This special issue of JPP features selected contributions from the 7th International Conference on the Physics of Dusty Plasmas (ICPDP 2014), held in New Delhi, India March 3–7, 2014.

The dust acoustic wave (DAW) was first discussed by P. K. Shukla in May of 1989 at the First Capri Workshop on Dusty Plasmas. In the past 25 years, the subsequent publication of the linear and nonlinear properties of the DAW (Rao, N. N., Shukla, P. K. and Yu, M. Y. 1990 Planet. Space Sci.38, 543) has generated and sustained a large body of theoretical and experimental research that has clarified the physics of collective effects in dusty plasmas. A unique feature of the DAW is that it can be observed (literally) using laser illumination and high-speed videography, revealing details of wave-particle interactions at an unprecedented single particle level. This paper attempts to review some of the contributions and extensions of dust acoustic wave physics, as well as identify recent findings that illustrate the potential importance of this dust wave in the agglomeration of dust particles.

Using the Sagdeev pseudopotential method, the properties of negative dust-acoustic supersolitons are investigated in a plasma comprising cold negative dust and Boltzmann and Cairns non-thermal positive ions. Supersolitons have electric field profiles with additional wiggles on traditional bipolar structures, and their existence requires pseudopotentials having two sub-wells before a root is reached. Once the existence ranges are determined in parameter space, typical pseudopotential, supersoliton and electric field profiles can be easily generated. Their characteristics are very robust and yield dust and dust-ion-acoustic supersolitons in a wide range of compositional models and parameter ranges.

Charging of dust grains and related phenomena are fundamental problems in the physics of complex plasmas. The relative motion of grains and plasma breaks the symmetry in dust charging and gives rise to the wake in plasma density and potential, which can significantly influence the dynamics of other grains. This paper gives an overview of dust charging in two- and multi-component plasma flows and related wake effects, and presents recent results from self-consistent particle-in-cell (PIC) simulations. The role of wakefields is considered in the context of charging of downstream grains.

The Magnetized Dusty Plasma Experiment (MDPX) device is a newly constructed research instrument for the study of dusty (complex) plasmas. The MDPX device is envisioned as an experimental platform in which the dynamical behavior of all three charged plasma components, the electrons, ions, and charged microparticles (i.e., the ‘dust’) will be significantly influenced by the magnetic force. This brief paper will provide a short overview of the design, magnetic performance, and initial plasma measurements in the MDPX device.

The dust acoustic wave (DAW), associated with longitudinal dust oscillations in dusty plasmas, can be self-excited from the free energy of ion streaming. It is not only a fundamental plasma wave but also a paradigm to understand the generic dynamical behaviors of self-excited nonlinear longitudinal density waves through optically monitoring particle motion and dust density evolutions over a large area. In this paper, the dynamical behaviors of the wave-particle interaction and wave breaking in ordered self-excited DAW with straight wave fronts, and the defect-mediated wave turbulence with fluctuating defects and chaotic low amplitude hole filaments along defect trajectories in the 2+1D space-time space, are briefly reviewed. The first experimental observation of acoustic vortices with helical waveforms in self-excited acoustic-type defect-mediated wave turbulence, and the dynamics of spontaneous pair generation, propagation, and pair annihilation of acoustic vortices, is demonstrated and discussed.

The Kelvin-Helmholtz (KH) instability is studied in a two dimensional strongly coupled dusty plasma medium using a fluid approach as well as through a molecular dynamic (MD) simulation. For the fluid description the generalized hydrodynamic (GH) model which treats the strongly coupled dusty plasma as a visco-elastic fluid is adopted. For the MD studies the ensemble of particles are assumed to interact through a Yukawa potential. Both the approaches predict a stabilization of the KH growth rate with an increase in the strong coupling parameter. The present study also delineates the temporal evolution and the interaction of transverse shear waves with the collective dynamics of the dusty plasma medium within the framework of both these approaches.

Using a fluid theory approach, this article provides a comparative study on the evolution of nonlinear waves in dusty plasmas, as well as other plasma environments, viz electron-ion, and electron-positron plasmas. Where applicable, relevance to satellite measurements is pointed out. A range of nonlinear waves from low frequency (ion acoustic and ion cyclotron waves), high frequency (electron acoustic and electron cyclotron waves) in electron-ion plasmas, ultra-low frequency (dust acoustic and dust cyclotron waves) in dusty plasmas and in electron-positron plasmas are discussed. Depending upon the plasma parameters, saw-tooth and bipolar structures are shown to evolve.

The formation of carbon nanoparticles in low pressure magnetized H2/CH4 and H2/C2H2 plasmas is investigated using infrared quantum cascade laser absorption, mass spectrometry, and electrostatic probe measurements. Results showed that dust formation is correlated to the presence of a significant amount of large positively charged hydrocarbon ions. Large negative ions or neutral hydrocarbon were not observed. These results, along with a qualitative comparison of diffusion and reaction characteristic, suggest that a positive ion may contribute to the growth of nanoparticles in hydrocarbon magnetized plasmas.

Theoretical and numerical works on dusty plasmas with cylindrical symmetry are presented. The main purpose has been to investigate behavior of dust particles in strongly coupled dusty plasmas which are expected to be realized in the planned experiments by PK-4 on the International Space Station and experiments by PK-4J, a similar apparatus constructed in Japan. The distribution of dust particles is analyzed on the basis of the drift-diffusion equations and, with the effect of discreteness taken into account, structure formations are numerically simulated.

The formation of nanoparticles from the sputtering of graphite and tungsten cathodes in direct-current discharges is investigated. The successive phases of growth present specificities according to the cathode material. The evolution of the discharge and plasma parameters during the growth phases accounts for the nanoparticle-plasma electrostatic coupling. This evolution also presents strong differences as a function of the cathode material. Features characterising each case are discussed.

A simplified description of dynamical response of strongly coupled medium is desirable in many contexts of physics. The dusty plasma medium can play an important role in this regard due to its uniqueness, as its dynamical response typically falls within the perceptible grasp of human senses. Furthermore, even at room temperature and normal densities it can be easily prepared to be in a strongly coupled regime. A simplified phenomenological fluid model based on the visco - elastic behaviour of the medium is often invoked to represent the collective dynamical response of a strongly coupled dusty plasma medium. The manuscript reviews the role of this particular Generalized Hydrodynamic (GHD) fluid model in capturing the collective properties exhibited by the medium. In addition the paper also provides new insights on the collective behaviour predicted by the model for the medium, in terms of coherent structures, instabilities, transport and mixing properties.

In this brief communication we have explored whether the electron emission from the boundary region surfaces (or from additional fine structured dust particles/droplets of some benign material put purposely in the area surrounding the surfaces) can act as an efficient cooling mechanism for boundary region surfaces/dust electrons and hence the lattice. In order to estimate the contribution of this cooling process a simple kinetic model based on charge flux balance and associated energetics has been established. Along with some additional sophistication like suitable choice of material and modification in the work function via surface coating, the estimates show that it is possible to keep the temperature of the plate/particles well within the critical limit, i.e. melting/sublimation point for the desired regime of incident heat flux.

A collective behavior of dust particles in a complex plasma with a magnetic field (up to 4 kG) is investigated. Dust particles form a dust disk which is rotating in a horizontal plane pushed by ions rotating with the E × B drift as a trigger force. The thickness of the disk is determined by controlling the experimental conditions. The disk rotates in a horizontal plane and forms a two-dimensional thin structure when the pressure pAr is relatively high. The dust particles are ejected from near the disk center and form a rotation in the vertical plane and, hence, forms a helical vortex when the disk is thick for relatively low pAr. The reason the dust disk has the different thickness is due to the neutral pressure. Under a higher (lower) neutral gas pressure, the disk becomes two (three) dimensional due to the influence of the neutral drag force.

Two types of electro-acoustic shock structures, namely dust-ion-acoustic (DIA) and dust-acoustic (DA) shock structures, formed in two different kind of dusty plasma systems have been theoretically investigated. The sources of dissipation, which are responsible for the formation of DIA and DA shock structures in these dusty plasma systems, are identified. The conditions for the formation of these shock structures and their new basic features are pinpointed. The implications of the results in experimental observations are also discussed.

The results on dusty plasmas over the Moon are reviewed. The problems concerning the dusty plasma over the lunar surface are formulated.

Using 2D molecular dynamics (MD) simulation, the equilibrium and dynamical properties of a gravitationally equilibrated Yukawa liquid are investigated. We observe that due to asymmetry introduced in one direction by gravity, several interesting features arise. For example, for a given value of coupling parameter Γ, screening parameter κ and according to a chosen value of gravitational force g (say in y-direction), the system is seen to exhibit super-, sub- or normal diffusion. Interestingly, x-averaged density profiles, unlike a barotropic fluid, acquire sharp, free surface with scale free linear y-dependence. As can be expected for a system with macroscopic gradients, self-diffusion calculated from Green–Kubo's (GK) formalism does not agree with that obtained from Einstein–Smoluchowski (ES) diffusion. A 2D-angular radial pair correlation function g(r, θ) clearly indicates asymmetric features induced by gravity. We observe that due to compression in y-direction, though in liquid state for all values of gravity considered, the transverse mode is found to be predominant as compared to the longitudinal mode, leading to a novel Anisotropic Solid-like Yukawa liquid (ASYL). In in-homogenous Yukawa liquids studied here, Mach cones are found to be asymmetric. When density gradient direction is set in the direction opposite to gravity, the equilibrium is shown to be unstable to Rayleigh–Taylor (RT) instabilities resulting in transport.