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Dust aggregates are formed in a laboratory plasma as monodisperse spheres are accelerated in a self-excited dust density wave. The asymmetric charge on the aggregates causes them to rotate as they interact with the sheath electric field or other aggregates The charge and dipole moment can be estimated and compared to numerical models. "Dust molecules", where two particles are electrostatically bound but not physically touching, are also observed.

International audience; Reactive plasmas are an excellent source for dust particles with different characteristics. In the work presented herein the nanoparticles produced in such systems were post-processed by means of annealing, VUV/x-ray irradiation, and ion bombardment.

Nebbat and Annou (c.f.Ref.[1]) proposed a time dependent non‐linear model that considers vortices as a consequence of an instability, and where the plasma is considered ideal. In this note, we propose another approach consisting of including the grain‐grain interaction force it in the pressure term. The fluid is no longer considered ideal and the pressure term is to be modified accordingly to account for the non‐ideality of the dust fluid. We choose a Van Der Waals equation of state. A comparison is conducted between both approaches.

In this quick overview I will discuss the physical and dynamical consequences of the interaction of fine dust with plasmas, which are generally magnetized, in a variety of cosmic environments. While the number of topics that can be covered, are of necessity, highly limited, they will nevertheless span a wide range of space, from planetary and cometary magnetospheres to the interstellar medium. I will conclude with a few comments on the future, particularly in anticipation of the forthcoming space missions.

The principal features of dust particles influence on plasma parameters of positive column of glow discharge in neon at cryogenic temperature are studied experimentally. It was found that the effect of dust particles in cryogenic plasma is observed even at those values of discharge currents and dust particle numbers, at which this effect was not observed at room temperature.

Interaction between dust grains in a dusty plasma could be both repulsive and attractive. The electrostatic interaction between two negatively charged dust particulates is repulsive, while the shadowing force affecting them is attractive. In some experimental conditions, for two negatively dust particles, there is some grain separation zone for which the attractive shadowing force exceeds the repulsive forces between them. So the resultant interaction force will be attractive. The possibility of dust crystal formation in this zone have been discussed. We consider the models of three negatively charged dust particulates which are suitable for the conditions of plasma paremeters. In this conditions numerical simulations demonstrate that there is some grain separation zone for which the attractive interaction is larger than the repulsive force between them and also the formation of dust crystals will be possible.

With the advancing miniaturization of technological applications, processes on the mesoscale become increasingly important. This is the scale where the individual movement of particles transforms into cooperative behavior–behavior that cannot be explained by investigating the motion of individual particles alone.Complex plasmas are ideally suited to study the limits of cooperative behavior [1]. The time scales of the dynamics of the microparticles embedded in the plasma are such that their movement can be fully resolved, and an investigation on the atomistic (kinetic) level is possible. In addition, complex plasmas can be considered a model system for ordinary fluids: The internal microparticle dynamics is basically undamped and is characterized by the similarity parameters matching those of other fluids. This similarity does not break down even at small scales: For instance, in [2], microparticle droplets comprised of only a few 1000–10000 particles were examined. In these experiments, the Weber number (...

The gravitational instability of infinite homogeneous magnetized dusty plasma with radiative process is studied with the help of relevant dusty magnetohydrodynamic (MHD) equations using normal mode analysis. The dispersion relation is obtained with radiative pressure and magnetic field, which is discussed for the transverse and longitudinal mode of propagations. The improvement in the Jeans condition of instability due to dust, magnetic field and radiative pressure is discussed. We find that in transverse mode of propagation the condition of Jeans instability of dusty plasma is modified by magnetic field and radiative pressure. In case of longitudinal mode it is unaffected by magnetic field as this mode provides the Alfven mode separately with the gravitational mode.

We present the model, which describes nonlinear dust ion‐acoustic (DIA) perturbations in complex plasmas with electromagnetic radiation. We study time‐evolution of the individual DIA soliton and interaction of two DIA solitons.

In this paper, developed method of microdroplet injections into plasma at low gas pressure to form ordered structure in strata of dc glow discharge are presented.

Numerical and experimental investigations of the DC discharge in Neon in the tube with radius unevenly changed from 13.8 to 30 mm are presented. A formation of a dusty structure in standing stratum has been observed and simulated.

Low temperature structures and dynamics of Yukawa particles in systems with cylindrical symmetry are analyzed by theory and numerical simulations. Particles are organized into well‐defined thin concentric shells forming triangular lattices with defects on each shell and structural parameters are expressed by simple interpolation formulas including the limiting case of Coulomb particles. In the case of mixtures, different components form separate shells in the alternating order; A shell in the one‐component case is separated into a smaller shell of larger charges and a larger shell of smaller charges. Under the force field along the cylindrical axis, the electric field for example, the relative motion between different components can be induced. The mobility associated with relative motion is estimated and, when appropriate conditions are satisfied, the system creates a ‘screw’ composed of fine particles.

We investigate the Jeans instability of self‐gravitating magnetized dusty plasma including the effect of polarization force on the massive charged dust grains. The basic dusty magnetohydrodynamic (MHD) equations are constructed considering the effect of magnetic field, gravitational force and polarization force. A general dispersion relation and condition of Jeans instability is obtained using normal mode analysis. It is found that polarization force modifies the condition of Jeans instability but it is unaffected due to magnetic field. The polarization force has destabilizing while magnetic field has stabilizing influence on the growth rate of Jeans instability.

In Langevin‐Dynamics simulations of large aggregates of up to 106 dust grains we study the continuous transition from a liquid‐like to a solid state. In this freezing two‐dimensional Yukawa liquid the hexagonal solid phase cascades to larger scales by domain merging, while defects pile up on the domain boundaries creating filamentary regions of enhanced grain mobility. The formation of larger crystal domains from merging is the analogy of vortex merging in two‐dimensional fluid turbulence, and the filaments of enstrophy dissipation in the fluid is the analogy of the thin strands of enhanced mobility surrounding the domains. The geometry of these filaments exhibit similar intermittent properties in the two systems and are characterized by an evolving multifractal dimension spectrum.

The mechanisms dominating the dynamical behavior of a 2D system of charged microparticles immersed in a plasma during a non‐equilibrium phase transition from an unordered to a crystalline state are investigated experimentally. It is found that lattice defects play a decisive role in determining the nature of the transition. This result is deduced from the analysis of defect arrangements and consideration of energy distribution and the application of a new theoretical model of a phase transition in a 2D system [1, 2]. The experimental findings are supported by a molecular‐dynamics simulation of a 2D system of particles crystallizing into an ordered structure.

The experiments in dc glow discharge argon plasma containing dust particles and placed in external magnetic field of the range 200–600 Gs were performed. The dust structures rotations in external magnetic field were observed. Angular velocities, Larmor radii and frequencies of the particles rotations were calculated for the different values of the magnetic field.

A fully kinetic (Vlasov) numerical scheme for dusty plasma dynamics is presented. The parametric dependence of Landau damping of dust‐ion acoustic waves on the electron‐to‐ion temperature ratio and dust concentration is discussed.

Using an energy resolved mass spectrometer we measured the ion energy and abundance of SinH2n+1+(n = 1…5) ions reaching the growing surface as a function of temperature and pressure in a very high frequency (VHF) hydrogen diluted silane plasma. We observed an increase in ion energy with increasing substrate temperature for all species. For low mass ions, we observe an increase in the number of ions reaching the growing surface with increasing temperature, whereas the count rate for high mass ions decreases with increasing temperature. This result confirms the hypothesis that a higher substrate temperature will prevent the plasma from going into the dusty γ′‐regime by suppressing the polymerization reactions of silyl into larger polysilanes which are the precursors for the dust formation.

Stereoscopy is an ideal method to investigate three‐dimensional dynamic processes in dusty plasmas. With more than two (three in our case) cameras, a three‐dimensional reconstruction of the recorded particle structures is possible. This enables investigations on novel dynamic phenomena of dusty plasmas. For the camera calibration of a multi‐view stereo setup, two methods are described: First, recording a target in different orientations, and second, calibrating the system inherently from the dust‐particle images.

Based on adiabatic model and nonlinear screening of the dust grains immersed in electron-ion plasma, an important relation is obtained between the maximum potential (and therefore the charge) of the dust grain and the temperature of the electrons. A Thomas-Fermi equation suggesting the existence of dust atom with a well-defined atomic radius is also derived. Briefly a new approach for obtaining floating potential has been introduced. This novel approach is valid for those cases when the standard OML theory is not applicable. © 2011 American Institute of Physics. Book subtitle: SIXTH INTERNATIONAL CONFERENCE ON THE PHYSICS OF DUSTY PLASMAS ispartof: pages:383-384 ispartof: DUSTY/COMPLEX PLASMAS: BASIC AND INTERDISCIPLINARY RESEARCH: Sixth International Conference on the Physics of Dusty Plasmas vol:1397 pages:383-384 ispartof: International Conference on the Physics of Dusty Plasmas location:Garmisch-Partenkirchen (Germany) date:16 May - 20 May 2011 status: published

Dusty plasmas formation in Earth's magnetosphere is considered. The main consequences of the presence of dusty plasmas in Earth's magnetosphere are discussed. Also we discuss the effects which can be caused by a micrometeoroid shower appearing after the destruction of a cosmic body by an explosion. We show that the presence of charged dust particles can result in the formation of a current system in the magnetosphere and study its possible consequences for Earth's environment.

The interaction of a supersonic projectile with a static dust cloud trapped in an rf discharge under microgravity conditions is examined. It is observed that the projectile forms a dust‐free cavity in its wake. The cavity dynamics can be divided into an initial impulse and a subsequent elastic response that can be modeled by a damped harmonic oscillator.

Magnetized plasmas with oppositely charged dust grains can exist in laboratory or space environments, as can oppositely charged nanoparticles such as Fullerenes. Such plasmas are spatially structured, with sharp or diffuse boundaries, and ocalized surface wave modes can exist near the interface of the plasma with the adjoining medium. Resonances and cutoffs of the waves can occur in the structured surface, which can lead to wave energy absorption and wave damping. Such plasmas can show distinctive features, analogous to pair plasmas, in particular Alfven resonance absorption.

Experimental study on dust dynamics in cryogenic plasma is presented. Dust particles are introduced into an rf discharge plasma in the vapor of liquid helium. Charged dust particles are extracted from the rf plasma into a diffused plasma closer to the surface of the liquid helium. The thermophoretic force is found to play an important role in the dynamics of dust particles.

New results from the recent experiments using the “Plasma Kristall‐4”, “PK‐4”, onboard of the parabolic flight plane A‐300 Zero‐G are presented. These are: a) structural and dynamics properties of dusty plasma clouds containing elongated dust particles—microrods; b) formation of a boundary‐free dust cluster due to attractive forces caused by ion fluxes in a bulk plasma region; c) shock wave in dusty plasma driven by the electrical manipulative electrode in polarity switching direct current discharge. Physical models of the observed phenomena are presented and discussed. Universal possibilities of the “PK‐4” setup are demonstrated.

This work presents an analytical model for the physical understanding of the charge distribution on pure (with high work function) and dirty (with low work function) ice dust particles in polar mesospheric clouds PMCs (NLCs and PMSEs). The analysis is based on number and energy balance of constituents and allows the charge to be only an integral multiple (positive or negative) of the electronic charge.

In this experiment we investigate the charge of dust particles when they are exposed to external UV‐radiation. The determination of the changes in charge of the dust particles is given by a combination of two methods to evaluate electrical charge: the resonance method and the normal mode analysis. This contribution describes the experimental setup and the determination of the charge differences.

We address an experimental observation of shear flow of micron sized dust particles in a strongly coupled complex plasma in presence of a homogeneous magnetic field. Two concentric Aluminum rings of different size are placed on the lower electrode of a radio frequency (rf) parallel plate discharge. The modified local sheath electric field is pointing outward/inward close to the inner/outher ring, respectively. The microparticles, confined by the rings and subject to an ion wind that driven by the local sheath electric field and deflected by an externally applied magnetic field, start flowing in azimuthal direction. Depending upon the rf amplitudes on the electrodes, the dust layers show rotation in opposite direction at the edges of the ring-shaped cloud resulting a strong shear in its center. MD simulations shows a good agreement with the experimental results., Comment: 2 pages with a figures

SCEPTIC3D now includes charge‐exchange collisions, and is used to examine ion collection by a floating conducting sphere (small compared to the electron debye length) in the presence of a background neutral drift. The enhancement of ion collection at moderate collisionalities seen for the stationary case is weakened as the drift speed increases from the ion thermal speed to the ion sound speed, above which no enhancement is seen.

In this investigation we have studied how dust concentration and superthermality of electrons affect the instability growth rate of dust electron‐acoustic waves. Both type of dark and bright envelope solitons are observed.

In this contribution the behavior of microparticles trapped in the curved plasma sheath in the corner of a horizontal rf electrode and a vertical wall is investigated by experiments and simulation. Three types of walls are studied, namely a dielectric wall, a floating conductive wall, and a conductive wall at the same potential as the rf electrode.

The charge on an aggregate immersed in a plasma environment distributes itself over the aggregate's surface; this can be approximated theoretically by assuming a multipole distribution. The dipole-dipole (or higher order) charge interactions between fractal aggregates lead to rotations of the grains as they interact. Other properties of the dust grains also influence the agglomeration process, such as the monomer shape (spherical or ellipsoidal) or the presence of magnetic material. Finally, the plasma and grain properties also determine the morphology of the resultant aggregates. Porous and fluffy aggregates are more strongly coupled to the gas, leading to reduced collisional velocities, and greater collisional cross sections. These factors in turn can determine the growth rate of the aggregates and evolution of the dust cloud. This paper gives an overview of the numerical and experimental methods used to study dust agglomeration at CASPER and highlights some recent results.

Using the traditional Sagdeev pseudopotential approach, the existence of large amplitude solitons is investigated for a plasma composed of cold negative dust, adiabatic positive dust, non‐thermal ions and Boltzmann electrons. The lower and upper soliton Mach number limitations are determined as a function of various parameters and physical reasons are provided as to why these Mach number limits occur. Some regions in parameter space have been identified where only negative or positive solitons occur, whereas, other regions support the coexistence of both positive and negative potential solitons.

Low frequency electrostatic and electromagnetic waves in a dense magnetoplasma are studied. The dispersive contribution of electron quantum effects in an electron‐ion plasma in the presence of positively or negatively charged dust particles in the background is emphasized. By employing the quantum hydrodynamic model, a linear dispersion relation is derived which shows coupling of electrostatic and shear Alfven modes which shows influence of electron quantum effects and dust density.

In this work, we have generalized the computation of Bohm criterion for electronegative complex plasma. For this, we have established a one‐dimensional, unmagnetized and stationary theoretical model where the positive ions and dust particles are modeled by fluid equations. The electrons and negative ions are considered in thermodynamic equilibrium; therefore they obey to Boltzmann's statistic. In this case, the numerical results show that the generalized Bohm velocity is small compared to the classical value. For electronegative dusty plasma, the corrections are less important.

Dust transport on the lunar surface is likely facilitated by the variable electric fields that are generated by changing plasma conditions. We have developed an experimental apparatus to study lunar photoelectric phenomena and gain a better understanding of the conditions controlling dust transport. As an initial step, Langmuir probe measurements are used to characterize the photoelectron plasma produced above a Zr surface, and these techniques will be extended to CeO2 and lunar simulant surfaces.

The particles are obtained by PECVD in radiofrequency (13.56 MHz) low pressure plasmas (90%CH4‐10%Ar). During the particle growth, the particles trap electrons and modify the EEDF, and the electrical and optical characteristics of the plasma. The plasma is analyzed by Optical Emission Spectroscopy. The excitation temperature and the electron temperature are calculated from the Hα, Hβ, Hγ Balmer hydrogen line intensities and from Ar ones. The temporal evolutions of the temperatures during the particle formation are compared and discussed.

We investigate experimentally the dynamics of the wake field and the high speed projectile travelling along the channels formed by the surrounding long vertical chains of the chain‐bundle dusty plasma liquids (CBDPLs) consisting of negatively charged dusts suspended in weakly ionized low pressure discharges, in which the downward ion flow not only causes the formation of long vertical chains but also can temporarily sustain the downward dust acoustic waves trigged by external perturbations. For the supersonic projectile channeling in the quiescent CBDPL, the excitation of the downward travelling narrow wake field associated with the elliptical motions of the background dusts is observed. The continuous increase and the subsequent oscillation of the drag force on the projectile as the projectile speed goes below the resonant velocity for wave excitation manifest the strong projectile‐wake field interaction, especially after the wake field catches up the subsonic projectile. The acceleration and surfing of ...

A purely kinetic instability of the dust acoustic mode in inhomogeneous plasmas is discussed. In the presence of a magnetic field, electrons and ions may be magnetized while at the same time dust grains may remain un‐magnetized. Although the dynamics of the light species is strongly affected by the magnetic field, the dust acoustic mode may still propagate in practically any direction. The inhomogeneity implies a source of free energy for an instability that develops through the diamagnetic drift effects of the magnetized species.

We used a dusty plasma technique to obtain Al‐Cu‐Fe quasicrystal powder particles coated by nickel. The samples of macro‐composites were obtained from the powders by cold pressing and following annealing in hydrogen. The structure of the samples and tribological properties were investigated.

Dust particles are grown in the plasma by sputtering a polymer layer previously deposited on the electrodes. A dust‐free region called the void appears in the center of the plasma as the result of two opposite forces, an inward electrostatic force and an outward ion drag force. To study this region of enhanced luminosity, an optical non intrusive diagnostics is used. Laser induced fluorescence allows to measure several characteristics like the evolution of the excited neutral argon density and the temperature in the plasma.

We have investigated the dynamics of propagation of electrostatic solitary waves in a plasma consisting of charged dust particles, negative and positive ions and superthermal (kappa) electrons. Using Sagdeev potential method, the energy‐balance like equation is derived to study the role of dust concentration, negative ion concentration, as well as of superthermality on solitary structures.

In‐situ cosmic dust instruments and measurements played a critical role in the emergence of the field of dusty plasmas. The major breakthroughs included the discovery of β‐meteoroids, interstellar dust particles within the solar system, Jovian stream particles, and the detection and analysis of Enceladus's plumes. The science goals of cosmic dust research require the measurements of the charge, the spatial, size and velocity distributions, and the chemical and isotopic compositions of individual dust particles. In‐situ dust instrument technology has improved significantly in the last decade. Modern dust instruments with high sensitivity can detect submicron‐sized particles even at low impact velocities. Innovative ion optics methods deliver high mass resolution, m/dm>100, for chemical and isotopic analysis. The accurate trajectory measurement of cosmic dust is made possible even for submicron‐sized grains using the Dust Trajectory Sensor (DTS). This article is a brief review of the current capabilities of...

Systematic particle temperature measurements have been performed in argon and molecular gas mixtures. The energy balance at low pressures could be consistently described by a simple model within the entire parameter range. Measured particle temperatures and modeled energy fluxes between particles and plasma are presented.

Interstellar dust can enter the solar system through the relative motion of the Sun with respect to the Local Interstellar Cloud. The trajectories of the dust through the solar system are not only influenced by gravitation and solar radiation pressure forces, but also by the Lorentz forces due to the interaction of the interplanetary magnetic field with the charged dust particles. The interplanetary magnetic field changes on two major time scales: 25 days (solar rotation frequency) and 22 years (solar cycle). The short‐term variability averages out for regions that are not too close (>∼2 AU) to the Sun. This interplanetary magnetic field variability causes a time‐variability in the interstellar dust densities, that is correlated to the solar cycle.In this work we characterize the flow of interstellar dust through the solar system using simulations of the dust trajectories. We start from the simple case without Lorentz forces, and expand to the full simulation. We pay attention to the different ways of mod...

It is demonstrated that it can be essential to use a self‐consistent kinetic approach in order to study the ion modes and the shielding of charged dust particles in a weakly ionized plasma with an ion flow driven by an electric field.

Results of experimental investigations of instabilities in cryogenic DC discharge were presented. Different types of dusty plasma instabilities (self‐excited oscillations, vortices and complex oscillations) were observed. The dependence between frequencies of oscillations and the gas pressure for structures with self‐excited oscillations at temperatures from 10 to 300 K was obtained. It was revealed that decreasing of gas temperature can lead to damping of self‐excited oscillations. A relative gradient of the particles charge causing the dusty plasma instabilities was estimated.

A bow shock is observed in a two‐dimensional flow of charged micro particles in a complex plasma. A thin conducting wire is placed vertically against the flow to make a potential barrier as an obstacle against the flow. A void is formed around the potential barrier surrounding the wire. When the flow velocity exceeds the dust acoustic velocity, the density in front of the void increases and forms the bow shock.

The modulational instability of dust‐acoustic waves is investigated, relying on a recently proposed model for strong electrostatic interactions between the highly charged dust particles. The resulting effect on the occurrence (threshold, growth rate) of modulational instability is investigated. Our results can in principle be tested experimentally.