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Vol 62, No 8 (2017)

Theoretical and Mathematical Physics

Unipolar model of negative corona discharge: Comparison of calculated and experimental I–V characteristics for the sphere–plane electrode system

Mel’nikova N.V., Samusenko A.V., Safronova I.F.

Abstract

Substantial computational resources and time are needed for computer simulation of the corona discharge with allowance for the sheath processes. This circumstance necessitates a search for and development of simplified models in which the processes in the sheath of corona discharge are reduced to the boundary condition at the surface of active electrode. A unipolar model that takes into account only one type of carriers is considered, and the boundary condition on the discharge electrode describes the rate of variations in the electron-flux density from the sheath. The calculated I–V characteristics are compared with experimental data for interelectrode distances ranging from several millimeters to several centimeters to reveal the applicability of the model. The simulated and experimental results are in good agreement at interelectrode distances of greater than 1 cm.

Technical Physics. 2017;62(8):1135-1138
pages 1135-1138 views

The formation of composite chaotic multiattractors containing inhomogeneities

Prokopenko V.G.

Abstract

Two methods for introducing inhomogeneities into composite chaotic multiattractors have been proposed. The first method makes it possible to change the mutual arrangement of multiattractor elements. The second method allows one to preset differences between chaotic attractors forming a multiattractor.

Technical Physics. 2017;62(8):1139-1147
pages 1139-1147 views

Recurrent procedure for constructing nonisotropic matrix elements of the collision integral of the nonlinear Boltzmann equation

Ender I.A., Bakaleinikov L.A., Flegontova E.Y., Gerasimenko A.B.

Abstract

We have proposed an algorithm for the sequential construction of nonisotropic matrix elements of the collision integral, which are required to solve the nonlinear Boltzmann equation using the moments method. The starting elements of the matrix are isotropic and assumed to be known. The algorithm can be used for an arbitrary law of interactions for any ratio of the masses of colliding particles.

Technical Physics. 2017;62(8):1148-1155
pages 1148-1155 views

Gases and Liquids

Effect of nonequilibrium near-electrode layers on the structure of EHD flows in the three-ions model of a dielectric liquid

Stishkov Y.K., Bogdanov D.V.

Abstract

An electrohydrodynamic (EHD) flow is a spontaneous flow of a liquid in the electrode gap under the action of a strong electric field. Most experimental data from an investigation of the velocity field of EHD flows were obtained in the wire-over-plane electrode configuration. For this system, the flow can be treated as a 2D flow. We report on the results of a computer simulation of the complete system of electrohydrodynamics equations in the three-ion model of a dielectric liquid. The structure of nonequilibrium dissociation–recombination layers and their effect on the structure of EHD flows have been analyzed based on the results of the computer simulation of EHD flows in liquids with different low-voltage conductivities for the wireover- plane electrode system.

Technical Physics. 2017;62(8):1156-1162
pages 1156-1162 views

On the stability of capillary waves on the surface of a space-charged dielectric liquid jet moving in a material medium

Shiryaeva S.O., Grigor’ev A.I., Mikheev G.E.

Abstract

We have derived and analyzed the dispersion equation for capillary waves with an arbitrary symmetry (with arbitrary azimuthal numbers) on the surface of a space-charged cylindrical jet of an ideal incompressible dielectric liquid moving relative to an ideal incompressible dielectric medium. It has been proved that the existence of a tangential jump of the velocity field on the jet surface leads to a periodic Kelvin–Helmholtz- type instability at the interface between the media and plays a destabilizing role. The wavenumber ranges of unstable waves and the instability increments depend on the squared velocity of the relative motion and increase with the velocity. With increasing volume charge density, the critical value of the velocity for the emergence of instability decreases. The reduction of the permittivity of the liquid in the jet or an increase in the permittivity of the medium narrows the regions of instability and leads to an increase in the increments. The wavenumber of the most unstable wave increases in accordance with a power law upon an increase in the volume charge density and velocity of the jet. The variations in the permittivities of the jet and the medium produce opposite effects on the wavenumber of the most unstable wave.

Technical Physics. 2017;62(8):1163-1170
pages 1163-1170 views

Air flow control around a cylindrical model induced by a rotating electric arc discharge in an external magnetic field. Part II

Munhoz D.S., Zavershinskii I.P., Klimov A.I., Kazanskii P.N., Molevich N.E., Moralev I.A., Polyakov L.B., Porfir’ev D.P., Sugak S.S., Tolkunov B.N.

Abstract

The effect of twisting a near-wall gas flow around a cylindrical model induced by a magnetoplasma actuator on the external subsonic flow around this model has been studied.

Technical Physics. 2017;62(8):1171-1176
pages 1171-1176 views

Plasma

Two-dimensional model of the Penning discharge in a cylindrical chamber with the axial magnetic field

Surzhikov S.T.

Abstract

The drift–diffusion model of a Penning discharge in molecular hydrogen under pressures of about 1 Torr with regard to the external electric circuit has been proposed. A two-dimensional axially symmetric discharge geometry with a cylindrical anode and flat cathodes perpendicular to the symmetry axis has been investigated. An external magnetic field of about 0.1 T is applied in the axial direction. Using the developed drift–diffusion model, the electrodynamic structure of a Penning discharge in the pressure range of 0.5–5 Torr at a current source voltage of 200–500 V is numerically simulated. The evolution of the discharge electrodynamic structure upon pressure variations in zero magnetic field (the classical glow discharge mode) and in the axial magnetic field (Penning discharge) has been studied using numerical experiments. The theoretical predictions of the existence of an averaged electron and ion motion in a Penning discharge both in the axial and radial directions and in the azimuthal direction have been confirmed by the calculations.

Technical Physics. 2017;62(8):1177-1188
pages 1177-1188 views

Solid State

Fine structure and mechanical properties of the shape-memory Ni50Ti32Hf18 alloy rapidly quenched by spinning

Kuranova N.N., Pushin A.V., Uksusnikov A.N., Belosludtseva E.S., Kourov N.I., Kuntsevich T.E., Pushin V.G.

Abstract

We have reported the results of investigations of the structure and chemical and phase compositions of the amorphous Ni50Ti32Hf18 alloy prepared by rapid quenching from melt by spinning and subjected to heat treatments. The specific features of the fine polycrystalline alloy structure formation depending on the heat-treatment mode have been studied by transmission and scanning electron microscopy, chemical microanalysis, electron diffraction, and X-ray diffraction analysis. According to the data on the temperature behavior of electrical resistivity, critical temperatures of devitrification and subsequent thermoelastic martensitic transformation B2 → B19′ have been determined. The mechanical properties in different heat-treatment modes have been investigated.

Technical Physics. 2017;62(8):1189-1193
pages 1189-1193 views

Dynamics of the nanosecond destruction of stressed granite during shock loading

Shcherbakov I.P., Vettegren V.I., Mamalimov R.I., Makhmudov K.F.

Abstract

The method of luminescence with a time resolution of 2 ns has been applied to studying the dynamics of the surface destruction of uniaxially compressed granite by a shock wave caused by electric discharge in air near its surface. The shock impact causes emission of jets of positively charged ions from the most strongly distorted regions on the sample surface. It has been discovered that, when the compressing stress reaches ~0.92–0.95 times the sample’s breaking stress, two maxima can be observed on the time dependence of the jet intensity. The first maximum corresponds to the shock wave reaching the sample surface and the second maximum corresponds to the crack destroying the sample.

Technical Physics. 2017;62(8):1194-1196
pages 1194-1196 views

Thermal mechanisms responsible for the irreversible degradation of superconductivity in commercial superconductors

Romanovskii V.R.

Abstract

Conditions for the irreversible propagation of thermal instabilities in commercial superconductors subjected to intense and soft cooling have been formulated. An analysis has been conducted using two types of the superconductor’s I–V characteristics, i.e., an ideal I–V characteristic, which assumes a step superconducting-to-normal transition, and a continuous I–V characteristic, which is described by a power law. The propagation rate of thermal instabilities along the superconducting composite has been determined. Calculations have been made for both subcritical and supercritical values of the current. It has been shown that they propagate along a commercial superconductor in the form of a switching wave. In rapidly cooled commercial superconductors, the steady-state rate of thermal instability propagation in the longitudinal direction can only be positive because there is no region of steady stabilization. It has been proved that, in the case of thermal instability irreversible propagation, the rise in the commercial superconductor temperature is similar to diffusion processes that occur in explosive chain reactions.

Technical Physics. 2017;62(8):1197-1206
pages 1197-1206 views

Spinodal decomposition of tungsten-containing phases in functional coatings obtained via high-energy implantation processes

Davydov S.V., Petrov E.V.

Abstract

We have studied structural and phase transformations in tungsten-containing functional coatings of carbon steels obtained during the high-energy processes of implanting tungsten carbide micropowders by the method of complex pulse electromechanical processing and micropowders of tungsten by technology of directed energy of explosion based on the effect of superdeep penetration of solid particles (Usherenko effect). It has been shown that, during thermomechanical action, intensive steel austenization occurs in the deformation zone with the dissolution of tungsten carbide powder, the carbidization of tungsten powder, and the subsequent formation of composite gradient structures as a result of the decay of supercooled austenite supersaturated by tungsten according to the diffusion mechanism and the mechanism of spinodal decomposition. Separate zones of tungsten-containing phases of the alloy are in the liquid-phase state, as well as undergo spinodal decomposition with the formation of highly disperse carbide phases of globular morphology.

Technical Physics. 2017;62(8):1207-1213
pages 1207-1213 views

Single-mode Nd:YAG laser with transverse diode pumping and multiloop self-pumped phase-conjugate cavity

Burkovskii G.V., Fedin A.V., Bol’shanin D.O., Pogoda A.P., Boreisho A.S.

Abstract

A high-power compact repetitively pulsed Nd:YAG laser with transverse diode pumping and multiloop self-pumped phase-conjugate cavity is proposed. Pulse trains with an energy of 1.5 J and beam quality parameter of M2 ≤ 1.2 are generated at a divergence of 0.4 mrad and luminance of 5 × 1014 W/(cm2 sr). The peak power of single-frequency pulses is greater than 15 MW at an energy of 170 mJ and a laser bandwidth of 300 MHz.

Technical Physics. 2017;62(8):1214-1217
pages 1214-1217 views

Landauer–Datta–Lundstrom model for terahertz transistor amplifier based on graphene

Davidovich M.V.

Abstract

A transistor has been considered in the form of three electrodes connected by graphene ribbons or by metal quantum wires (nanowires) that operate on the principle of the current control by the changing voltage at the central electrode (gate). The analysis has been carried out according to the Landauer–Datta–Lundstrom model in equilibrium approximation for electrodes while fixing their potentials. We have obtained linear models and nonlinear terms in the determining current, and calculated the nonlinear current–voltage performances of graphene nanoribbons.

Technical Physics. 2017;62(8):1218-1227
pages 1218-1227 views

Physics of Nanostructures

Kinetics and mechanisms of the UV-radiation-assisted formation of gold nanoparticles in HAuCl4-doped chitosan solutions

Gracheva T.A., Kuz’micheva T.A., Perevezentsev V.N., Smirnova L.A., Mochalova A.E., Salomatina E.B.

Abstract

Using methods of optical spectroscopy and small-angle X-ray scattering, the kinetics of the UV radiation-induced formation of gold nanoparticles in HAuCl4-doped water–acid solutions of chitosan has been studied from the very beginning of the reaction. It has been shown that, during synthesis, as the mean size of nanoparticles grows from 2.9 to 6.3 nm, the maximum of the plasmon resonance shifts toward shorter waves (535–523 nm), whereas for a fully formed ensemble of nanoparticles, the reverse trend is observed. It has been found experimentally that the particle size distribution curve changes during synthesis. Based on the inverse problem analysis, conclusions have been drawn regarding the dominant mechanisms behind nanoparticle growth.

Technical Physics. 2017;62(8):1228-1232
pages 1228-1232 views

Optics

Study of the distributed H-parameter of an anisotropic optical fiber in a multi-layer coil of a fiberoptic gyroscope

Mukhtubaev A.B., Aksarin S.M., Strigalev V.E., Novikov R.L.

Abstract

An investigation has been performed on the distributed H-parameter in an anisotropic optical fiber with an elliptical strained shell in a multilayer coil of a fiberoptic gyroscope. Each fiber length is ~50 m and there are five layers. Studies have been carried out using three variants of coils. In the first variant, the layers were permeated by epoxy; in the second coil, the layers were permeated with silicon-based material; and, in the third variant, the coils were wound up without impregnation (using dry winding). The different influence of compressive mechanical stresses on the distributed H-parameter of the studied fiber has been observed depending on the variant of coil impregnation.

Technical Physics. 2017;62(8):1233-1235
pages 1233-1235 views

Radiophysics

Theoretical analysis of wave dispersion in the slow-wave structure such as a coaxial ribbed line

Yelizarov A.A., Pchelnikov Y.N., Shaymardanov R.V.

Abstract

The wave dispersion in the slow-wave structure such as a coaxial ribbed line has been analyzed. For the case of the excitation of an axially symmetric wave in this structure, the generalized dispersion equation has been obtained using the method of sewing the conductivities. The particular cases of a solution of the dispersion equation have been analyzed, as well as its solutions for relatively high and low frequencies, since these cases are of practical interest. The parameters of a coaxial ribbed line have been simulated and the dependences of the slowing coefficient and the wave impedance of the structure on its geometrical dimensions have been obtained.

Technical Physics. 2017;62(8):1236-1241
pages 1236-1241 views

Amplification of short-wave radiation based on the resistive instability of a relativistic electron beam (Quasi-optical theory)

Ginzburg N.S., Malkin A.M., Zheleznov I.V., Sergeev A.S., Kocharovskaya E.R.

Abstract

The quasi-optical approach has been used to study the linear and nonlinear stages of instability of an electron beam propagating near a flat boundary of an absorbing medium with dissipative characteristics that can be described by the Leontovich impedance boundary conditions. It has been shown that resistive instability can be used to amplify radiation in the short-wave ranges, including the terahertz range. The instability increments and the efficiency of energy transfer have been determined.

Technical Physics. 2017;62(8):1242-1249
pages 1242-1249 views

Electrophysics, Electron and Ion Beams, Physics of Accelerators

Isotopic ratio of evaporated ions, critical ionization distances, and ionization regions in the process of the field evaporation of molybdenum at high temperatures

Golubev O.L., Blashenkov N.M.

Abstract

A magnetic mass spectrometer with a field ion source has been used to study the steady-state field evaporation of molybdenum at a temperature of 1000–2000 K. Ions of all seven molybdenum isotopes have been observed in the process of evaporation; only low-charge ions Mo+2 and Mo+ have been detected. The critical ionization distances and ionization regions for single- and double-charge Mo ions have been identified based on the measured ion energies and the experimentally determined intensity of the evaporation field. It has been demonstrated that ions are produced in the process of field evaporation of surface atoms at certain distances from the emitter surface in a very narrow spatial region.

Technical Physics. 2017;62(8):1250-1254
pages 1250-1254 views

Physical Electronics

Higher harmonics in the output spectrum of a generator with turbulent electron beam

Kalinin Y.A., Starodubov A.V., Fokin A.S.

Abstract

Formation of electron bunches in turbulent electron beams is numerically simulated and experimentally studied. A prototype of a laboratory generator is proposed, and control parameters (in particular, electron spread with respect to longitudinal velocities and additional deceleration of electron beam by electrostatic field of collector) that affect the characteristics of electron bunches and provide an increase in the number and amplitude of higher harmonics in the output spectrum are determined.

Technical Physics. 2017;62(8):1255-1258
pages 1255-1258 views

Biomedical Physics

Simulation of synaptic coupling of neuron-like generators via a memristive device

Gerasimova S.A., Mikhaylov A.N., Belov A.I., Korolev D.S., Gorshkov O.N., Kazantsev V.B.

Abstract

A physical model of synaptically coupled neuron-like generators interacting via a memristive device has been presented. The model simulates the synaptic transmission of pulsed signals between brain neurons. The action on the receiving generator has been performed via a memristive device that demonstrates adaptive behavior. It has been established that the proposed coupling channel provides the forced synchronization with the parameters depending on the memristive device sensitivity. Synchronization modes 1: 1 and 2: 1 have been experimentally observed.

Technical Physics. 2017;62(8):1259-1265
pages 1259-1265 views

Short Communications

Dynamics of a nanoparticle rotating in the near field of a heated solid surface

Dedkov G.V., Kyasov A.A.

Abstract

General expressions for the force of attraction to the surface and the projections of torque exerted on a particle rotating near a solid surface at an arbitrary orientation of the angular velocity vector have been found. It has been shown that the particle decelerates over time and the angular velocity vector tends to be oriented perpendicularly to the surface at any initial conditions.

Technical Physics. 2017;62(8):1266-1269
pages 1266-1269 views

The space charge layer of the electrical probe taking into account the collisions

Sysun V.I., Ignakhin V.S.

Abstract

The space charge layer of a cylindrical probe has been considered under moderate pressures. A precise solution of Poisson’s equation has been obtained in the approximation of strong field taking into account collisions with atoms. The approximate expression for a space charge layer in the cylindrical geometry without collisions has been suggested; the expression yields an error of up to 1% at 1 ≤ \(\frac{r_{sh}}{r_p}\) ≤ 200. A simplified approximate expression for a space charge layer under moderate pressures, which is suitable for practical calculations, has also been proposed.

Technical Physics. 2017;62(8):1270-1273
pages 1270-1273 views

Interactions between nanosecond laser radiation and a surface of single-crystal strontium titanate

Pozygun I.S., Seropyan G.M., Sultanov I.R., Sychev S.A., Teploukhov A.A.

Abstract

The formation of local structurally modified areas on the surface of single-crystal strontium titanate has been considered. To this end, the fields of elastic mechanical stresses have been produced by irradiating the surface by a focused nanosecond laser beam.

Technical Physics. 2017;62(8):1274-1276
pages 1274-1276 views

Nanocomposite polymer structures for optical sensors of hydrogen sulfide

Sergeev A.A., Mironenko A.Y., Nazirov A.E., Leonov A.A., Voznesenskii S.S.

Abstract

Composite coatings based on gold and silver nanoparticles reduced in situ in the film of chitosan polysaccharide are studied. In the presence of hydrogen sulfide, the maximum of plasmon resonance of the nanoparticles that is proportional to the analyte concentration decreases. The detection limits for hydrogen sulfide are 0.1 and 5 ppm for the chitosan/silver and chitosan/gold nanocomposites, respectively.

Technical Physics. 2017;62(8):1277-1280
pages 1277-1280 views

Spin-tunneling magnetoresistive elements based on multilayered nanostructures

Amelichev V.V., Belyakov P.A., Vasil’ev D.V., Zhukov D.A., Kazakov Y.V., Kostyuk D.V., Orlov E.P., Kasatkin S.I., Krikunov A.I.

Abstract

The results of studies of characteristics of spin-tunneling magnetoresistive (STMR) elements fabricated from multilayered nanostructures using a mask technique have been considered. The parameters of magnetic annealing of STMR elements have experimentally been obtained. The results of these experiments have shown that a magnitude of the magnetoresistive effect can increase by four to five or more times. The test samples of STMR elements, which have a magnitude of the giant magnetoresistive effect up to 50% and a resistance of 30–35 kΩ, have been studied in the absence of a magnetic field.

Technical Physics. 2017;62(8):1281-1283
pages 1281-1283 views

Determination of subpixel microdisplacements of speckle structure using the phase shift of spatial spectrum field

Maksimova L.A., Ryabukho P.V., Mysina N.Y., Ryabukho V.P.

Abstract

An experimental method for measurement of subpixel microdisplacements of speckle structure based on the parameters of the linear phase shift in the field of the complex spatial spectrum of the displaced structure is proposed and experimentally implemented. The phase shift is determined when a phase shift of spectrum is numerically added and the correlation analysis of the resulting linear phase shift in the spatial spectrum of specklegrams is performed. The method provides additional possibilities in the measurements using digital speckle photography when the period of interference fringes formed in the total spatial spectrum of specklegrams is significantly greater than the spectral width.

Technical Physics. 2017;62(8):1284-1287
pages 1284-1287 views

Influence of a low-temperature GaN cap layer on the electron concentration in AlGaN/GaN heterostructure

Andreev A.A., Vavilova E.A., Ezubchenko I.S., Zanaveskin M.L., Maiboroda I.O.

Abstract

The influence of low-temperature passivating GaN cap layers on the electrophysical parameters of a 2D electron gas (2DEG) in heterostructure high-electron mobility transistors has been studied. It has been found that thin GaN layers deposited in situ at 550°C do not exhibit polar properties and do not change the carrier concentration in the 2DEG. However, GaN layers deposited at 830°C decrease the carrier concentration in the 2DEG, which is in agreement with theoretical calculations. Using the reflected high-energy electron diffraction technique, it has been established that this effect may be associated with different structures and morphologies of GaN layers deposited at different temperatures.

Technical Physics. 2017;62(8):1288-1291
pages 1288-1291 views