Vol 62, No 7 (2017)

An electrostatic problem has been solved for a dielectric inclusion that consists of an anisotropic core and an anisotropic shell. The inclusion is immersed in a uniform isotropic medium (matrix) subjected to a uniform electric field. It is assumed that the outer boundaries of the core and shell are ellipsoidal and become confocal after a linear nonorthogonal transformation that removes the anisotropy of the dielectric properties of the shell. Analytical expressions have been derived for the potential and strength of the electric field in the matrix and also in the shell and core of the inclusion, and an expression for the polarizability tensor of the inclusion has been deduced. It has been shown that the results agree with the well-known solutions in partial (limiting) cases.

It has been shown that, in the article by G. B. Malykin and V. I. Pozdnyakova “On the Velocity of a Light Spot Moving over a Cylindrical Screen” [Tech. Phys. 52, 133 (2007)], errors were made in the calculation of the velocity of a light spot moving over a cylindrical screen. As a result, incorrect formulas were obtained to calculate the velocity of the light spot as applied to classical mechanics and the Tangherlini transformation. Correct formulas for calculating the velocity of a light spot moving over a cylindrical in classical mechanics and in the Tangherlini transformation are proposed.

The time of extraction of negative ions from the ionization chamber of a static mass spectrometer has been measured as a value that significantly exceeds the time of their free exit from the chamber. It has been established that anomalously long ion extraction time is due to their adsorption on the ionization-chamber walls; as a result, their arrival at the analyzer tube is delayed. It has been shown that negative ions, which were initially generated as noninfinitely long-lived ones with respect to auto splitting off of an additional electron, are stabilized to everlasting ions due to adsorption, and the subsequent contribution from infinitely long-lived ions to the total ion flux reaching the recording system distorts the results of measuring the ion lifetime. It has been shown that some of the adsorbed ions are annihilated because of neutralization due to the additional electron tunneling to the surface. The probability of tunneling increases with an increase in temperature; thus, the temperature dependence of the ion lifetime is also distorted.

A numerical experiment on the simulation of the two-phase flow formed during spraying of a liquid by a nozzle has been described. The radial and axial velocity profiles of the droplets and gas in the free spray and in the two-phase flow through a cylindrical apparatus have been calculated and represented taking into account the early drag crisis of droplets and peculiarities of turbulent friction in the gas, which was detected in previous experiments. The distinguishing feature of the numerical model of the two-phase flow is that it employs the differential equations describing the nonstationary flow of a compressible gas as the initial equations. In transition to their difference analog, the familiar Lax–Wendorff algorithm has been used. A comparison of the results of calculations based on this model with experimental data has demonstrated their concordance.

The destruction of homogeneous and composite barriers with metal-ceramic intermediate layers that interact with WNiFe-90 alloy impactors has been investigated. A comparison of the results for different types of barriers was provided based on the weight equivalence, i.e., the equality of weight per unit barrier area along the thickness. The initial impact velocity was in the range of 0.8–1.1 km/s. The registration of the process from the moment of strike of impactor to the formation of the developed fragmentation flow behind the barrier was carried out by a high-speed video camera. The displacement–time dependences for the characteristic planes of the target configuration, i.e., the rear end of the impactor and the rear surface of the barrier were plotted by processing video film. An analysis of these dependences allowed us to identify the features of barrier destruction. The strong difference in the geometry of the zones of destruction and the dynamics of the process for monolithic and composite barriers has been noted.

A comparative examination of the critical energy density of explosive decomposition of pentaerythritol tetranitrate exposed either to an electron beam of a GIN-600 accelerator (240 keV, 20 ns) with an explosive emission cathode or to this beam combined with metal low-temperature diode plasma has been performed. It has been demonstrated that the contribution of plasma to the development of explosive decomposition is appreciable at explosion probabilities P ≤ 0.2. At higher energy densities and explosion probabilities P ≥ 0.5, the contribution of plasma to the overall beam energy density did not exceed 10%.

The composition and structure of Si layers implanted into titanium nickelide single crystals with different orientations relative to the ion beam propagation direction have been studied using Auger electron spectroscopy and transmission electron microscopy. The role of the “soft” [111]_B2 and “hard” [001]_B2 NiTi orientations in the formation of the structure of ion-modified surface layer, as well as the defect structure of the surface layers of the single crystals, has been revealed. Orientation effects of selective sputtering and channeling of ions, which control the composition and thickness of the oxide and amorphous layers being formed, ion and impurity penetration depth, as well as the concentration profile of the Ni distribution over the surface, have been detected.

The mathematical model of a high-speed collision between bodies with arbitrary elongation and massive metallic obstacles has been suggested. The model is based on the energy balance and stage-by-stage scheme of formation of a crater. The collision process has been considered to be the quasi-stationary penetration of the deformed impactor and inertial deepening of a crater at the final step. A comparison of the calculations with the results of numerical simulations and physical experiment has shown satisfactory agreement.

The instability of the electrical properties of lithium niobate single crystals of congruent composition subjected to reducing thermochemical treatment has been investigated by impedance spectroscopy. It has been shown that the subsequent heating of the reduced lithium niobate samples in dry air up to 380 K or higher is accompanied by the progressive increase in their electric resistance, which is due to the oxidization of the crystal surface layers.

A simple comprehensible method for producing graphite and alumina films has been suggested. The optical properties of a graphite suspension in toluene and a suspension of natural clay with a high content of alumina particles in water have been studied. It has been found that the optical density of the suspensions varies from layer to layer, and the lowest optical density has been observed in upper layers. Graphite and aluminum films have been prepared by taking samples from different depths. The microstructure of the films has been examined. It has turned out that alumina particles coalesce into regularly shaped objects in the form of snowflakes. In addition, alumina films obtained from samples taken from different depths of the suspension have different thicknesses. In thin and thick films, the particle size is 0.29 and 2.81 μm or more, respectively.

The temperature dependences of the dc conductivity and thermoelectric coefficient of TlGdS₂ in the temperature interval of 77–373 K have been studied for the first time. It has been found that, at low temperatures (114–250 K), the compound has conductivity of the p-type and charge transfer in its energy gap follows the hopping mechanism. The main parameters of localized electronic states in the energy gap have been determined.

The influence of the annealing temperature from the interval between the solidus and liquidus temperatures of Bi₉₂Sb₈ solid solution on its structure and galvanomagnetic and thermoelectric properties has been studied. It has been shown that films of bismuth–antimony solid solution grown by thermal evaporation in a vacuum will have a large-grained structure after annealing at temperatures higher than the solidus temperature of the solid solution. It has been found that these films offer the lowest resistivity, the highest relative magnetoresistance, and the highest mobility of charge carriers. As the annealing temperature approaches the liquidus temperature, the probability that a dendritic structure will form and antimony-enriched regions will appear grows. This causes an increase in the charge carrier concentration and a decrease in the resistivity with a decrease in the relative magnetoresistance and charge carrier mobility.

Triple Bragg diffraction in a paratellurite crystal has been considered for the case when the plane of diffraction is oblique to the optical axis of the crystal. It has been shown that effective photoelastic constants for isotropic and anisotropic diffraction depend on the inclination of the plane of diffraction insignificantly. Triple Bragg diffraction of 0.63-μm coherent radiation in paratellurite at a 47.3-MHz slow acoustic wave has been experimentally demonstrated. For an optical power of 0.69 W delivered to a piezoconverter, the relative intensities of diffraction orders equal ~0.4, 0.4, 0.1, and 0.1, respectively.

A method that enables the online processing of the experimental field emission data for the large-area emitters has been developed. This is based on an analysis of the SK diagram of volt-ampere characteristics and the plotting of a calibration grid for the efficient microscopic parameters, such as the work function, the area of emission and the coefficient of the amplification field. The application of this technique has enabled us to elucidate the behavior of a graphene-based nanocomposite emitter while changing the voltage. The noise characteristics, as well as their correlation with adsorption and desorption processes, have also been analyzed.

A new gas-inlet system in the gas-discharge chamber of an ion source has been developed that makes it possible to adjust the arc discharge burning mode and the parameters of the plasma ion emitter. The measurements of the main electrotechnical parameters of the ion source and signals of secondary-emission probes have been performed. Based on the obtained data, the profile of power distribution in a beam has been restored. The optimum form of the control signal for the gas inlet valve of the atom injector of the spherical Globus-M tokamak has been selected.

Relatively simple probe and optical experiments were performed, confirming the presence of two main scenarios for the formation of the longitudinal characteristics of a short (without positive column) glow discharge. 1. At low pressures, when there is a single point of sign reverse of the electric field at the maximum of the plasma density, the anode fall is negative and the magnitude of the anode fall is small, there is no ionization and the anode area is dark. 2. Upon an increase in pressure, two points of field reversal are to be expected, the sign of the anode fall is positive and the anode fall of potential is comparable to the gas ionization potential; therefore, the intensive ionization directly at the anode, which glows brightly, takes place.

Based on modern advances in electronics and optoelectronics, experimental and theoretical works on verifying the quantum-optical model of a living neuron have been outlined for the purpose of designing a quantum neuristor, which is a new element of neural network informatics.