National Science Center Kharkov Institute of Physics and Technology

Kharkov, Ukraine

National Science Center Kharkov Institute of Physics and Technology

Kharkov, Ukraine
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Uvarov D.V.,National Science Center Kharkov Institute of Physics and Technology
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

Positive energy unitary irreducible representations of SU(2,2) can be constructed with the aid of bosonic oscillators in (anti)fundamental representation of SU(2)L×SU(2)R that are closely related to Penrose twistors. Starting with the correspondence between the doubleton representations, homogeneous functions on projective twistor space and on-shell generalized Weyl curvature SL(2,C) spinors and their low-spin counterparts, we study in the similar way the correspondence between the massless representations, homogeneous functions on ambitwistor space and, via the Penrose transform, with the gauge fields on Minkowski boundary of AdS5. The possibilities of reconstructing massless fields on AdS5 and some applications are also discussed. © 2016 The Author


Grant
Agency: European Commission | Branch: H2020 | Program: RIA | Phase: NFRP-16-2015 | Award Amount: 2.05M | Year: 2015

The overall aim of the project is to create greater security of energy supply and contribute to the security of supply of nuclear fuel for Russian designed pressurized water reactors (VVER) operating in the EU by diversification of fuel sources in the short / medium term and in full compliance with nuclear safety standards. By that, the project addresses the topic NFRP 16 2015. The scientific objectives of the proposed project include increased knowledge concerning the behaviour of the VVER-440 fuel during operation. State-of-the-art methods will be verified against an extensive database, including operating experience from several VVER-440 reactors as well as a number of other reactor designs and a wide range of operating conditions. The ability to accurately predict the fuel behaviour will be improved and thereby also the safety margins. New knowledge as well as identification of needs of technology development and improvements will be created in the fields of technologies for mechanical design, thermo-mechanical fuel rod design, and safety analysis for VVER fuel. In addition to the technological advances, the project will identify the variation in licensing requirements between the authorities in the different countries. Through such identification, it will become clear that standardization would be beneficial and will foster a dialogue between the authorities/regulatory bodies. The new knowledge will be exploited through innovation processes but will also be used for further research and recommendation to policy makers as well as for creating impact among the target groups of the project. Results will be presented to the members of the VVER community, i.e. the utilities, universities and other organizations with close links to the nuclear energy industry. Articles and papers presenting the work and the results of the project will be targeted for nuclear industry, magazines and conferences.


Alekseechkin N.V.,National Science Center Kharkov Institute of Physics and Technology
Journal of Physical Chemistry B | Year: 2012

The multivariable theory of nucleation (J. Chem. Phys.2006, 124, 124512) is applied to the problem of vapor bubbles formation in pure liquids. The presented self-consistent macroscopic theory of this process employs thermodynamics (classical, statistical, and linear nonequilibrium), hydrodynamics, and interfacial kinetics. As a result of thermodynamic study of the problem, the work of formation of a bubble is obtained and parameters of the critical bubble are determined. The variables V (the bubble volume), ρ (the vapor density), and T (the vapor temperature) are shown to be natural for the given task. An equation for the dependence of surface tension on bubble state parameters is obtained. An algorithm of writing the equations of motion of a bubble in the space {V, ρ, T}-equations for V̀, ρ̀, and T̀-is offered. This algorithm ensures symmetry of the matrix of kinetic coefficients. The equation for T̀ written on the basis of this algorithm is shown to represent the first law of thermodynamics for a bubble. The negative eigenvalue of the motion equations which alongside with the work of the critical bubble formation determines the stationary nucleation rate of bubbles is obtained. Various kinetic limits are considered. One of the kinetic constraints leads to the fact that the nucleation cannot occur in the whole metastable region; it occurs only in some subregion of the latter. Zeldovich's theory of cavitation is shown to be a limiting case of the theory presented. The limiting effects of various kinetic processes on the nucleation rate of bubbles are shown analytically. These are the inertial motion of a liquid as well as the processes of particles exchange and heat exchange between a bubble and surrounding liquid. The nucleation rate is shown to be determined by the slowest kinetic process at positive and moderately negative pressures in a liquid. The limiting effects of the processes of evaporation-condensation and heat exchange vanish at high negative pressures. © 2012 American Chemical Society.


Uvarov D.V.,National Science Center Kharkov Institute of Physics and Technology
Nuclear Physics B | Year: 2010

The Type IIA superstring action on the AdS4 × CP3 background, obtainable by the double dimensional reduction of the AdS4 × S7 supermembrane, is considered in the κ-symmetry light-cone gauge, in which the light-like directions are chosen on the D = 3 Minkowski boundary of AdS4. Such choice of the gauge condition relies on representing the AdS4 × S7 background isometry superalgebra osp (4 | 8) (and correspondingly the osp (4 | 6) isometry superalgebra of the AdS4 × CP3 background) as D = 3 extended superconformal algebra. The gauge-fixed action includes contributions up to the 4th power in the fermions. © 2009 Elsevier B.V. All rights reserved.


Alekseechkin N.V.,National Science Center Kharkov Institute of Physics and Technology
Journal of Non-Crystalline Solids | Year: 2011

A solution of the problem of calculating the volume fraction of a phase growing by a diffusion-type law is given. This is meant that the growth velocity Ṙ of a nucleus is a decreasing function of its radius R. The growth law Ṙ~1/Rn-1, n > 1, is employed for demonstrative calculations. The solution is obtained in the framework of the classical Johnson-Mehl-Avrami approach which uses the concept of non-physical phantom nuclei. Probabilistic treatment of this approach is offered and the necessity of phantom nuclei is confirmed. The Johnson-Mehl-Avrami approach is compared with Kolmogorov's method and its extension - the differential critical-region method; the latter yields the same equations for the volume fraction. In the case of the growth law considered, phantom nuclei contribute to the incrementing of the transformed volume fraction. The obtained equations for the volume fraction are shown to cancel this contribution; hence they yield the true value of this quantity. Two successive approximations for the volume fraction are considered analytically and the numerical evaluation of the effect of phantom nuclei is given for different values of n. © 2011 Elsevier B.V. All rights reserved.


Uvarov D.V.,National Science Center Kharkov Institute of Physics and Technology
Nuclear Physics B | Year: 2013

Massless superparticle model is considered on the OSp(4|6)/(SO(1, 3) × U(3)) supercoset manifold and in the AdS4×CP3 superspace. In the former case integrability of the equations of motion is rather obvious, while for the AdS4×CP3 superparticle we prove integrability in the partial κ-symmetry gauge for which 4 anticommuting coordinates related to the broken conformal supersymmetry are set to zero. This allows us to propose expression for the Lax pair that may encode complete equations of motion for the AdS4×CP3 superparticle. © 2012 Elsevier B.V.


Bondarenco M.V.,National Science Center Kharkov Institute of Physics and Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

Coherent radiation spectrum from high energy e± in a bent crystal with arbitrary curvature distribution along the longitudinal coordinate is evaluated, based on the stationary phase approximation. For a uniformly bent crystal a closed-form expression for the spectrum is derived. The spectrum features include a dip at its beginning and the sharp end, which may split into two breaks depending on the particle incidence angle. Estimates of nondipole radiation and multiple scattering effects are given. The value for the crystal bending angle at which the dipole coherent bremsstrahlung theory holds best appears to be ∼10-4 rad. © 2010 The American Physical Society.


Bondarenco M.V.,National Science Center Kharkov Institute of Physics and Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

For volume reflection process in a bent crystal, exact analytic expressions for positively- and negatively-charged particle trajectories are obtained within a model of parabolic continuous potential in each interplanar interval, with the neglect of incoherent multiple scattering. In the limit of the crystal bending radius greatly exceeding the critical value, asymptotic formulas are obtained for the particle mean deflection angle in units of Lindhard's critical angle, and for the final beam profile. Volume reflection of negatively charged particles is shown to contain effects of rainbow scattering and orbiting, whereas with positively charged particles none of these effects arise within the given model. The model predictions are compared with experimental results and numerical simulations. Estimates of the volume reflection mean angle and the final beam profile robustness under multiple scattering are performed. © 2010 The American Physical Society.


Patent
National Science Center Kharkov Institute of Physics and Technology | Date: 2013-09-18

The invention relates to a technique for forming flows of vacuum arc cathode erosion plasma to produce high quality coatings. The plasma flows are transported in a plasma-optical system from an arc evaporator to the outlet of a plasma source under the effect of a transporting magnetic field generated using electromagnetic coils. The transporting magnetic field is generated by the superposition of a constant magnetic field and additional magnetic fields of variable strength which deflect the plasma flows from the surfaces of the structural elements of the plasma source. The strength of the corresponding additional magnetic field increases as the plasma flow approaches the surface of a structural element of the plasma source and decreases as the plasma flow moves away from the surface of that element. In the device for implementing the above method, a vacuum arc power supply (15) is connected to an anode (2) via the winding of an electromagnetic coil (16) which surrounds said anode. In a linear embodiment of the plasma-optical system, an electrically conductive section of a tube (11) inside the anode (2) is electrically connected to one end of the winding of an electromagnetic deflection coil (12). The other end of this winding is connected to the positive terminal of the vacuum arc power supply (15). Using the above method and device significantly reduces loss of macroparticle-free plasma.


Patent
National Science Center Kharkov Institute of Physics and Technology | Date: 2014-10-08

The invention relates to the vacuum arc cathode plasma source anode unit. The invention can be used predominantly as a part of linear vacuum arc cathode plasma source with micro particle filtering together with various vacuum arc evaporators and plasma guides for plasma transport. The anode unit includes an anode encircled by the electromagnetic focusing coil and shaped as a tube segment. Inside, the anode contains an electromagnetic deflection coil which is placed coaxially to it in the electro conductive shell and whose magnetic field is directed opposite to the magnetic field of the electromagnetic focusing coil. Inside, the deflection coil contains a constant deflection magnet which is placed on its axis close to the butt end directed towards the anode inlet and whose magnetic field is co-directed with the magnetic field of the electromagnetic deflection coil. The anode unit characterized in that it includes an additional constant magnet which is placed inside the electromagnetic deflection coil on its axis close to the butt end directed opposite to the anode inlet and whose magnetic field is directed opposite to the magnetic field of the constant deflection magnet. The positive terminal of the arc power supply source is connected both to the anode through the winding of the electromagnetic focusing coil and to the shell of the electromagnetic deflection coil through its winding. Due to this, the dynamic equilibrium of plasma flows traveling in the gap between the inner anode surface and the outer surface of the electromagnetic deflection coil shell is achieved. This significantly reduces plasma losses.

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