A. P. Nefedov

Crystallization of a dusty plasma in the positive column of a glow discharge

The formation of macroscopic ordered structures in the standing striations of a stationary glow discharge in Ne is observed. A Coulomb quasicrystal is formed by spherical glass particles with diameters of 50–63 μm and charge Zp~7·105e. The interparticle distance is approximately 300 μm. This corresponds to a nonideality parameter Γ~5·104, which leads to crystallization in the Yukawa model. The factors leading to the formation of a quasicrystal in the striations are discussed.

Ordered structures in a nonideal dusty glow-discharge plasma

The formation of ordered structures of charged macroparticles in a constant-current neon glow-discharge plasma is investigated. Experiments were performed with two types of particles: thin-walled glass spheres 50–63 μm in diameter and particles of Al2O3, 3–5 μm in diameter. Formation of quasicrystalline structures is observed in the standing strata and in an artificially created double electric layer. The formation of extended filamentary structures of macroparticles in the absence of visible stratification of the positive column has been observed for the first time. The influence of the discharge parameters on the formation of the ordered structures and their melting is examined. The form of the interaction potential between the charged macroparticles is considered, as well as changes in the conditions for maintaining the discharge in the presence of high concentrations of dust particles.

Dust particles in a nuclear-induced plasma

Abstract For the first time we have performed experiments in a nuclear-induced plasma with micron-sized dust macroparticles injected into it. The plasma was formed in atmospheric air by alpha-particles and fission fragments of 252 Cf as well as by beta-active particles. In both cases ordered liquid-type structures of dust particles levitating in the interelectrode space were observed.

Formation of liquidlike and crystalline structures in dusty plasmas

Under certain conditions in a dusty plasma, which is a low-temperature plasma with dust grains, the strong interaction between grains can give rise to gas-liquid-solid-state phase transitions. A study is made of ordered (liquidlike and crystalline) grain structures in various kinds of dusty plasmas: a thermal plasma at atmospheric pressure, a plasma of a dc glow discharge, and a UV radiation-driven plasma. The results of experimental observations of ordered dust structures are reported, and the characteristic features of the dust structures and the conditions for their appearance are discussed.

Dust grain charging in the nuclear-induced plasma

Abstract For the first time we have performed experiments in the nuclear-induced neon plasma with micron-sized dust grains injected into it and calculated grain electric charges in a single track of 252 Cf fission fragment and in electron and ion drift flows. Levitating ordered structures of dust grains were observed. The results of calculations are in good agreement with the experiment.

Ordered structures of microparticles in a glow discharge

The possibilities are analyzed and experimentally investigated of the formation and destruction of structures of charged microparticles in a glow discharge plasma in different gases. The use of a conical discharge tube and the introduction of an orifice plate into that tube enable one to stabilize the strata and obtain dust formations of different types. Given a fairly high concentration of dust particles in a structure, this structure itself affects the local properties of the plasma.

Anomalously high kinetic energy of charged macroparticles in a plasma

A number of recent experimental investigations of nonideal plasmas containing macroparticles have revealed an anomalous increase in that part of the kinetic energy of these macroparticles that corresponds to their random motion. In this paper a model is proposed for the dynamic motion of charged macroparticles that explains this phenomenon.Calculations based on this model are compared with experimental results.

Nuclear Induced Dusty Plasma Structures

Publisher Summary This chapter describes the experiments conducted in the nuclear-induced plasma with micron-sized dust macro-particles injected into it. The experiments suggest that the plasma was formed in the atmospheric air by alpha-particles and fission fragments of 252Cf as well as by beta-active particles. In both cases, ordered liquid-type structures of dust particles levitating in the interelectrode space were observed. When the electric field intensity was less than 20 V/cm, regions of levitation of macro-particles forming ordered liquid-type dust structures were observed in the interelectrode space. With an increase in the electric field, the vortex movement of macro-particles occurred. The initial direction of a rotation of dust particles was from the radioactive source.

Liquid and crystal dust structures in low temperature plasmas

A study of the strongly coupled dusty plasma was carried out over a wide range of plasma pressures and temperatures. The plasma was investigated under conditions of low pressure dc current and inductively-coupled rf gas discharges and under nuclear induced plasma conditions. The plasma was also formed from positively charged dust grains in the presence of a flux of ultraviolet photons. The results of experimental observations of ordered dust structures are reported, and the characteristic features of the dust structures and the conditions for their appearance are discussed.

Formation of ordered structures and collective phenomena in dusty plasmas

Dust particle ordering is discussed in various types of low-temperature plasma, such as dc glow discharges, UV- and radioactivity induced plasmas. Nuclear induced plasma was formed in the rare gases by alpha-particles and fission fragments of 252Cf. The ordered liquid-type structures of dust particles levitating in the interelectrode space have been observed. To remove charged particles from a volume an electrostatic probe has been designed and used. The dynamics of the formation of ordered structures of macroparticles charged by photoemission under the action of solar radiation under microgravitational conditions is studied experimentally and theoretically. An analysis and comparison of tile results of the experimental and theoretical investigations permit drawing a conclusion regarding the possibility of the existence of extended ordered formations of macroparticles charged by photoemission under microgravitational conditions.