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A. G. Zagorodny

Publications and source records attributed to A. G. Zagorodny.

At least 19 recordsLinked to original sources
arXiv2025

Thermodynamic relation for the systems with inhomogeneous distribution of particles

For the system with inhomogeneous distribution of macroscopic parameters we obtain thermodynamic relation which depends on the spatial point (coordinate). In our approach, to obtain such a relation we use the basic ideas of the method of nonequilibrium statistical operator combined with the Hubbard-Stratonovich transformation. First of all, we define the thermodynamic relation for the system with homogeneous distribution of particles. Possible behavior peculiarities of systems with different character of interaction in nonequilibrium case are predicted. By saddle-point method we find the dominant contributions to the partition function and obtain all thermodynamic parameters of the systems with different character of interaction. The formations of saddle state in all systems of interacting particles at different temperatures and particle distributions have the same physical nature and therefore they can be described in the same way. We consider the systems with attractive and repulsive interactions as well as self-gravitating systems.

cond-mat.stat-mech↗
arXiv2020

Electromagnetic field energy in an absorptive medium with temporal and spatial dispersion

General relations for electromagnetic field energy outside the transparency domain are proposed. It is shown that charged particle contribution to the energy of electromagnetic perturbations in the general case can be described in terms of a bilinear combination of the dielectric polarizability of the medium. The explicit form of such contribution is found. The relations obtained are used to generalize the Planck law to the case of an absorptive medium.

cond-mat.stat-mech↗
arXiv2019

Statistical description of the Universe formation

Statistical description of the Universe as non-equilibrium system has been proposed. Based on two fundamental principles, i.e., the law of increasing entropy and the principle of minimum energy of the system and try to answer the question of what the reasons of the Big Bang and the birth of the Universe were.

physics.gen-ph↗
arXiv2019

Internal magnetic field distribution in plasmas

We calculate stationary probability distribution of magnetic field, generated by moving charges of plasma environment, and stationary probability distribution of force, acting on charged particle in this environment, with magnetic interaction taken into account. While the former happens to be the Holtsmark distribution, the latter is a modified Holtsmark distribution. In contrast to prior works, we did no assumptions on the velocity distribution function and thus obtained results should be applicable to wider spectrum of models. Presented results can be experimentally verified through studies of Zeeman effect or movement of small charged Brownian particles in plasma.

cond-mat.soft↗
arXiv2018

To the Problem of Electromagnetic Field Energy in the Medium with Temporal and Spatial Dispersion Outside the Transparency Domain

The problem of calculation of electromagnetic field energy outside the transparency domain is discussed. It is shown that charged particle contribution to the energy of electromagnetic perturbations in the general case can be described in terms of bilinear combination of the dielectric polarizability of the medium. The explicit form of such contribution is found. The relations obtained are used to generalize the Planck's law to the case of absorptive medium.

physics.plasm-ph↗
arXiv2017

Collective diffusion of a colloidal particles in a liquid crystal

The collective diffusion effects in system of a colloidal particles in a liquid crystal has been proposed. In this article described peculiarity of collective diffusion colloidal particles in a liquid crystal, which can be observe experimentally. The diffusion coefficient should be crucial dependence from temperature and concentration of particles. In system colloidal particles arise from the elastic distortion of the elastic director field the inter-particle interaction. These interaction can cause nontrivial collective behavior, as the results the non-monotonic dependence collective diffusion. Are predicted a nontrivial behavior collective diffusion of colloidal particles in a liquid crystal.

cond-mat.soft↗
arXiv2017

Peculiarities of oscillator with nonlinear cordinate-dependent mass

A nonlinear model of the scalar field with a coupling between the field and its gradient is developed. It is shown, that such model is suitable for the description of phase transition accompanied by formation of spatial inhomogeneous distribution of the order parameter. The proposed model is analogous the mechanical nonlinear oscillator with the coordinate-dependent mass or velocity-dependent elastic module. Besides, for some value of energy the model under consideration possesses exact analytical solution. We assume that this model can related to the spinodal decomposition, quark confinement, or cosmological scenario. All predictions can be verified experimentally.

cond-mat.stat-mech↗
arXiv2017

On the nature of the Mossbauer effect

The spectrum of electromagnetic waves emitted by an oscillator trapped in an external potential well is studied. It is assumed that the natural frequency of the oscillator is much greater than the frequency of oscillations in the potential well. We consider the quantum model of emission with regard to the recoil effect. The highest intensity of the absorption and emission lines is observed on the natural frequency of the oscillator when the recoil energy is equal to the energy of the quantum of low-frequency (LF) oscillations in the potential well. A certain decrease in the amplitude of the emission and absorption lines is noted caused by the oscillations of the potential well due to, for example, the presence of the phonon spectrum. The relaxation times of the oscillator LF motion in the potential well, resulted from the phonon emission, are estimated. It is concluded that these processes have no influence on the observed features of the emission and absorption of high-frequency photons. This model can be applied to description of the emission and absorption of gamma rays in the crystal structures even in the presence of the phonon spectrum on condition that the relaxation time of the LF movements in the potential well is greater than the lifetime of the HF oscillator.

quant-ph↗
arXiv2016

On the nature of periodically pulsating radiation sources

A change in the character of maser generation in a two-level system is found when the initial population inversion exceeds some threshold value proportional to the square root of the total number of atoms. Above this threshold, the number of photons begins to grow exponentially with time and the pulse with short leading edge and broadened trailing edge is generated. In this work, we attempt to explain the nature of this threshold. Coherent pulse duration estimated by its half-width increases significantly with increasing inversion, if all other parameters are fixed and the absorption is neglected. The inclusion of the energy loss of photons leads to the fact that the duration of coherent pulse is almost constant with increasing inversion, at least well away from the threshold. If there is exist a recovery mechanism for the population inversion, the pulsating mode of stimulated emission generation becomes possible. The integral radiation intensity at this may be increased several times. This approach can be used for analysis of the cosmic radiation that might help explain a great variety of pulsating radiation sources in space.

quant-ph↗
arXiv2015

Free energy analysis for a system of interacting particles arranged in Bravais lattice

We propose a method of free energy calculation for a system of interacting particles arranged in a Bravais lattice. It will be shown how to treat divergences for infinite unbounded systems with "catastrophic" potetntials like Coulomb and compare two of them. Besides, we show that current method may be used not only for essentially classical systems, but for some quantum as well. Two systems are considered: grains in dusty plasma and electrons on the liquid-helium surface. For dusty-plasma parameters of grain's lattice are calculated by numerical solution of obtained equations. Electrons on the liquid-helium surface are analyzed to get localization distance. Besides, conditions for existence of electron lattice are found.

cond-mat.stat-mech↗
arXiv2015

Ion heating, burnout of the HF field and ion sound generation under the development of a modulation instability of an intense Langmuir wave in a plasma

The development of one-dimensional parametric instabilities of intense long-wave plasma waves is considered in terms of the so-called hybrid models, when electrons are treated as a fluid and ions are regarded as particles. The analysis is performed for both cases when the average plasma field energy is lower (Zakharov's hybrid model -- ZHM) or greater (Silin's hybrid model -- SHM) than the plasma thermal energy. The efficiency of energy transfer to ions and to ion perturbations under the development of the instability is considered for various values of electron-to-ion mass ratios. The energy of low-frequency (LF) oscillations (ion-sound waves) is found to be much lower than the final ion kinetic energy. We also discuss the influence of the changes in the damping rate of the high-frequency (HF) field on the instability development. Reduced absorption of the HF field leads to the retardation of the HF field burnout within plasma density cavities and to the broadening of the HF spectrum. At the same time, the ion velocity distribution tends to the normal distribution in both ZHM and SHM.

physics.plasm-ph↗
arXiv2015

Kinetics of ions during the development of parametric instability of intensive Langmuir waves in plasma

Nonlinear regimes of one-dimensional parametric instabilities of long-wave plasma waves are considered for the cases when the average plasma field energy density is less (Zakharov's model) or greater (Silin's model) than the plasma thermal energy density. The hybrid models presented in this paper treat the electrons as a fluid by way of an equation for the high-frequency wave and treat the ions kinetically with a super-particle simulation. This makes possible consideration of non-resonant particles trapped by high-frequency oscillations and the influence of trajectory crossing on the development of the parametric instability. The evolution of ion energy distribution is studied. It is shown that after saturation of the instability, the ion kinetic energy density normalized to the initial field energy density is of the order of the ratio of linear growth rate to the plasma frequency, for the case when the initial field energy far exceeds the plasma thermal energy. In this case, the ion energy distribution is different from the Maxwellian.In the opposite case of hot plasma, the ions acquire a part of initial field energy, which is approximately equal to the half of ratio of initial Langmuir field energy to the plasma thermal energy. At this, the ion kinetic energy distribution is close to the Maxwellian, and it is reasonably to speak about ion temperature. The crossing of ion trajectories in the surrounding of density cavities is a reason of instability quenching in both cases.

physics.plasm-ph↗
arXiv2014

The statistical description of the electron system on the liquid helium surface

It is known that homogeneous distribution of particles in Coulomb-like systems can be unstable, and spatially inhomogeneous structures can be formed. A simple method for describing such inhomogeneous systems and obtaining spacial distributions of electron density is proposed and applied to the case of two-dimensional electron systems on surface of liquid helium. A free energy functional for the model in mean field approximation is obtained. Creation of various types of structures, such as long-range periodical modulation and multi-electron dimples, is predicted by minimizing this functional.

cond-mat.stat-mech↗
arXiv2013

A model of phase transitions with coupling between the order parameter and its gradient

A model of phase transitions with coupling between the order parameter and its gradient is proposed. It is shown, that this nonlinear model is suitable for the description of phase transitions accompanied by the formation of spatially inhomogeneous distributions of the order parameter. Exact solutions of the proposed model are obtained for the special cases which can be related to the spinodal decomposition or cosmological scenario. The proposed model is analogical to the mechanical nonlinear oscillator with the coordinate-dependent mass or velocity dependent elastic module. Based on this analogy, the existence of the limit cycles is established.

cond-mat.stat-mech↗
arXiv2013

Metal - non-metal transition and the second critical point in expanded metals

Based on the non-relativistic Coulomb model within which the matter is a system of interacting electrons and nuclei, using the quantum field theory and linear response theory methods, opportunity for the existence of the second critical point in expanded metals, which is directly related to the metal--nonmetal transition, predicted by Landau and Zeldovitch, is theoretically justified. It is shown that the matter at the second critical point is in the state of true dielectric with zero static conductivity. The results obtained are in agreement with recent experiments for expanded metals. The existence of the second critical point is caused by the initial multi-component nature of the matter consisting of electrons and nuclei and the long-range character of the Coulomb interaction. (Accepted in PTEP)

cond-mat.stat-mech↗
arXiv2012

Unification of the standard and gradient theories of phase transition

We show, that the standard model of phase transition can be unified with the gradient model of phase transitions using the description in terms of the gradient of order parameter. The generalization of the gradient theory of phase transitions with regard to the fourth power of the order parameter and its gradient is proposed. Such generalization makes it possible to described wide class of phase transitions within a unified approach. In particular it is consistent with the nonlinear models, that can be used to describe a phase transition with the formation of spatially inhomogeneous distribution of the order parameter. Typical examples of such structures (with or without defects) are considered. We show that formation of spatially inhomogeneous distributions of the order parameter in the course of a phase transitions is a characteristic feature of many nonlinear models of phase transitions.

cond-mat.stat-mech↗
arXiv2009

From BBGKY Hierarchy to Non-Markovian Evolution Equations

The problem of description of the evolution of the microscopic phase density and its generalizations is discussed. With this purpose, the sequence of marginal microscopic phase densities is introduced, and the appropriate BBGKY hierarchy for these microscopic distributions and their average values is formulated. The microscopic derivation of the generalized evolution equation for average value of the microscopic phase density is given and the non-Markovian generalization of the Fokker-Planck collision integral is deduced.

physics.plasm-ph↗