Technical Physics最新文献

The conditions of resonant (almost complete) tunneling of photons (plane monochromatic electromagnetic waves) through layered dielectric and metal-dielectric structures are considered. Resonant tunneling occurs at frequencies at which the resonance conditions for the corresponding structures of open resonators are met. For metal-dielectric structures, the possibility of tunneling in the optical range with a strong barrier in the IR range is shown, which can be used to control the transmission of window panes.

The electrical properties of Co_n(CoO)_{100 – n} composite thin films obtained by ion-beam sputtering of a composite target in an argon atmosphere and a mixed atmosphere of argon and oxygen (98% Ar + 2% O₂) have been studied. It has been established that if oxygen is introduced into the deposition chamber, the position of the percolation threshold shifts towards lower concentrations of the metal phase. It is associated with the special morphology of the films, when small metal Co nanoparticles are located along the boundaries of larger CoO particles, as well as a decrease in the size of inclusions of the metal phase. Studies of the temperature dependences of the electrical resistivity of synthesized Co_n(CoO)_{100 – n} films have shown that when the metal phase content is up to the percolation threshold the dominant mechanism of charge transfer in the temperature range of 80−140 K is the variable range hopping mechanism of conduction through localized states near the Fermi level, replaced by the nearest neighbors conductivity in the temperature range of 140–300 K. For beyond the percolation threshold Co_n(CoO)_{100 – n} thin films, the conductivity is determined by a network of metal granules and is characterized by a positive temperature coefficient of electrical resistance.

The interaction of photons of the cosmological gamma-ray background radiation to photons of extragalactic background light with producing electron-positron pairs is considered. It is shown that the majority of positrons is produced with energy 10 GeV–1 TeV.

The physico-mathematical model applied to ground tests for geomagnetic plasma exposure based on the combined consideration of surface and bulk processes of transport and charge accumulation for calculating the kinetics of charging high-resistance dielectrics irradiated by medium-energy monoenergetic electrons (from 6 to 30 keV) is proposed. The model takes into account the contribution to the charging of the dielectric by the trains of longitudinal optical phonons generated by each thermalizing primary electron with energy below the band gap of the dielectric, which supplements the induced conduction current due to the generation of electron-hole pairs. As a result, the current induced by trains of longitudinal optical phonons of the tunnel conductivity through free electron traps is introdused, as well as the current induced in the conduction band due to multiphonon ionization the electron traps by trains of longutudinal optical phonons in the region of existence of electric field. Using the example of the α-Al₂O₃ (sapphire) dielectric, the results of computer simulation of the internal currents distributions, charges, and electric field in the dielectric with the open surface irradiated by monoenergetic electrons with energies from 6 to 30 keV are presented according with the achievement the quasi-equilibrium in the irradiated part of the dielectric and with switching of the energy of primary electrons during the irradiation process.

A Penning ion source for a miniature linear accelerator is investigated. A discharge current dependence on the anode voltage for several pressure values is calculated. The estimates are based partly on simplified theoretical models, partly on experimental data obtained on previous work. The ion current component is selected from the obtained dependences and the ion current component value, extracted from the ion source, is estimated. The extracted current dependences and the ion extraction efficiency coefficient value on the voltage at the anode at different source output aperture diameters are calculated.

An experimental study of the normal spectral emissivity of technical nickel, palladium and platinum in the solid polished and liquid phases near the melting points was carried out by the radiation method. The emission measurement was recorded by the bandwidth of the applied narrowband filters. The dependence of metal emission on the wavelength in the range of the radiation spectrum 0.26–10.6 μm is obtained. A comparative analysis with the literature data of other authors is carried out. A theoretical calculation of the emission is given according to the classical electromagnetic theory Hagen’s formula and Rubens.

The heat equation, based on Fourier’s law, is commonly used for description of heat conduction. However, Fourier’s law is valid under the assumption of local thermodynamic equilibrium, which is violated in very small dimensions and short timescales, and at low temperatures. As a replacement for Fourier’s law, many models have been proposed within the framework of various theories. In this paper we study the behavior of solutions to an initial value problem in 3D in the framework of the linearized ballistic-conductive (BC) model. As a result, an unphysical effect is detected when the temperature in the heat wave takes negative values.

An alternative material has been proposed as an absorber for a mask blank for lithography in the vicinity of a wavelength of 11.2 nm – Ni. It has been established in this work that the optimal angle for efficient sputtering of Ru, Be, and Ni targets by accelerated argon ion sources for fabrication of a Ru/Be multilayer structure with an upper Ni layer is an angle of 60° degrees. At this angle, the etching rate for all three materials is 35 ± 5 nm/min at an argon ion energy of 800 eV and an ion current density of 0.5 mA/cm².

We have provided an independent analysis of HD and H₂ absorption lines in several systems in our Galaxy using FUSE space telescope archival data and neutral carbon and metal lines in these systems using HST archival data. The obtained HD column densities lie in the range from ∼10¹⁴ to ∼10¹⁶ cm^–2. The obtained column densities were used to estimate physical conditions in the analyzed systems, including cosmic ray ionization rate, which were obtained in the range from ζ ∼ 10^–17 to ∼10^−15.5 s^–1.

Using laser evaporation method of a target with followed condensation in a flow of buffer gas (Ar or He) the preparation of ZnSe, Fe : ZnSe, Cu : ZnSe nanopowders and their properties were studied. It is shown that for the same gas pressure (100 kPa), ZnSe nanoparticles obtained in helium have a smaller average size (11 nm), than in argon (18 nm). An increase in Ar pressure from 100 to 300 kPa led to an increase in the size of nanoparticles even further 2 times. The influence of laser radiation parameters and gas parameters on productivity of nanopowders obtaining was studied process. The nanopowders had cubic and hexagonal crystalline ZnSe phases, the content of which varied within certain limits depending on gas parameters. A comparison of theoretical and experimental data suggests that a significant part of nanoparticles were formed by desublimation of vapor directly into the solid phase. The results of the first studies of pressing and sintering of ZnSe nanopowders, obtained by laser method, are shown.