Plasma-dust Structures Research Articles

Cooperative formation of dust structures in plasma

The formation and destruction of ordered dust structures in glow discharges are investigated experimentally. The initial construction phase of an ordered structure is related to the construction of its cooperative field and is determined by the number of particles and by the existence of crystallization centers. After the structure has been constructed, it influences the local plasma properties and the discharge current-voltage characteristics. The recovery of the structure after weak exposure takes place at local equilibrium, while, after intense exposure to high-voltage nanosecond pulses, it is determined by the fluctuation level and the degree of chaotization in the system.

Plasma-dust structures at cryogenic temperatures

Plasma-dust structures at cryogenic temperatures

Potential of a dust grain in a nitrogen plasma with a condensed disperse phase at room and cryogenic temperatures

The first numerical study is presented of the self-consistent potential of a dust grain in a nitrogen plasma with a condensed disperse phase at room and cryogenic temperatures and at high gas pressures for which the electron and ion transport in the plasma can be described in the hydrodynamic approximation. It is shown that the potential of the dust grain is described with good accuracy by the Debye potential, in which case, however, the screening radius turns out to be larger than the electron Debye radius. The difference between the radii is especially large in a plasma with high ionization rates (about 1016–1018 cm−3 s−1) at room temperature. It is found that, in a certain range of the parameters of a nitrogen dusty plasma, the parameter describing the interaction between the grains exceeds the critical value above which one would expect the formation of plasma-dust structures such as Coulomb crystals. For a plasma at cryogenic temperature (T=77 K), this range is significantly wider.

Particle simulation of dust structures in plasmas

In the Earth's gravity, the dust in plasmas can form into a solid-like state In the plasma sheath. These ordered structures occur due to the balance of the interparticle forces, the gravitational force, and the sheath electric field. We have developed a particle simulation model to study the behavior of strongly coupled dust in plasmas under conditions of normal gravity and microgravity. The model includes a complete first-principles representation of the short-range strong forces of a shielded Coulomb system, as well as the long-range wake forces of a plasma with the ions streaming through the dust. The effects of charged particle scattering with neutrals and with other charges are included. Magnetic fields in the plasma may also be incorporated in the model.

The effect of the gas temperature gradient on dust structures in a glow-discharge plasma

An experimental investigation is performed of the effect of the neutral gas temperature gradient on plasma-dust formations in the positive column of a glow discharge. It is demonstrated that the thermophoretic forces arising due to the temperature gradient are comparable with radial electric fields and define the condition of formation and different shapes of plasma-dust structures, in particular, the formation of rings in the vicinity of tube walls. A model description of this effect is given.