Том 43, № 2 (2017)

Using the methods of numerical integration, a temperature field has been calculated that arose in the surface layer of titanium nickelide target with NiTi₂ intermetallic inclusions during irradiation by a lowenergy high-current electron beam with a duration of the order of a microsecond. The calculated temperature field has been compared with that obtained previously for a target of stainless steel 316L containing MnS inclusions. It has been found that, as in the case of stainless steel, the regions of inclusions are overheated. However, the temperature increase for NiTi₂ (12 K) is significantly lower than in the case of stainless steel 316L (283 K). The dynamics of melting of these systems are also considerably different.

A method for determination of the contact-area functions for diamond indenters of nanohardness testers using a metrological atomic-force microscope with three-coordinate laser interferometer is proposed. Face shapes of a number of indenters of Berkovich pyramid type are measured. The precision of the indenter surface coordinates measurement is 1 nm. It is demonstrated that the indenter tip shape changes in the course of its use; in particular, for the first 100 nm the deviation from the ideal pyramid can exceed 30 nm. Thus, one of the methods for verification of the contact-area function for an indenter is its periodic calibration using a metrological atomic-force microscope.

An electric field with potentials that is homogeneous in Euler terms satisfies the principle of similarity of trajectories that was derived by Yu.K. Golikov. Such fields are a useful tool for the development of electron and ion optical systems with unique properties. In this paper, the principle of similarity of trajectories is generalized to the case of a magnetic field and a combined electric and magnetic field that are homogeneous in Euler terms.

The possibility of generating random noiselike radiation in gyro-amplifiers with a helical corrugated waveguide when introducing delayed feedback has been shown. The cyclotron resonance detuning corresponding to the maximum slope of the amplitude characteristic of an amplifier after saturation is optimal for implementing the mode of developed dynamic chaos. Assessments are carried out for the parameters of a noise generator based on an experimentally implemented gyro-travelling-wave tube of 35-GHz band, according to which the generation of multifrequency radiation is possible with a spectrum width of 3—4 GHz, an average power up to 70 kW, and an efficiency of order of 10%.

The stationary Penning discharge has been numerically simulated using the diffusion–drift model in the pressure range p = 0.5–5 Torr at emf E of 100 and 200 V. The two-dimensional electrodynamic-discharge structure has been investigated in the calculation region between a cylindrical anode and two flat disk cathodes. Configurations of the discharge plasma and averaged azimuthal motion rates of electrons and ions have been obtained. The evolution of the plasma configuration at a change in pressure, emf, and magneticfield induction is discussed.

The influence of specific features of the band structure of graphenes on the energy storage in supercapacitors is considered. The mechanism of enhancement of the energy-storage density in such materials relative to that in three-dimensional materials is predicted.

We have experimentally studied the excitation of wake fields in a dielectric structure by a train of relativistic electron bunches and the acceleration of subsequent bunches of the same train due to detuning of the bunch repetition frequency relative to that of the wake field excited in the dielectric structure at the Cherenkov resonance. Electron bunches of the first (leading) part of the train excite the wake wave, and bunches of the second (trailing) part of this train are shifted to the accelerating phase of the wake wave so as to gain additional energy. The possibility of controlling the number (repetition frequency) of bunches exciting the wake field in the dielectric structure and the number of subsequently accelerated bunches has been investigated by changing the value of detuning.

We have studied the activation of magnesium hydride decomposition by means of its pressing with a catalyst. It is established that pressing leads to the formation of metal nuclei, which favor a decrease in the temperature threshold of magnesium hydride decomposition. The introduction of catalytic additives also reduces the temperature of dehydrogenation. The most effective in this respect was found to be the addition of nickel powder.

The initiation of discharge by model hydrometeors between an artificial-thunderstorm cell (aerosol cloud) of negative or positive polarity and ground has been experimentally studied. It is established for the first time that the conditions of cloud–ground spark discharge initiation by hydrometeors, as well as the characteristics of discharge significantly depend on the polarity of charged cloud. The effect of hydrometeor arrays can be manifested by the cloud–ground lightning initiated in a thundercloud and used for developing scientific principles of artificial lightning discharge.

The electric conductivity of individual multiwalled carbon nanotubes (CNTs) doped with nitrogen has been studied in as-synthesized, heat-treated, and argon-ion-irradiated states by the method of electrostatic force microscopy (EFM). Modelling of transverse cross-section profiles of EFM images were used to determine the potential difference across the probe tip–CNT gap (U_tip-CNT), which is a parameter related to the conductivity of CNTs. A strong correlation between the specific volume conductivity of a CNT layer and average U_tip-CNT value has been found for all types of samples. It is established that a change in the conductivity of N-doped CNTs upon thermal annealing and argon-ion irradiation is caused by modification of the composition and/or concentration of defects in CNT walls.

The structure of GaP films grown by molecular-beam epitaxy on vicinal Si(1113) substrates has been studied by X-ray diffraction. It is established that the crystalline lattice of a pseudomorphic film rotates about the <110> axis toward increasing deviation from the singular orientation, while the subsequent relaxation leads to rotation in the opposite direction. This is valid for the films of both (001) and (001̄) polarities. Differences between the surface morphologies of relaxed and pseudomorphic GaP films are revealed.

We have studied the structure of flow formed in the boundary layer at the lateral edge of the discharge zone of a dielectric barrier discharge plasma actuator. It is established that a region with nonzero component of tangential velocity exists near the plasma layer boundary. At some distance downstream of the actuator, a concentrated vortex is formed with the axis aligned with the flow direction. In the presence of two closely spaced boundaries of the plasma region, a pair of counter-rotating vortices is formed. Separate microdischarges in the plasma layer also appear to be a source of similar longitudinal vortices with smaller amplitude.

We propose a new method for the formation of zinc nanosystems by condensation of a weakly supersaturated Zn vapor in pores of the anodic-oxidized aluminum membrane (AOA)–silicon substrate system. For this purpose, a weak Zn vapor flow is created by magnetron sputtering of Zn target in a high-purity inert gas atmosphere and maintaining a temperature of the porous AOA membrane outer surface higher than that of the substrate. This drives a directional Zn vapor flow inward membrane parallel to the pore generatrix and favors effective penetration of Zn vapor into the membrane.