A. N. Ryabinkin

Coagulation of dust grains in the plasma of an RF discharge in argon

Results are presented from experimental studies of coagulation of dust grains of different sizes injected into a low-temperature plasma of an RF discharge in argon. A theoretical model describing the formation of dust clusters in a low-temperature plasma is developed and applied to interpret the results of experiments on the coagulation of dust grains having large negative charges. The grain size at which coagulation under the given plasma conditions is possible is estimated using the developed theory. The theoretical results are compared with the experimental data.

Synthesis and characterization of macrocomposites based on nickel-coated quasi-crystalline Al-Cu-Fe powder

Disperse composite materials consisting of quasi-crystalline Al-Cu-Fe particles covered by nickel nanolayers have been obtained using a dusty plasma trap coating technology. These powders were processed into macrocomposites by cold pressing with subsequent sintering in hydrogen. The macrocomposites were studied by the electron microscopy, electron-probe microanalysis, and X-ray diffraction techniques. It is established that sintering at ∼750°C yields a high-strength macrocomposite that is not fractured under tribological testing conditions. Despite the fact the samples sintered at 750°C contain about 50 wt % of β phase, their friction coefficient is close to that of Al-Cu-Fe quasi-crystals.

Orbital Motion of Dust Particles in an rf Magnetron Discharge. Ion Drag Force or Neutral Atom Wind Force

Microparticles with sizes up to 130 μm have been confined and the velocity and diameter of particles in a plasma trap of an rf magnetron discharge with an arc magnetic field have been simultaneously measured. The motion of the gas induced by electron and ion cyclotron currents has been numerically simulated using the Navier-Stokes equation. The experimental and numerical results confirm the mechanism of the orbital motion of dust particles in the magnetron discharge plasma that is associated with the orbital motion of the neutral gas accelerated by electron and ion drift flows in crossed electric and magnetic fields.

Effect of selective coagulation of the like charged particles in a dusty plasma trap

The phenomenon of selective coagulation of the like charged disperse particles in dusty plasma was theoretically predicted and experimentally revealed. The effect lies in sharp acceleration of coagulation processes after injection into a plasma trap particles which sizes appreciably exceed Debye length and the average size of the particles initially forming a dusty plasma cloud. The absorption process of the fine fraction by the larger particles takes place.

Application of dusty plasma for production of disperse composite materials

Objectives and achievements of the production of disperse composite materials (DCMs) which consist of particles with a metal coating are represented. The prospects of the DCM production by the dusty plasma method based on confining a cloud of micron-sized particles in a discharge plasma and on magnetron sputtering are shown. The method was tested in the preparation of catalyst materials, a superhard diamond polycrystalline material, and a polyquasicrystalline material with a low friction coefficient. The results of investigations of the structure and properties of powdered and sintered DCMs are presented.

Equirate magnetron sputtering of mosaic copper-graphite targets

Based on experimental data on sputtering of copper-graphite cathodes, we propose a mechanism of equirate sputtering of elements of mosaic targets prepared from materials the sputtering yields of which differ by almost an order of magnitude. The mechanism takes into account the occurrence of a height discontinuity between the mosaic elements at the initial stage of sputtering, the redistribution of ion fluxes between the elements, and the effects related to the mass transfer in plasma and the implantation of sputtered atoms into the mosaic elements of the different variety.

Dusty Plasma Technology of DCM with Nanostructure Surface Layer Production

The technique of disperse composite material (DCM) production was developed. The technique based on using special dusty plasma trap in RF plasma, in which fine particles levitate and are exposed by the atomic beam. The two types of covering were obtained: “cauliflower” or smooth, depending on process condition.

Structure and tribological properties of composite materials based on Al–Cu–Fe formed at high pressure

The use of high pressure (~8 GPa) in the formation of composite quasi-crystalline materials from powders made it possible to create practically poreless samples with a density close to the maximum known for this type of quasi-crystals. For samples with a nickel binder, sintered at a temperature of 550°C, a very low coefficient of friction was obtained, which retain its value during the testing.

Neutral gas rotation in magnetron discharge

We have experimentally established the existence and determined the velocity of motion of the neutral component of plasma in a planar magnetron discharge, which takes place in the direction of drift of the charged plasma component in crossed electric and magnetic (E × B) fields. For this purpose, we have studied the propagation of a small gaseous additive over the plasma ring of dc magnetron discharge in the diffusion regime. The obtained temporal dependences of the intensity of atomic emission spectra of the additive in various regions of the plasma ring are compared to the results of numerical solution of the diffusion equation for the experimental conditions studied.

Dusty Plasma Technology for the Quasicrystalline Composites Production

We used a dusty plasma technique to obtain Al‐Cu‐Fe quasicrystal powder particles coated by nickel. The samples of macro‐composites were obtained from the powders by cold pressing and following annealing in hydrogen. The structure of the samples and tribological properties were investigated.