Vol 82, No 11 (2019)

A comparative study of ZrSiB coatings obtained by magnetron sputtering with the use of cathodes of different phase composition is carried out. The optimal compositions from the point of view of maximum heat resistance are revealed.

Metallographic studies of hardened zones of steel 40Kh were carried out. Regression equations were obtained and the surface depth and width of the hardened zones as functions of the beam scanning speed and radiation power at different beam defocusing were plotted with the help of a full factorial experiment. Comparative wear tests showed that, with increasing hardening area to 100% of the friction surface, the wear resistance increases by a factor of 4.47 as compared to normalized steel.

Experiments are carried out on a simulation stand with a plasma-beam facility in order to study the formation of “fuzz” on the initial and pre-nitrided tungsten surface. The parameters of the experiments of the nitriding and formation of the tungsten “fuzz” are given. The results of materials science study are shown. The characteristics of the tungsten “fuzz” on the nitrided and non-nitrided tungsten surfaces are determined and the results obtained are analyzed.

A numerical model of trapping of the radiation-induced charge in the bulk and on the surface of the oxide layer of a MOS transistor has been developed. The model takes into account the generation of point defects under fast neutron irradiation. The volume and surface charges obtained by the numerical modeling have been used to calculate the drain—gate characteristic of the MOS transistor exposed to neutron irradiation in different doses and accompanying high-energy gamma-ray irradiation. To model the effect of neutron irradiation, different methods for estimating the rate of point defect generation in a two-component material (SiO₂) have been developed. The simulated drain—gate characteristic is shown to agree well with the experimental data obtained at the concentration of hole traps and their capture cross sections lying within the published data for an unirradiated device after exposure to gamma rays from a ⁶⁰Co gamma source and after irradiation with fast neutrons with an average energy of ∼1 MeV and accompanying gamma rays using a pool-type reactor.

Analytical expressions and a numerical method for calculation of distribution functions of hard spheres g_ij(r) based on inverting the Laplace transform for functions rg_ij(r) obtained from the Percus—Yevick equation are obtained. The method for calculation of radial distribution functions is applicable for any distances between hard spheres; it is verified by comparison of numerical results and Monte Carlo simulations. The application of the developed method for calculation of the radial distribution functions of metal atoms is demonstrated. Distribution functions are required to construct a universal theoretical model of equation of state capable of describing both dense multicomponent gas and condensed substances (liquid or solid phases) with high accuracy which is substantially faster than computer experiments (Monte Carlo and molecular dynamics methods).

The paper presents simulation of shock-wave compression of liquid helium. Considering the possible ionization at high compression rates is shown to increase the accuracy of prediction of the helium properties.

In the paper, the problem of magnetic drag and origination of energy losses in noncontact bearings based on high-temperature superconducting tapes is considered. The model configurations of bearings in which a superconducting tape is a stator and a set of permanent magnets is a rotor are investigated. It is shown that the magnetic friction can be neglected in the case where more than eight permanent magnets compose the rotor. This result indicates the possibility to create scaled magnetic bearings for the systems of long-term energy storage, for example, flywheel energy storage systems.

This paper presents the results of studying the nonequilibrium processes in second generation HTS tapes under the action of pulsed current loads. In the study, we used short current pulses of various amplitudes from 0.9 to 5 values of the superconductor critical current. The minimum rise time of the current was 8 µs, and the pulse duration was from 1 to 250 µs. Comparisons in the behavior of samples under long current pulses with current rise time more than 3 ms were carried out. A qualitative difference in the formation of an nonequilibrium state during short and long current pulses was found. A stable current flow with amplitudes up to 4 times larger than the critical current was obtained without degradation of the superconductor. Experimental results were analyzed on the basis of the dynamic resistance model in the flux flow regime.

To realize the simulation experiments with the use of two ion beams at the injection complex of the BELA accelerator (Based on ECR ion source Linear Accelerator), it is necessary to determine the energy and irradiation angle of the beam of light ions which will be implanted into the region of radiation damage induced by heavy-ion beam. The depth of light-ion implantation is determined by the energy and kind of particles initiating the damage, as well as by their incidence angle. It is supposed that the incidence direction of heavy ions will coincide with the normal to the specimen surface. In our work, the necessary implantation zone for the iron ion beam with an energy of 3.2 MeV is located at depths of 300–800 nm. The simulation of the hydrogen and helium ion paths in the material of the iron target in the energy range from 150 to 600 keV at the angle to the normal from 0° to 65° is performed. The range of energies and irradiation angles for the hydrogen and helium ions are determined for the implantation into the radiation-induced defect-formation zone.

Longitudinal beam dynamics is investigated in a traveling-wave field with variable synchronous phase assumed to be a control function. The dynamic controlled process is considered to be a complex of synchronous particle motion and the motions of particles of a beam. In generalization, the model is represented by a system of integro-differential equations. The problem of joint optimization of program motion and the ensemble of perturbed motions is formulated. Numerical simulation of beam dynamics is performed; the example of optimization is considered.

It is well known today that a continuous stream of highly ionized plasma is emitted from the Sun’s surface. This plasma is called the solar wind and consists of protons, electrons, and light nuclei. The solar wind pushes the solar magnetic field into interplanetary space to form the interplanetary magnetic field. The interplanetary magnetic field is a dynamical system that depends on the solar cycle and the Sun’s rotation phase. Thus, the Solar System is a natural plasma physics laboratory with an enormous multitude of different effects showing the current state of the system. By recording cosmic-ray fluxes, one can study the behavior of the interplanetary magnetic field and obtain information about processes that occur both on the Sun’s surface and throughout the Solar System. The main short-time variations in cosmic-ray intensity include the 27-day variations and the Forbush decreases. These variations are caused by complex solar plasma structures, which are generated by different processes on the Sun’s surface and propagate through space in a wide range of velocities. Cosmic-ray fluxes recorded with the PAMELA magnetic spectrometer on board the Resurs DK1 satellite in 2006–2016 are used to show some examples of cosmic-ray variations.

An approach is proposed for determining the flexoelectric coefficient for polar liquids based on the results of an investigation of the polarization of dielectrics induced by an electric field and a shock wave. It is shown that the initial shock-induced polarization and the flexoelectric effect may be considered equivalent concepts linking the orientational polarization with the pressure gradient. The results of testing the approach on the experimental data for water and nitrobenzene give reason to believe that it can be used in estimating the polarization in inhomogeneous pressure fields.

The electron-optical characteristics of transparent aluminum-magnesium spinel ceramics doped with various copper fluences are studied. As a result of the ion-beam modification, the formation of new optically active centers, caused by intrinsic defects of the matrix and impurity copper ions, occurs. At implantation doses of 1 × 10¹⁷ cm⁻², metallic copper nanoparticles are formed in the matrix, which are characterized by the absorption of electromagnetic radiation with an energy of 2 eV due to the effect of plasmon resonance.

The effect of irradiation with soft X-rays produced by a laser plasma source equipped with an X-ray concentrator on the properties of the CdHgTe semiconductor are investigated. For this purpose, the mass concentration of atoms in the near-surface layer of the material is measured. It is demonstrated that the action of soft X-ray radiation leads to change in the solid-solution composition at the surface via a nonthermal mechanism and generates surface defects.

The results of research on determining the volume particle-size distributions for a two-component polydisperse system of silica-sol solution by combining the quasi-Newton gradient minimization and the simulated annealing methods are presented. These data are compared with the results obtained earlier using both of these methods separately. It is shown that combination of these methods allows one to expand the intervals of convergence to a stable solution significantly and thus improve the efficiency of reconstruction of the particle-size distributions from small-angle X-ray scattering data.