Collisional Dusty Plasma Research Articles

Low-frequency drift instabilities in a strongly magnetized collisional dusty plasma

We investigate drift instabilities in the dust acoustic or dust lower-hybrid frequency regimes in a nonuniform, collisional, strongly magnetized dusty plasma. It is assumed that the magnetic field strength is such that the ions and electrons are magnetized, while the negatively charged dust grains are collisional and nonmagnetized. We consider a situation in which the negatively charged dust is spatially localized, creating an electron depletion or electron ‘hole’, with an electron density gradient in the opposite direction to a dust density gradient at the boundaries. In this case, low-frequency drift instabilities can be driven by the electron E0 × B0 and diamagnetic drifts, where E0 and B0 are the dc electric and magnetic fields, respectively. Using parameters that may be representative of possible laboratory conditions, it is found that the critical drift for such drift instabilities can be lower than that for the excitation of a low-frequency Hall current instability, which is driven primarily by the ion Hall current.

Iondust two-stream instability in a collisional magnetized dusty plasma

The effect of an external magnetic field on an ion-dust two-stream instability in a collisional dusty plasma is investigated. We consider the parameter regime in which the ions and electrons are strongly magnetized, while the charged dust is unmagnetized. The presence of a magnetic field tends to hinder the growth of the instability. The implications for laboratory dusty plasmas such as 'plasma crystals' are discussed.

Wave Drag Due to Dust Acoustic Waves in Collisional Dusty Plasmas

The ion drag force on dust grains in a dusty plasma contributes significantly to the formation of equilibrium dust layers and void regions in radio-frequency discharges. In addition to the drag due to the direct collection of ions and to momentum transfer of ions in the electric field near grains, dust grains can also be subject to a drag force due to the effect of coherent waves, such as dust acoustic waves that can grow because of the drift of plasma ions relative to charged grains induced by an externally imposed electric field. Here, we examine wave drag due to unstable dust acoustic waves in a collisional dusty plasma using numerical simulations. We study the drag as a function of grain size as well as neutral-ion and neutral-dust collisions in both one-dimensional periodic systems, in which it is easier to study the instability properties per se, and in aperiodic configurations in order to assess effects associated with dust drag and void formation. For the parameter range considered, we find that in the absence of background collisions, the instability tends to saturate by trapping the plasma ions in the electrostatic waves, which does not affect the dust grains very much. Including ion-neutral collisions tends to suppress ion trapping, which in turn leads to larger wave amplitudes and trapping of the dust, resulting in significant drag on the dust grains. Inclusion of neutral-dust collisions leads to a grain size-dependent result, with the persistence of trapping of, and thus drag on, larger grains only. For the parameters of this study, the wave drag force is much larger than the ion drag usually considered.

Electrostatic acoustic modes in a self-gravitating complex plasma with variable charge impurities

A linear theory of dust acoustic (DA) and dust ion-acoustic (DIA) waves in a self-gravitating collisional dusty plasma contaminated by variable-charge impurities is presented for a self-consistent closed system. The ion-drag force arising from the ion orbital motion as well as momentum transfer from all the ions and self-gravitation are taken into consideration. The physical processes, viz., dust-charge relaxation, ionization, recombination and collisional dissipations are also taken into account self-consistently. The generalized dispersion relation describing the coupling of the acoustic modes with the dust-charge relaxation mode (CRM) and damping of the waves is derived and analyzed numerically.

Acoustic Surface Waves in a Collisional Dusty Plasma

Electrostatic low frequency surface waves propagating on the planar interface between a dusty plasma and vacuum are investigated taking into account ion-neutral, ion-dust and neutral-dust collisions as well as ionization. Both the temporal and spatial attenuation rates and the damping of the dust-acoustic surface modes due to collisions and ionization are derived.

Nonlinear Development of a Low-Frequency Hall Current Instability in a Dusty Plasma

The nonlinear evolution of dust waves generated by a low-frequency Hall current instability in a collisional dusty plasma is investigated with theory and nonlinear numerical simulations. The instability is driven by an electron E × B current and is an analog of the well-known Farley–Buneman instability in the dust acoustic type wave regime. This instability is believed to have broad applications to irregularity production in regions where dust is present in the earth’s ionosphere such as noctilucent clouds and meteor trails. The results indicate that the instability nonlinearly saturates with dust heating and the production of secondary waves that propagate in a direction perpendicular to the primary dust acoustic type waves. Results of the investigation also indicate that dust-neutral collisions increase the amplitude of the unstable dust waves after nonlinear saturation. Possible mechanisms for the production of the secondary waves as well as implications of these waves are described.

Modulational Instability of Dust Ion Acoustic Waves in a Collisional Dusty Plasma**The project supported by National Natural Science Foundation of China under Grant No. 10347006

The modulational instability of dust ion acoustic waves in a dust plasma with ion-dust collision effects is studied. Using the perturbation method, a modified nonlinear Schrödinger equation contains a damping term that comes from the effect of the ion-dust collision is derived. It is found that the inclusion of the ion-dust collision would modify the modulational instability of the wave packet and could not admit any stationary envelope solitary waves.

Dust-acoustic wave instability at the diffuse edge of radio frequency inductive low-pressure gas discharge plasma

A spontaneous excitation of a grain density wave in a dusty cloud of monodisperse particles suspended at the diffuse edge of an rf inductive gas discharge has been discovered. The main physical parameters of this wave (phase velocity, wavelength, and growth rate) and of the background plasma (distributions of the electron density, electron temperature, and space potential) were measured. A theoretical model of the observable phenomenon based on the theory of dust acoustic waves in a collisional dusty plasma correlates well with the experimental data in a broad range of experimental conditions. The influence of a varying dust grain charge on the development of the observed dusty plasma instability has been analyzed. It is shown that the necessary condition for the instability excitation is the availability of a permanent electrical field (E0 ⩾3 V/cm) in the dusty cloud region.

Hall instabilities in dusty plasmas

A unified treatment is presented of Hall instabilities in collisional dusty plasmas, using fluid equations for all charged components. Two modes are generally possible: one with frequencies in the ion-acoustic range (the Farley–Buneman mode), and the other with frequencies in the dust-acoustic range. The real and imaginary parts of the mode frequencies are obtained as functions of the electric field, E 0 , perpendicular to the magnetic field, B, permeating the plasma. Calculations are performed for laboratory-type plasmas, and for ionospheric-type plasmas.

Nonlinear evolution of dust waves driven by cross‐field electron currents

The nonlinear evolution of dust waves generated by a low‐frequency Hall current instability in a magnetized collisional dusty plasma is investigated with theory and nonlinear numerical simulations. This instability is believed to have broad applications to irregularity production in regions where dust is present in the earth's ionosphere such as noctilucent clouds and meteor trails. The instability is driven by an electron current and is an analog, in the dust acoustic type wave regime, of the well‐known Farley‐Buneman instability. The results indicate that the instability nonlinearly saturates with dust heating and the production of secondary waves that propagate in a direction perpendicular to the primary dust acoustic type waves.

Dust Acoustic Gravity Vortices in Collisional Dusty Plasma

We study dust acoustic gravity modes in a partially ionized collisional dusty plasma in linear and non linear limits. In the linear regime unstable collisional dust acoustic gravity waves are found. In the non linear regime we found that the presence of frictional force strongly affects various type of vortex formation. It is shown that the condition for the formation of chains of vortices is modified due to the frictional force. Possible applications of the result in context of lower planetary dusty atmosphere and astrophysical dusty fluid are discussed.

Dust–dust lower hybrid waves in a collisional dusty plasma

The excitation of dust lower hybrid waves is considered in collisional plasmas with opposite polarity grains. Typical frequencies are on the order of ω c+ω c− , where ω c+ and ω c− are the gyrofrequencies of the positive and negative dust grains. The mode growth rates are calculated, for laboratory-type plasmas, as functions of the zero-order electric field, E 0 , applied along the magnetic field, B , permeating the plasma.

A note on ion–dust streaming instability in a collisional dusty plasma

This note investigates an ion-dust streaming instability with frequency ω less than the dust collision frequency νd, in an unmagnetized collisional dusty plasma. Under certain conditions, a resistive instability can be excited by an ion drift on the order of the ion thermal speed, even when the dust acoustic wave is heavily damped. The effect of weak collisions on the usual dust acoustic instability in the regime ω > νd is also considered. Applications to experimental observations of low-frequency fluctuations in laboratory d.c. glow discharge dusty plasmas are discussed.

Nonlocal theory of drift type waves in a collisionless dusty plasma

A nonlocal theory is formulated to study drift waves in a collisionless multicomponent (dusty) plasma in a sheared slab geometry. The dynamics of dust particles and ions are treated by fluid models, whereas the electrons are assumed to follow the Boltzmann distribution. It is found that the usual stability of drift waves in a sheared slab geometry is destroyed by the presence of dust particles. A drift wave is excited which propagates with a new characteristic frequency modified by dust particles. This result is similiar to our earlier work for the collisional dusty plasma [Chakraborty et al., Phys. Plasmas 8, 1514 (2001)].

Parallel propagation effects on low-frequency Hall current instability in a dusty plasma

A Hall current instability in the dust acoustic frequency regime in a collisional dusty plasma is extended to finite propagation parallel to the magnetic field. The instability was previously investigated with application to dusty meteor trails in the lower E-region. An effect of the parallel propagation is to shift the unstable wavelength regime to slightly longer wavelengths. In addition, growth rates can maximize slightly away from perpendicular to the magnetic field under certain conditions. Possible applications to dusty plasmas containing positively charged dust in the 90– 95 km altitude region of the Earth's E-region are discussed.

Ion acoustic shock waves in a collisional dusty plasma

The effect of ion–dust collisions on small amplitude nonlinear dust ion acoustic waves has been investigated. Analytical investigation shows that propagation of the small amplitude wave is governed by Korteweg–de Vries (KdV) Burger equation. It is found that the coefficient of the Burger term is proportional to the ion viscosity, which arises through ion–dust collisions and depends on the temperatures and number densities of the electrons, ions and also on the number density of dust grains, as seen in a recent experiment (Nakamura et al.). Numerical investigations on the basis of that experimental data show that the dust–ion acoustic wave exhibits both oscillatory and monotonic shocks depending on the number density of dust particles, as observed in that experiment [Nakamura et al., Phys. Rev. Lett. 83, 1602 (1999)].

Nonlocal theory of drift type waves in a collisional dusty plasma

A nonlocal theory of low-frequency drift-type waves has been developed in a magnetized collisional dusty plasma in a sheared slab geometry. It is shown that the well-known stability of the drift waves in a sheared slab geometry does not hold in the presence of dust particles and a new unstable mode exists for typical laboratory plasma parameters.

Instability of higher-harmonic electrostatic dust cyclotron waves

Conditions for exciting higher-harmonic electrostatic dust cyclotron waves in a collisional dusty plasma are investigated. Linear kinetic theory is used, and the effects of neutral–charged particle collisions are taken into account. In a plasma with negatively charged dust, electrostatic dust cyclotron waves can be driven unstable by ions drifting along the magnetic field. It is found that, under certain conditions, the critical ion drift for the excitation of higher-harmonic electrostatic dust cyclotron waves (i.e., ω ∼ mΩd, where m [ges ] 2 and Ωd is the dust cyclotron frequency) can be comparable to the critical drift for the excitation of the fundamental cyclotron harmonic (i.e., ω ∼ Ωd). Stability conditions are investigated for ranges of parameters that may be relevant to laboratory dusty plasmas.

Current-driven dust ion-acoustic instability in a collisional dusty plasma with charge fluctuations

The extended fluid analysis of the excitation of dust ion-acoustic waves (DIAWs) in a collisional dusty plasma [Merlino, IEEE Trans. Plasma Sci. 25, 60 (1997)] is reconsidered to include self-consistently the fluctuations in the charges of the dust grains, which liberate or capture electrons and protons. The numerical results show that the dust charge fluctuations can have a significant influence on the excitation of the DIAW and may deeply modify its nonlinear features.

Dusty plasma near a conducting boundary with dust-neutral collisions

Using the usual fluid model the behavior of an unmagnetized dusty plasma near a conducting boundary with dust-neutral collisional effect is studied. The plasma consists of electrons, ions, negatively charged micron size dust particles, and neutrals. The Sagdeev potential for collisionless case is also calculated and found that it has different structure for plasmas with and without dusts. An expression for gradient of potential (i.e., the electric field) for collisional dusty plasma with dust–neutral collisions is calculated. The relation between the dust acoustic velocity and the collisionality has been discussed.