THE ⁸Be GROUND STATE FORMATION IN ¹⁶О(γ,4α)-REACTION

S.N. Afanas’ev

Full Text :   (1200 kB, Rus.) 

Abstract
The reaction ¹⁶O(γ,4α) was studied with the aid of a diffusion chamber placed in a magnetic field in the energy range Еγ < 40 MeV. The ground of the 8Be nucleus manifested in the distribution of events with respect to the excitation energy of two alpha particles. A particle was identified as α₃ and α₄. The partial cross section for the channel formation ground state ⁸Be was measured versus the photon energy. Fourth resonances have been observed in the cross section. The energy corresponding to the ith maximum of the partial cross section and the excitation energy of the ith level of the ⁸Be nucleus have been found to be correlated as Е_γⁱ(¹⁶О) = E₀ⁱ(⁸Be) + ε(¹⁶О), where ε(¹⁶О) is the reaction ¹⁶О(γ,4α) threshold. Qualitatively, the results have been explained on the basis of the model of photon absorption by a quasiberyllium. At the analysis of distributions on kinetic energy of α-particles it is certain, that α₁-particle escapes from the ¹²C nucleus, while the remaining α₂-particles with α₃ and α₄ particles form an excited nucleus ¹²C.

KEY WORDS: diffusion chamber, photodisintegration, the excitation energy, quasiberyllium

ON MECHANISMS OF RELAXATION PROCESSES OF HEAT AND MASS TRANSFER IN STRUCTURED HETEROGENEOUS MEDIA

M.Yu. Kovalevsky, V.A. Kutovoy, L.B. Logvinova

Full Text :   (630 kB, Rus.) 

Abstract
There have been investigated the mutual effect of heat and mass transfer processes on the geometry of inhomogeneous microstructure in a condensed medium. The thermodynamics of such states is described along with the standard parameters, additional physical quantities, which set the form and dimension of extended structural elements of the medium. The nonlinear relaxation equations of dynamics have been obtained, and their relationship with phenomenological theory of drying heterogeneous media has been discussed. It was shown that kinetic coefficients, associated with internal structure describe relaxation mechanisms in the media.

KEY WORDS: condensed matter, relaxation dynamics, kinetic coefficients, structure, drying.

ELECTRON ENERGY INCREASE IN STOCHASTICALLY GIVEN FIELD AND GAS DISCHARGE

V.M. Ostroushko

Full Text :   (1240 kB, Ukr.) 

Abstract
Possibilities of application of results of the works for non-collision plasma heating in stochastic field to high frequency low-pressure gas discharge are clarified. An electron motion in the stochastically given field is considered, and it is shown that electrons energy increase is determined with presence of power at resonant frequencies, regardless of presence or absence of field jumps, and stochasticity is only the mean to transfer power to resonant frequencies. There are presented the examples of such stationary stochastic processes with and without of field jumps, in which electron energy gradually increases with time, and the examples of such ones, in which electron energy remains limited. It is compared the energy, which electron can obtain in the bounded gap under field action in presence and in absence of collisions, and it is pointed out that in both cases randomness does not increase the effectiveness of the process of electron energy gain.

KEY WORDS: high-frequency discharge, collisional heating, stochastic correlation, power spectrum, oscillation phase

MEASUREMENTS OF ANGULAR DISTRIBUTIONS OF ELECTRON BREMSSTRAHLUNG METHOD BASED ON CXR

O.S. Deiev

Full Text :   (1200 kB, Rus.) 

Abstract
The spectral-angular characteristics of the electrons bremsstrahlung from amorphous targets were calculated in program code GEANT 4.9.2. The angular distributions of the bremsstrahlung yield from Si and W targets with different thickness for electron energy E_e = 30…1200 МeV were calculated. It is shown that the width angular distributions N_γ(θ) at half maximum θ_½ decreased with increasing Еe and increased with increasing Z and targets thickness. The interaction of electron bremsstrahlung with the secondary targets material was modeled in which characteristic X-ray radiation (CXR) are excited. The calculations for the secondary targets with different transverse size corresponding to given values of the solid angle, which selected the portion of bremsstrahlung flux, were performed. Calculated angular dependence of CXR and the corresponding angular distributions of bremsstrahlung are compared.

KEY WORDS: bremsstrahlung , CXR, angular distributions, modeling, GEANT 4.9.2

RELATIVISTIC TRANSPORT EQUATIONS IN TOROIDAL PLASMAS

I. Marushchenko, N.A. Azarenkov

Full Text :   (1150 kB, Rus.) 

Abstract
Relativistic formulation for the equations describing a neoclassical collisional transport in hot plasmas confined in toroidal systems, which conserves a formal structure of the standard (non-relativistic) theory and allows to include the relativistic consideration in the standart transport codes with minimal changes, is proposed. All formulations are based on the relativistic drift equations of motion and relativistic drift-kinetic equation. Due to a transparent physical interpretation and formal similarity to the generally accepted theory of collisional transport, the proposed formulation allows one to produce a quantitative verification of the validity range of nonrelativistic results predicted by the neoclassical transport models in hot plasmas.

KEY WORDS: relativistic plasma, kinetics, transport equations.

THE PROTOTIPE OF BONNER NEUTRON SPECTROMETER OF ACTIVATION TYPE

A.Yu. Buki, S.A. Kalenik, I.L. Semisalov, I.S. Timchenko, A.S. Zadvorny, M.G. Shevchenko, V.J. Kasilov, S.P. Gokov, S.S. Kochetov, G.I. Ledovskoy, P.L. Makhnenko

Full Text :   (3111 kB, Rus.) 

Abstract
The prototype of Bonner sphere neutron spectrometer of activation type has been created. It is composed of 5-polyethylene spheres with a diameter from 9.0 to 24.5 cm. Indium as activated material inside these spheres is used. We tested the neutron spectrometer, using neutron radiation from converter which was installed at the thirty-MeV output channel of the accelerator complex LINAC-300. As a result of mathematical processing of the measurement data of the induced radioactivity in indium, neutron spectrum was restored. The spectrum, which obtained in this experiment, is similar to the well-known neutron spectrum from the γ, n-reaction with heavy nuclei, which produces neutrons in converter of the accelerator. Energy range of spectrometer was determined and we consider possibility of its expansion. An issue of efficiency, sensitivity and use conditions of the spectrometer is being discussed. The experience, obtained in this work, will be used to optimize the design of a working version of the spectrometer.

KEY WORDS: neutron spectrometer, neutron fields, simulation, induced radioactivity, gamma-radiation detection

IGNITION AND BURNING MODES OF DC HOLLOW CATHODE DISCHARGE

V.A. Lisovskiy, I.A. Bogodielnyi

Full Text :   (3800 kB, Rus.) 

Abstract
In this paper, we measured the breakdown curves of a dc glow discharge with hollow cathode and flat electrodes. It is shown that at low gas pressure (p ≤ 0.05 Torr), the left branches of the breakdown curves for the hollow cathode and the flat electrodes are identical. At high gas pressures (p ≥ 0.3 Torr), the right branch of the breakdown curve of the discharge with a hollow cathode is close to the breakdown curve for the distance between the plane electrodes, equal to the gap between the edge of the plates of the hollow cathode and flat anode. Current-voltage characteristics of the hollow cathode discharge were measured. It is shown that with low gas pressure p < 0.1 Torr discharge is in the high-voltage (electron beam) form with ascending current-voltage characteristic, when secondary electrons are accelerated along electric field lines and form an electron beam. In the gas pressure range p ≥ 0.1 Torr the discharge at low current burns in the glow mode, in which the discharge glow is practically absent in the cavity between the plates of the cathode, and the current-voltage characteristic of the discharge is ascending. At higher current the discharge goes into the hollow cathode mode, filling the space between the plates, and it has an almost vertical current-voltage characteristic. The transition from a glow discharge mode into a hollow one possesses a hysteresis. At gas pressures p ~ 1 Torr the hollow cathode effect disappears, since the thickness of the cathode layer is small compared with the gap between the plates of the cathode. It is shown that when the collectors are placed on the anode across the gap between the plates of the hollow cathode, the radial profile of the electron current to the anode in the mode of electron beam has a sharp maximum at the axis of the discharge chamber. The profile is flatter if the chain of collectors on the anode is directed along the cavity of the cathode. Increasing the gas pressure leads to a strong scattering of the electron beam, and the radial profiles of electron current to the anode are approximately the same in both transverse directions in the glow mode as well as in the hollow cathode one.

KEY WORDS: DC glow discharge, hollow cathode, discharge ignition, the current-voltage characteristics, the radial structure, burning modes

EXPERIMENTAL STUDY OF TRANSITION RADIATION BY NONRELATIVISTIC ELECTRON BUNCHES ON DIFFERENT ELECTRODYNAMIC HETEROGENEITIES

S.S. Geraschenko, V.I. Gritsenko, V.I. Muratov, V.D. Fedorchenko

Full Text :   (1700 kB, Rus.) 

Abstract
Electromagnetic transition radiation by coherent nonrelativistic electron bunches on different electrodynamic heterogeneities are experimentally studied in the paper. It was shown that transition radiation spectra considerably effected by rapidity of reorientation of conduction electron movement direction, which can be observed during passage of bunches through diaphragms. Spiral structures were used to enlarge power of transition radiation. The average power for superposed electric and magnetic dipoles more than 10 times exceeded the average power on the system of diaphragms.

KEY WORDS: electron bunch, transition radiation, diaphragm, spiral, electromagnetic pulse.

ANOMALOUS GROWTH OF THE DIFFUSION IN SPACE-PERIODIC SYSTEMS WITH A LOW ENERGY DISSIPATION

I.G. Marchenko, I.I. Marchenko

Full Text :   (1700 kB, Rus.) 

Abstract
Computer simulation methods were used to investigate the particle diffusion in the periodic spatial potential under constant force exposure. The paper shows that, unlike a superdamped case, in the systems with weak energy dissipation a new critical force value arises due to the appearance of a fork-like bifurcation point. About this point an exponential growth of the diffusion coefficient with temperature decreasing is observed. It is noted that the time of transition to the steady-state distribution tends to infinity while the temperature tends to zero.

KEY WORDS: diffusion, computer simulation, crystals, Langevin equation

MATERIALS AND SAMPLE PREPARATION FOR SIMULATION OF SUPERCRITICAL FLUID EXTRACTION OF URANIUM IN CARBON DIOXIDE MEDIUM

B.V. Borts, I.G Goncharov, A.V. Mazilov, S.F. Skoromnaya, V.I. Tkachenko

Full Text :   (1670 kB, Rus.) 

Abstract
A description of the installation for the supercritical fluid extraction of uranium complexes in the carbon dioxide medium, as well as instrumentation for the analysis of the test materials are presented. A method of selection of granites, which are used to modeling the material of technogen dumps of nuclear power or nuclear fuel of nuclear reactors are described. A description of the method of sample preparation and analysis of extracts on maintenance of the uranium are presented. On the example of the different kinds of granites with elevated content of the uranium it is shown that the methods of sampling and sample preparation of the starting material can be used for modeling of supercritical fluid extraction with carbon dioxide complexes of uranium from materials of nuclear power.

KEY WORDS: installation of supercritical fluid extraction, method for the selection of granites, sample preparation method, supercritical fluid extraction.

EFFECTS OF GAMMA-ACTIVATION AND FUNCTIONALITY CHARACTERISTICS OF SUPERDISPERSED ZrO₂ –CATALYSTES IN METHANOL CONVERSION

I.D. Fedorets, N.P. Khlapova, N.P. Dikiy, E.P. Medvedeva, D.V. Medvedev, V.L. Uvarov, D.S. Bakay

Full Text :   (1630 kB, Rus.) 

Abstract
On the example of a model system the methanol conversion influence of effects of γ-activation of nano ZrO2-catalystes is investigated on their functional characteristics in the processes of heterogeneous catalysis. Influence of γ-activation nanopowder ZrO₂ on direction and reaction yield was controled up on the series of experiments at room temperature with nominally clean ZrO₂ and with ZrO₂ with addition of nano-Fe₂O₃ (~3%) in their initial and the γ-activated state. Activating of samples was carried out by bremsstrahlung on high- current electronic accelerator in NSC KIPT at energy of electrons 22 MeV and a current 500 μA. The features of structural transformations in γ-activated ZrO₂ were researched the method of X-ray diffractometry. It was shown that in the structure of ZrO2 no essential changes and γ-activated particles of oxide keep monophase state and crystallinity of the initial state. Catalytic activity of ZrO₂ and ZrO₂/Fe₂O₃ before and after their γ-activated was estimated on the absorbency of products of convertion reaction of methanol on the spectrophotometer of SF-46. The found out the sharp increase of activity of ZrO₂-catalystеs after theirγ-activated is ascribed to synergy of factors of ionizing radiation - big ionization losses of Auger electrons near a surface ZrO₂ nanoparticles from ⁸⁹Zr - and influences of high-reactionary formations of heterogeneous catalysis.

KEY WORDS: nanopowder ZrO₂, electron accelerator, gamma-activation, X-ray diffractometry, methanol conversion, activity of ZrO₂ - catalystes

STRUCTURAL FEATURES AND SPIN WAVES IN THIN FILMS OF YTTRIUM-IRON GARNET

V.G. Kirichenko, O.V. Kovalenko

Full Text :   (2200 kB, Rus.) 

Abstract
Тhe results of the study of structure formation ferromagnets for magnetooptical devices. Briefly examines the processes of interaction of spin waves with yttrium iron garnet, including thin-film structures. The possibilities of application of Mossbauer spectroscopy to determine the structure and phase composition of the garnet structure parameters and communication with the pumping of spin waves.

KEY WORDS: ferrite garnets, structure, spin waves, thin films, Mossbauer spectroscopy

DEVELOPMENT OF TECHNOLOGY FOR CAPACITIVE DEIONIZATION WATER

V.I. Golota, L.M. Zavada, D.V. Kudin, S.V. Rodionov

Full Text :   (1600 kB, Ukr.) 

Abstract
The article describes the development of the capacitive deionization technology based on carbon materials with extended surface and peculiarities of the application of titanium-modified carbon material SAUT-1S in the manufacture of CDI cells. Experimental results presented in the article show that capacitive deionization cells being developed have high sorption capacity that does not depend on the charging current.

KEY WORDS: electrical double layer, carbon materials, capacitive deionization.

INFLUENCE OF PARAMETERS OF ION DEPOSITION IN PULSED MODE ON CHARACTERISTICS OF DIAMONDLIKE COATING

V.V. Vasylyev, A.I. Kalinichenko, V.E. Strel’nitskij

Full Text :   (920 kB, Rus.) 

Abstract
A pulsed mode of DLC coating deposition is theoretically investigated. In this mode a deposited ion flow of plasma environment with energy of E₀ ~ (20÷200) eV is modified by superimposing of pulsed potential U ≤ 1000 V. It was shown that intrinsic stress in a DLC coating can be decreased in several times without of essential decrease of sp³-bonded carbon concentration compared with DLC made in stationary mode deposition at E₀ ion energy. A method of optimization of pulsed mode parameters is proposed which is based on analysis of location of thermoelastic peaks of ions on phase P, T-diagram of carbon.

KEY WORDS: DLC coating, plasma-based ion deposition, pulsed mode deposition, intrinsic stress, phase P, T-diagram of carbon, non-local thermoelastic peak of ion

CHARGED PIONS PRODUCTION IN HEAVY-ION COLLISIONS AT SPS ENERGY

V.S. Trubnikov

Full Text :   (940 kB, Rus.) 

Abstract
We present experimental results on inclusive charged pions production in peripheral collisions of ²⁰⁸Pb ions at top SPS energy √S = 17.3 GeV. Invariant cross sections are presented as functions of and . Experimentally obtained 288 values fill the phase space restricted to 0 <p_T< 2 GeV and 0 ≤ x_F ≤ 0,4.

KEY WORDS: high-energy physics, heavy ion collisions, inclusive particle production