Showing papers on "Dusty plasma published in 2023"

Dynamics and head-on collisions of multidimensionaldust-acoustic shock waves in a self-gravitating magnetized electron depleteddusty plasma

Abstract: The dynamics and collisions of dust-acoustic (DA) shock excitationstraveling in opposite directions are theoretically investigated in athree-dimensional self-gravitating magnetized electron-depleted dusty plasma(EDDP) whose ingredients are extremely massive warm positive and negativecharged dust grains as well as ions that follow the $q-$nonextensivedistribution. The linear analysis and the extended Poincare-Lighthill-Kuo(PLK) method are used to derive the dispersion relation, the two-sidedKorteweg-de Vries Burgers (KdVB) equations as well as the phaseshift that occurs due to the wave interaction. It is found that gravitationintroduces jeans-like instability, reduces the wave damping rate, decays theaperiodic oscillatory structure of DA excitations, and strongly affects theamplitude, steepness, and occurrence of monotonic compressive andrarefactive shocks. Numerical simulations also highlighted the stabilizingrole of the magnetic field and the singularities of the collision process ofmonotonic shock fronts as well as the undeniable influence of viscosity, ionnonextensivity, and obliqueness between counter-traveling waves on the phaseshift and collision profiles. The present results may be useful to betterunderstand interactions of dust acoustic shock waves (DASHWs) in thelaboratory and astrophysical scenarios such as dust clouds in the galacticdisk, photo-association regions separating H II regions from dense molecularclouds, Saturn's planetary ring, and Halley Comet.

Dust ion acoustic shock and solitary waves in a magnetized multi-component plasma with superthermal electrons

Abstract: The nonlinear wave propagation in dusty plasmas has received great interest in recent decades due to its significance in interpreting some astrophysical phenomenon. Wave propagation in dust-particle plasmas is likely to differ significantly from that in normal plasmas. Depending on their time scales, several types of acoustic waves propagate in dusty plasmas. The propagation of DIA waves was investigated through a system of multi-component dusty plasma. The study shows the effect of the magnetic field and superthermal parameters on the Sagdeev potential. The Sagdeev potential falls with decreasing ω ci values and rising superthermal parameter k values. Bifurcation analysis is taken into our consideration and shown graphically under the two conditions (A > 0 ) and (A < 0). The presented theoretical work is useful in fully understanding disturbances of the electrostatic in space dusty plasmas.

Cylindrical and spherical modified Gardner solitons in five component dusty plasmas

Abstract: The propagation of nonplanar (cylindrical or spherical) Gardner solitons (GSs) in a plasma system containing nonthermally distributed heavy ions, light ions, q nonextensive distributed electrons, and arbitrarily charged dusts is studied theoretically and numerically. The modified Gardner equation is derived using the reductive perturbation method. The basic properties (amplitude, polarity, speed, and so on) of nonplanar dust-acoustic Gardner solitons (DA GSs) are analyzed numerically. Numerical analysis shows that the properties of the DA GSs in cylindrical and spherical geometry differ from those in planar geometry. The findings of the present study considerably contribute to space plasma and laboratory plasma.

Cosmic ray-driven magnetohydrodynamic (MHD) waves in magnetized self-gravitating dusty molecular clouds

Abstract: The impact of galactic cosmic rays (CRs) in terms of CR pressure and parallel CR diffusion has been investigated on the low-frequency magnetohydrodynamic (MHD) waves and linear gravitational instability in the typical dusty plasma environment of molecular clouds (MCs). The dusty fluid model is formulated by combining the equations of the magnetized electrons/ions and dust particles, including the CR effects. The interactions between CR fluid and gravitating magnetized dusty plasma have been studied with the help of modified dispersion properties of the MHD waves and instabilities using the hydrodynamic fluid-fluid (CR-plasma) approach. CR diffusion affects the coupling of CR pressure-driven mode with dust-Alfvén MHD mode and causes damping in the MHD waves. It persists in its effect along the direction of the magnetic field and is diminished across the magnetic field. The phase speed diagram shows that for super-Alfvénic wave, the slow mode becomes the intermediate Alfvén mode. The fundamental Jeans instability criterion remains unaffected due to CR effects, but in the absence of CR diffusion, the effects of dust-acoustic speed and CR pressure-driven wave speed are observed in the instability criterion. It is found that CR pressure stabilizes while CR diffusion destabilizes the growth rates of Jeans instability and significantly affects the gravitational collapse of dusty MCs. The charged dust grains play a dominant role in the sub-Alfvénic and super-Alfvénic MHD waves and the collapse of MCs, triggering gravitational instability. The consequences have been discussed to understand the gravitational instability in the dense photodissociation regions (PDRs) of dusty MCs.

On the stability of two-dimensional modulated electrostatic wavepackets in non-Maxwellian dusty plasma-application in Saturn's magnetosphere

Abstract: Motivated by observations of localized electrostatic wavepackets by the Voyager 1 and 2 and Cassini missions in Saturn's magnetosphere, we have investigated the evolution of modulated electrostatic wavepackets in a dusty plasma environment. The well-known dust-ion acoustic (DIA) mode was selected to explore the dynamics of multi-dimensional structures, by means of a Davey-Stewartson (DS) model, by taking into account the presence of a highly energetic (suprathermal, kappa-distributed) electron population in combination with heavy (immobile) dust in the background. The modulational (in)stability profile of DIA wavepackets for both negative as well as positive dust charge is investigated. A set of explicit criteria for modulational instability (MI) to occur is obtained. Wavepacket modulation properties in 3D dusty plasmas are shown to differ from e.g. Maxwellian plasmas in 1D. Stronger negative dust concentration results in a narrower instability window in the $K$ (perturbation wavenumber) domain and a suppressed growth rate. In the opposite manner, the instability growth rate increases for higher positive dust concentrations and the instability window gets larger. In a nutshell, negative dust seems to suppress instability while positive dust appears to favor the amplitude modulation instability mechanism.

Particle simulation of the strong magnetic field effect on dust particle charging process

Abstract: A particle-in-cell simulation is modeled and run on a dusty plasma to determine the effect of the magnetic field on the process of dust-particle charging through electron-ion plasma. The electric field is solved through the Poisson equation, and the electron-neutral elastic scattering, excitation, and ionization processes are modeled through Monte Carlo collision method. The effects observed from the initial density of the plasma, the initial temperature of the electrons, and the changing magnetic field are included in this simulation model. In the dust particle charging process, saturation time and saturation charge are compared. An increase in the magnetic field does not reduce time to reach the saturation state. Determining the magnetic field boundaries which depend on the physical properties of the plasma, can be contributive in some areas of dusty(complex) plasma. The applications of the results obtained here for fusion plasma conditions and space and laboratory plasmas are discussed. The results here can be applied in future simulation models with a focus on the dust particle movement and their effect on plasma, leading to the modeling of different astrophysical plasmas thorough laboratory experiments.

Simulation of DC glow discharge plasma with free-moving dust particles in the radial direction

Abstract: A self-consistent fluid model is developed to investigate the radial distributions of dusty plasma parameters in a DC glow discharge, in which the extended fluid approach of plasma particles and the transport equations of dust particles are coupled. The electrical interaction between charged dust particles is considered in the model. The time evolution of radial distributions of dust density, plasma density, the radial component of electric field and the forces acting on dust particles when dust density tends to be stable, are obtained and analyzed under different discharge currents and dust particle radii. It is shown that the dust density structure is determined mainly by the radial electrostatic force, thermophoretic force and ion drag force in the discharge tube, and both discharge current and dust particle radius have an obvious effect on the transport processes of dust particles. The dust particles gather in the central region of the discharge tube for low discharge current and small dust radius, then dust voids are formed and become wider when the discharge current and dust radius increase. The plasma parameters in the dust gathering region are obviously affected by the dust particles due to the charging processes of electrons and ions to the dust surface.

Study on the Absorption Properties of Terahertz Circularly Polarized Wave in FPL Model Fully Ionized Dusty Plasma

Abstract: In this article, Boltzmann’s general plasma kinetics and the Fokker–Planck–Landau (FPL) collision model of dusty plasma are used to obtain the expression of the dielectric coefficient of dusty plasma under the influence of an external magnetic field and the collision condition of the fully ionized FPL model. The charging effect of dusty plasma is fully considered. The absorption characteristics of circularly polarized waves in the terahertz band under different plasma parameters are calculated and analyzed by using the transfer matrix method. Results show that the intensity of the external magnetic field, the size and concentration of dust particles, the effective collision frequency and thickness of dusty plasma, the incidence angle of the electromagnetic waves, and the electron temperature greatly influence the absorption characteristics of circularly polarized electromagnetic waves. The propagation characteristics of circularly polarized waves caused by different external magnetic fields are evaluated. An absorption band is formed near the cyclotron frequency when the external magnetic field increases to a certain extent, and the direction of the electron cyclotron and the rotation direction of the polarized wave are consistent. The position and frequency band of dusty plasma can be controlled by artificially changing the magnitude of the external magnetic field. These results provide a theoretical basis for the study of electromagnetic wave propagation in weakly colliding, fully ionized dusty plasma and the propagation mechanism of an electromagnetic wave in the local high-temperature area of the hypersonic target.

Dust acoustic solitary waves in dusty plasma with nonuniform temperature

Abstract: In this paper, the dust acoustic wave is studied in conditions where the dust temperature is not constant. This model includes negatively charged dust particles and thermal ions. The reductive perturbation technique is used and the new point in this study is the nonuniformity of the plasma temperature. The nonconstancy of the temperature is entered as a first-order perturbation in the calculations, and finally the modified Korteweg–de Vries (mKdV) equation is derived. The solution of the modified KdV equation clarifies the change in soliton shape of the wave when it moves in the perturbation plasma. We show how the soliton wave undergoes deformation and amplitude reduction during propagation when it encounters a region with a different temperature. The output of this research can be effective to better understand the wave behavior in a real plasma with nonuniform temperature.

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

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

Formation of ordered structure in spray of thermal dusty plasmas

Abstract: An ordered structure of macroscopic particles has been experimentally observed in a classical neutral thermal plasma using a laser time-of-flight system. The strongly coupled thermal plasma consists of Ce0₂ particles and electrons emitted by the latter under atmospheric pressure and temperature of 1700 K. The particles are charged positively and suspended in a plasma flow. Their charge is about 10³e and the calculated value of a Coulomb coupling parameter γ_p is >120 that corresponds to a strongly coupled plasma.

Effect of the ion drag force on head‐on collisions between two nonlinear dust acoustic waves in a strongly coupled dusty plasma

Abstract: The effect of dust grain pressure on the head-on collision of two dust-acoustic solitary waves in non-magnetized, collisionless, and strongly coupled dust plasma has been investigated [J. Plasma Phys. (2020), 86, 905,860,111]. In this paper, the model is augmented by incorporating the ion drag force on dust grains. By way of the extended perturbation method of Poincaré-Lighthill-Kuo, Korteweg-de Vries equations are derived. The wave characteristics along with the phase shifts after the head-on collision are analytically established and numerically assessed. It revealed a non-negligible decrease in the wave amplitude and the phase shift.

Dust cloud dynamics in a non-equilibrium plasma

Abstract: Voids in dusty plasma are a new phenomenon, which is still not completely understood. In this work we study void formation in the sheath of a radio-frequency (RF) dusty plasma. By injecting micrometer sized dust particles into the plasma, we form a dust cloud in the sheath. The behaviour of the cloud as a function of RF power and gas pressure has been investigated using video imaging. Both dependencies show a threshold for the void formation. This threshold is characterised by a sudden decrease in the inter-particle distance, while in the non-void mode the distance increases with power and pressure. We have performed Langmuir probe measurements of the floating potential in the bulk plasma close to the sheath in order to estimate the form of the potential well trapping the dust grains.

On the force exerted on a non-spherical dust grain from homogeneous, stationary, non-magnetized plasma

Abstract: It is shown that stationary non-spherical dust grain immersed into stationary non-magnetized plasma can experience a force caused by the grain-plasma interactions.

Quantum Effects on Cylindrical Dust-ion Acoustic Waves in a Semiclassical Dense Dusty Plasma

Abstract: The nonlinear cylindrical dust ion acoustic waves are studied in a collisional unmagnetized dense dusty plasma medium containing inertialess degenerated electrons and positrons, fluid ions, negatively charged dust fluid and neutrals in the background, including exchange-correlation effects of both electrons and positrons. Employing the reductive perturbation method, the damped Kadomstev–Petviashvili equation is derived in the framework of two-dimensional cylindrical geometry. An approximate analytical solution of this equation is also discussed. The quantum and geometrical effects on the dust ion acoustic waves have been investigated. It is found that the dust ion acoustic wave is modified by quantum diffraction, Fermi statistics and exchange-correlation potential. Moreover, it has been found that the nebulon structures of quantum dust ions acoustic wave are formed due to the Cartesian geometry and the transverse perturbation. It is also observed that the nebulon structure is significantly modified by the exchange-correlation effects.

Effects of trapped electrons on the sheath at the boundary of a dusty plasma

Abstract: In the present paper, the characteristic behaviors of the sheath in an unmagnetized dusty plasma that contained trapped electrons, cold ions, and variable-charged dusts are investigated, based on the Sagdeev potential approach. The result shows that both the formation and structure of the sheath are modified by the trapped electrons. At the sheath edge, the critical ion Mach number decreases as the trapping parameter β increases. It is noted that the effect of electron trapping on the ion-entering-sheath-velocity is indirect, and closely related to the dust charge variation. In the sheath, the increased β leads to the enlargement of the sheath thickness and the absolute value of electrostatic potential, which results in the redistribution of particle densities. Moreover, the results of the Maxwellian case are essentially recovered when β = 1. As expected, the present results can give more insight into the interaction processes that happened on the plasma-wall interface.

Solitons and double layers in opposite polarity dusty plasma having superthermal electrons and trapped ions

Abstract: Abstract Nonlinear dust acoustic solitons and double layers (DLs) are investigated in a four component dusty plasma consisting of superthermal electrons, superthermal trapped ions, positive and negative dust grains. The reductive perturbation method is employed to derive Schamel Korteweg de Vries (S-KdV) equation and modified Schamel Korteweg de Vries (mSKdV) equation. It is found that the nonlinear structures only with negative potential (rarefactive) can be formed in a two-dust (both positive and negative) plasma in the presence of superthermal trapped ions. In the earlier investigations, it was reported that both rarefactive (dip) and compressive (hump) nonlinear structures are possible in the plasma having both positive and negative dust species in the absence of trapped ions. Here, it is pointed out that the ions trapping does not allow the formation of compressive nonlinear structures. The results can be used to understand the dynamics of small amplitude solitary waves and double layers in dusty plasmas of cometary tails, planetary magnetospheres and interstellar clouds. PACS numbers: 52.27.Cm, 52.30.Ex, 52.35.Sb

Observation of high phase velocity of dust acoustic waves with elongated dust grains in a cryogenic dusty plasma experiment

Abstract: Self-excited dust acoustic waves (DAWs) with a high phase velocity were observed in the cryogenic dusty plasma experiment, where submillimeter, elongated, and fractal-like water-ice dust grains are formed. The phase velocity of the observed DAWs was obtained by the fast Fourier transform of the sequential images of the DAWs and it ranges from 8 to 15 cm s−1. The length of the dust grains was measured between 100 and 250 μm and the thermal speed of the dust grains was obtained between 1.5 and 2.8 cm s−1. It is shown that the linear theory including the effect of the dust thermal speed can explain the observed fast phase velocity. The possible mechanisms by which the submillimeter dust grains gain such high kinetic energies are discussed.

Twisted dust-acoustic waves in a self-gravitating dusty plasma with nonextensive q-distributed electrons and ions

Abstract: We have investigated the twisted dust-acoustic waves (TDAWs) in an electrostatic self-gravitating dusty plasma whose electrons and ions are modelled by nonextensive q-distribution function while massive dust particles are Maxwellian distributed. A well-known kinetic theory is employed for this purpose where perturbed distribution function, electrostatic and gravitational potentials are expressed with Laguerre–Gauss functions. The governing equations of kinetic theory are solved together under paraxial approximations. The dispersion relations and instability growth rates are obtained for two situations; a) super-extensivity (q < 1) and b) sub-extensivity (q > 1). Significant modifications concerning the wave frequencies and growth rates are presented with respect to self-gravitation parameter, twist parameter, nonextensive parameter and streaming speed. It is observed that wave frequency and growth rate of TDAWs reduces in the presence of self-gravitating effects. Furthermore, the growth rates exhibit a significant enhancement in amplitude with the increase in twist parameter, q-parameter and streaming speed. Our present results may have applications in interstellar dust clouds and in the dusty plasma environments of Halley’s Comet.