Vol 63, No 11 (2018)

Within the framework of nonrelativistic electrodynamics, general formulas have been obtained for the tangential dissipative force of electrostatic friction and the normal attraction force of an axially symmetric probe moving parallel to a smooth surface of homogeneous substrates or substrates coated with thin films upon various combinations of materials. As a numerical example, the interaction of a metal sphere moving above a metal surface has been studied. The calculation results are compared with the available experimental and theoretical results of other authors.

Nonstationary perturbation theory is used to study generation of quantum vortices resulting from ionization of hydrogen-like atom by an ultrashort pulse of classical electromagnetic field. It is shown that the vortices are determined by quantum interference effects.

Kinetics of water droplets on the surface of shielded metal electrodes is studied in the presence of external electric field. It is shown that the difference of contact angles of droplet fragments on the control electrodes plays the key role in motion. It is also shown that a droplet always moves toward the negative electrode regardless of the polarity of control electrodes and grounding for the dielectric system under study. The theoretical analysis of the results is based on the Lippmann equation written for a polarized droplet that is localized on control electrodes shielded with a multilayer insulator.

An experimental study was conducted on the interaction of a carbon dioxide axisymmetric jet with a stationary and rotating gas-permeable barrier. Flow patterns and spatial distributions of CO₂ concentrations are described depending on experimental conditions. The possibility of using obtained results for setting up various physico-chemical processes is considered.

The conversion of hydrocarbons during the treatment of a methane–ethane mixture with a barrier discharge in an electrophysical setup was experimentally studied. The theoretical estimation of plasmakinetic processes occurring in a discharge was performed for the developed plasmachemical reactor using the ZDPlasKin algorithm. Experimental results were in agreement with theoretical estimates.

A method of centrifugal casting of aluminum composites in a mixture with Al₂O₃ and C is proposed and proved by experiments. It is shown that there is a possibility of constructing gradients of admixtures, that is, of hardening the surface layer. It is specified how the concentration gradients are formed: the first technique is use of buoyance force and the second technique is redistribution of nuclei by size when they are exposed to rotation.

The experimental results of electrical and thermal characteristics of circuit boards based on aluminum with a nanostructured layer of anodic aluminum oxide and copper conductors for assembling high-power field-effect transistors have been considered. It has been shown that the presence of a thin dielectric layer and thick aluminum base with high thermal conductivity provides a uniform distribution of heat generated by the active element over the entire volume of the board without formation of local regions with increased temperature. The experimental results have shown that the temperature gradient between the heat source and anodic aluminum oxide surface is about 17–18°C at a surface heat power of 4.4 W/cm².

Nanometer Ce_0.8(Sm_0.75Sr_0.20Ba_0.05)_0.2O_{2 – δ} powder with mean nanoparticle size of 15 nm has been obtained by laser evaporation of a solid-phase target followed by condensation. The nanopowder has been used to prepare suspensions for electrophoretic deposition in a mixed isopropanol : acetyl acetone = 50 : 50 vol % disperse medium offering the unique property of self-stabilization. Optimal conditions for electrophoretic deposition have been found, and uniform thin-film electrolytic coatings have been formed on a La₂NiO₄ cathodic carrier substrate (12–15% porosity). It has been shown that the resulting electrolyte offers a high adhesivity and has, after sintering at 1400°C, a compact granular structure with grains from 1 to 8 μm in size. The conductivity of the 2-μm-thick electrolyte equals 0.1 S/cm at 650°C.

Fixtures that ensure high accuracy and repeatability of installation of optical elements on an optical bench, were proposed by Kelvin and Maxwell in order to solve problems of experimental physics. These surprisingly simple devices were known as kinematic couplings in English-language literature and have been used for many years in various scientific and applied researches. Based on the idea behind these devices, we consider the possibility of developing mechanical self-setting locks for assembly and automatic deployment of solid multi-mirror reflectors of space telescopes. The results of kinematic analysis and physical simulation of the proposed devices are presented.

An electrostatic prism is an electron- and ion-optical device that transforms a parallel input beam of charged particles into a parallel output beam that is deflected by an angle dependent on the energy of a charged particle beam. The principle of similarity of trajectories for electric fields that are homogeneous in Euler terms provides perfect optical properties of electrostatic prisms when the fields with zero power of homogeneity are used. It is shown that the Donkin formula for 3D homogeneous harmonic functions makes it possible to employ analytical expressions using homogeneous electric potentials of a zero power. A few examples of electrostatic prisms are calculated using the Donkin formula.

The simulation results of elastic strain of an aligned carbon nanotube under the influence of a local external electric field are reported. A method for inducing controllable nonuniform elastic strain in a vertically aligned carbon nanotube, which is a prerequisite for a reproducible memristive effect in such nanotubes, is developed. The passage of current through elastically strained carbon nanotubes with aspect ratios from 20 to 30 is examined experimentally. It is demonstrated that the resistance of a nanotube with its relative strain changing from 0.02% to 0.07% increases by a factor of 5.2 in the high-resistance state due to an increase in the strength of the internal electric field, thus resulting in a stronger memristive effect.

The evolution of fractal nanoparticles of medium size and concentration, which are formed and dynamically change during hydrolytic polycondensation, has been investigated using IR spectroscopy. It is shown that the application of the Smoluchowski rapid coagulation model combined with analysis of the characteristic absorption line intensity in the IR spectra provides a satisfactory estimate of evolution processes occurring in sols of orthosilisic acid. The obtained spectroscopic dependences are compared qualitatively with atomic force microscopy data.

The possibility of using neutron diffraction in quantitative analysis of residual austenite in steels is investigated. According to the obtained results, some properties of neutron diffraction by two-phase structures remain size-independent, which makes it possible to use large composite standards. It is shown that this approach ensures admissible accuracy without using a priori coefficients.