KELVIN-HELMHOLTZ (KH) DISSIPATIVE INSTABILITY AND ITS VERSATILE MANIFESTATIONS IN THE ENVIRONMENT

V.I. Tkachenko

Full Text :   (2000 kB, Rus.) 

Abstract
The review of the conditions for the occurrence and development of Kelvin-Helmholtz (KH) dissipative instability at the interface of two viscous flows with different densities and different rates of velocities is considered. The energetic interpretation of the wind instability in the absence and presence of viscosity in the media is made. The impermeable or "percolation" boundary conditions should be used to adequately describe the KH dissipative instability are specified. With the use of the "percolation" boundary conditions the development of the waves of the water's indused by the wind, the development of explosive interactions of air-water flow perturbations with regard to their viscosity, the development of shear instabilities at the interface of steel samples, where the boundary is loaded with an oblique shock wave, and shear instabilities in metals at their joint rolling in a vacuum are investigated. The examples of manifestations of the KH dissipative instability in the environment are submitted.

KEY WORDS: Kelvin-Helmholtz instability, viscous media, dissipative instability, explosive instability, threshold speed, wind disturbance.

THE SPACE-TIME EVOLUTION OF THE PROCESS OF TRANSITION RADIATION BY RELATIVISTIC ELECTRON

N.F. Shul’ga, S.V. Trofymenko, V.V. Syshchenko

Full Text :   (360 kB, Rus.) 

Abstract
The problem of relativistic electron's transition radiation on thin metallic ideally conducting plate is considered. The space-time evolution of the electromagnetic field, which arises before and after passing of the electron of the metallic plate, is discussed. It is shown that at the moment of time t after the passing of the plate the electron's field reflected from it on distances r > ct is not equal to zero. The potential jump at r = ct intirely defines the characteristics of backward transition radiation. Similar image of field evolution takes place in the direction of the electron's velocity. The analogy in the development of space-time image of electromagnetic field evolution in the processes of transition radiation and bremsstrahlung during the momentary scattering of relativistic electron at large angle is discussed. Special attention is drawn to the transition radiation of "half-bare" electron on metallic plate which is placed on different distances from the scattering point where partial "undressing" of the electron occurs. It is shown that "half-bare" state of the electron manifests itself by suppression of the transition radiation and by oscillation type of the transition radiation's characteristics dependence on the distance between the plate and the scattering point. The conditions for such effects are discussed. Some problems of measurements of transition radiation and bremsstrahlung spectral-angular density are considered. It is shown that the results of these measurements should substantially depend on the detector's size and its position relatively to the point of the electron's passing through the plate and to the scattering point.

KEY WORDS: transition radiation, bremsstrahlung, coherence length, relativistic electron, electromagnetic field potentials.

SCATTERING OF HIGH ENERGY PARTICLES IN THE FIELD OF DEFORMED CRYSTALLINE ATOMIC PLANES

N.F. Shul’ga, V.I. Truten’, V.V. Boyko

Full Text :   (270 kB, Rus.) 

Abstract
The problem of fast charged particles scattering in the field of continuous potential of deformed crystalline planes of atoms is considered. It is shown that given problem presents the problem of charge particles scattering in the central field which potential is the set of potential wells located on big distances from the center of crystal curvature. Deflection functions are received for particles scattering in such field. The possibility of reflection for positively and negatively charged particles from deformed crystalline atomic planes on the angles reaching two critical plane channeling angles is shown. Conditions for realization of this effect practically for all particles of the bunch are received. The possibilities of particles deflection on positively and negatively scattering angles and analogue of the orbiting effect at scattering are shown. The conditions for existence of these effects are discussed.

KEY WORDS: elastic scattering, scattering in central field, volume reflection, scattering on deformed crystals, deflection function.

VARIATIONS OF ELECTRON FLUXES IN THE EARTH RADIATION BELTS IN MAY, 2009 DUE TO “STEP-F“ DEVICE OBSERVATIONS

O.V. Dudnik

Full Text :  

Abstract
The analysis of electron flux variations in radiation belts of the Earth in May, 2009, is performed on the base of data obtained from the satellite telescope of electrons and protons STEP-F as a part of scientific apparatus complex "PHOTON" on board the spacecraft "CORONAS-PHOTON". The temporal connection of particle intensity changes that were detected by the view cone of the device in the radiation belts at the bases of drift shells with various phases of weak magnetic storm of May, 8, as well as with parameters of high speed solar wind streams is investigated. The empirical values of electron life time in the outer and inner radiation belts are defined for particles with various energies. The possible dependence of electron life time in the outer belt on their pitch-angle distribution at fixed energy is discussed.

KEY WORDS: magnetosphere of the Earth, radiation belts, electrons, pitch-angle distribution, magnetic storm, solar activity, solar wind, Brazil magnetic anomaly, particle acceleration.

DESCRIRTION OF THE ELASTIC NUCLEON-NUCLEUS SCATTERING BASED ON THE SKYRME FORCES

I.L. Semisalov, V.I. Kuprikov, V.V. Pilipenko

Full Text :   (430 kB, Rus.) 

Abstract
The model of microscopic optical potential based on calculations of the one-particle Green function mass operator using the effective Skyrme nucleon-nucleon forces has been applied for describing cross sections and analyzing powers of the elastic nucleon-nucleus scattering. The Skyrme force parameters have been optimized by fitting a chosen angular distribution of the elastic neutron-nucleus scattering with simultaneous control of main characteristics of the nuclear matter and the binding energy and rms charge radius of the target nucleus. The found Skyrme forces have been used to analyze differential cross sections and analyzing powers of elastic neutron scattering by nuclei in a wide range of mass numbers. The calculations have given a satisfactory description of experimental data on elastic neutron-nucleus scattering and reasonable values of the main parameters for the symmetric nuclear matter and even-even nuclei. Analogous calculations have been performed for describing experimental data on the elastic proton-nucleus scattering, which have yielded encouraging results.

KEY WORDS: nucleon-nucleus scattering, optical potential, Skyrme interaction, Hartree-Fock method, nuclear matter.

METHODS OF MEASURING PHYSICAL CHARACTERISTICS OF PARTIAL COMPONENTS OF MULTICOMPONENT SAMPLES

A.Yu. Buki

Full Text :   (200 kB, Rus.) 

Abstract
Consideration is given to the methods of obtaining experimental data relating to the substances, which make up multicomponent measurable samples. The methods are applicable to the samples comprising an arbitrary number of components; their use is not restricted to a single-type experiment. The application of the methods is illustrated by the example of obtaining the spectra of electrons scattered by ⁶Li and ⁷Li nuclei, which were measured from two targets having different isotopic composition. As a result, the measurements gave the spectra of electrons scattered by the nuclei of each of the isotopes involved, as if the experiment were made on isotopically pure targets.

KEY WORDS: physical measurement technique, pure materials, multicomponents samples, data analysis, isotopes

OUTPUT CHANNEL OF THE ELECTRON BEAM WITH ENERGIES UP TO 30 MEV FOR RESEARCH PHOTO AND ELECTRONUCLEAR REACTIONS

V.I. Kasilov, A.Yu. Buki, S.P. Gokov, S.S. Kochetov, K.S. Kokhnyuk, L.A. Makhnenko, P.L. Makhnenko, I.V. Mel’nitsky, V.F. Popov, I.L. Semisalov, O.A. Shopen, V.M. Khvastunov

Full Text :   (200 kB, Rus.) 

Abstract
The description of the experimental equipment and components produce beams of electrons and photons for the study of photo-and electronuclear reactions in the energy region of giant resonance are presented. Shows the measured spectra of electrons used in the experiments. The questions of creation a parallel transport system of beam, which will provide a beam of electrons, satisfy a minimum background, with a spread of energy ~ 1%. Methods for measuring product yields of photo-and electronuclear processes are discussed.

KEY WORDS: methods of physical measurements, electron, photon, parallel transport system of beam.

FORMING OF ELECTRON BEAM IN MAGNETRON GUN WITH SECONDARY-EMISSION CATHODE USING THE MAGNETIC SYSTEM BASED ON PERMANENT MAGNETS

N.I. Ayzatskiy, A.N. Dovbnya, V.V. Zakutin, N.G. Reshetnyak, V.P. Romas’ko, I.A. Chertishcev, T.A. Kovalenko, N.A. Dovbnya, O.M. Utva

Full Text :   (780 kB, Rus.) 

Abstract
The paper presents the results of investigations into the electron beam formation in the magnetron gun using the magnetic system based on the NdFeB permanent annular magnet. Unlike a magnetic solenoid designed for magnetic-field generation, the system used in the work reported has smaller size and weight, does not require cooling and power supply. A compact magnetron gun with a secondary-emission cathode has been constructed and different modes of electron beam formation were applied and investigated.

KEY WORDS: magnetron gun, electron beam, secondary-emission cathode, permanent annular magnets, NdFeB

ACCUMULATING AND ANNEALING RADIATION DEFECTS IN ZIRCONIUM ALLOYED BY DYSPROSIUM AND GADOLINIUM

V.N. Borysenko, Yu.T. Petrusenko

Full Text :   (720 kB, Rus.) 

Abstract
The research results of the influence of the alloying dysprosium and gadolinium atom concentration on the accumulation and annealing kinetics of radiation defects in the zirconium irradiated by the 2MeV electrons are represented here. It is shown that entering the oversized dysprosium and gadolinium atoms into the zirconium matrix leads to retarding the increase in the relative electrical resistance on the electron fluence in comparison with pure zirconium, that is stipulated by the additional annihilation of interstitial atoms and vacancies in the elastic fields produced by oversized impurity atoms. A significant influence of the alloying elements on the annealing kinetics of point defects in zirconium is revealed, stipulated by formation of interstitial-impurity and vacancy-impurity complexes.

KEY WORDS: electron irradiation, radiation defects, zirconium, recovery stages, point defects.

EFFECT OF HIGH HYDROSTATIC PRESSURE ON METAL-DIELEKTRIK TRANSITION AND PSEUDOGAP IN OXYGEN UNDERDOPED НО₁BA₂CU₃O_7-δ SINGLE CRYSTALS

R.V. Vovk, Z.F. Nazyrov, A.A. Zavgorodniy, M.A. Obolenskii

Full Text :   (630 kB, Ukr.) 

Abstract
In precent work the effect of high hydrostatic pressure on electroresistance in an ab-plane of Нo₁Ba₂Cu₃O_7-δ single crystals with an oxygen deficient is investigated. It is shown, that redistribution of labile oxygen induced by a high pressure leads to occurrence structural relaxation processes in volume of experimental samples. Thus there is an significant displacement of the temperature range that corresponds to metal-dielectric type transitions and the pseudo-gap anomaly.

KEY WORDS: НоВaCuO single crystals, hydrostatic pressure, labile oxygen, pseudo-gap anomaly, metal-dielectric transitions, twin boundaries.

INFLUENCE OF GRYSTALLITE SIZE ON THERMO- AND ELECTRO- CONDUCTIVITIES OF NANODIAMOND COATING

S.F. Dudnik, A.I. Kalinichenko, V.E. Strel’nitskij

Full Text :   (280 kB, Rus.) 

Abstract
Dependence of thermo- and electro- conductivities of nanocrystalline diamond coating on crystalline size and boundary layer depth is theoretically investigated. Nanodiamond is considered as two-phase material composed of dielectric diamond grains segregated by thin graphite layers with electronic conductivity. Derived expressions for thermoconductivity and resistivity show accordance with experimental data.

KEY WORDS: nanodiamond coating, crystalline grain, boundary layer, thermoconductivity, electroconductivity

STRUCTURE AND PROPERTIES OF GAMMA ACTIVATED NANOPARTICLES OF ZINC OXIDE

I.D. Fedorets, N.P. Khlapova, N.P. Dikiy, A.N. Dovbnya, E.P. Medvedeva, Yu.V. Lyashko, N.S. Lutsay, D.V. Medvedev, V.L. Uvarov

Full Text :   (1115 kB, Rus.) 

Abstract
Activation of nanoparticles of magnetite is carried out by slowing-down γ - radiation on high-current electronic accelerator in NSC KIPT at energy of electrons 22 MeV and a current 500 μA. The analysis of component-phase structure and state of crystal structure of activated and initial nanoparticles ZnO was carried out by X-ray diffractometry methods. The transformations have been analysed and it was shown that there were no essential changes in structure of ZnO: activated nanoparticles of magnetite keep monophase state and crystallinity of initial state. To study influence nanoparticles ZnO on adenocarcinoma Ehrlich cells It was demonstrated, that nanoparticles ZnO can be used as effect factor for destruction of adenocarcinoma Ehrlich cells.

KEY WORDS: nanoparticles oxide zinc, electron accelerator, gamma-activation, X-ray diffractometry, biological sample.

COMPONENTLY-SELECTIVE CORROSION OF AUSTENITIC STEELS IN LIQUID SODIUM

V.G. Kirichenko, V.N. Leonov

Full Text :   (330 kB, Rus.) 

Abstract
Results of examination structurally-phase changes in austenitic steels 12Х18Н10Т and 08Х16Н15М3Б after staying in the environment of liquid sodium are presented. It is discovered componently-selective corrosion of austenitic steels in the liquid sodium, caused by the selective character of washing away of components of steels at staying in sodium. It leads to structurally-phase transformations (including to γ→α transition in surface layer), porosity, and probably to reduction of mechanical characteristics of a steel. Local chemical inhomogenety shaped in the course of corrosion of near-surface layer is one of the main reasons of interdependent processes γ→α transformation, development of porosity, origin and growth of other phases. At corrosion in sodium the modification of a local environment of nuclei ⁵⁷Fe in near-surface layer is observed at processing γ→α transformation at the expense of concentration reduction in a composition of near-surface layer not only nickel, but also chromium. Increase of corrosion resistance depends on stability of austenitic phase concerning γ→α transition and reduction of tendency to pore formation.

KEY WORDS: componently-selective corrosion, austenitic steels, phase transformations, sodium, liquid-metal coolant

INFLUENCE OF INTERFACE ROUGHNESS ON SPIN-DEPENDENT TUNNELING

I.N. Marushchenko, V.M. Karpan, N.A. Azarenkov, P.J. Kelly

Full Text :   (1160 kB, Rus.) 

Abstract
A quantitative study of the interface roughness effect on the transport properties of Fe|vacuum|Fe magnetic tunnel junctions is presented. From the first principle calculations with taking into account the parameter-free electronic structure it has been found that the surface roughness produces a very strong effect on the spin-polarized transport. The obtained results are important for understanding the mechanism responsible for the giant tunneling magnetoresistance.

KEY WORDS: spin-polarized transport, magnetic tunnel junction, surface states, disorder.

ABOUT POSSIBILITY MANUFACTURING OF THE DIAGNOSTIC MEDICAL ISOTOPE TECHNETIUM 99М IN UKRAINE

I.S. Guk, S.G. Kononenko, F.A.Peev

Full Text :   (470 kB, Rus.) 

Abstract
Application of diagnostic isotopes for identification of cancer diseases in the world and Ukraine is analysed. More than in 80 % of analyses for these purposes the isotope^99mTc is used. Data about various methods of manufacture of an isotope with use of reactors and charged particle accelerators are cited. It is shown, that use of a photonuclear mode of manufacture of an isotope by means of an electron accelerator with superconducting accelerating structures can be the most effective for Ukraine.

KEY WORDS: isotope, nuclear methods, diagnostics, electron accelerator, aberration, ^99mTc.