Accurate freezing and melting equations for the Lennard-Jones system

Analyzing three approximate methods to locate liquid-solid coexistence in simple systems, an observation is made that all of them predict the same functional dependence of the temperature on density at freezing and melting of the conventional Lennard-Jones system. The emerging equations can be written as $T={\mathcal A}\rho^4+{\mathcal B}\rho^2$ in normalized units. We suggest to determine the values of the coefficients ${\mathcal A}$ at freezing and melting from the high-temperature limit, governed by the inverse twelfth power repulsive potential. The coefficients ${\mathcal B}$ can be determined from the triple point parameters of the LJ fluid. This produces freezing and melting equations which are exact in the high-temperature limit and at the triple point, and show remarkably good agreement with numerical simulation data in the intermediate region.Comment: 6 pages, 1 figur

Ionization enhanced ion collection by a small floating grain in plasmas

It is demonstrated that the ionization events in the vicinity of a small floating grain can increase the ion flux to its surface. In this respect the effect of electron impact ionization is fully analogous to that of the ion-neutral resonant charge exchange collisions. Both processes create slow ion which cannot overcome grain' electrical attraction and eventually fall onto its surface. The relative importance of ionization and ion-neutral collisions is roughly given by the ratio of the corresponding frequencies. We have evaluated this ratio for neon and argon plasmas to demonstrate that ionization enhanced ion collection can indeed be an important factor affecting grain charging in realistic experimental conditions.Comment: 7 pages, 1 figure, submitted to Physics of Plasma

Shielding of a small charged particle in weakly ionized plasmas

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.Comment: This is a short review pape

Channeling of particles and associated anomalous transport in a 2D complex plasma crystal

Implications of recently discovered effect of channeling of upstream extra particles for transport phenomena in a two-dimensional plasma crystal are discussed. Upstream particles levitated above the lattice layer and tended to move between the rows of lattice particles. An example of heat transport is considered, where upstream particles act as moving heat sources, which may lead to anomalous heat transport. The average channeling length observed was 15 - 20 interparticle distances. New features of the channeling process are also reported

Self-diffusion in strongly coupled Yukawa systems (complex plasmas)

We show that the idea of mapping between the Newtonian and Brownian diffusivities proposed and tested on a class of particle systems interacting via soft and ultra-soft potentials (IPL, Gaussian core, Hertzian, and effective star-polymer) by Pond {\it et al}., [Soft Matter {\bf 7}, 9859 (2011)] is also applicable to the Yukawa (screened Coulomb) interaction. Some of the implications of this result with respect to self-diffusion in strongly coupled complex (dusty) plasmas are discussed.Comment: 9 pages, 3 figures, submitted to Phys. Plasma

Wake-mediated propulsion of an upstream particle in two-dimensional plasma crystals

The wake-mediated propulsion of an "extra" particle in a channel of two neighboring rows of a two-dimensional plasma crystal, observed experimentally by Du et al. [Phys. Rev. E 89, 021101(R) (2014)], is explained in simulations and theory. We use the simple model of a pointlike ion wake charge to reproduce this intriguing effect in simulations, allowing for a detailed investigation and a deeper understanding of the underlying dynamics. We show that the nonreciprocity of the particle interaction, owing to the wake charges, is responsible for a broken symmetry of the channel that enables a persistent self-propelled motion of the extra particle. We find good agreement of the terminal extra-particle velocity with our theoretical considerations and with experiments.Comment: 7 pages, 4 figures, PRL (https://journals.aps.org/prl/), updated version with correct author affiliation

Self-diffusion in strongly coupled Yukawa systems (complex plasmas)

We show that the idea of mapping between the Newtonian and Brownian diffusivities proposed and tested on a class of particle systems interacting via soft and ultra-soft potentials (IPL, Gaussian core, Hertzian, and effective star-polymer) by Pond {\it et al}., [Soft Matter {\bf 7}, 9859 (2011)] is also applicable to the Yukawa (screened Coulomb) interaction. Some of the implications of this result with respect to self-diffusion in strongly coupled complex (dusty) plasmas are discussed.Comment: 9 pages, 3 figures, submitted to Phys. Plasma

Nonlinear structures of strongly coupled complex plasmas in the proximity of a presheath/sheath edge

The formation of a steady-state nonlinear potential structure of a double-layer type near the presheath/sheath edge of a plasma discharge is theoretically investigated in complex plasmas containing Boltzmann electrons, cold fluid ions and strongly coupled microparticles. Equilibrium of the particles is provided by the electrostatic force and an effective 'dust pressure' associated with electrostatic interactions between the highly charged grains. The results are of importance for complex plasma experiments in microgravity conditions, for thermophoretically levitated configurations and for processing plasmas loaded by nanometer-sized microparticles

Glass-Transition Properties from Hard Spheres to Charged Point Particles

The glass transition is investigated in three dimensions for single and double Yukawa potentials for the full range of control parameters. For vanishing screening parameter, the limit of the one-component plasma is obtained; for large screening parameters and high coupling strengths, the glass-transition properties crossover to the hard-sphere system. Between the two limits, the entire transition diagram can be described by analytical functions. Different from other potentials, the glass-transition and melting lines for Yukawa potentials are found to follow shifted but otherwise identical curves in control-parameter space.Comment: 6 pages, 5 figure