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Том 46, № 1 (2019)
- Год: 2019
- Статей: 11
- URL: https://journals.rcsi.science/1068-3356/issue/view/14147
Article
Formation of a Train of Picosecond Laser Pulses with a Maximum Power Density to 107 W/cm2 upon Electron-Beam Excitation of a Semiconductor Target
Аннотация
The dependence of the pulse shape of laser radiation of a CdS semiconductor target on the parameters of the exciting subnanosecond electron beam (EB) is studied. The effect of the time to reach the threshold excess carrier density (ECD) on the laser radiation pulse shape is considered. A train of laser radiation pulses with a maximum intensity to 107 W/cm2 is obtained at modulating EB pulses by a frequency of 5 GHz. It is shown that an increase in the ECD during the lifetime can be used to further increase the intensity and to reduce the laser radiation duration in the picosecond range.
1-4
Growth of Si/Si1_xGex/Si (x < 0.1) Quantum Wells by Modulating Ge Molecular Flow. I. Molecular Beam Epitaxy
Аннотация
Single quantum wells in the system Si1_xGex/Si with x < 0.1 are grown by molecular-beam epitaxy in the mode of periodic Ge molecular flow interruption during the formation of the alloy layer. It allowed an increase in the operating current of the source electron gun, which provided a more stable molecular Ge flow. The grown heterostructures are studied by transmission scanning electron microscopy methods
5-8
On the Ion Drift in Cold Gas
Аннотация
The problem of ion drift in such a strong electric field that the ion drift velocity significantly exceeds the thermal velocity of atoms is considered. In the case where the ion mass is identical to the gas particle mass, scattering is isotropic in the center-of-mass system and the ion scattering cross section is independent of the collision velocity (hard sphere model). The ion velocity distribution function is calculated by the Monte Carlo method, its characteristics and diffusion coefficient are determined. A comparison with known numerical and analytical solutions is performed. It is found that average characteristics (drift velocity, longitudinal and transverse temperatures) are in very good agreement with the values obtained from integral relations for the two-temperature Maxwellian distribution; however, the ion velocity distribution itself differs significantly from the shifted two-temperature Maxwellian distribution.
9-12
Effect of Diamond Grain Orientation on the Local Conductivity of Laser-Induced Graphitized Surface Layer
Аннотация
Graphitized structures are fabricated on a polycrystalline diamond surface using an excimer KrF laser. It is found that the layer grown on the {001} crystallite, has a lower resistance and thickness than that on the {111} surface. A model of the formation of oriented nanocrystalline graphite is proposed to explain the observed effects.
13-15
Evaluation of the Effect of Moisture Content in the Wood Sample Structure on the Quality of Tomographic X-Ray Studies of Tree Rings of Stem Wood
Аннотация
For the first time, the effect of moisture content in the structure of wood samples on the quality of the results of the study of their internal structure using high-resolution X-ray computer tomography is considered. The tomographic method for determining the internal distribution of the structure and density of tree rings of stem wood can be used to solve problems in the field of dendroclimatology and biometeorology.
16-18
Ways to Improve the TV-Type Detector
Аннотация
The ways to improve operating characteristics of the TV-type proton detector related to the enhancement of the energy release emission brightness is studied. A working example of the proton detector with an extended energy range (depth—dose) from 30 to 207.5 MeV is fabricated.
19-22
Designing Proton and Electron Detector for Monitoring Solar Cosmic Rays
Аннотация
The project of the compact space detector for measuring proton (10–100 MeV) and electron (to 10 MeV) energy spectra in solar cosmic rays is presented. The detector can operate in two modes: differential (each event is reconstructed) and integral (only energy spectrum and radiation composition are reconstructed at a high loading).
23-25
Application of SU(2) Group Fibration for Kinetic Problems of Polyatomic Molecules
Аннотация
We point out the region in 3D-space permitted by symmetry that is available for the translational motion of rotating molecules. This region belongs to the one-parametric subgroup noted as fiber. It has the range of 0–1 for real variable and is disposed on the straight line directed by basic quaternion. The base part of fibration contains the two-dimensional sphere known as a symmetry structure which describes rotations of solid body. As an example of polyatomic molecules we use in this study water molecules. When water molecules are related to the fiber type of symmetry they must move in one direction pointed by basic quaternion in opposite to the three mutually orthogonal directions statistically adopted. The movement of molecules in one direction which, however, can be arbitrary oriented in 3D-space allow us to give the explanation of experimental results.
26-28
29-31
On the Photon Size and Localization Region
Аннотация
It is generally accepted that the photon size is equal to its wavelength. However, interference of single photons was observed in [4] at a difference between arm lengths of the Mach—Zehnder interferometer much longer than the wavelengths of used photons. This raises the question about the photon localization region to which the present study is devoted.
32-35
Study of Microstructure Features of the Surface Region of the Photovoltaic Converter with an Antireflective Porous Silicon Film and an n+—p Junction
Аннотация
Using methods for measuring photocurrent and Raman scattering spectra the surface region microstructure of the silicon photovoltaic converter with n+—p junction and an antireflective porous silicon film is studied. The n+—p junction is formed by thermal diffusion of phosphorus from a porous film. It is found that high-temperature treatment during diffusion results in coarsening silicon crystallites and a decrease in the defect density in the porous silicon film. It is noted that the n+ —p junction is formed within the largest crystallites of the porous silicon film.
36-39