Showing papers on "Dusty plasma published in 2010"

Dust ion acoustic solitons in a plasma with kappa-distributed electrons

Abstract: Dust ion acoustic solitons in an unmagnetized dusty plasma comprising cold dust particles, adiabatic fluid ions, and electrons satisfying a κ distribution are investigated using both small amplitude and arbitrary amplitude techniques. Their existence domain is discussed in the parameter space of Mach number M and electron density fraction f over a wide range of values of κ. For all κ>3/2, including the Maxwellian distribution, negative dust supports solitons of both polarities over a range in f. In that region of parameter space solitary structures of finite amplitude can be obtained even at the lowest Mach number, the acoustic speed, for all κ. These cannot be found from small amplitude theories. This surprising behavior is investigated, and it is shown that fc, the value of f at which the KdV coefficient A vanishes, plays a critical role. In the presence of positive dust, only positive potential solitons are found.

Plasma Physics: An Introduction to Laboratory, Space, and Fusion Plasmas

Abstract: Definition of the Plasma State.- Single Particle Motion in Electric and Magnetic Fields.- Stochastic Processes in a Plasma.- Fluid Models.- Plasma Waves.- Plasma Boundaries.- Instabilities.- Kinetic Description of Plasmas.- Dusty Plasmas.- Plasma Generation.

Simulations of the photoelectron sheath and dust levitation on the lunar surface

Abstract: [1] The lunar surface represents a complex plasma environment due to the presence of solar ultraviolet (UV) radiation, the incoming solar wind flux and charged, levitated micron- and sub-micron sized dust particles. Photoemission due to solar UV radiation dominates the charging environment, creating a photoelectron sheath above the lunar surface. To further investigate the dusty plasma environment on the surface of the Moon, a one-dimensional particle-in-cell (PIC) code has been designed specifically for the lunar surface. The code has been validated against analytic solutions for photoelectron sheaths with basic photoelectron energy distributions. Simulations have focused on the role of the emitted photoelectron energy distribution and solar UV variability in determining the sheath profile. Additionally, the charging and levitation of test dust particles in the photoelectron sheath are studied. Limits on the maximum size and height of levitated dust grains are also presented.

Variable charge dust acoustic solitary waves in a dusty plasma with a q-nonextensive electron velocity distribution

Abstract: A first theoretical work is presented to study variable charge dust acoustic solitons within the theoretical framework of the Tsallis statistical mechanics. Our results reveal that the spatial patterns of the variable charge solitary wave are significantly modified by electron nonextensive effects. In particular, it may be noted that for −1 1 provides qualitatively opposite results: electron nonextensivity makes the solitary structure more spiky. Our results should help in providing a go...

Introduction to complex plasmas

Abstract: Complex Plasmas- Classical and Quantum Plasmas- Principles of Transport in Multicomponent Plasmas- to Quantum Plasmas- to Quantum Plasma Simulations- Quantum Effects in Plasma Dielectric Response: Plasmons and Shielding in Normal Systems and Graphene- Strongly Coupled and Dusty Plasmas- Imaging Diagnostics in Dusty Plasmas- Structure and Dynamics of Finite Dust Clusters- Statistical Theory of Spherically Confined Dust Crystals- PIC-MCC Simulations of Capacitive High-Frequency Discharge Dynamics with Nanoparticles- Molecular Dynamics Simulation of Strongly Correlated Dusty Plasmas- Reactive Plasmas, Plasma-Surface Interaction, Technological Applications- Nonthermal Reactive Plasmas- Formation and Deposition of Nanosize Particles on Surfaces- Kinetic and Diagnostic Studies of Molecular Plasmas Using Laser Absorption Techniques- X-Ray Diagnostics of Plasma-Deposited Thin Layers- The Use of Nonthermal Plasmas in Environmental Applications- Complex (Dusty) Plasmas: Application in Material Processing and Tools for Plasma Diagnostics

Effects of polarization force and effective dust temperature on dust-acoustic solitary and shock waves in a strongly coupled dusty plasma.

Abstract: A strongly coupled dusty plasma containing strongly correlated negatively charged dust grains and weakly correlated (Maxwellian) electrons and ions has been considered. The effects of polarization force (which arises due to the interaction between thermal ions and highly negatively charged dust grains) and effective dust temperature (which arises from the electrostatic interactions among highly negatively charged dust and from the dust thermal pressure) on the dust-acoustic (DA) solitary and shock waves propagating in such a strongly coupled dusty plasma are taken into account. The DA solitary and shock waves are found to exist with negative potential only. It has been shown that the strong correlation among the charged dust grains is a source of dissipation and is responsible for the formation of the DA shock waves. It has also been shown that the effects of polarization force and effective dust-temperature significantly modify the basic features (e.g., amplitude, width, and speed) of the DA solitary and shock waves. It has been suggested that a laboratory experiment be performed to test the theory presented in this work.

Dust ion-acoustic solitary and shock waves in a dusty plasma with non-thermal electrons

Abstract: A theoretical investigation of the one dimensional dynamics of nonlinear electrostatic dust ion-acoustic (DIA) waves in an unmagnetized dusty plasma consisting of ion fluid, non-thermal electrons and fluctuating immobile dust particles has been made by the reductive perturbation technique. The basic features of DIA solitary and shock waves are studied by deriving the Korteweg-de Vries (KdV) and KdV Burger equations, respectively. It is shown that the special patterns of nonlinear electrostatic waves are significantly modified by the presence of the non-thermal electron component. In particular, the rarefactive solitary and shock structures are found with smaller amplitude in comparison to the isothermal case. The transition from DIA solitary to shock waves is also studied which is related to the contributions of the dispersive and dissipative terms. It is found that the dust charge fluctuation is a source of dissipation, and is responsible for the formation of the dust ion-acoustic shock waves. Furthermore, the dissipative effect becomes important and may prevail over that of dispersion as the population of non-thermal electrons present decreases. The present investigation may be of relevance to electrostatic solitary structures observed in many space dusty plasma, such as Saturn’s E-ring.

Viscoelasticity of 2D liquids quantified in a dusty plasma experiment.

Abstract: The viscoelasticity of two-dimensional liquids is quantified in an experiment using a dusty plasma. An experimental method is demonstrated for measuring the wave-number--dependent viscosity $\ensuremath{\eta}(k)$, which is a quantitative indicator of viscoelasticity. Using an expression generalized here to include friction, $\ensuremath{\eta}(k)$ is computed from the transverse current autocorrelation function, which is found by tracking random particle motion. The transverse current autocorrelation function exhibits an oscillation that is a signature of elastic contributions to viscoelasticity. Simulations of a Yukawa liquid are consistent with the experiment.

Electromagnetic pulses generated by meteoroid impacts on spacecraft

Abstract: [1] Meteoroid impacts on spacecraft are known to cause mechanical damage, but their electrical effect on spacecraft systems are not well characterized. Several reported spacecraft anomalies are suggestive of an electrical failure associated with meteoroid impact. We present a theory to explain plasma production and subsequent electric fields occurring when a meteoroid strikes a spacecraft, ionizing itself and part of the spacecraft. This plasma, with a charge separation commensurate with different specie mobilities, can produce a strong electromagnetic pulse (EMP) at broad frequency spectra, potentially causing catastrophic damage if the impact is relatively near an area with low shielding or an open umbilical. Anomalies such as gyrostability loss can be caused by an EMP without any detectable momentum transfer due to small (<1 μg) particle mass. Subsequent plasma oscillations can also emit significant power and may be responsible for many reported satellite anomalies. The presented theory discusses both a dust-free plasma expansion with coherent electron oscillation and a dusty plasma expansion with macroscopic charge separation.

Observation of the spatial growth of self-excited dust-density waves

Abstract: The growth of a naturally occurring dust-density wave (DDW) is experimentally observed using high-speed imaging. This low frequency wave (∼25 Hz) grows in amplitude as it propagates downward through a dusty plasma. The wave’s linear growth rate −ki is measured using a phase-sensitive analysis method. For the conditions studied here, the growth rate increases as gas pressure decreases. At a critical gas pressure, which is observed, a balance between an ion-flow instability and dissipation by neutral gas drag determines a threshold for wave propagation. A linear dispersion relation is derived, taking into account the effects of strong-coupling, to compare to the experiment.

Spatial frequency clustering in nonlinear dust-density waves.

Abstract: Self-excited density waves were studied in a strongly coupled dusty plasma of a radio-frequency discharge under microgravity conditions. The spatiotemporal evolution of the complicated three-dimensional wave field was investigated and analyzed for two different situations. The reconstructed instantaneous phase information of the wave field revealed a partial synchronization within multiple distinct domains. The boundaries of these regions coincide with the locations of topological defects.

Evolution of shear-induced melting in a dusty plasma.

Abstract: The spatiotemporal development of melting is studied experimentally in a 2D dusty plasma suspension. Starting with an ordered lattice, and then suddenly applying localized shear, a pair of counterpropagating flow regions develop. A transition between two melting stages is observed before a steady state is reached. Melting spreads with a front that propagates at the transverse sound speed. Unexpectedly, coherent longitudinal waves are excited in the flow region.

Modulational instability of dust acoustic solitons in multicomponent plasma with kappa-distributed electrons and ions

Abstract: In the present investigation the modulational instability (MI) of dust acoustic wave (DAW) in four-component dusty plasma consisting of negative and positive charged dust grains and kappa (κ) distributed electrons and ions is studied. Considering the multifluid plasma model and using the reductive perturbation technique, nonlinear Schrodinger equation, which governs the MI of DAW, is obtained. It is found that presence of positive dust component, kappa-distributed electrons (κe), ions (κi), and temperature ratio (σ) significantly modify the domain of the MI and localized envelope excitations. Further, the effects of these parameters on the growth rate of MI have also been discussed in detail.

Time-dependent cylindrical and spherical dust-acoustic solitary and shock waves in a strongly coupled dusty plasma in the presence of polarization force

Abstract: Time-dependent cylindrical and spherical dust-acoustic (DA) solitary and shock waves propagating in a strongly coupled dusty plasma in the presence of polarization force (which arises due to the interaction between thermal ions and highly negatively charged dust grains) are investigated. It is shown that cylindrical and spherical DA solitary and shock waves exist with negative potential, and that the strong correlation among the charged dust grains is a source of dissipation, and is responsible for the formation of cylindrical or spherical DA shock structures. It is also shown that the effects of polarization force significantly modify the basic features (e.g. amplitude, width, and speed) of cylindrical or spherical DA solitary or shock structures. The implications of our results in laboratory experiments are briefly discussed.

Nonlinear wave propagation in strongly coupled dusty plasmas.

Abstract: The nonlinear propagation of low-frequency waves in a strongly coupled dusty plasma medium is studied theoretically in the framework of the phenomenological generalized hydrodynamic (GH) model A set of simplified model nonlinear equations are derived from the original nonlinear integrodifferential form of the GH model by employing an appropriate physical ansatz Using standard perturbation techniques characteristic evolution equations for finite small amplitude waves are then obtained in various propagation regimes The influence of viscoelastic properties arising from dust correlation contributions on the nature of nonlinear solutions is discussed The modulational stability of dust acoustic waves to parallel perturbation is also examined and it is shown that dust compressibility contributions influenced by the Coulomb coupling effects introduce significant modification in the threshold and range of the instability domain

Head-on collision of dust-acoustic solitary waves in an adiabatic hot dusty plasma with external oblique magnetic field and two-temperature ions

Abstract: In the present paper, the characteristics of the head-on collision between two dust-acoustic solitary waves (DASWs) in an adiabatic dusty plasma consisting of variable negatively charged dust grains, isothermal electrons and two-temperature isothermal ions in the presence of an external oblique magnetic field are investigated. Using the extended Poincare–Lighthill–Kuo (PLK) method, the Korteweg–de Vries (KdV) equations and the analytical phase shifts after the head-on collision of two solitary waves are derived. The effects of the magnetic field and its obliqueness, two different type of isothermal ions and the dust particles adiabaticity are discussed. It is found that these factors significantly affect the phase shifts.

Shielding of a test charge: Role of plasma production and loss balance

Abstract: Shielding of a test charge in a highly collisional plasma is studied taking into account plasma production and loss processes. It is shown that the electric potential distribution is in general different from the conventional Debye–Huckel (exponentially screened Coulomb) form. The obtained results can be of great importance for a variety of phenomena including basic interactions, transport, phase transitions, and self-organization in conventional electron-ion and complex (dusty) plasmas.

Thermodynamic and transport properties of nonideal systems with isotropic pair potentials.

Abstract: The equations of state and the structural, thermodynamic, and transport properties of the two- and three-dimensional nonideal dissipative systems consisting of particles interacting with different isotropic pair potentials are studied in a wide range of parameters typical for laboratory dusty plasma. Simple semiempirical expression for the energy density in liquid systems is considered. Comparison of the theoretical and numerical results is presented.

Clustering of settling charged particles in turbulence: theory and experiments

Abstract: Atmospheric clouds, electrosprays and protoplanetary nebula (dusty plasma) contain electrically charged particles embedded in turbulent flows, often under the influence of an externally imposed, approximately uniform gravitational or electric force. We have developed a theoretical description of the dynamics of such systems of charged, sedimenting particles in turbulence, allowing radial distribution functions (RDFs) to be predicted for both monodisperse and bidisperse particle size distributions. The governing parameters are the particle Stokes number (particle inertial time scale relative to turbulence dissipation time scale), the Coulomb-turbulence parameter (ratio of Coulomb 'terminal' speed to the turbulence dissipation velocity scale) and the settling parameter (the ratio of the gravitational terminal speed to the turbulence dissipation velocity scale). The theory is compared to measured RDFs for water particles in homogeneous, isotropic air turbulence. The RDFs are obtained from particle positions measured in three dimensions using digital holography. The measurements verify the general theoretical expression, consisting of a power law increase in particle clustering due to particle response to dissipative turbulent eddies, modulated by an exponential electrostatic interaction term. Both terms are modified as a result of the gravitational diffusion-like term, and the role of 'gravity' is explored by imposing a macroscopic uniform electric field to create an enhanced, effective gravity.

Kinetics of complex plasmas having spherical dust particles with a size distribution

Abstract: This paper presents an analysis of the kinetics of an illuminated complex plasma having spherical dust particles with a size distribution. It has been pointed out that in the steady state, the electric potential on the surface of all the particles is the same; as a corollary, all particles carry a charge of the same sign. It is seen that in the steady state, the plasma parameters are determined by the number per unit volume and root mean square radius of the dust particles. This fact makes the analysis similar to that for a complex plasma with dust of uniform size. It is seen that it is essential to consider both the number and energy balance of the constituents of the complex plasma. A parametric analysis, a discussion of the numerical results thus obtained, and conclusions have also been given.

Effect of ionization/recombination processes on the electrical interactions between positively charged particles in highly collisional plasmas

Abstract: The effect of ionization and recombination processes on the electrical interactions between a pair of small charged particles in highly collisional plasmas is discussed. In particular, it is shown that these processes suppress the long-range attraction between positively charged particles. The condition corresponding to the vanishing of attraction is derived. The role of the effect for conditions of existing experiments is estimated.

On dust ion acoustic solitary waves in collisional dusty plasmas with ionization effect

Abstract: The propagation of solitary waves in an unmagnetized collisional dusty plasma consisting of a negatively charged dust fluid, positively charged ions, isothermal electrons, and background neutral particles is studied. The ionization, ion loss, ion–neutral, ion–dust, and dust–neutral collisions are considered. Applying a reductive perturbation theory, a damped Korteweg–de Vries (DKdV) equation is derived. On the other hand, at a critical phase velocity, the dynamics of solitary waves is governed by a damped modified Korteweg–de Vries (DMKdV) equation. The nonlinear properties of solitary waves in the two cases are discussed.

Modified KP-Burger and KP-Burger equations in coupled dusty plasmas with variable dust charge and non-isothermal ions

Abstract: The modified Kodomtsev-Petviashvili-Burger (mKP-Burger) and Kodomtsev-Petviashvili-Burger equations are derived in strongly coupled dusty plasmas containing non-isothermal ions, Boltzmann distributed electrons and variable dust charge. We use reductive perturbation method and discuss on solitary waves and shock waves solutions of these equations.

Growth of embryonic dust particles in a complex plasma

Abstract: A model describing the growth of embryonic dust grains on account of accretion of neutral atoms and positively charged ionic species in a complex plasma has been developed. In deference to the recent emphasis on the character of the openness in complex plasma, the investigation is based on the balance of the number density and energy of electrons, ions, and neutral particles as well as the energy balance of the dust particles and the charge neutrality condition. To discuss the kinetics of the growth of the size of dust the processes of accretion of electrons, ions, and neutral species on the dust particles, the ionization of neutral atoms, and recombination of electrons and ions, and the elastic collisions between the constituent species of the dusty plasma have been considered; the energy exchange associated with these processes has also been taken into account. The dependence of the growth of dust particles and other relevant parameters on number density of embryonic dust grains has, in particular, been explored.

Shielding of a Small Charged Particle in Weakly Ionized Plasmas

Abstract: In this paper, we present a concise overview of our recent results concerning the electric potential distribution around a small charged particle in weakly ionized plasmas. A number of different effects which influence plasma screening properties are considered. Some consequences of the results are discussed, mostly in the context of complex (dusty) plasmas.

Determination of dust grain charge and screening lengths in the plasma sheath by means of a controlled cluster rotation

Abstract: Dusty plasma experiments with flat dust clusters are often performed in the boundary sheath of radio frequency discharges at typical gas pressures of 1–100 Pa. The interaction of the dust grains is usually assumed to be of the Yukawa type, which is determined by the particle charge and the screening length. For the experimental determination of these quantities we present a method that does not require prior knowledge of the plasma parameters. The method is based on the application of centrifugal forces by means of a rotating electrode method (REM). The results are critically compared with an analysis of thermally excited normal modes, which can be studied at pressures below 10 Pa. The REM has a wider range of applicability that can be extended to 100 Pa.

Soliton energy of the Kadomtsev–Petviashvili equation in warm dusty plasma with variable dust charge, two-temperature ions, and nonthermal electrons

Abstract: The propagation of nonlinear waves in warm dusty plasmas with variable dust charge, two-temperature ions, and nonthermal electrons is studied. By using the reductive perturbation theory, the Kadomtsev–Petviashivili (KP) equation is derived. The energy of the soliton has been calculated. By using standard normal modes analysis a linear dispersion relation has been obtained. The effects of variable dust charge on the energy of the soliton and the angular frequency of the linear wave are also discussed. It is shown that the amplitude of solitary waves of the KP equation diverges at the critical values of plasma parameters. We derive solitons of a modified KP equation with finite amplitude in this situation.