment of dust particles to the spatial structure of the wire mesh in the top electrode and occur at high magnetic fields (B ≥ 1 T) and low neutral pressure (P ≤ 100 mTorr). A pair of parameters will be established to characterize the degree to which the dust particles are affected by these imposed ordered structures on both long and short time scales. Using these parameters, it will be shown that a correlation exists between the onset of imposed...

Oblique Interaction of Dust-ion Acoustic Solitons with Superthermal Electrons in a Magnetized Plasma

Abstract: The oblique interaction between two dust-ion acoustic (DIA) solitons travelling in the opposite direction, in a collisionless magnetized plasma composed of dynamic ions, static dust (positive/negative) charged particles and interialess kappa distributed electrons is investigated. By employing extended Poincare–Lighthill–Kuo (PLK) method, Korteweg–de Vries (KdV) equations are derived for the right and left moving low amplitude DIA solitons. Their trajectories and corresponding phase shifts before and after their interaction are also obtained. It is found that in negatively charged dusty plasma above the critical dust charged to ion density ratio the positive polarity pulse is formed, while below the critical dust charged density ratio the negative polarity pulse of DIA soliton exist. However it is found that only positive polarity pulse of DIA solitons exist for the positively charged dust particles case in a magnetized nonthermal plasma. The nonlinearity coefficient in the KdV equation vanishes for the ne...

Dust dressed solitons in a dusty plasma: The effect of polarization forces

Abstract: In this paper, dressed solitons in dusty plasma in the presence of polarization forces acting on the dust grains are investigated. Including fourth-order nonlinearities of electric potential and integrating the resulting energy equation, an exact soliton solution is obtained for dust acoustic waves in dusty plasma. This exact solution reduces to the dressed soliton solution obtained for the system using renormalization procedure in the reductive perturbation method, when Mach number is expanded in terms of soliton velocity. An equation including higher-order corrections is also derived, and the polarization effect is show to have a significant role in the characteristics of these corrections.

The Rotation of Complex Plasmas in a Stratified Glow Discharge in the Strong Magnetic Field

Abstract: The dusty plasma was created in a glow discharge in a magnetic field with induction up to 10 000 G. The setup and dc discharge conditions for this unique experiment are described. Dusty plasma exists in the form of volumetric dust structures or dust clusters rotating in the magnetic field. Quantitative results are presented in the form of dependence of an angular velocity of rotation on the magnetic induction. The rotational dynamics of a dusty plasma found experimentally is complex. It has a rotation inversion, a sharp change in the growth rate, and an instability region in which a partial loss of the dust component occurs. In the case where it is possible, the quality interpretation for the obtained dependence is given. The regions of the magnetic field are found in which the ion drag force dominates, the region where the dust structure is entrained by the moving gas of the discharge, and the region of slow growth of the rotation speed, which has not yet been uniquely interpreted.

Modulated dust-acoustic wave packets in an opposite polarity dusty plasma system

Abstract: The nonlinear propagation of the dust-acoustic bright and dark envelope solitons in an opposite polarity dusty plasma system (composed of non-extensive $q$-distributed electrons, isothermal ions, and positively as well as negatively charged warm dust) have been theoretically investigated. The reductive perturbation method (which is valid for a small, but finite amplitude limit) is employed to derive the nonlinear Schrodinger equation. Two types of modes (namely, fast and slow dust-acoustic (DA) modes) have been observed. The conditions for the modulational instability (MI) and its growth rate in the unstable regime of the DA waves are significantly modified by the effects of non-extensive electrons, dust mass, temperatures of different plasma species, etc. The implications of the obtained results from our current investigation in space (viz. Jupiters magnetosphere, upper mesosphere, and comets tails) and laboratory (e.g. direct current and radio-frequency discharges, plasma processing reactors, fusion plasma devices, and solid-fuel combustion products, etc.) dusty plasmas are briefly discussed.

Generation of rogue waves in space dusty plasmas

Abstract: The basic features of dust-acoustic (DA) waves (DAWs) in a four component dusty plasma system (containing inertial cold and hot dust grains and inertialess non-extensive ions and electrons) have been theoretically investigated by deriving the nonlinear Schrodinger equation The analytic analysis under consideration demonstrates two types of modes, namely, fast and slow DA modes The unstable domain, which can be recognized by the critical wave number (kc), gives rise to the DA rogue waves (DARWs) It is observed that the amplitude and width of the DARWs are significantly modified by various plasma parameters The present results should be useful in understanding the conditions for modulational instability of DAWs and generation of DARWs in Saturn F-rings

Solutions of nonplanar KP-equations for dusty plasma system with GE-method

Abstract: The propagation of three-dimensional nonlinear dust acoustic waves in a dusty plasma consisting of positive and negative dust grains as well as Boltzmann distributed electrons and ions is investigated. Using a reductive perturbation method, Cylindrical Kadomtsev-Petviashvili and Spherical Kadomtsev-Petviashvili equations, appropriate for describing the evolution of the system, are derived. The Generalized Expansion method is used to find the various solutions of the obtained nonlinear Kadomtsev-Petviashvili equations. New classes of triangular, hyperbolic solitary, rational, and Jacobi elliptical type solutions are obtained and graphically presented. It is found that the proposed dusty plasma model can support solitary waves with compressive and rarefactive potential pulses. Moreover, the effects of plasma parameters on this solitary wave structure are investigated. The current findings are applied to a cosmic-type plasma in different regions of space, viz. cometary tails, mesosphere, and Jupiter's magnetosphere as well as laboratory-type plasma such as low temperature experiments, where a dusty plasma with opposite polarity is dominant.The propagation of three-dimensional nonlinear dust acoustic waves in a dusty plasma consisting of positive and negative dust grains as well as Boltzmann distributed electrons and ions is investigated. Using a reductive perturbation method, Cylindrical Kadomtsev-Petviashvili and Spherical Kadomtsev-Petviashvili equations, appropriate for describing the evolution of the system, are derived. The Generalized Expansion method is used to find the various solutions of the obtained nonlinear Kadomtsev-Petviashvili equations. New classes of triangular, hyperbolic solitary, rational, and Jacobi elliptical type solutions are obtained and graphically presented. It is found that the proposed dusty plasma model can support solitary waves with compressive and rarefactive potential pulses. Moreover, the effects of plasma parameters on this solitary wave structure are investigated. The current findings are applied to a cosmic-type plasma in different regions of space, viz. cometary tails, mesosphere, and Jupiter's magnet...

Electron energy probability function in the temporal afterglow of a dusty plasma

Abstract: The kinetic description of the electron energy probability function (EEPF) in a dusty afterglow plasma is considered for two typical cases: when the rate of electron-neutral momentum-transfer collisions is independent of the electron energy and when it is a power function of the electron energy. The electron Boltzmann equation is solved using the method of characteristics and analytical expressions for the EEPF are obtained for different initial EEPFs (including both Maxwellian and Druyvesteyn distributions) at electron energies larger than the dust-surface potential. The analytical EEPF functions are then used to analyze several experimental parameter regimes of the dust radius and density, the dust-charge decay time, the afterglow duration, etc. It is also found that absorption of electrons by the dust particles plays an important role in determining the EEPF in a dusty afterglow.

Magnetosonic cnoidal waves and solitons in a magnetized dusty plasma

Abstract: An investigation of magnetosonic nonlinear periodic (cnoidal) waves is presented in a magnetized electron-ion-dust ( e−i−d) plasma having cold dust fluid with inertialess warm ions and electrons. The reductive perturbation method is employed to derive the Korteweg-de Vries equation. The dispersion relation for magnetosonic cnoidal waves is determined in the linear limit. The magnetosonic cnoidal wave solution is derived using the Sagdeev pseudopotential approach under the specific boundary conditions. There is the formation of only positive potential magnetosonic cnoidal waves and solitary structures in the high plasma-β limit. The effects of various plasma parameters, viz., plasma beta (β), σ (temperature ratio of electrons to ions), and μd (ratio of the number density of dust to electrons) on the characteristics of magnetosonic cnoidal waves are also studied numerically. The findings of the present investigation may be helpful in describing the characteristics of various nonlinear excitations in Earth's magnetosphere, solar wind, Saturn's magnetosphere, and space/astrophysical environments, where many space observations by various satellites confirm the existence of dust grains, highly energetic electrons, and high plasma-β.

The effects of variable dust size and charge on dust acoustic waves propagating in a hybrid Cairns–Tsallis complex plasma

Abstract: The propagation characteristics of dust acoustic waves (DAWs) in a dusty plasma consisting of variable size dust grains, hybrid Cairns–Tsallis-distributed electrons, and nonthermal ions are studied. The charging of the dust grains is described by the orbital-motion-limited theory and the size of the dust grains obeys the power law dust size distribution. To describe the nonlinear propagation of the DAWs, a Zakharov–Kuznetsov equation is derived using a reductive perturbation method. It is found that the nonthermal and nonextensive parameters influence the main properties of DAWs. Moreover, our results reveal that the rarefactive waves can propagate mainly in the proposed plasma model while compressive waves can be detected for a very small range of the distribution parameters of plasma species, and the DAWs are faster and wider for smaller size dust grains. Applications of the present results to dusty plasma observations are briefly discussed.

Dust-acoustic shock waves in a dusty plasma with non-thermal ions and super-thermal electrons

Abstract: The propagation of dust-acoustic shock waves (DASWs) in a collisionless unmagnetized dusty plasma (containing super-thermal electrons of two distinct temperatures, non-thermal ions, and a negatively charged viscous dust fluid) has been theoretically investigated by deriving and solving the nonlinear Burgers' equation. It has been observed that the viscous force acting on the dust fluid is a source of dissipation, and is responsible for the formation of DASWs, and that the basic features (viz., amplitude, polarity, width, etc.) of the DASWs are significantly modified by the presence of super-thermal electrons and non-thermal ions. The possible applications of this investigation in Earth's mesosphere, the solar atmosphere, Saturn's magnetosphere, etc., have also been briefly addressed.

Landau damping of dust acoustic solitary waves in nonthermal plasmas

Abstract: Dust acoustic (DA) solitary and shock structures have been investigated under the influence of Landau damping in a dusty plasma containing two temperature nonthermal ions. Motivated by the observations of Geotail spacecraft that reported two-temperature ion population in the Earth's magnetosphere, we have investigated the effect of resonant wave-particle interactions on DA nonlinear structures. The Korteweg-de Vries (KdV) equation with an additional Landau damping term is derived and its analytical solution is presented. The solution has the form of a soliton whose amplitude decreases with time. Further, we have illustrated the influence of Landau damping and nonthermality of the ions on DA shock structures by a numerical solution of the Landau damping modified KdV equation. The study of the time evolution of shock waves suggests that an initial shock-like pulse forms an oscillatory shock at later times due to the balance of nonlinearity, dispersion, and dissipation due to Landau damping. The findings of ...