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Electron beam annealing of a thin film of amorphous silicon suboxide with a stoichiometric coefficient of 0.5 was carried out in a vacuum chamber. The exposure time was 10~min at an accelerating electron beam voltage of 1000 V and a current strength of 75 mA. Using probe measurements and calculations, the transverse distribution of the current density in the electron beam was obtained, which was in good agreement with normal distribution. The current density on the beam axis was 0.8 mA/mm². It was found that the electron beam annealing of the thin film of amorphous suboxide silicon led to the formation of crystalline silicon nanoparticles with a size of (4.1±0.1) nm. The crystallite sizes do not depend on the electron beam current density, in contrast to the degree of crystallinity, which decreases from 40% on the beam axis to zero (amorphous structure) on the periphery. It is assumed that in the process of formation nanocrystalline silicon, a liquid phase is formed.

This paper presents a brief overview of experimental studies carried out at the Institute of Thermophysics of the Siberian Branch of the Russian Academy of Sciences, to investigate the gas dynamics of low-density supersonic jets, including the creation of a vacuum gas-dynamic complex, the development of electron beam and laser methods diagnostics, studies of the influence of viscosity and nonequilibrium effects on the region of free supersonic expansion and the shock-wave structure of underexpanded jets. Problems are considered, and examples of using vacuum stands to model the power, thermal, and polluting effects of full-scale jets of orientation engines on the structural elements of spacecraft and orbital stations are presented.

Specific features of gas flows exhausting from supersonic nozzles to a submerged space under conditions of clusterization are considered. Radiation of particles in the flow is initiated by a well-focused high-voltage electron beam. Radiation is measured by a high-resolution camera and a spectrometer with a wide range of wavelengths. For characteristic sizes of jets of condensing gases in the entire range of examined stagnation pressures and background ambient space, it is possible to use the same dependence on the parameters as that in the case with a correction factor for taking into account the influence of condensation, which, in turn, depends on the cluster size. The form of the correction factor is presented. The dependence of the previously detected process of formation of a secondary external jet in flows of easily condensing gases (“cluster wake”) is studied. The reasons and conditions for the emergence of this effect are considered. The processes of formation of the traditional spindle-shaped jet and the new secondary jet are compared. The results of measurements of the diameters of the traditional and secondary jets in the maximum cross sections by means of photometry in various exhaust regimes are reported. The reasons for the differences in formation of the traditional and secondary jets under conditions of developed condensation of particles are considered. The “cluster wake” is found to affect the process of gas penetration from the ambient space to the supersonic flow. Specific features of radiation of the particles of the “cluster wake” are considered, and the time of existence of radiation in the excited state is estimated.

Supersonic gas flow from an annular nozzle into a low-pressure chamber is studied numerically using kinetic and continuum approaches. Such flows are used in gas-jet plasmachemical technologies based on the use of an electron beam passing through an axial channel. The study is performed by the direct simulation Monte Carlo (DSMC) method and by solving continuum equations using ANSYS Fluent software. It is shown that the solutions obtained are in good agreement with each other even in low-density regions of the electron beam channel. This leads to the conclusion that ANSYS Fluent software is suitable for simulating flows of this type.

Wettability of textured surfaces of copper and carbon substrates is under study. It is revealed that the geometric parameters of the textures being created (e.g., depth and regularity) significantly affect the surface lyophilicity and the manner in which a water droplet spreads and moves. The contact angles obtained experimentally are consistent with the angles obtained via molecular dynamics simulations.

Dimensionless parameters and similarity laws that describe the geometric dimensions of a cermet weld bead formed during direct metal deposition are determined. A VT-6 titanium alloy and ceramics (silicon carbide, SiC) with different volume fractions are used as a powder mixture. A model for estimating the thermophysical parameters of a heterogeneous material is proposed. It is shown that, regardless of the volume fraction of ceramics, the dimensionless geometric parameters of a single track (depth, width, and height) depend on two dimensionless parameters: normalized enthalpy and the Peclet number. Also, these dependences can be approximated by algebraic expressions.

Results of a numerical simulation of an unsteady flow in an axisymmetric intake with internal compression tested in a hotshot wind tunnel with a fixed-volume settling chamber are discussed. The present simulations reveal the main features of various modes: unsteady processes of wind tunnel and intake starting, quasi-steady flow over the started intake with a supersonic flow velocity in the intake duct, and subsequent ulterior transition to the flow with a detached bow shock wave in front of the air intake with a subsonic flow velocity in the duct. A previously unknown mode of the flow over the intake with pulsing motion of the bow shock wave is observed. It is shown that pulsations decay with time, and the bow shock wave position in the incoming flow becomes stabilized at a certain distance from the leading edge of the intake with the test flow in the wind tunnel being preserved.

The problem of instantaneous injection or withdrawal of Newtonian fluid through an injection or production well into an infinite reservoir with a vertical main fracture of constant width at a given constant bottomhole pressure and constant reservoir pressure is considered. Analytical solutions are obtained for the pressure fields in the fracture and reservoir during injection or withdrawal of fluid, as well as for the flow velocity in the fracture. An explicit expression for the fluid leak-off (leak-in) from the fracture into the reservoir (from the reservoir into the fracture) and equations of particle trajectories in in the fracture and reservoir are obtained. For the solutions obtained, graphs are plotted for the pressure fields, fluid velocity distributions in the fracture, and fluid leak-off from the final fracture into a finite reservoir for different reservoir permeabilities.

Direct numerical simulation of interaction between a laminar boundary layer and a shock wave at a Mach number of 1.45 is performed. The influence of a periodic thermal source on the nature of this interaction is described.

The aim of this research to assess the thermal performance of a locally developed two-phase closed thermosyphon system charged with methanol. The performance of the system is examined through experiments to determine the impact of changes in the electrical heat power, liquid charge, flow rate, inclination angle, and cooling water temperature on the output temperature. Temperatures at various points of the heat pipe, as well as cooling water, are recorded. Several fluid loadings are examined, ranging from 4 to 9 ml, which corresponds to the limits of the half full and overfilled evaporator. Different flow rates in the interval 0.2-0.7 kg/min, heat input in the interval 13.0-41.4 W, and cooling water temperature in the interval 15-35 °C are considered. According to the findings, the ideal liquid fill ratio provides the best results in terms of the output temperature, and the heat transfer coefficient is between 64 and 71%. The impact of the adiabatic zone insulation on the temperature distribution along the heat pipe is illustrated.