Physical aspects of dust–plasma interactions

Low-pressure gas discharge plasmas are known to be strongly affected by the presence of small dust particles. This issue plays a role in the investigations of dust particle-forming plasmas, where the dust-induced instabilities may affect the properties of synthesized dust particles. Also, gas discharges with large amounts of microparticles are used in microgravity experiments, where strongly coupled subsystems of charged microparticles represent particle-resolved models of liquids and solids. In this field, deep understanding of dust–plasma interactions is required to construct the discharge configurations which would be able to model the desired generic condensed matter physics as well as, in the interpretation of experiments, to distinguish the plasma phenomena from the generic condensed matter physics phenomena. In this review, we address only physical aspects of dust–plasma interactions, that is, we always imply constant chemical composition of the plasma as well as constant size of the dust particles. We also restrict the review to two discharge types: dc discharge and capacitively coupled rf discharge. We describe the experimental methods used in the investigations of dust–plasma interactions and show the approaches to numerical modelling of the gas discharge plasmas with large amounts of dust. Starting from the basic physical principles governing the dust–plasma interactions, we discuss the state-of-the-art understanding of such complicated, discharge-type-specific phenomena as dust-induced stratification and transverse instability in a dc discharge or void formation and heartbeat instability in an rf discharge.     

The effects of dust temperature and the dust charge variation in a dusty plasma with vortex—like ion distribution

By considering both the dust temperature and the dust charge variation in dusty plasma with vortex-like ion distribution, we obtained a modified Korteweg－de Vries equation. It indicates that the effect of dust charge variation can cause the one-dimensional soliton amplitude to become larger, and the dust temperature can cause the soliton amplitude to become larger as well. Moreover, as the dust temperature increases, the soliton amplitude will increase.     

Modulational instability of ultra-low-frequency shear dust Alfvén waves in a plasma medium of positive and negatively charged dust fluids

The propagation of finite amplitude ultra-low-frequency shear dust Alfvén (SDA) waves, and their modulational instability in a magnetized plasma medium of positive and negatively charged dust fluids have been theoretically investigated by using the reductive perturbation method. The derivative nonlinear Schrödinger equation is derived to examine the stability analysis of such SDA waves. It is found that the SDA waves propagating in such an opposite polarity dust plasma medium are modulationally unstable, and that the instability criterion and the growth rate of these unstable SDA waves in such a novel opposite polarity dust plasma medium are found to be significantly different from those in electron–ion or electron–positron plasma media. The implications of the present investigation in different space environments and laboratory devices are briefly discussed.     

Effect of dust charge variation on dust—acoustic solitary waves in a magnetized two—ion—temperature dusty plasma

The effect of dust charge variation on the dust-acoustic solitary structures is investigated in a warm magnetized two-ion-temperature dusty plasma consisting of a negatively and variably charged extremely massive dust fluid and ions of two different temperatures. It is shown that the dust charge variation as well as the presence of a second component of ions would modify the properties of the dust-acoustic solitary structures and may exite both dust-acoustic solitary holes (soliton waves with a density dip) and positive solitons (soliton waves with a density hump).     

Scattering properties of polluted dust in 1.6-μm wavelength

Three typical polluted dust particles （i.e., single coated dust, two-sphere/spheroid system, and coated dust with ag- gregate） including internal and semi-external mixtures are modeled, and their scattering properties at 1.6-μm wavelength are calculated by using the generalized multi-sphere Mie-solution （GMM） method. We investigate the influences of par- ticle size, morphology, and chemical composition on the scattering parameters of polluted dust particles. The analysis results demonstrate that the single scattering albedo of coated dust is much smaller than that of pure dust, especially for the spheroidal black carbon （BC） coated dust. When a dust particle semi-mixes with another aerosol particle to form a two-sphere/spheroid system, its scattering properties are much more sensitive to the size and species of monomers than the monomer shape. If an aggregated BC attaches to the coated dust, the scattering properties of whole particle mainly depend on the host particle （coated dust）.     

The impact of cosmic dust on the Earth’s climate

Flows of material particles, viz., cosmic rays and cosmic dust, are perpetually coming from space into the Earth’s atmosphere; these are particles sized from 0.001 μm to dozens or hundreds of μm. The paper shows that cosmic rays influence the main parameters of the atmosphere’s electricity, and cosmic dust influences global cloudiness, albedo and the Earth’s climate. Original Russian Text ? V.I. Ermakov, V.P. Okhlopkov, Yu.I. Stozhkov, 2009, published in Vestnik Moskovskogo Universiteta. Fizika, 2009, No. 2, pp. 104–106.     

Radial asymptotics of Lemaître–Tolman–Bondi dust models

We examine the radial asymptotic behavior of spherically symmetric Lemaître–Tolman–Bondi dust models by looking at their covariant scalars along radial rays, which are spacelike geodesics parametrized by proper length ?, orthogonal to the 4-velocity and to the orbits of SO(3). By introducing quasi-local scalars defined as integral functions along the rays, we obtain a complete and covariant representation of the models, leading to an initial value parametrization in which all scalars can be given by scaling laws depending on two metric scale factors and two basic initial value functions. Considering regular “open” LTB models whose space slices allow for a diverging ?, we provide the conditions on the radial coordinate so that its asymptotic limit corresponds to the limit as ? → ∞. The “asymptotic state” is then defined as this limit, together with asymptotic series expansion around it, evaluated for all metric functions, covariant scalars (local and quasi-local) and their fluctuations. By looking at different sets of initial conditions, we examine and classify the asymptotic states of parabolic, hyperbolic and open elliptic models admitting a symmetry center. We show that in the radial direction the models can be asymptotic to any one of the following spacetimes: FLRW dust cosmologies with zero or negative spatial curvature, sections of Minkowski flat space (including Milne’s space), sections of the Schwarzschild–Kruskal manifold or self-similar dust solutions.     

Impacts of fast meteoroids and a plasma–dust cloud over the lunar surface

The possibility of the formation of a plasma–dust cloud in the exosphere of the Moon owing to impacts of meteoroids on the lunar surface is discussed. Attention is focused on dust particles at large altitudes of ~10–100 km at which measurements were performed within the NASA LADEE mission. It has been shown that a melted material ejected from the lunar surface owing to the impacts of meteoroids plays an important role in the formation of the plasma–dust cloud. Drops of the melted material acquire velocities in the range between the first and second cosmic velocities for the Moon and can undergo finite motion around it. Rising over the lunar surface, liquid drops are solidified and acquire electric charges, in particular, owing to their interaction with electrons and ions of the solar wind, as well as with solar radiation. It has been shown that the number density of dust particles in the plasma–dust cloud present in the exosphere of the Moon is ?10^?8 cm^?3, which is in agreement with the LADEE measurements.     

The instability of electrostatic wave in a magnetized dusty plasma with nonadiabatic dust charge fluctuation

The effects of external magnetized field and nonadiabatic dust charge fluctuation on instability of wave incorporating the nonthermally distributed ions and the temperatures of ion and dust in dusty plasmas are investigated. A linear dispersion relation is obtained. The numerical results show that the external magnetized field, fast ions and nonadiabatic dust charge fluctuation have strong influence on the frequency and the damping of wave.     

Comment on “Potential profile near the virtual cathode in presence of charged dust”

The characteristics of the virtual cathode and its potential profile in the presence of negatively charged dust particles have been reported by Rathod et al. They have studied the role of charged dust particles in the formation of virtual cathode near the emitting surface. Two conditions of the dust charge number, Z_d = 1 and Z_d = 1,000 are used to study the role of dust density (n_d) for the formation of virtual cathode. This work is original and will be more interesting in case of using the correct model equations and realistic dusty plasma conditions.     

Influence of cosmic rays and cosmic dust on the atmosphere and Earth’s climate

The results of studying the cosmic ray fluxes in the Earth’s atmosphere and their influence on the atmospheric electricity, as well as the effect of cosmic dust entering the terrestrial atmosphere from the interplanetary space on the Earth’s climate are briefly discussed. A forecast of the climate cooling in the forthcoming 50 years is given.     

2.5–300 μm laboratory observations of submicron SiC particles as cosmic dust candidates

Three different kinds of α-SiC and one β-SiC sample which have undergone the same treatment procedures have been studied morphologically. Their absorption spectra have also been measured in the range 2.5–300 μm. Outside the typical 11.5 μm absorption band, all spectra show an FIR trend which can be fitted by a power law λ^-γ. The steepness is seen to increase as a function of sample purity. For the highest purity, 99.3%, γ = 1.4. The lowest values are interpreted as being due to the presence of some contaminants in the samples, metallic Fe mainly and also free C and free SiO. β-SiC also shows a λ^-γ spectrum with γ ≅ 1.0, while that measured by Tanabé et al. ⁷ is found to be characterized by γ = 1.4 again. This difference is tentatively interpreted as being due to a higher purity of the Japanese group sample. The results of our analysis seem to suggest that α-SiC and β-SiC differ morphologically, while their FIR spectra follow a similar λ^-1.4 trend. Astronomical observations at these long wavelengths do not allow any identification of the actual SiC type existing in space which, on the contrary, can probably be identified by analysing the 11.5 μm band.     

Mössbauer and VNIR study of dust generated from olivine basalt: application to Mars

Mössbauer spectroscopy of surface rocks, soil, and dust on Mars from the Mars Exploration Rovers (MER) suggests that the mineral olivine is widespread on the surface. Detection of the mineral by near-IR optical spectroscopy from Martian orbit indicates that it is found in relatively small isolated outcrops concentrated in the floors and rims of craters distributed around the ancient cratered highlands of Mars. To shed light on this apparent paradox, we have performed a detailed Mössbauer and visible-near-IR (VNIR) investigation of dust generated from Icelandic olivine basalt, which is a good Mössbauer analogue to the igneous rocks at Gusev crater on Mars. The results show that the amount of olivine relative to pyroxene can be underestimated by almost an order of a magnitude in VNIR reflectance spectra, most probably because of the longer effective optical path length in pyroxene compared to olivine.     

Effect of viscosity on dust–ion acoustic shock wave in dusty plasma with negative ions

The properties of dust–ion acoustic (DIA) shock wave in a dusty plasma containing positive and negative ions is investigated. The reductive perturbation method has been used to derive the Korteweg–de Vries–Burgers equation for dust acoustic shock waves in a homogeneous, unmagnetized and collisionless plasma whose constituents are Boltzmann distributed electrons, singly charged positive ions, singly charged negative ions and cold static dust particles. The KdV–Burgers equation is derived and its stationary analytical solution is numerically analyzed where the effect of viscosity on the DIA shock wave propagation is taken into account. It is found that the viscosity in the dusty plasma plays as a key role in dissipation for the propagation of DIA shock.     

Evolution of dust shells in Tolman–Bondi space–time according to the Weierstrass approach

The Einstein evolution of a dust shell universe with spatial spherical symmetry is analyzed. The implicit and parametric solutions of Tolman–Bondi equations are proposed in order to show its agreement with the rectilinear solutions of Kepler’s problem. Finally, a complete systematization of Tolman–Bondi models is obtained through the classical Weierstrass approach.     

Nonlinear ion-acoustic structures in a nonextensive electron–positron–ion–dust plasma: Modulational instability and rogue waves

The nonlinear propagation of planar and nonplanar (cylindrical and spherical) ion-acoustic waves in an unmagnetized electron–positron–ion–dust plasma with two-electron temperature distributions is investigated in the context of the nonextensive statistics. Using the reductive perturbation method, a modified nonlinear Schrödinger equation is derived for the potential wave amplitude. The effects of plasma parameters on the modulational instability of ion-acoustic waves are discussed in detail for planar as well as for cylindrical and spherical geometries. In addition, for the planar case, we analyze how the plasma parameters influence the nonlinear structures of the first- and second-order ion-acoustic rogue waves within the modulational instability region. The present results may be helpful in providing a good fit between the theoretical analysis and real applications in future spatial observations and laboratory plasma experiments.     

Bifurcation analysis of nonlinear and supernonlinear dust–acoustic waves in a dusty plasma using the generalized (r,q) distribution function for ions and electrons

Bifurcation analysis of dust acoustic (DA) periodic waves in three components, unmagnetized dusty plasma system is investigated using the generalized (r, q) distribution function for ions and electrons. Depending on the different parameters of the system considered, all possible phase portraits, including periodic, homoclinic, superperiodic, and superhomoclinic trajectories, are presented. The existence of rarefactive and compressive solitary waves is proved. Also, the plasma system under consideration supports both nonlinear and supernonlinear DA periodic waves. It has been found that the double spectral indices r and q play a decisive effect on the bifurcation of the waves.     

Reply to: “Comment on: ‘Spherical Kadomtsev–Petviashvili equation and nebulons for dust ion-acoustic waves with symbolic computation’ ” [Phys. Lett. A 361 (2007) 520]

Dusty plasmas exist almost everywhere in the Universe and relevant nonlinear studies are encouragingly going to non-planar geometry. On our recent construction of a spherical Kadomtsev–Petviashvili model for the dust-ion-acoustic waves in a cosmic dusty plasma [B. Tian, Y.-T. Gao, Phys. Lett. A 340 (2005) 243], Hong [W.P. Hong, Phys. Lett. A (2006), doi:10.1016/j.physleta.2006.11.021, in press] comments that certain interesting coordinate transformations exist, with presentation of a transformed equation (TE) and nebulon solutions. In this Reply, we point out that the TE is valuable to the studies on both cosmic plasmas and applied mathematics. We obtain an auto-Bäcklund transformation on the TE and more general nebulons. With series of pictures, we discuss nebulon structures out of the TE, and address that there are cosmic plasma systems for which the TE is valid. We remove a constraint set in that Comment so that the TE can be useful for the Saturn-F-ring-typed dusty plasmas as well.