Experimental study of transport of macroparticles in plasma RF-discharge

Experimental study of the kinematic viscosity and the diffusion is performed for macroparticles of different sizes in plasma of a capacitive radio-frequency (RF-) discharge. Experimental examination of the Einstein-Stokes relation between the viscosity and diffusion constants is carried out. A comparison of the measured transport constants with the existing numerical data is presented.     

Numerical Simulation of Dust Void Evolution in Complex Plasmas with Ionization Effect

We develop the nonlinear theory of dust voids [Phys. Rev. Lett. 90 （2003） 075001], focusing particularly on effects of the ionization, to investigate numerically the void evolution under cylindrical coordinates [Phys. Plasmas 13 （2006） 064502]. The ion velocity profile is solved by a more accurate ion motion equation with the ion convection and ionization terms. It is shown that the differences between the previous result and the one obtained with ionizations are significant for the distributions of the ion and dust velocities, the dust density, and etc., in the void formation process. Furthermore, the ionization can slow down the void formation process effectively.     

Effect of Thermionic Emission on Dust-Acoustic Solitons in a Dust-Electron Plasma

The effects of thermionic emission on dust-acoustic solitons with a very small but finite amplitude in a dustelectron plasma are studied using the reductive perturbation technique. The self-consistent variation of dust charge is taken into account. It is shown that the thermionic emission could significantly increase the dust positive charge. The dependences of the phase velocity, amplitude, and width of such solitons on the dust temperature and the dust work function of dust material are plotted and discussed.     

Dust Lattice Waves of Dusty Plasma Chain with an External Magnetic Field

Dust lattice waves of a one-dimensional plasma crystal chain with an external magnetic field are investigated. When the magnetic field is in the vertical direction （θ- 0）, perpendicular to the chain, the vertical transverse mode is not affected, while the horizontal transverse mode is coupled with the longitudinal mode. In the high frequency range, we obtain an ‘upper-hybrid＇ dust lattice mode and in the low frequency range, we obtain a ＇lower-hybrid＇ dust lattice mode. Between the two modes, a ＇gap＇ is formed. When the magnetic field is oriented to the chain （0 = π/2）, the longitudinal mode is not affected while both the horizontal and vertical transverse modes are shifted due to the effect of the magnetic field.     

Oscillation modes in Coulomb clusters with variable charges

The mode spectra of small N=3 and N=7 clusters of dust particles with fluctuating charges are analyzed. It is demonstrated that the main effect related to the charge fluctuations is a splitting of the spectrum modes. The splitting depends the value of the charge variance. It is found that the most affected mode is the fundamental pure rotational mode. The least affected modes are pure translational ones while other modes demonstrate mixed response to the variance of the charge fluctuations.     

Cylindrical and spherical dust ion-acoustic solitary waves in quantum plasmas

Dust ion-acoustic solitary waves in unmagnetized quantum plasmas are studied in spherical and cylindrical geometries. Using quantum hydrodynamic model, the electrostatic waves are investigated in the weakly nonlinear limit. A deformed Korteweg-de Vries (dKdV) equation is derived by using the reductive perturbation method and its numerical solutions are also presented. The quantum diffraction and quantum statistical effects incorporated in the system modifies the characteristics of dust ion-acoustic waves in cylindrical and spherical geometries. The role of stationary dust particles in quantum plasmas are also discussed. It is shown that the cylindrical and spherical dust ion-acoustic solitary waves behave quite differently from one-dimensional planar solitary waves in quantum plasmas.     

Dust-lower-hybrid waves in quantum plasmas

The dispersion relation of the dust-lower-hybrid wave has been derived using the quantum hydrodynamic model of plasmas in an ultracold Fermi dusty plasma in the presence of a uniform external magnetic field. The dust dynamics, electron Fermi temperature effect, and the quantum corrections give rise to significant effects on the dust-lower-hybrid wave of the magnetized quantum dusty plasmas.     

Small amplitude variable charge dust Bernstein-Greene-Kruskal double layers

A first theoretical attempt is made to investigate small amplitude, variable charge dust Bernstein-Greene-Kruskal (BGK) double layers (DLs). The nature of the dust BGK-DLs (compressive or rarefactive), their strength and thickness depend sensitively on the net negative charge residing on the grain surface, the dust grain dynamics and, more interestingly, on the ion-to-electron temperatures ratio.     

Excitation of the dust ion-acoustic and dust acoustic-like perturbations by plasma density ripples

It is shown that the dust ion-acoustic (DIA) and dust acoustic (DA)-like perturbations can be excited by the electron density and ion density ripples, respectively. For this purpose, we use the relevant equations for the DIA and DA-like disturbances and derive the standard Mathieu equation. The latter admits unstable solutions, demonstrating that both the DIA and DA-like mode can be driven on account of the free energy in the plasma density ripples.     

On the existence of ion-acoustic solitary waves in a gravitating dusty plasma having charge fluctuation

Theoretical investigation on the propagation of ion-acoustic waves in an unmagnetized self-gravitating plasma has been made for the existence of solitary waves using the reductive perturbation method. It is observed that nonlinear excitations follow a coupled third-order partial differential equation which is slightly different from the usual case of coupled Korteweg-de Vries (K-dV) system. It appears that the system so deduced is a two-component generalization of the previous one derived by Paul et al. (1999) in which it was shown that ion-acoustic solitary waves can not exist in such system.     

Nonlinear localized dust acoustic waves in a charge varying dusty plasma with trapped ions

The problem of nonlinear variable charge dust acoustic waves in a dusty plasma with trapped ions is revisited. The correct non-isothermal ion charging current is presented for the first time based on the orbit motion limited (OML) approach. The variable dust charge is then expressed in terms of the Lambert function and we take advantage of this new transcendental function to investigate nonlinear localized dust acoustic waves in a charge varying dusty plasma with trapped ions more rigorously.     

Formation of dust-acoustic shock waves in a strongly coupled cryogenic dusty plasma

The nonlinear propagation of ultra-low-frequency dust-acoustic (DA) waves in a strongly coupled cryogenic dusty plasma has been investigated, by using the Boltzmann distributed electrons and ions, as well as modified hydrodynamic equations for strongly coupled charged dust grains. The reductive perturbation technique is used to derive the Burger equation. It is shown that strong correlations among negatively charged dust particles acts like a dissipation, which is responsible for the formation of the DA shock waves. The latter are associated with the negative potential, i.e. with the compression of negatively charged cryogenic dust particle density. It is also found that the effective dust-temperature, which arises from electrostatic interactions among negatively charged dust particles, significantly affects the height of the DA shock structures. New laboratory experiments at cryogenic temperature should be conducted to verify our theoretical prediction.     

A quantum hydrodynamic model for multicomponent quantum magnetoplasma with Jeans term

The effect of Jeans term in a multicomponent self-gravitating quantum magnetoplasma is investigated employing the quantum hydrodynamic (QHD) model. The effects of quantum Bohm potential and statistical terms as well as the ambient magnetic field are also investigated on both dust and ion dynamics driven waves in this Letter. We state the conditions that can drive the system unstable in the presence of Jeans term. The limiting cases are also presented. The present work may have relevance in the dense astrophysical environments where the self-gravitating effects are expected to play a pivotal role.     

Dispersion properties of low-frequency electrostatic oscillations in metallic carbon nanotubes

Dispersion properties of low-frequency electrostatic waves in metallic carbon nanotubes (CNTs) are investigated. We assume that metallic CNTs are charged due to the field emission, and hence the metallic nanotubes can be regarded as charged dust rods surrounded by degenerate electrons and ions. We deduce the perturbed electron and ion number densities by using the quantum hydrodynamic model, while the dust rod density perturbation follows the classical expression. The Poisson equation, in turn, gives the dispersion relation for the low-frequency electrostatic oscillations in our three-species bounded plasma system composed of metallic CNTs. The oscillation frequency of CNTs can be used for diagnostic purposes, e.g. for the determination of charge on nanotubes.     

Effect of deviations from isothermality of ions on the propagation of localized dust-acoustic waves

The effect of deviations from isothermality of ions on arbitrary amplitude dust-acoustic solitary structures is studied in an unmagnetized dusty plasma which consists of a negative charged dust fluid, free electrons and hot ions obeying a trapped distribution. For the finite deviation from isothermality of ions, the basic properties of large amplitude solitary waves are studied by employing pseudo-potential approach. It is shown that the effect of such ion behavior changes the maximum values of the Mach number and the amplitude for which solitary wave can exist. For the case that the deviation from isothermality due to nonlinear resonant particle effects is small, calculations by reductive perturbation method leads to a generalized Korteweg-de Vries equation with mixed nonlinearity. The latter admits a stationary dust-acoustic solitary solution with similar width and qualitatively different amplitude in comparison to the case that deviations from isothermality are finite. Furthermore, effects of the equilibrium free electron density and such trapped ions on the amplitude of solitary structures imply a non-uniform transition from the Boltzmann ion distribution to the trapped ion one.     

Electrostatic Nonlinear Structures in Dissipative Electron--Positron--Ion Quantum Plasmas

Low frequency （in comparison to ion plasma frequency） ion-acoustic shocks and solitons in superdense electronpositron-ion quantum plasmas are studied. The quantum hydrodynamic model is used incorporating quantum Bohm forces and Fermi-Dirac statistical corrections to derive the deformed Korteweg de Vries-Burgers （dKdVB） equation in weakly nonlinear limit. The travelling wave solution of dKdVB equation is presented and results are discussed in different limits. It is found that shock height increases with increase of quantum pressure, positron concentration and dissipation. Further, it is seen that the width of soliton decreases with increase of quantum pressure     

Propagation and Interaction of Ion-Acoustic Solitary Waves in a Two-Dimensional Plasma Consisting of Isothermal Electrons and Hot Ions

We study the propagation and interaction of ion-acoustic solitary waves in a simple two-dimensional plasma by using the extended Poincare Lighthill-Kuo perturbation method. We consider the interaction between two ion-acoustic solitary waves with different propagation directions in such a system, and obtain two Korteweg-de Vries equations for small but finite amplitude solitary waves along both ξ and η trajectories. The effects of the ratio of ion temperature σ the ratio of heat capacity γ and the colliding angle a on the amplitude, the width of the new nonlinear wave created by the collision between two solitary waves are studied. The effects of these parameters on both the colliding solitary waves are examined as well. It is found that all the above-mentioned parameters have significant effects on the properties of these nonlinear waves.     

Ion-acoustic shock waves with negative ions in presence of dust particulates

Dust acoustics shock waves have been investigated experimentally in a homogeneous unmagnetized dusty plasma device containing negative ions. When the negative ion density larger than a critical concentration ‘rc’ negative shock waves were observed instead of positive shock waves. Again when it is nearly equal to ‘rc’ both positive and negative shock waves propagate. The experimental findings are compared with modified KdV-Burgers equation. The velocity of the shock waves are also measured and compared with the numerical integration of modified KdV-Burgers equation.     

Nonplanar dust ion-acoustic solitary and shock waves in a dusty plasma with electrons following a vortex-like distribution

Properties of nonplanar (viz. cylindrical and spherical) dust ion-acoustic (DIA) solitary and shock waves propagating in a dusty plasma containing charge fluctuating stationary dust, inertial warm ions, and non-isothermal electrons following a vortex-like distribution, are investigated by the reductive perturbation method. It has been shown that all the basic features of the DIA solitary and shock waves are significantly modified by the effects of vortex-like electron distribution, dust charge fluctuation, and nonplanar cylindrical and spherical geometries. The implications of our results in some space and laboratory dusty plasma environments are briefly discussed.     

Nonplanar Ion-Acoustic Solitons in Electron-Positron-Ion Quantum Plasmas

The propagation of nonplanar quantum ion-acoustic solitary waves in a dense, unmagnetized electron-positronion （e-p-i） plasma are studied by using the Korteweg-de Vries （KdV） model. The quantum hydrodynamic （QHD） equations are used taking into account the quantum diffraction and quantum statistics corrections. The analytical and numerical solutions of KdV equation reveal that the nonplanar ion-acoustic solitons arc modified significantly with quantum corrections and positron concentration, and behave differently in different geometries.