Table of contents

This paper is a preface to the proceedings of the XXXI International Conference on Equations of State for Matter, which was held in Elbrus settlement, in the Kabardino-Balkar Republic of the Russian Federation, during March 1-6, 2016. The conference was devoted to the seventieth anniversary of birth of Aleksey Vladimirovich Bushman (16.10.1946-6.12.1993), the author of classic works on equations of state for matter over a wide range of thermodynamic parameters on phase diagram.

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

A caloric equation-of-state model, which represents the relation of pressure with density and internal energy, is applied for titanium in the bcc and liquid phases. Thermodynamic characteristics along the cold-compression curve at T = 0 and Hugoniots are calculated for the metal and compared with available data from shock-wave experiments at high energy densities.

The atomic number scaling of electron binding energies in the free atoms is found. It is demonstrated in the calculations by the different theoretical models and in the experimental data. Hence the simple way to estimate an inner binding energy level in a free atom is proposed.

Lithium—the lightest alkali metal exhibits unexpected structures and electronic behavior at high pressures. Like the heavier alkali metals, Li is bcc at ambient pressure and transforms first to fcc (at 7.5 GPa). The post-fcc high-pressure form Li-cI 16 (at 40-60 GPa) is similar to Na-cI 16 and related to more complex structures of heavy alkalis Rb-oC52 and Cs- oC84. The other high pressure phases for Li (oC88, oC40, oC24) observed at pressures up to 130 GPa are found only in Li. The different route of Li high-pressure structures correlates with its special electronic configuration containing the only 3 electrons (at 1s and 2s levels). Crystal structures for Li are analyzed within the model of Fermi sphere-Brillouin zone interactions. Stability of post-fcc structures for Li are supported by the Hume-Rothery arguments when new diffraction plains appear close to the Fermi level producing pseudogaps near the Fermi level and decreasing the crystal energy. The filling of Brillouin-Jones zones by electron states for a given structure defines the physical properties as optical reflectivity, electrical resistivity and superconductivity. To understand the complexity of structural and physical properties of Li above 60 GPa it is necessary to assume the valence electron band overlap with the core electrons and increase the valence electron count under compression.

The paper examines the reaction of an isotropic solid to infinitesimal and finite density perturbations. The boundary of stability against relatively small homogeneous and inhomogeneous deformations, and also the kinetic boundary of strength of a Lennard-Jones solid are determined in molecular dynamics experiments at negative pressures. It is shown that on the spinodal a solid retains its reducing reaction to small long-wave inhomogeneous perturbations. The work of formation of a critical pore also has a nonzero value on the spinodal.

Quantum-statistical calculations of shock compressibility of iron are performed. Electronic part of thermodynamic functions is calculated in the framework of three quantum-statistical approaches: the Thomas-Fermi, the Thomas-Fermi with quantum and exchange corrections and the Hartree-Fock-Slater models. The influence of ionic part of thermodynamic functions is taken into account separately with using three models: the ideal gas, the one-component plasma and the charged hard spheres models. The results of calculations are presented in the pressure range from 1 to 10⁷ GPa for samples with initially densities 7.85, 4.31 and 2.27 g/cm³. Calculated Hugoniots are compared with available experimental data.

A novel approach to calculate thermodynamically consistent shell corrections in wide range of parameters is used to predict the region of validity of the Thomas-Fermi approach. Calculated thermodynamic functions of electrons at high density are consistent with the more precise density functional theory. It makes it possible to work out a semi-classical model applicable both at low and high density.

In the framework of the theory of inhomogeneous electron gas, we consider a model to calculate the static multipole polarizability. The analysis shows the possibility of the specific dependence of the electron density perturbation (potential) of an atom in a weak external electrostatic field.

The semiempirical free-energy relation for hydrostatically compressed isotropic solid was written for body-centered-cubic (bcc) vanadium as a function of the specific volume and temperature with the phonon component and the contribution of the electronic subsystem. According to the thermodynamic rules the thermal as well as caloric equations of state are defined through the partial derivatives of free energy. A thermal equation of state gives the pressure as a function of volume and temperature. Caloric equation of state specifies the energy as a function of volume and temperature also. The proposed equations of state of bcc vanadium have been verified by comparison of calculated high-pressure isotherms, heat capacity, volume thermal expansion coefficient and Hugoniot with experimental data. The developed equations of state allow to calculate thermal properties of compressed bcc vanadium under static pressure and shock pressures 0-70 GPa and temperatures 100-1000 K.

A simple caloric equation-of-state model is proposed to describe thermodynamic properties of solid materials without phase transitions with the minimum number of parameters as initial data. The thermal vibrations of the crystal lattice are described by the Debye approximation. The parameter values on the zero isotherm are calculated analytically from the generalized form of the Grüneisen function. Thermodynamic characteristics are calculated in the wide range of densities and pressures. The results of the theoretical calculations for these materials are exhaustively compared with the available experimental data for high energy densities.

The results of numerical experiments on modeling of shock wave loading of solid and porous heterogeneous materials on the example of molybdenum and some alloys included molybdenum as a component are presented. A thermodynamically equilibrium model is applied to describe the behavior of solid and porous materials. This model ensures good compliance with the experiment in a wide range of pressures. The gas in pores, which is a component of the medium, is taken into account in this model. The equation of state of the Mie-Grüneisen type with allowance for the dependence of the Grüneisen coefficient on temperature is used for condensed phases. The applied model allows the behavior of the molybdenum with porosity from 1 to 3 to be calculated under shock-wave loading at pressures above 5 GPa in the one-velocity and one-temperature approximations, as well as on the assumption of equal pressures for all the phases. Computational results are compared with the well-known experimental results obtained by different authors. The model permits the shock-wave loading of solid and porous alloys with molybdenum in their composition to be described reliably solely by using species parameters.

The paper presents analysis of experimental data on hydrostatic and shock-wave compression of TATB energy-saturated material. The semi-empirical Mie–Grüneisen equation of state was used to describe thermodynamic properties of metastable molecular crystals without considering phase transitions. The equation of state describes experimental data on isothermal compression of a molecular crystal, and this data are obtained using the powder diffraction method. The Hugoniot curve expression plausibly describes shock-compression data on the studied material having various initial porosities.

Ultrafine materials were produced under conditions of extreme energy effects on the mixture of graphite and Ni-Mn catalysts. For the purpose to obtain various forms of carbon, including diamond-like forms, experiments were performed on a MIG high-current generator with the current amplitude of 2-2.5 MA and current rise time of 100 ns. The composition of the explosion products was studied using x-ray diffraction and x-ray phase analyses, the impedance spectroscopy, optical and scanning electron microscopy, x-ray microanalysis and energy dispersive x-ray analysis and the laser confocal Raman microscopy. It was found that the carbon in the studied materials is in the graphite, diamond-like (the faceted particles or agglomerates of faceted particles in size about or less than 250 nm) and amorphous forms.

A series of numerical experiments on shock loading of graphite between water layers is realized. A simple model of the phase transition of graphite to diamond is formulated. The general scheme of the computational experiment is based on mechanical and thermal interactions of different substances (graphite, diamond, water) subjected to impact by a massive steel flyer in a cylindrical channel. The process of graphite-to-diamond transformation is traced out. The important problem of retaining the formed diamond sample and some favorable conditions to solve this question are discussed.

The detonation nanodiamond is a new perspective material. Ammunition recycling with use of high explosives and obtaining nanodiamond as the result of the detonation synthesis have given a new motivation for searching of their application areas. In this work nanodiamond powder has been investigated by the method of synchronous thermal analysis. Experiments have been carried out at atmospheric pressure in the environment of argon. Nanodiamond powder has been heated in the closed corundum crucible at the temperature range of 30-1500 °C. The heating rates were varied from 2 K/min to 20 K/min. After the heat treatment, the samples have been studied by the x-ray diffraction and the electron microscopy. As one of the results of this work, it has been found that the detonation nanodiamond has not started the transition into graphite at the temperature below 800 °C.

An analysis is presented of experimental data where fluid-fluid phase transitions are observed for different substances at high temperatures with triple points on melting curves. Viscosity drops point to the structural character of the transition, whereas conductivity jumps remind of both semiconductor-to-metal and plasma nature. The slope of the phase equilibrium dependencies of pressure on temperature and the consequent change of the specific volume, which follows from the Clapeyron-Clausius equation, are discussed. P(V, T) surfaces are presented and discussed for the phase transitions considered in the vicinity of the triple points. The cases of abnormal P(T) dependencies on curves of phase equilibrium are in the focus of discussion. In particular, a P(V, T) surface is presented when both fluid-fluid and melting P(T) curves are abnormal. Particular attention is paid to warm dense hydrogen and deuterium, where remarkable contradictions exist between data of different authors. The possible connection of the P(V, T) surface peculiarities with the experimental data uncertainties is outlined.

In this work, the atomistic simulations of rapid melting of aluminum are performed. We use the two-temperature approach separately describing the ionic and electronic subsystems of crystal. Both ideal and defect states of initial lattice are considered. The dependence of melting temperature on pressure is investigated in the simulations of thermal equilibrium establishment in the systems with plate interphase boundaries. Non-equilibrium melting of aluminum is studied in simulations with the constant rate of heat energy supply. The maximal temperatures of overheated material before complete melting are obtained in dependence of energy supply rate. Presence of initial defects of lattice substantially decreases the overheating of material. Electronic heat conductivity significantly accelerates the thermal equilibrium establishment in systems with interphase boundaries and decreases the drop of temperature after beginning of melting in the systems with constant rate of heating.

We discuss various thermodynamic equations used to represent the properties along the saturation line (fluid density, gas density, order parameter, mean diameter, etc) in a neighborhood of the critical temperature T_c. These properties are described scaling functions, depending on some parameters including the critical exponents α and β. Along with well-known models, we investigate a new model that represents the mean diameter as a sum of two scaling members in the critical region. The first term of this sum depends on the exponent, a and the second one depends on exponent, 2β. In the paper is given a methodological rationale for the new function representing the mean diameter. We have made numerical estimates for sulphur hexafluoride using the parameters involving with the above scaling equations.

Thermal accommodation coefficients at collisions of solitary argon atoms at room temperature with iron clusters at temperatures 200-2500 K are calculated. Molecular dynamics method is applied. Finnis-Sinclair potential is used to describe interaction between iron atoms in clusters. The incident atom interacts with a cluster through the Buckingham potential. The number of incident atom trajectories is from 10000 to 100000. Initial velocities of incident atoms obey the Maxwell distribution. Thermal accommodation coefficient is calculated for 2 sizes of cluster, 9 and 27 atoms.

Anomalous phase diagrams in subclass of simplified ("non-associative") Coulomb models is under discussion. The common feature of this subclass is absence on definition of individual correlations for charges of opposite sign. It is e.g. modified OCP of ions on uniformly compressible background of ideal Fermi-gas of electrons OCP(∼), or a superposition of two non-ideal OCP(∼) models of ions and electrons etc. In contrast to the ordinary OCP model on non-compressible ("rigid") background OCP(#) two new phase transitions with upper critical point, boiling and sublimation, appear in OCP(∼) phase diagram in addition to the well-known Wigner crystallization. The point is that the topology of phase diagram in OCP(∼) becomes anomalous at high enough value of ionic charge number Z. Namely, the only one unified crystal- fluid phase transition without critical point exists as continuous superposition of melting and sublimation in OCP(∼) at the interval (Z₁ < Z < Z₂). The most remarkable is appearance of pseudo-critical points at both boundary values Z = Z₁ ≈ 35.5 and Z = Z₂ ≈ 40.0. It should be stressed that critical isotherm is exactly cubic in both these pseudo-critical points. In this study we have improved our previous calculations and utilized more complicated model components equation of state provided by Chabrier and Potekhin (1998 Phys. Rev. E 58 4941).

An experimental technique based on fast electrical heating for investigation of thermophysical properties of refractory materials under high pressures and at high temperatures is considered. A set of thermophysical properties of refractory materials such as specific enthalpy, specific heat capacity, specific resistivity, melting heat of eutectic Mo-C and thermal expansion of graphite and tantalum were determined. The obtained temperature of eutectic melting of MoC_0.82 shows close agreement with equilibrium Mo-C phase diagram.

It is shown that, for the temperature determination of the isothermal opaque bodies system, one can use the same techniques those are used to determine the temperature of a free-radiating opaque body. For an isothermal system of opaque bodies, a relationship was obtained, which relates the wavelength of maximum spectral radiation, the spectral effective emissivity and the thermodynamic temperature. In particular, this relationship can be used as an additional condition to determine the thermodynamic temperature of the isothermal system of bodies by the thermal radiation spectrum of the target surface, when the effective emissivity of the radiation source is unknown.

The methods of investigations of a thermal conductivity of materials in the field of centrifugal radial and circumferential and vibration accelerations have been developed. The setup for investigation of thermophysical characteristics properties of materials on a spin rig, using a vacuum chamber, under the influence of centrifugal radial and circumferential accelerations and on a vibration rig under the influence of vibration accelerations have been proposed. The results of the investigations of an unsteady thermal state of heat-conductors (metal samples) in the field of centrifugal and vibration accelerations are given. From the analysis of the results of experimental investigations one can conclude that the thermal conductivity of the heat-conductors increases significantly by increasing the rotation frequency or amplitude of oscillations in comparison with a steady state. Thus, this increase of the thermal conductivity is associated with an increase of the electron drift velocity under the influence of centrifugal and vibration accelerations according to Wiedemann-Franz law. The results obtained are of practical importance for the calculations of the thermal state of the rotating parts of aircraft engines and other energy turbomachines.

The positive ions of 3d metal and argon compounds (metal argide ions, MAr⁺) play essential role in the mass spectrometry with argon plasma sources. At the same time their thermodynamical properties are still not sufficiently studied. Rough estimations of the internal partition functions of MAr⁺ have been made by Witte and Houk in order to calculate the concentration ratio between metal and metal argide ions in the plasma. In this work we performed more accurate estimations of the internal partition functions for VAr⁺ and CoAr⁺, for which the experimental measurements of molecular constants are available. The thermodynamic functions and equilibrium constant for reaction M⁺ + Ar = MAr⁺ were obtained for the temperatures up to 104 K. The molecular constants were used to construct the potential curves for the ground and excited states of the molecules. The one-dimensional Schrodinger equation was solved using the Level code to find the rovibronic levels of the electronic states for the specified potential. Different potential models such as a simple Morse potential and the potential with the long range electrostatic attraction were used for comparison.

We consider the lattice gas approach to statistical mechanics of fluid adsorbed on random surfaces with fluid-fluid and fluid-surface potentials. It was shown that effective Hamiltonian contains quenched random interactions and random site fields. Their statistical features combine the properties of random geometry and fluid-fluid pair interaction potential. The high-temperature expansion leads to infinite-ranged random field model and Sherrington–Kirkpatrick spin-glass model. Thermodynamic properties are evaluated using replica theory procedure widely used to analyze quenched disorder systems. On the other hand we consider the random field model in random graph with finite connectivity instead of previous "infinite-ranged" approximations. This model has been investigated using finite connectivity technique. The replica symmetry ansatz for the order function is expressed in terms of an effective-field distribution. Analysis of random geometry effects on thermodynamic properties in such approach was done for the first time.

The generalization of thermodynamics in formalism of fractional derivatives is presented. One-parametric "fractal" state equation with second virial coefficient is obtained. The calculation of entropy S and compressibility z of the refrigerant freon R409B for the pressure range from 0.01 to 3.8 MPa and temperature range from 210 to 370 K is given.

The pressure driven flow of a viscous incompressible fluid in a 2D channel with sudden contraction and expansion is investigated numerically. The attention is concentrated on studying conditions of occurrence of the elongational flow in a narrow section of the channel. To this end, interconnection between flow patterns and axial velocities is analyzed at different Reynolds numbers.

The flow peculiarities of the Newtonian and Carreau-Yasuda power-law fluids in a microchannel with the striped superhydrophobic wall is studied numerically. The driving forces leading to deviation of streamlines from the channel axis are analyzed.

The dynamic processes which take place during high-speed impact of two metal plates with different densities are investigated using three-dimensional numerical simulations. It is shown that as a result of the impact the Rayleigh-Taylor instability forms which leads to the formation of three-dimensional ring-shaped structures on the surface of the metal with smaller density. The comparative analysis of the metals interface deformation process with the use of different equations of state is performed.

With the use of the molecular dynamic simulations, we investigated the effect of the high-speed (500 m/s, 1000 m/s) copper nanoparticle impact on the mechanical properties of an aluminum surface. Dislocation analysis shows that a large number of dislocations are formed in the impact area; the total length of dislocations is determined not only by the speed and size of the incoming copper nanoparticle (kinetic energy of the nanoparticle), but by a temperature of the system as well. The dislocations occupy the whole area of the aluminum single crystal at high kinetic energy of the nanoparticle. With the decrease of the nanoparticle kinetic energy, the dislocation structures are formed in the near-surface layer; formation of the dislocation loops takes place. Temperature rise of the system (aluminum substrate + nanoparticle) reduces the total dislocation length in the single crystal of aluminum; there is deeper penetration of the copper atoms in the aluminum at high temperatures. Average energy of the nanoparticles and room temperature of the system are optimal for production of high-quality layers of copper on the aluminum surface.

This article presents calculation of the nucleation rate for liquid metals (Al, Fe, Mo) based on molecular dynamic simulation for embedded atom method (EAM) potentials. The dependence of nucleation rate on pressure and temperature could be approximated accurately in the form of classical nucleation theory taking into account surface tension dependency on pore radius σ = σ₀/(1 + 2δ/r), where σ—surface tension, δ—the Tolman length. Basing on the results of the calculations, we have developed a model allowing calculating the spall strength of liquid metals under tension using such parameters as surface tension, viscosity, which could be measured experimentally. The obtained results for Mo and Al are consistent with experimental data and direct MD calculations at strain rates approx. 10¹⁰-10¹¹ s^-1.

An accurate description of the vibrational density of states is required for calculation of thermodynamic properties of crystal lattices as well as defect migration rates in the Vineyard theory framework. In this work we use EAM and MEAM interatomic potentials and apply the zero temperature lattice dynamics calculations and the velocity autocorrelation function calculations at finite temperatures to study vibrational density of states in bcc molybdenum and bcc uranium lattices. The latter case is especially interesting since γ-U is thermodynamically not favorable at low temperatures and is not observed in experiments.

Molecular dynamics study of shear viscosity behavior of liquid aluminum is performed. The embedded atom method potential is used at the simulation of isobaric cooling. The viscosity is calculated using the Green–Kubo formula. The stress autocorrelation functions are obtained in the range 300-1200 K. The calculated kinematic viscosity is in agreement with the experimental data for the temperatures above melting temperature. The steep change of the shear viscosity is found below 650 K which we associate with the glass transition and is in a good agreement with the temperature which is obtained using the calorimetric criterion Kolotova et al (2015 J. Non-Cryst. Solids 429 98). The viscosity coefficient can not be calculated using the direct atomistic simulations below that temperature.

In this paper, we present our first results in the study of the details of nucleation in the homogeneous carbon gas phase using computer calculations with molecular dynamics methods. Direct and controlled molecular-dynamics approaches are used and two reactive potentials (ReaxFF and AIREBO) are compared. The calculations have shown that the nucleation process in the AIREBO model is going more actively than in the ReaxFF one.

Molecular-dynamic investigations of Al+Cu, Al+Ti and Al+Mg nanocomposite strength under high-rate uniaxial tension were carried out in this work. We consider two different mechanisms of reduction of the tensile strength of a material with inclusions in comparison with a pure material of matrix. The first mechanism is connected with a stress concentration in matrix near a stiff and strong inclusion (Ti, Cu); in this case, the fracture occurs inside the matrix and does not touch the inclusion. The second mechanism acts in the case of a soft and weak inclusion (Mg); the fracture begins inside the inclusion and thereafter propagates into the matrix. The tensile strength of the systems is determined at varied strain rates (in the range from 0.1/ns to 30/ns at the temperature 300 K) and varied temperatures (in the range from 300 K to 900 K at the strain rate 1/ns).

Ion diffusion in a liquid usually could be treated as a movement of an ion cluster in a viscous media. For small ions this leads to a special feature: diffusion coefficient is either independent of the ion size or increases with it. We find a different behavior for small ions in liquid xenon. Calculation of the dependence of an ion diffusion coefficient in liquid xenon on the ion size is carried out. Classical molecular dynamics method is applied. Calculated dependence of the ion diffusion coefficient on its radius has sharp maximums at the ion radiuses 1.75 and 2 Å. Every maximum is placed between two regions with different stable ion cluster configurations. This leads to the instability of these configurations in a small region between them. Consequently ion with radius near 1.75 or 2 Å could jump from one configuration to another. This increases the speed of the diffusion. A simple qualitative model for this effect is suggested. The decomposition of the ion movement into continuous and jump diffusion shows that continuous part of the diffusion is the same as for the ion cluster in the stable region.

We study structural properties of cubic and tetragonal phases of U-Mo alloys using atomistic simulations: molecular dynamics and density functional theory. For pure uranium and U-Mo alloys at low temperatures we observe body-centered tetragonal (bct) structure, which is similar to the metastable γ°-phase found in the experiments. At higher temperatures bct structure transforms to a quasi body-centered cubic (q-bcc) phase that exhibits cubic symmetry just on the scale of several interatomic spacings or when averaged over time. Instantaneous pair distribution function (PDF) differs from PDF for the time-averaged atomic coordinates corresponding to the bcc lattice. The local positions of uranium atoms in q-bcc lattice correspond to the bct structure, which is energetically favourable due to formation of short U-U bonds. Transition from bct to q-bcc could be considered as ferro-to paraelastic transition of order-disorder type. The temperature of transition depends on Mo concentration. For pure uranium it is equal to about 700 K, which is well below than the upper boundary of the stability region of the α-U phase. Due to this reason, bct phase is observed only in uranium alloys containing metals with low solubility in α-U.

The results of the atomistic simulation of a superionic transition and melting of stoichiometric UN₂, UO₂ and TiH₂ have been presented. Simulation shows that superionic transitions of UO₂ and TiH₂ take place at temperature below melting temperature, while UN₂ did not show such feature. This difference in properties of studied structures is caused by various gap between formation energies of Frenkel pair defects for sublattices. The possibility of describing the superionic transition within the theory of second-order phase transitions has been discussed, the conditions of the existence of superionic transition have been discussed.

Within the frame of molecular dynamics the equations of state of noble gases and their mixtures have been obtained by means of time averaging procedure for virial based equation with account of three-body interaction. It has been shown, that equations of state can be extrapolated by van-der-Waals-type equations. The corresponding parameters have been calculated. A visible foliation of Xe and Kr components of Kob-Andersen mixture has been found.

Molecular dynamics is applied to calculate diffusion coefficients of n-triacontane C₃₀H₆₂ using Einstein-Smoluchowski and Green-Kubo relations. The displacement 〈Δr²〉(t) has a subdiffusive part 〈Δr²〉 ∼ t^α, caused by molecular crowding at low temperatures. Longtime asymptotes of 〈v(0)v(t)〉 are collated with the hydrodynamic tail t^-3/2 demonstrated for atomic liquids. The influence of these asymptotes on the compliance of Einstein-Smoluchowski and Green-Kubo methods is analyzed. The effects of the force field parameters on the diffusion process are treated. The results are compared with experimental data.

Non-congruent gas-liquid phase transition (NCPT) have been studied previously in modified Coulomb model of a binary ionic mixture C(+6) + O(+8) on a uniformly compressible ideal electronic background /BIM(∼)/. The features of NCPT in improved version of the BIM(∼) model for the same mixture on background of non-ideal electronic Fermi-gas and comparison it with the previous calculations are the subject of present study. Analytical fits for Coulomb corrections to equation of state of electronic and ionic subsystems were used in present calculations within the Gibbs-Guggenheim conditions of non-congruent phase equilibrium. Parameters of critical point-line were calculated on the entire range of proportions of mixed ions 0 < X < 1. Strong "distillation" effect was found for NCPT in the present BIM(∼) model. Just similar distillation was obtained in the variant of NCPT in dense nuslear matter. The absence of azeotropic compositions was revealed in studied variants of BIM(∼) in contrast to an explicit existence of the azeotropic compositions for the NCPT in chemically reacting plasmas and in astrophysical applications.

A new effective two-fluid model is presented. This model is based on the developed equation of state of binary mixtures. In this model division of all components of mixture into two groups with close well-depth parameters is supposed. Thus, the multicomponent mixture is presented in the form of effective two-component fluid. This technique precludes mistake made by effective one-fluid model in calculation of thermodynamic parameters of multicomponent mixture with considerably different well-depth parameters of components. Calculations of the ternary mixtures of various compositions are carried out. It is shown that the results of calculations obtained with the presented method are in better agreement with the experimental data as compared to the similar calculations based on the effective one-fluid model.

The results of experimental studies of methane–n-pentane mixture filtration in a porous medium under isothermal conditions in pressure range typical for gas-condensate reservoirs are presented. Interest in the filtration problem of such mixtures is aroused by the need to intensify production of heavy fractions of gas-condensate-valuable hydrocarbons, consisting of methane and its higher homologues. Different flow regimes including oscillatory one are observed during gas-condensate extraction under natural conditions. Our studies have shown that there are multiple flow regimes including self-oscillating one under isothermal conditions for this type of mixtures depending on the initial pressure, the kind of the mixture's phase diagram and the permeability coefficients of the liquid and gas phases in the porous medium.

At the present time, a considerable part of the largest dry gas reservoirs in Russia are found in the stage of declining production, therefore active exploitation of gas-condensate fields will begin in the coming decades. There is a significant discrepancy between the project and the actual value of condensate recovery factor while producing reservoir of this type, which is caused by insufficient knowledge about non-equilibrium filtration mechanisms of gas-condensate mixtures in reservoir conditions. A system of differential equations to describe filtration process of two-phase multicomponent mixture for one-, two- and three-dimensional cases is presented in this work. The solution of the described system was made by finite-element method in the software package FlexPDE. Comparative distributions of velocities, pressures, saturations and phase compositions of three-component mixture along the reservoir model and in time in both cases of equilibrium and non-equilibrium filtration processes were obtained. Calculation results have shown that system deviation from the thermodynamic equilibrium increases gas phase flow rate and reduces liquid phase flow rate during filtration process of gas-condensate mixture.

To eliminate shortcomings of raw plant materials pelletizing process with thermal treatment (low-temperature pyrolysis or torrefaction) can be applied. This paper presents a mathematical model of energy-technological complex (ETC) for combined production of heat, electricity and solid biofuels torrefied pellets. According to the structure the mathematical model consists of mathematical models of main units of ETC and the relationships between them and equations of energy and material balances. The equations describe exhaust gas straining action through a porous medium formed by pellets. Decomposition rate of biomass was calculated by using the gross-reaction diagram, which is responsible for the disintegration of raw material. A mathematical model has been tested according to bench experiments on one reactor module. From nomographs, designed for a particular configuration of ETC it is possible to determine the basic characteristics of torrefied pellets (rate of weight loss, heating value and heat content) specifying only two parameters (temperature and torrefaction time). It is shown that the addition of reactor for torrefaction to gas piston engine can improve the energy efficiency of power plant.

A large-scale self-similar crystallized phase of finite gravitationally neutral universe (GNU)—huge GNU-ball—with spherical 2D-boundary immersed into an endless empty 3D- space is considered. The main principal assumptions of this universe model are: (1) existence of stable elementary particles-antiparticles with the opposite gravitational "charges" (M+_gr and M_-gr), which have the same positive inertial mass M_in = |M_±gr| ≥ 0 and are equally presented in the universe during all universe evolution epochs; (2) the gravitational interaction between the masses of the opposite charges" is repulsive; (3) the unbroken baryon-antibaryon symmetry; (4) M_+gr-M_-gr "charges" symmetry, valid for two equally presented matter-antimatter GNU-components: (a) ordinary matter (OM)-ordinary antimatter (OAM), (b) dark matter (DM)-dark antimatter (DAM). The GNU-ball is weightless crystallized dust of equally presented, mutually repulsive (OM+DM) clusters and (OAM+DAM) anticlusters. Newtonian GNU-hydrodynamics gives the observable spatial flatness and ideal Hubble flow. The GNU in the obtained large-scale self-similar crystallized phase preserves absence of the cluster-anticluster collisions and simultaneously explains the observable large-scale universe phenomena: (1) the absence of the matter-antimatter clusters annihilation, (2) the self-similar Hubble flow stability and homogeneity, (3) flatness, (4) bubble and cosmic-net structures as 3D-2D-1D decrystallization phases with decelerative (a ≤ 0) and accelerative (a ≥ 0) expansion epochs, (5) the dark energy (DE) phenomena with Λ_VACUUM = 0, (6) the DE and DM fine-tuning nature and predicts (7) evaporation into isolated huge M_±gr superclusters without Big Rip.

Linear programming methods were used for solving the optimization problem of schemes and operation modes of distributed generation energy complexes. Applicability conditions of simplex method, applied to energy complexes, including installations of renewable energy (solar, wind), diesel-generators and energy storage, considered. The analysis of decomposition algorithms for various schemes of energy complexes was made. The results of optimization calculations for energy complexes, operated autonomously and as a part of distribution grid, are presented.

Internet resources (databases, web sites and others) on thermodynamic properties R = (p,T,s,...) of technologically important substances are analyzed. These databases put online by a number of organizations (the Joint Institute for High Temperatures of the Russian Academy of Sciences, Standartinform, the National Institute of Standards and Technology USA, the Institute for Thermal Physics of the Siberian Branch of the Russian Academy of Sciences, etc) are investigated. Software codes are elaborated in the work in forms of "client functions" those have such characteristics: (i) they are placed on a remote server, (ii) they serve as open interactive Internet resources. A client can use them for a calculation of R properties of substances. "Complex client functions" are considered. They are focused on sharing (i) software codes elaborated to design of power plants (PP) and (ii) client functions those can calculate R properties of working fluids for PP.

In the paper, we discuss such unexpected features in the wave evolution in solids as strongly nonlinear uniaxial elastic compression in a picosecond time range, a departure from self-similar development of the wave process which is accompanied with apparent sub-sonic wave propagation, changes of shape of elastic precursor wave as a result of variations in the material structure and the temperature, unexpected peculiarities of reflection of elastic-plastic waves from free surface.

The study of destruction of samples with crack-type macro defects in shockwave microsecond duration range mode with amplitude up to 1 GPa was carried out using the magnetic pulse method of pressure pulse creation. The result analysis held on the basis of computer modeling of stressed condition and thermodynamic approach. The relation between the surface fracture energy and the material parameter, such as the energy accumulation time required for destruction, was revealed.

The results of numerical simulation of wave formation under an oblique impact of metal plates during explosion welding are presented. The numerical simulation was carried out on the basis of the elastoplastic approximation. It is shown that the elastoplastic behavior of metals may be a possible source of instabilities. Further evolution of the process of wave formation and the formation of a periodic wave structure of the interface are already determined by the hydrodynamic behavior of materials. The temperature at the contact boundary of plates obtained in the calculation exceeds the melting point. The calculated wavelengths coincide with the experimental data.

Glycerol and silicone oil were studied experimentally under shock-wave loading conditions at different temperatures and strain rates. It was found that the temperature has a significant influence on the spall strength of glycerol near the point of phase transition and weak influence on the spall strength of silicone oil. The spall strength of the silicone oil does not depend on the strain rate also. Dynamic viscosity of glycerol measured at the wave front found to be strain rate sensitive.

Limestone behavior under explosive loading was investigated. The behavior of the limestone by the action of the three types of explosives, including granular, ammonite and emulsion explosives was studied in detail. The shape and diameter of the explosion craters were obtained. The observed fragments after the blast have been classified as large, medium and small fragments. Three full-scale experiments were carried out. The research results can be used as a qualitative test for the approbation of numerical methods.

In a set of shock experiments under comparable porosities at pressures of about 35 GPa the melting behavior of porous copper was investigated. All experiments were performed with the impedance corrected sample recovery system and different degrees of decompression were used. It was possible to reduce the degree of molten metal in parts of the sample after sample recovery down to zero. The avoiding of melting was possible only by avoiding larger degrees of adiabatic decompression. This behavior implies a complete dependence of the melting on the release path for porous copper under the given conditions. The zones, where the melting processes are avoided, include also areas with intense micro jetting. Because also in these zones melting does not occur, it is possible that the melting curve of copper along the Hugoniot is not yet solved. The experiments have verified, that it is possible to use equation-of-state calculations for the solid state only, concerning the pressure area of currently commercial interest for the production of nitrides and diamond with copper-powder as pressure medium. Furthermore in this work the role of different parts of the sample recovery capsule is described to improve the comparability of shock wave synthesis experiments. On the other hand, the experimentally results given in this work show significant differences to data, obtained by a number of simulations.

A mixture of powdered Cu and CuO has been subjected to shock-wave pressure of 350 kbar with following quenching of the vacuum-encapsulated product to 77 K. The ac magnetic susceptibility measurements of the samples have revealed metastable superconductivity with T_c ≈ 19 K, characterized by glassy dynamics of the shielding currents below T_c. Comparison of the ac susceptibility and the DC magnetization measurements infers that the superconductivity arises within the granular interfacial layer formed between metallic Cu and its oxides due to the shock-wave treatment.

The paper presents new experimental data on properties of porous media under shock-wave loading. We considered materials with different nature of porosity. The porosity in the silicone rubber and the epoxy resin was produced by glass microspheres filler. Open porosity was realized in a fibrous material made from glass fibers with corundum. It was shown that two-wave configuration was formed in materials with closed porosity. Such structure of the pulse with a precursor was not observed in samples with open porosity. As a result of analysis of experimental data, Hugoniots for the investigated materials were obtained.

The development of macroparticles acceleration methods for high-speed impact simulation in a laboratory is an actual problem due to increasing of space flights duration and necessity of providing adequate spacecraft protection against micrometeoroid and space debris impacts. This paper presents results of experimental study of a two-stage light- gas magnetoplasma launcher for acceleration of a macroparticle, in which a coaxial plasma accelerator creates a shock wave in a high-pressure channel filled with light gas. Graphite and steel spheres with diameter of 2.5-4 mm were used as a projectile and were accelerated to the speed of 0.8-4.8 km/s. A launching of particle occurred in vacuum. For projectile velocity control the speed measuring method was developed. The error of this metod does not exceed 5%. The process of projectile flight from the barrel and the process of a particle collision with a target were registered by use of high-speed camera. The results of projectile collision with elements of meteoroid shielding are presented. In order to increase the projectile velocity, the high-pressure channel should be filled with hydrogen. However, we used helium in our experiments for safety reasons. Therefore, we can expect that the range of mass and velocity of the accelerated particles can be extended by use of hydrogen as an accelerating gas.

The paper presents the diagnostic system for velocity measurements in laser- driven equations of state experiments. Two Mach-Zehnder line-imaging VISAR-type (velocity interferometer system for any reflector) interferometers form a vernier measuring system and can measure velocity in the interval of 5 to 50 km/s. Also, the system includes a passive channel that records target luminescence in the shock wave front. Spatial resolution of the optical layout is about 5 μm.

The quark-gluon plasma fireball expansion, appearing in the collision of relativistic heavy ions, can be accompanied by the wave anomalies associated with the quark-hadron phase transition. Namely, the composite rarefaction wave, which includes the rarefaction shock, can arise instead of a simple rarefaction wave. The emphasis of the given work is focused on the special features of these wave processes induced by nonzero quark-gluon plasma velocity at the beginning of the hydrodynamic stage of the fireball expansion. The simulation has been conducted in the framework of relativistic hydrodynamics. The equation of state used is based on the variant of the MIT-bag model. The initial conditions are formulated under the assumption that the distributions of the energy density and the baryon number density are uniform, while the radial velocity changes linearly from zero at the center to the assigned value at the fireball border. The results of the calculations have shown the strong dependence of the wave phenomena observed on the initial velocity distribution.

Self-oscillating mode of reaction front propagation in multiphase flow in the porous medium with chemically active skeleton is investigated numerically. The considered flow represents an immiscible displacement process, such that the displacing fluid and the skeleton of the porous medium have chemically active components which react with production of gaseous phase. The calculations have demonstrated strong influence of the reaction kinetics on stability of the reactive flow. The presence of a time delay between the change of concentration of the reactants and the change of the reaction rate is shown to stimulate transition of the reaction front propagation to the oscillatory mode.

We performed the molecular dynamic simulations of the high-velocity impact of thin copper impactor with copper targets with both flat and nanostructured rear surface. It is shown that the spall fracture threshold can be increased due to the presence of nanostructures on the rear surface of target. Presence of protrusions changes the stress state and provokes an intensive plastic deformation. As a result, a part of the compression pulse energy dissipates due to the plastic deformation in this surface layer. It leads to decrease of the tensile wave amplitude and, consequently, an increase of the spallation threshold in terms of the incident shock wave intensity. The threshold increase is essential if the protrusion height is about the compression pulse width, which is controlled by the impactor thickness first of all.

A continuum model of tensile fracture of solid metals is formulated for the cases of pure aluminum and D16 alloy. It is verified within a wide range of strain rates using results of molecular dynamics simulations and known experimental data. The model considers the growth of spherical voids driven by plastic deformation in their vicinities. Both thermofluctuation nucleation of new voids and growth of the pre-existing ones are considered. The stress concentration areas near inclusions are taken into account in the case of alloy. The model is applied to description of the back-side spallation of metal targets exposed to the shock wave loading initiated by high-velocity impact; calculations are performed in 1D case. Results of comparison with known experimental back surface velocity histories are presented.

The rate of a homogeneous nucleation of nanovoids in expanded aluminum is researched in this work. Typical lifetime of the system in a metastable state at a negative pressure as well as coefficients of surface tension and nucleation frequency at the temperatures 300 and 500 K are obtained with the help of molecular dynamic simulation. The large value of the pre-exponential factor should be noted, which requires further detailed investigations.

Dynamic behavior of metals under intensive loading is characterized by intensive nucleation and growth of defects (microshears and microcracks) both under shock-wave compression and unloading conditions that may reduce to spallation and in some cases to multiple spallation. Spall fracture in material produced by the action of tensile stress in bulk of sample when two decompression waves collide. For higher amplitudes of shockwave the initiation of secondary spallation appears when intensity of residual wave is enough. The purpose of present investigation is consists on formulation of physical-mathematical model of dynamic behavior of metals under shock compression loadings. Plate impact test is considered. Wide range constitutive model based on the statistical theory for solids with defect (microshears and microcracks) was developed. Comparison of microstructure investigation and numerical simulation results of spall fracture (including secondary spallation) in vanadium is presented.

The results of coordinated experimental and numerical studies of fracture of materials and structures under impact are given in the present paper. Numerical simulation is carried out by the author finite element software package EFES, allowing to simulate a threedimensional setting behavior of complex structures under dynamic loads. Fracture of metallic materials and structures are investigated in the speed range of interaction 50-3000 m/s.

Manufacturing durable and high-strength concrete structures has always been a relevant objective. Therefore special attention has been paid to non-metallic composite reinforcement. This paper considers experimental and numerical studies of nature of fracture and crack formation in concrete beams with rod composite reinforcement. Fiber glass rods, 6 mm in diameter, have been used as composite reinforcement. Concrete elements have been tested under dynamic load using special pile driver. The obtained results include patterns of fracture and crack formation, maximum load value and maximum element deflection. Comparative analysis of numerical and experimental studies has been held.

Using modification of Maxwell model of viscoelastic medium, we have performed 2D simulations of the polymethylmethacrylate (PMMA) plates impingement at high velocities. Previously, we had investigated numerically the influence of the viscoelastic properties upon the dynamics of 1D shock-wave flows in PMMA. It was shown that, in a limit of weak shock waves, the accounting of the viscoelastic properties allows one to achieve a better agreement of calculated results and experimental data on the shock wave velocity magnitude than in the case of hydrodynamic calculations. In the present work, we make a generalization of the polymer material deformation model to the case of 2D stress state. The equation is written for the plastic deformation tensor, which describes the relaxation of the maximal shear stress.

This paper presents experiments on explosive compaction of boron carbide powder and modeling of the stress state behind the shock front at shock loading. The aim of this study was to obtain a durable low-porosity compact sample. The explosive compaction technology is used in this problem because the boron carbide is an extremely hard and refractory material. Therefore, its compaction by traditional methods requires special equipment and considerable expenses.

Deflagration-to-detonation transition (DDT) in aluminum-ammonium perchlorate (Al/AP) loose-packed charges (80% porosity) has been studied. The charges were manufactured from preliminary mechanoactivated mixtures. The mixtures placed in steel tubes 10 mm in diameter were ignited by Nichrome wire. It was found that it is possible to distinguish three parts corresponding to different stages of DDT process development. Steady-state detonation velocity reached the level of 2500 m/s at the distance of 90 mm from the ignition point.

Experiments on initiation of chemical transformation in mechanically activated thermit mixtures are described. The initiation was produced by shock loading of compact porous thermit specimens in a semi-enclosed volume by explosion of an HE charge. Energy losses for shock wave passing through the thermit specimens and expansion rate of the field of chemical transformations in a free space were estimated.

When a metal plate is subjected to a strong shock impact, its free surface emits a flow of particles of different sizes (shock-wave "dusting"). Traditionally, the process of dusting is investigated by the methods of pulsed x-ray or piezoelectric sensor or via an optical technique. The particle size ranges from a few microns to hundreds of microns. The flow is assumed to include also finer particles, which cannot be detected with the existing methods yet. On the accelerator complex VEPP-3-VEPP-4 at the BINP there are two experiment stations for research on fast processes, including explosion ones. The stations enable measurement of both passed radiation (absorption) and small-angle x-ray scattering on synchrotron radiation (SR). Radiation is detected with a precision high-speed detector DIMEX. The detector has an internal memory of 32 frames, which enables recording of the dynamics of the process (shooting of movies) with intervals of 250 ns to 2 μs. Flows of nano- and microparticles from free surfaces of various materials (copper and tin) have been examined. Microparticle flows were emitted from grooves of 50-200 μs in size and joints (gaps) between metal parts. With the soft x-ray spectrum of SR one can explore the dynamics of a single microjet of micron size. The dynamics of density distribution along micro jets were determined. Under a shock wave (∼ 60 GPa) acting on tin disks, flows of microparticles from a smooth surface were recorded.

Here we present experimental data on measuring condensed carbon nanoparticle sizes in trinitrotoluene (TNT) detonation. Nanoparticle sizes were determined from measured distributions of small-angle x-ray scattering (SAXS). The work was carried out at the VEPP- 4M (BINP) accelerator complex. In this work, we also carried out a SAXS simulation with a real spectrum on the SYRAFEEMA (Synchrotron Radiation Facility for Exploring Energetic Materials) station (wiggler radiation, TNT absorption, absorption of the DIMEX-3 detector). Comparison of the calculated and measured SAXS distribution allows one to obtain the dynamics of the average sizes of carbon nanoparticles behind the detonation front using a pink synchrotron radiation (SR) beam. The measured particle sizes in the chemical reaction zone are ≈ 2 nm. Carbon nanoparticles with a maximum size of ≈ 4-5 nm are found outside the chemical reaction zone.

This paper presents the results of electron microscopy and x-ray diffraction studies of the recovered carbonaceous residue (soot) from the detonation of some high explosives: TNT, a mixture of TNT and RDX (50/50), benzotrifuroxane, and triaminotrinitrobenzene. The use of the same experimental setup allowed a qualitative and quantitative comparison of the detonation products formed under similar conditions. The results clearly show differences in the morphology of graphite-like and diamond inclusions and in the quantitative content of nanodiamonds for the explosives used in this study.

The stability of one-dimensional flow, which occurs at the absence of influence of the boundaries, and instability at the edge of the charge has been investigated in liquid high explosive bis-(2-fluoro-2.2-dinitro-ethyl)-formal (FEFO) and in the mixtures of FEFO with methanol. The structure of the detonation wave was recorded by a VISAR interferometer and by high-speed streak camera. For FEFO it was found strong velocity oscillations in chemical reaction zone but the boundary at the edge of the charge was smooth. When the methanol concentration changes in the interval 10-20%, the stabilization of detonation front is observed and failure reaction waves are occurred at the edge of the charge. Further increase of the concentration of the inert diluent results in the instability of the detonation front at existing of the reaction failure waves. Obtained results show, therefore, that the failure reaction waves and stability of one-dimensional detonation front appear, in general, independently.

One of the methods of experimental investigation of cylindrical detonation wave formed by the multipoint initiation method is presented in this work. The experimental setup was specially developed for this purpose. Two types of "Nanogate" high-speed cameras were used in the experiments. The phenomenological descriptions of initiation process, dynamic of formation of detonation wave and gas dynamic flow of detonation products are presented. This method in combination with the other modern methods will allow carrying out more profound investigations of such problems.

The methods of mathematical modeling based on the latest experimental data are proposed to conduct a study of the cylindrical detonation process and gas dynamics of the explosion products. The numerical simulation of converging cylindrical detonation waves at multipoint initiation for the recent experiments in IPCP RAS was conducted. The results of the numerical simulation and the experiment are compared.

The Zeldovich-Neumann-Doering theory of ideal detonation allows one to describe adequately the detonation of charges with near-critical diameter. For smaller diameters, detonation velocity can differ significantly from an ideal value expected based on equilibrium chemical thermodynamics. This difference is quite evident when using non-ideal explosives; in certain cases, this value can be up to one third of ideal detonation velocity. Numerical simulation of these systems is a very labor-consuming process because one needs to compute the states inside the chemical reaction zone, as well as to obtain data on the equation of state of high-explosive detonation products mixture and on the velocity of chemical reaction; however, these characteristics are poorly studied today. For practical purposes, one can use the detonation shock dynamics model based on interrelation between local velocity of the front and its local curvature. This interrelation depends on both the equation of state of explosion products, and the reaction velocity; but the explicit definition of these characteristics is not needed. In this paper, experimental results are analyzed. They demonstrate interrelation between the local curvature of detonation front and the detonation velocity. Equation of detonation front shape is found. This equation allows us to predict detonation velocity and shape of detonation wave front in arbitrary geometry by integrating ordinary differential equation for the front shape with a boundary condition at the charge edge. The results confirm that the model of detonation shock dynamics can be used to describe detonation processes in non-ideal explosives.

Here we extend consistent simulations to reactive materials by the example of AB model explosive. The kinetic model of chemical reactions observed in a molecular dynamics (MD) simulation of self-sustained detonation wave can be used in hydrodynamic simulation of detonation initiation. Kinetic coefficients are obtained by minimization of difference between profiles of species calculated from the kinetic model and observed in MD simulations of isochoric thermal decomposition with a help of downhill simplex method combined with random walk in multidimensional space of fitting kinetic model parameters.

We examined the approximate method to calculate composition and thermodynamic parameters of hydrocarbons-air nonequilibrium explosion products based on the assumption of the existence of a partial chemical equilibrium. With excellent accuracy of calculating thermodynamic properties and species mass fraction the respective stiff system of detailed kinetics differential equations can be replaced by the one differential equation or the two differential equations and a system of algebraic equations. This method is always consistent with the detailed kinetic mechanism. The constituent equations of the method were derived and the respective computer code written. We examine the applicability of the method by solving the test problem. The proposed method simulation results are in excellent agreement with the detailed kinetics model results corresponding the stiff ordinary differential equation solver including NO time histories.

This paper considers the possibility of creating on new physical principles a highspeed current-limiting device (CLD) for the networks with voltage of 110 kV, namely, on the basis of the explosive switching elements. The device is designed to limit the steady short-circuit current to acceptable values for the time does not exceed 3 ms at electric power facilities. The paper presents an analysis of the electrical circuit of CLD. The main features of the scheme are: a new high-speed switching element with high regenerating voltage; fusible switching element that enables to limit the overvoltage after sudden breakage of network of the explosive switch; non-inductive resistor with a high heat capacity and a special reactor with operating time less than 1 s. We analyzed the work of the CLD with help of special software PSPICE, which is based on the equivalent circuit of single-phase short circuit to ground in 110 kV network. Analysis of the equivalent circuit operation CLD shows its efficiency and determines the CLD as a perspective direction of the current-limiting devices of new generation.

The autoignition of simple hydrocarbons, such as ethane, ethylene, and acetylene, in mixtures with oxygen diluted with Ar behind reflected shock waves in a temperature range of 1150-1800 K and a pressure of ∼ 0.1 MPa is studied using the chemiluminescence from electronically excited CH* (λ = 430 nm), C₂* (λ = 516.5 nm), OH* (λ = 308 nm), and CO₂* (λ = 363 nm). Our experimental results are in good agreement with the published data obtained under similar conditions. Numerical simulations within the framework of a well-tested kinetic mechanism closely reproduce the measured values of the ignition delay times and time profiles of the emission signals. A comparison of the experimental and calculated shapes of the emission signals made it possible to identify key reactions responsible for the chemiluminescence of the indicated emitters.

The experiments on the ignition of H₂-O₂ mixtures behind reflected shock waves were carried out. In these experiments the chemiluminescence of electronically excited OH* radicals (λ = 308 nm) at the early stage of the ignition induction period is studied over the temperature range of 800 < T < 1050 K at a pressure of 0.1 MPa. The OH* emission signal is measured for a time less than 1 ms, when the influence of physicochemical factors capable to influencing the homogeneous autoignition process such as flow turbulence in a boundary layer, various heterogeneous processes, and residual active particles is negligibly small. Significant difference between the ignition delay times derived from the pressure rise and sharp increase of the emission of electronically excited OH^* radicals was experimentally observed. The experiments showed that the onset of OH^* emission is always ahead of the time of pressure rise. Any regular dependence between the onset of OH^* emission and the initial temperature behind the reflected shock wave T₅₀ is not observed. This is indicative of a stochastic character of this process or hotspot ignition of the reactive mixture.

Studied is the influence of volume of hydrogen-air mixture, its composition and energy of its initiation on the formation of ignition centers before the front of spherical flame. During the experiments the mixture was placed into thin rubber envelopes of spherical shape having the initial volume of 7 and 40 m³. The mixture was initiated in the center of the reaction volume by the energy which was several times less than the critical energy of direct initiation of detonation. With increasing the initial volume of the mixture with the identical composition, registered is a decrease of the initiation energy at which the ignition centers before the front of spherical flame are formed.

The addition of hydrogen to the various hydrocarbon fuels being examined as a promising method for increasing the efficiency of the engine while improving their emission characteristics. This work is dedicated to experimental investigation of the ignition delay time C₃H₈-H₂ mixture in the air and analysis of the mechanisms responsible for the acceleration of chain reactions with the addition of hydrogen in propane, based on numerical simulation.

This paper represents experimental investigation of ignition of combustible gaseous mixture with reactive particles in the rapid compression machine at temperatures 950-1200 K and pressures 1.5-2.0 MPa. The experiments were carried out with stoichiometric methane-air mixture in the presence of coal particles with size 20-32 μm. It was found that the presence of these particles not only reduces ignition time but influences on the ignition temperature of mixture. It is ascertained that ignition time of methane in pure air is longer than with same mixture with addition coal dust. This difference is explained to preignition of methane near burning particles. It is shown that ignition of coal dust originates at the temperature of oxidant higher 850 K. Temperature of particles burning in methane-air and air environment heated by compression was measured. The mean temperature is 2500 K. It indicates possibility of premature ignition of gas mixture heated by compression to temperature 1000-1100 K by addition of coal particles.

The influence of small additions (0.3-2 ppm) of iron or carbon nanoparticles on ignition delay times in stoichiometric mixture of 20% (methane + oxygen) diluted in argon was investigated. The experiments were performed in 50 mm diameter shock tube behind reflected shock waves. The nanoparticles were synthesized in pyrolysis of 0.5-1% Fe(CO)₅ and 1-2% of C₆H₆ diluted in argon in the experiment before the ignition test. The residual nanoparticles were pulled into the flow behind incident and reflected shock wave from the shock tube walls and their volume fraction was measured by laser light extinction at the wavelength 633 nm. Additions of 0.3-2 ppm of iron nanoparticles to stoichiometric methane-oxygen mixture resulted in twofold decrease of ignition delays at temperatures below 1400 K relatively to calculated and experimental data for the mixture without nanoparticle addition. At additions of 0.4-1 ppm of carbon nanoparticles to stoichiometric methane-oxygen mixture a weak decrease of ignition delay relatively to the calculated data for the mixture without additives of carbon nanoparticles was observed.

The deceleration and attenuation of a detonation wave in hydrogen-air mixture was experimentally studied in a cylindrical channel. Inner walls of the wide section of the channel were covered with an acoustically absorbing layer. Experiments were carried out in hydrogen-air mixture at atmospheric pressure. Initially detonation was formed as a result of a deflagration to detonation transition. The dependence of velocity and pressure at the front of the detonation or shock wave on the thickness of the acoustically absorbing material and mixture composition (equivalence ratio) was presented. The results demonstrate that increasing the thickness of the porous material on the walls lead to further attenuation of the detonation wave to the point where it is not re-initiated at the distance of 15 calibers from the porous section. It was found that the recovery of the detonation wave after the passage of the acoustically absorbing section can happen if the shock wave velocity does not drop below Chapman-Jouguet acoustic velocity.

In the current work, stabilization of premixed laminar and lean turbulent flames for wide range of flow rates and equivalence ratios was performed. Methane-air mixture was ignited after passing through premixed chamber with beads and grids, and conical nozzle (Bunsen-type burner). On the edge of the nozzle a stabilized body-ring was mounted. Ring geometry was varied to get the widest stable flame parameters. This work was performed as part of the project on experimental investigation of premixed flames under microgravity conditions.

Diffusion torches in the transverse acoustic field studied experimentally. The structure and the luminosity of the torch were recorded by a high-speed camera with shadow device and photodetectors. The dependence of the length of a laminar methane plume on the average velocity and volumetric flow rate was measured. The frequency spectra of the luminosity of the flame at different flow rates of methane are obtained. Flame flicker frequency depending on the volume flow of methane had defined according to the obtained spectra. It was found that the flame flicker frequency is not dependent on the diameter of the burner. It is shown that the flickers are caused by changes in the geometric dimensions of the flame due to the convective instability of the column of hot gas surrounding the torch. The repetition frequency of the vortices in the column of hot gas surrounding the torch coincides with the frequency of the flicker of the flame. It is shown that the limits of flame detachment from burner and flame quenching does not change at the acoustic impact on the torch, the biggest acoustic impact has on the contrary attaching detached torch. Fuel speed range, in which there is detached steady torch, increases.

Propagation of the detonation front in hydrogen-air mixture was investigated in rectangular cross-section channels with sound-absorbing boundaries. The front of luminescence was detected in a channel with acoustically absorbing walls as opposed to a channel with solid walls. Flame dynamics was recorded using a high-speed camera. The flame was observed to have a V-shaped profile in the acoustically absorbing section. The possible reason for the formation of the V-shaped flame front is friction under the surface due to open pores. In these shear flows, the kinetic energy of the flow on the surface can be easily converted into heat. A relatively small disturbance may eventually lead to significant local stretching of the flame front surface. Trajectories of the flame front along the axis and the boundary are presented for solid and porous surfaces.

The frequency spectrum of acoustic disturbances that are emitted by accelerating flame front in an air-hydrogen mixture within an axially symmetric channel with a uniform cross section is experimentally determined. The effect of acoustic disturbances that are reflected from the closed end of the combustion chamber on the flame front acceleration is studied. It is revealed that the frequency spectrum of generated acoustic disturbances under experiment conditions has maximums at frequencies close to 250, 800, and 1500 Hz.

A technique has been developed for evaluating turbulent combustion characteristics in the presence of microdroplets obtained by vapor condensation in the course of rapid expansion. Experiments have been conducted to visualize spark-initiated flame propagation through hydrogen-air mixtures at various turbulent intensities, water-vapor volume fractions, and microdroplet concentrations.The influence of microdroplet suspensions on iginition and flame propagation is investigated.

The basic question raised in the paper concerns the origins of exothermal reaction kernels and the mechanisms of detonation onset behind the reflected shock wave in shock-tube experiments. Using the conventional experimental technique, it is obtained that in the certain diapason of conditions behind the reflected shocks a so-called "mild ignition" arises which is characterized by the detonation formation from the kernel distant from the end-wall. The results of 2-D and 3-D simulations of the flow evolution behind the incident and reflected shocks allow formulation of the following scenario of ignition kernels formation. Initial stage during and after the diaphragm rupture is characterized by a set of non-steady gasdynamical processes. As a result, the flow behind the incident shock occurs to be saturated with temperature perturbations. Further evolution of these perturbations provides generating of the shear stresses in the flow accompanied with intensification of velocity and temperature perturbations. After reflection the shock wave interacts with the formed kernels of higher temperature and more pronounced kernels arise on the background of reactivity profile determined by moving reflected shock. Exothermal reaction starts inside such kernels and propagates into the ambient medium as a spontaneous ignition wave with minimum initial speed equal to the reflected shock wave speed.

The present study discusses capabilities of dissipation-free CABARET numerical method application to unsteady reactive gasdynamic flows modeling. In framework of present research the method was adopted for reactive flows governed by real gas equation of state and applied for several typical problems of unsteady gas dynamics and combustion modeling such as ignition and detonation initiation by localized energy sources. Solutions were thoroughly analyzed and compared with that derived by using of the modified Euler-Lagrange method of "coarse" particles. Obtained results allowed us to distinguish range of phenomena where artificial effects of numerical approach may counterfeit their physical nature and to develop guidelines for numerical approach selection appropriate for unsteady reactive gasdynamic flows numerical modeling.

The CABARET method implementation for a weakly compressible fluid flow is in the focus of present paper. Testing both one-dimensional pressure balancing problem and a classical plane Poiseuille flow, we analyze this method in terms of discontinuity resolution, dispersion and dissipation. The method is proved to have an adequate convergence to an analytical solution for a velocity profile. We also show that a flow formation process represents a set of self-similar solutions under varying pressure differential and sound speed.

A prospective hypersonic HEXAFLY aircraft is considered in the given paper. In order to obtain the aerodynamic characteristics of a new construction design of the aircraft, experiments with a scaled model have been carried out in a wind tunnel under different conditions. The runs have been performed at different angles of attack with and without hydrogen combustion in the scaled propulsion engine. However, the measured physical quantities do not provide all the information about the flowfield. Numerical simulation can complete the experimental data as well as to reduce the number of wind tunnel experiments. Besides that, reliable CFD software can be used for calculations of the aerodynamic characteristics for any possible design of the full-scale aircraft under different operation conditions. The reliability of the numerical predictions must be confirmed in verification study of the software. The given work is aimed at numerical investigation of the flowfield around and inside the scaled model of the HEXAFLY-CIAM module under wind tunnel conditions. A cold run (without combustion) was selected for this study. The calculations are performed in the FlowVision CFD software. The flow characteristics are compared against the available experimental data. The carried out verification study confirms the capability of the FlowVision CFD software to calculate the flows discussed.

We formulate an approach to the study of the physics of interaction of galactic comets with the terrestrial planets and the Moon, based on idealized hydrodynamic models of "elastic" and "inelastic" impact proposed by M A Lavrentiev. According to these models, a large crater arises on the solid surface of planet in case of "elastic" collision, whereas the narrowly focused shock wave is formed in result of "inelastic" impact. This shock wave penetrates deep into the lithosphere rocks causing their heating. Using the factual data for Earth, Mars and Moon, we came to the conclusion that the interaction of galactic comets with planets goes on with the participation of both the physical processes at once. At that, with a decrease of power of gaseous envelope of planet, the action of "inelastic" collision mechanism is reduced, "elastic" —amplified.

We report on the ablation phenomena in gold sample irradiated by femtosecond laser pulses of moderate intensity. Dynamics of optical constants and expansion of a heated surface layer was investigated in a range from picosecond up to subnanosecond using ultrafast interferometry. Also morphology of the ablation craters and value of an ablation threshold (for absorbed fluence) were measured. The experimental data are compared with simulations of mass flows obtained by two-temperature hydrodynamics and molecular dynamics methods. Simulation shows evolution of a thin surface layer pressurized by a laser pulse. Unloading of the pressurized layer proceeds together with electron-ion thermalization, melting, cavitation and spallation of a part of surface liquid layer. The experimental and simulation results on two-temperature physics and on a fracture, surface morphology and strength of liquid gold at a strain rate ∼ 10⁹ s^-1 are discussed.

Time and spatial-resolved interferometric technique in a picosecond range was used for continuous registration of motion of iron target surface heated by femtosecond laser pulse. The magnitude of the tensile stress 0.5-1.3 GPa leading to fracture of molten iron at the strain rate of ∼ 10⁹ s^-1 was experimentally determined from the measured velocity histories of the spalled layer movement.

The optical response of thin silver film (of 60 nm thickness) coated on a glass prism (Kretschmann configuration) and heated by the femtosecond laser pulse of small intensity is investigated by the computational modeling. We have calculated the reflectance of p-polarized probe laser beam when it is incident onto the metal film from the glass side. Reflectance is calculated at incidence angles close to the surface plasmon resonance angle. We have considered first 100 ps after the action of femtosecond laser pulse onto the film surface. Changes in thermodynamic state and hydrodynamic motion of film material are described by the system of hydrodynamic equations taking into account different temperatures of electrons and ions (two- temperature state) and consequently two-temperature thermodynamics and kinetics at such early times. These changes define the changes in electron-ion and electron-electron collision frequencies. The collision frequencies of conduction electrons, being calculated in dependence on the density and electron and ion temperatures, allow us to find the Drude part of dielectric permittivity. Together with the interband contribution it gives possibility to calculate reflectance depending on the state of metal surface. It is shown a great importance of electron-electron interactions in the temporal behavior of reflectance at early times of laser-film interaction.

The movement of metal film placed on a glass substrate under action of ultra-short laser pulse is studied with using of two-temperature hydrodynamic calculations. The features of the oscillatory modes of movement of the film on the substrate under the influence of low-energy laser pulses are investigated. Transition from film delamination from the substrate as a whole to break of a film and flying away only a forward layer of a film is tracked at growth of the enclosed energy.

Study of material flow in two-temperature states is needed for a fundamental understanding the physics of femtosecond laser ablation. To explore phenomena at a very early stage of laser action on a metallic target our in-house two-temperature hydrodynamics code is used here. The early stage covers duration of laser pulse with next first few picoseconds. We draw attention to the difference in behavior at this stage between the cases: (i) of an ultrathin film (thickness of order of skin depth d_skin or less), (ii) thin films (thickness of a film is 4-7 of d_skin for gold), and (iii) bulk targets (more than 10d_skin for gold). We demonstrate that these differences follow from a competition among conductive cooling of laser excited electrons in a skin layer, electron-ion coupling, and hydrodynamics of unloading caused by excess of pressure of excited free electrons. Conductive cooling of the skin needs a heat sink, which is performed by the cold material outside the skin. Such sink is unavailable in the ultrathin films.

The goal of the paper is to explain experimental results concerning film blistering. Tightly focused diffraction limited ultrashort optical laser pulse illuminates a small spot at a surface of a thin metal film mounted upon a dielectric or semiconductor support (substrate). Film mechanically separates from substrate and form a cupola like bump in a rather narrow range of absorbed fluences. Below this range deformations inside the spot are negligible. While above the range the hole remains in a film in the irradiated spot. The paper presents physical model starting from absorption and two-temperature state and including, first, description of conductive redistribution of absorbed heat, melting, hydrodynamics of strong three-dimensional deformations of a moving film, and, second, freezing of molten metal.

We have investigated transport properties of an electron subsystem of copper heated by a femtosecond laser pulse. These properties change greatly in comparison with the room temperature solid metal. The electron temperature and pressure profiles significantly depend on these properties in bulk laser targets according to the two-temperature (2T) model. These profiles at the 2T stage are responsible for shock and rarefaction waves' formation. We have developed the analytical model of electroconductivity and heat conductivity of copper which takes into account changes of density, electron and ion temperatures. The model is based on the solution of the Boltzmann equation in the relaxation time approximation for consideration of electron collisions. Also we have carried out the first-principles calculations using the Kubo-Greenwood theory, methods of pseudopotential and linear augmented plane waves which are necessary to evaluate electron wavefunctions. We have provided the check of convergence of all parameters of our first-principles calculations. The results of our analytical model for electro- and heat conductivities are in good agreement with the data obtained using the linearized augmented plane wave (LAPW) method.

Interaction of laser pulses with clusters creates non-equilibrium warm dense matter systems. In this work we deploy wave packets molecular dynamics to study initial stage of aluminum cluster relaxation after irradiation with 25-400 fs pulses.

We use a wide-range model of thermodynamic, transport and optical properties for simulation of laser-induced dynamics of aluminum plasma. The model describes the laser energy absorption, electron thermal conductivity and two-temperature effects of electron-ion collisions as well as hydrodynamic motion of matter. The model successfully describes experiments on self-reflectivity in wide range of intensities, and angular dependence of reflectivity coefficient for S- and P-polarized pulses. Thus, the model can be used for prediction of the main parameters of aluminum plasma such as temperature, density, velocity, mean charge of ions for optimization of planned experiments.

The performed simulations in contrast to the previous studies have shown that the generation of the wake wave in the self-modulational regime, its wavebreaking with subsequent particle injection and acceleration occur for the initially Gaussian envelope of the laser pulse if the processes of tunnelling ionization are taken into account. The self-modulation evolve faster in comparison to the case without ionization because of the abrupt density inhomogeneities which appear at the front edge of the laser pulse because of ionization. These inhomogeneities lead to the three wave character of the resonance modulational instability. The ionization blueshifting of the laser light is observed in the simulations.

The acceleration of highly polarized electron beams are widely used in state-of-the-art high-energy physics experiments. In this work, a model for investigation of polarization dynamics of electron beams in the laser-plasma accelerator depending on the initial energy of electrons was developed and tested. To obtain the evolution of the trajectory and momentum of the electron for modeling its acceleration the wakefield structure was determined. The spin precession of the beam electron was described by Thomas-Bargman-Michel-Telegdi equations. The evolution of the electron beam polarization was investigated for zero-emittance beams with zero-energy spread.

The resonant excitation of the nonlinear wakefield by a single proton bunch is investigated with the parameters characteristic of the AWAKE experiment. It is shown that obtained structure of the wakefield at a distance more than twenty periods behind the driver proton bunch can be suitable for the side injection and further acceleration of the witness electron bunch in the wakefield.

For producing of high-quality accelerated electron bunches the structure of laser fields and accelerating wakefields inside the guiding structure should be regular enough to conserve a high value of accelerating longitudinal field throughout the propagation and avoid strong defocusing transverse fields. We had compared the efficiency of capillary waveguides and plasma channels in achieving of this goal, taking in mind different possible nonsymmetric conditions (like non-symmetric shape of laser spot, non-zero angle of incidence of a laser pulse or deviation of a focusing point relatively to the guiding structure axis) of laser pulses focusing in a guiding structure, always available in real experiments. The model for laser pulses propagation in guiding structures for the case of arbitrary dissymmetry of laser focusing is presented.

Experiments for verification of a functional dependence of the ablation pressure on the irradiated surface of a target upon the laser intensity in a range from 1.2 to 350 TW/cm² have been carried out. For that, at some intensities of the laser irradiation, time intervals between the laser pulse maximum and the moment of the shock-wave front arrival to the rear surface of the target were measured, which are dependent on the ablation pressure. Two schemes of the measurements were used. At the first scheme, at higher laser intensities, the front arrival moment is determined via an electron-optical camera when the rear surface begins glowing. At the second scheme, the front arrival moment is recorded when a probe laser pulse changes the character of the reflection by the rear surface of the irradiated target. Results of measurements are in agreement with the ablation pressure dependence upon the laser pulse intensity within 20%.

Important features of the theoretical model known as the ion model of plasma, which is used for quantum mechanical calculations of radiative opacity, are discussed. Reliability of ion-model results was tested with experiment, where measurements of X-pinch radiation energy yield for two exploding wire materials, NiCr and Alloy 188 were made. Theoretical estimations of radiative efficiency were compared with experimental results, and ion-model calculations agree well with the experimental data. Subsequently, the theoretical approach has been applied for theoretical and experimental studies of radiative and gas dynamic properties of plasma at high energy density. As it was found, the theoretical approach can be used for temperature diagnostics of Z-pinch plasma. Calculations of the spectral brightness were made for W plasma radiation at the temperatures 1 and 1.2 keV and the densities 1 and 2 g/cc.

Intensity dependence of the conversion efficiency of laser energy into the energy of hot electrons is determined with the aid of measurements and modeling of K_α-photon yield from silver targets irradiated by relativistically intense subpicosecond laser pulses. We take into account intensity dependence of the effective hot electron temperature assuming the Wilks' scaling. The measurements reveal approximately the same values of the K_α yield from a silver foil of 10 μm thickness, attached onto aluminium or plexiglass substrates, at the intensities about 10¹⁸ W/cm² and 2 × 10¹⁹ W/cm². Intensity dependence of the K_α yield from the silver foil, calculated using determined conversion efficiency of laser energy into the energy of hot electrons, is in agreement with the measurements.

A two-dimensional axisymmetric problem on fast ignition of a cylindrical target of precompressed DT-mixture surrounded by a stationary heat-insulated shell is considered. The target end is ignited with a proton beam, the intensity of which is independent of the radial coordinate. Self-radiation of plasma and α-particles of the thermonuclear reaction freely escape out of the fuel through the lateral boundary of the shell. It is shown that the ignition energy threshold for the mixture density 22 and 110 g/cm³ about 10 times less than in the case of the known problem with the radius of the beam much less than the radius of fuel. Previously developed quasi-one-dimensional model underestimates the ignition energy threshold by the target radius about 4 times in comparison with the problem under consideration. Estimates for the magnetic field and the shell density at which the corresponding problems are in some sense close to the problem under consideration are presented.

Application of external magnetic field to a laser-generated plasma flows allows to investigate stable, large aspect ratio plasma jets which are relevant to a number of astrophysical cases. In the experiment with 0.6 ns, 40 J laser pulses focused to 700 μm focal spot at solid CF₂ target in presence of 20 T poloidal magnetic field the parameters of the plasma jet were studied by means of spatially resolved x-ray spectroscopy. Focusing spectrometer with spatial resolution was used to record the temporally-integrated x-ray emission spectra of the plasma with spatial resolution along the jet propagation. Using the relative intensities of spectral lines emitted by F He-like ions, the electron temperature T_e and density N_e profiles of the plasma are obtained. It is shown that N_e decreases monotonically in the case without B-field, but demonstrates an extended density profile up to 10 mm when 20 T magnetic field is applied. N_e values are consistent with that observed via interferometry diagnostics, thus providing the confidence in our x-ray spectroscopy analysis techniques.

Mica crystals are widely applied in x-ray spectroscopy diagnostics since their ability to effectively reflect the radiation in different orders covering a wide range of photon energy, including sub-keV range hardly accessible with other crystals. Particularly, spherically bent mica crystals are commonly used in high energy density plasma imaging spectrometry diagnostics. However, the detailed reflectivity properties of bent mica crystals are not known well. Here we propose and verify the way to calibrate mica crystal spectral reflectivity in the experiment with relativistic laser plasma. The approach is based on the comparison of dense laser plasma x-ray spectra measured by focusing spectrometers with spatial resolution equipped, with examined mica and pre-calibrated alpha-quartz bent crystals. As a result, the normalized reflectivity of spherically bent mica crystal operated in 2^nd order of reflection was experimentally evaluated for the first time versus wavelength in the range of 6.7-8.7 Å. The obtained spectral calibration curve for bent mica crystal demonstrates remarkable difference to that one calculated for flat mica crystal and given in Henke tables and has to be applied further for a correct interpretation of the measured x-ray spectra.

While the plasma created by powerful laser expands from the target surface it becomes overcooled, i.e. recombining one. Improving of diagnostic methods applicable for such plasma is rather important problem in laboratory astrophysics nowadays because laser produced jets are fully scalable to young stellar objects. Such scaling is possible because of the plasma hydrodynamic equations invariance under some transformations. In this paper it is shown that relative intensities of the resonance transitions in He-like ions can be used to measure the parameters of recombining plasma. Intensity of the spectral lines corresponding to these transitions is sensitive to the density in the range of 10¹⁶-10²⁰ cm^-3 while the temperature ranges from 10 to 100 eV for ions with nuclear charge Z_n ∼ 10. Calculations were carried out for F VIII ion and allowed to determine parameters of plasma jets created by nanosecond laser system ELFIE (Ecole Polytechnique, France) for astrophysical phenomenon modelling. Obtained dependencies are quite universal and can be used for any recombining plasma containing He-like fluorine ions.

A diffraction component of angular resolution of spherical Q2131 and Ge422 crystals was calculated, measured in experiment and the good agreement was found. Simulation of geometrical component of angular resolution of bent crystals was also performed and the code is designed to simulate reflectivity of the concave crystals. Such code is also aimed to estimate the resolution of focusing x-ray spectrometers.

The surface of NaCl crystals outside and in the crater was examined using an x-ray photoelectron spectrometer. The comparative analysis of the XPS spectra showed that high- intensity laser irradiation has a significant impact on the state and composition of the surface of the ionic crystal.

The paper considers gas-dynamical processes evolving as a result of laser action in fused quartz. A conventional approach is used to construct a model for equation of state which provides an adequate description of the silica state at high densities of energy typical for local optical silica damage. Shock-wave processes generated in the medium due to the local laser energy deposition are calculated using fully conservative numerical technique. The obtained results provide relatively accurate description of the process in a wide range of parameters and allow further research to get clear interpretation of high-speed propagation of the laser absorbing front through the silica optical fiber.

Dependences of optical and mechanical strengths of glass composites with the drawn films upon the film thickness, particles packing density in a layer in the sol disperse phase and the particles diameter have been studied experimentally. We report that the laser ablation threshold energy density values decrease with the growth of the composites microhardness.

Stability of a liquid crater wall formed under the action of an ytterbium-fiber laser in the course of the Nd³+:Y₂O₃ nanopowder production is studied theoretically. It has been shown that hydrodynamic instability can develop on the melt-vapor interface as a result of the tangential discontinuity of the velocity between the vapor stream and molten crater wall. The characteristic spatial and temporal scales are estimated in the framework of the proposed qualitative model, they are found to be 20-90 μm and 20-50 μs, respectively, that is in good agreement with experimental data. Thus, the droplet formation time (during which the amplitude of the boundary perturbation reaches the wavelength order) is much smaller than a pulse duration of the ytterbium-fiber laser (1360 μs). This means that a significant amount of material can be removed from the crater due to formation of microscale droplets during the irradiation. This mechanism can explain the much greater crater depth for the fiber laser than for CO₂ laser (a pulse duration for which is 370 μs).

Optical monitoring of the thermal melting of materials caused by high power laser radiation uses the dependence of the reflectivity on the surface temperature. The thermal melting of the surface layer is considered as the nucleation followed by the nuclei coalescence. It cannot be detected using the reflectivity. In this article, the melting of the surface layer is studied experimentally for silver samples by measuring temperature of the samples and registering patterns of probing laser light scattered and specularly reflected from the surfaces. The samples having unidirectional roughness of a surface were heated in an electric furnace. The surfaces were oriented vertically and illuminated by the probing laser beam at the wavelength of 660 nm. The power and the divergence of the incident beam were approximately 50 mW and 0.3 mrad. The study has helped clarify the features of the patterns which allow detect the melting of the surface layer. Also we found a phenomenon similar to the directional crystallization. A rod of silver grew out the molten silver against the direction of the laser beam.

In present work, the radiation propagation in atmosphere from laser source to the receiver is considered by taking into account deviations of optical beam due to turbulence. The photon flux density on the receiver has been evaluated.

In general terms, we have considered matter as the system of charged particles and quantized electromagnetic field. For consistent description of the thermodynamic properties of matter, especially in an extreme state, the problem of quantization of the longitudinal and scalar potentials should be solved. In this connection, we pay attention that the traditional postulates of electrodynamics, which claim that only electric and magnetic fields are observable, is resolved by denial of the statement about validity of the Maxwell equations for microscopic fields. The Maxwell equations, as the generalization of experimental data, are valid only for averaged values. We show that microscopic electrodynamics may be based on postulation of the d'Alembert equations for four-vector of the electromagnetic field potential. The Lorenz gauge is valid for the averages potentials (and provides the implementation of the Maxwell equations for averages). The suggested concept overcomes difficulties under the electromagnetic field quantization procedure being in accordance with the results of quantum electrodynamics. As a result, longitudinal and scalar photons become real rather than virtual and may be observed in principle. The longitudinal and scalar photons provide not only the Coulomb interaction of charged particles, but also allow the electrical Aharonov-Bohm effect.

A combined dc electric-optical breakdown (λ = 213, 266, 355, 532 and 1064 nm; τ_FMWH = 68 ps, 18 ns; I₀ = 10⁹-10¹³ W/cm²; E_dc = 0-13.2 kV/cm) and discharge dynamics in argon has been experimentally investigated at pressures (p = 1.0 × 10¹-5.57 × 10⁵ Pa). Breakdown thresholds were evaluated at different gas pressures and irradiation wavelengths for 0.5 breakdown probability in terms of laser and electric components. It has been discovered that such a combined breakdown could take place at laser and electric components values significantly less than those for "pure" optical or electric impact.

In this paper, our experimental studies of dipole-dipole interactions in excited resonance gases are discussed. In weakly excited gas the dipole broadening of optical transitions is proportional to its density N. A gas medium can be identified by its density N as rarefied gas, where dipole broadening of atomic transitions is much less than Doppler width, or as dense gas, where dipole broadening is much more than Doppler width. According to our experiments the dipole broadening in rarefied gas does not depend on the optical excitation. This behavior is in a good agreement with predictions of standard theory for impact atomic collisions. In excited dense gas we observed the strong reduction of the dipole broadening. These experimental results are not described by standard theory for impact collisions. We suggested a simple description of the optical properties for excited dense gas.

The experimental investigation of iron-carbon nanoparticles synthesis by joint laser photolysis of iron pentacarbonyl in the mixture with methane or acetylene has been carried out. The radiation source used for photo-dissociation of precursors was a pulsed Nd:Yag laser operated at a wavelength of 266 nm. Under uv radiation the molecules of Fe(CO)₅ decomposed, forming atomic iron vapor and unsaturated carbonyls at well-known and readily controllable parameters. The subsequent condensation of supersaturated metal vapor resulted in small iron clusters and nanoparticles formation. It was assumed that the active catalytic surface of metal nanoparticles could activate the hydrocarbon molecules up to carbon layer formation on their surface. The growth process of the nanoparticles was observed by a method of laser light extinction. Additionally nanoparticle samples were investigated by a transmission electron microscope. The particle sizes were measured by microphotographs treatment. The sizes of synthesized particles from methane-iron-pentacarbonyl mixture were found to be in a range of 4-16 nm with a count median diameter of 8.9 nm and standard deviation of 1.13. These particles consisted of iron oxide without any carbon content. The particles formed in photolysis of acetylene-iron-pentacarbonyl mixture had the sizes of 3-7 nm with count median diameter of 4 nm and standard deviation of 1.28 and contained the essential amount of carbon. The iron cores were surrounded with a carbon shell.

III-nitride heterostructures in the form of multilayered quantum wells (MQWs) or quantum dots (QDs) and interacting Ge QDs ("quantum molecules") are promising candidates for high-speed intersubband (ISB) optical devices relying on the quantum confinement of electrons. Microstructural parameters (interatomic distances, coordination numbers, and Debye-Waller factors) were determined by means of EXAFS spectroscopy based on the Synchrotron Radiation, and the relationship between the variations in these parameters and the morphology of superlattices and symmetric assembles of QDs were established. The EXAFS technique has been used to study the local structure of thin hexagonal GaN/AlN MQWs grown by ammonia MBE at different temperatures. It is shown that the heterointerface intermixing leads to a decrease in the Ga-Al interatomic distance and the Ga-Ga coordination number in MQWs. The degree of intermixing in the boundary layers rises from 30% to 40% with increase of the growth temperature from 795 to 895 °C. It was found that in the first phase of quantum molecules growth Ge atoms concentration is 25%. With further growth (deposition of the base layers) Ge concentration increases up to 35-45%, depending on the temperature (from 610 to 550 °C) of deposition.

Studies of constructional material behavior under pulse power densities are very important both for fundamental researches and different applications. Modeling of shock wave generation in porous composites is complicated task because of complex structure of such materials. It is necessary to have rather detailed experimental database for verification of these models. In this paper, we present experiments that were carried out on high current electron accelerator "Calamary". We investigated the surface plasma expansion and mechanical kick pulse dependence from different energy fluxes. Also irradiated targets were investigated by electron microscope.

The atomic displacement cascades generated by radiation in the iron-chromium alloy were studied using molecular dynamics simulation. Atomic displacement cascades were generated by the primary knock-on atom, which energy varied from 1 to 20 keV. The simulation of the dynamics of atomic displacement cascades and the calculation of the cascade parameters (durations of the main stages, the size of the radiation-damaged region) in the iron-chromium alloy were made for different energies of primary knock-on atom. Sizes of formed point defect clusters and their distribution in the crystallite volume were calculated. To study radiation damage in iron-chromium alloy caused by generation and evolution of displacement cascades we analyzed spatial and quantitative distribution of the generated point defects and their clusters.

Processes of nuclear burning of various elements in the scheme of a compact inertial electrostatic confinement implemented on the basis of a nanosecond vacuum discharge (NVD) with low-energy hollow cathode were investigated experimentally earlier. This paper presents the results of a recent series of DD fusion experiments on the newly created experimental set-up NVD-2 combined with x-ray and neutron yield diagnostics. The voltage-current (VA) characteristics of the discharge, and the regimes of generation of x-ray and DD neutrons realized experimentally are presented and discussed. The experimental results are compared with the results of particle-in-cell simulation of the nuclear DD fusion processes in NVD using electrodynamic code KARAT. Recent series of DD fusion experiments have reproducing in TOF scheme some basic features of DD neutrons yield observed earlier. Meanwhile, the analysis of V-A characteristics and anode erosion shows that efficiency of energy deposition at initial stage of discharge is still insufficient, and the ways to optimize the electrophysical processes at NVD-2 are clarified.

The physics of plasma formation is discussed in the systems with inertial electrostatic confinement (IEC) during the convergent to the axis of cylindrical geometry of the ion flow accelerated periodically in the field of virtual cathode, which is formed by the injected electrons. The ranges of plasma parameters and the resulting neutron yield are determined for different modes of ion flux formation. The requirements are formulated to the technical parameters of the system with IEC to create both a powerful neutron source with a rate of generation exceeding 10¹⁰-10¹² particles/s and to achieve a positive energy output (analogue of Lawson criterion).

The neutron-free reaction of proton-boron nuclear burning accompanied with the yield of three alpha particles (p + ¹¹B → α + ⁸Be* → 3α) is of great fundamental and applied interest. However, the implementation of the synthesis of p +¹¹B requires such extreme plasma parameters that are difficult to achieve at well-known schemes of controlled thermonuclear fusion. Earlier, the yield of DD neutrons in a compact nanosecond vacuum discharge (NVD) of low energy with deuterated Pd anode have been observed. Further detailed particle-in-cell simulation by the electrodynamic code have recognized that this experiment represents the realization of rather old scheme of inertial electrostatic confinement (IEC). This IEC scheme is one of the few where the energies of ions needed for p + ¹¹B reaction are quite possible. The purpose of this work on simulation of proton–boron reaction is studying the features of possible p + ¹¹B burning at the IEC scheme based on NVD, thus, to look forward and planning the real experiment.

The results of full-scale experiments of lightning current flow through soil are presented. With the pulse high voltage generator the current of several tens of kiloamperes amplitude was created in soil on the length up to 70 m. The measured current and voltage profiles, the calculation of resistance and its profile between electrodes in soil are presented. The investigation of resistance value behavior was performed in case of several electrical breakdowns.

The major methods of biomass thermal conversion are combustion in excess oxygen, gasification in reduced oxygen, and pyrolysis in the absence of oxygen. The end products of these methods are heat, gas, liquid and solid fuels. From the point of view of energy production, none of these methods can be considered optimal. A two-stage thermal conversion of biomass based on pyrolysis as the first stage and pyrolysis products cracking as the second stage can be considered the optimal method for energy production that allows obtaining synthesis gas consisting of hydrogen and carbon monoxide and not containing liquid or solid particles. On the base of the two stage cracking technology, there was designed an experimental power plant of electric power up to 50 kW. The power plant consists of a thermal conversion module and a gas engine power generator adapted for operation on syngas. Purposes of the work were determination of an optimal operation temperature of the thermal conversion module and an optimal mass ratio of processed biomass and charcoal in cracking chamber of the thermal conversion module. Experiments on the pyrolysis products cracking at various temperatures show that the optimum cracking temperature is equal to 1000 °C. From the results of measuring the volume of gas produced in different mass ratios of charcoal and wood biomass processed, it follows that the maximum volume of the gas in the range of the mass ratio equal to 0.5-0.6.

A combination of feedstock pyrolysis and the cracking of the volatile pyrolysis products on the charcoal at 1000 °C allows to obtain a tarless synthesis gas which contains 90 vol% or more of carbon monoxide and hydrogen in approximately equal proportions. Basic component of aviation fuel was synthesized in a two-stage process from gas obtained by pyrolytic processing of biomass. Methanol and dimethyl ether can be efficiently produced in a two-layer loading of methanolic catalyst and γ-Al₂O₃. The total conversion of CO per pass was 38.2% using for the synthesis of oxygenates a synthesis gas with adverse ratio of H₂/CO = 0.96. Conversion of CO to CH₃OH was 15.3% and the conversion of CO to dimethyl ether was 20.9%. A high yield of basic component per oxygenates mass (44.6%) was obtained during conversion. The high selectivity of the synthesis process for liquid hydrocarbons was observed. An optimal recipe of aviation fuel B-92 based on a synthesized basic component was developed. The prototype of aviation fuel meets the requirements for B-92 when straight fractions of 50-100 °C (up to 35 wt%), isooctane (up to 10 wt%) and ethyl fluid (2.0 g/kg calculated as tetraethyl lead) is added to the basic component.

Thermal conversion methods of different biomass types into gaseous fuel are considered. The comparison of the gas mixtures characteristics (volume yield, composition and calorific value) that can be produced from the main biomass types by gasification and pyrolysis is presented. The merits and demerits of these methods are discussed. It is shown that the two-stage pyrolysis technology, which consists of the biomass pyrolysis and the consequent high-temperature conversion of pyrolysis gases and vapors into synthesis gas by filtration through a porous carbon medium, allows to achieve both a high degree of biomass conversion into gaseous fuel and a high energy efficiency.

Paper presents energy analysis of reactor for torrefaction with direct heating of granulated biomass by exhaust gases. Various schemes of gas flow through the reactor zones are presented. Performed is a comparative evaluation of the specific energy consumption for the considered schemes. It has been shown that one of the most expensive processes of torrefaction technology is recycling of pyrolysis gases.

Since the active exploitation and usage of classical non-renewable energy resources the most promising direction is the development of technologies of heat and electricity production from renewable sources—biomass. This is important in terms of reducing the harmful man-made influence of fuel-and-energy sector on the ecological balance. One of the most important aims when using biomass is its pre-treatment. The paper describes the fuel preliminary preparation for combustion with such technological process as torrefaction. Torrefaction allows bringing the biomass fuel as close as it possible to fossil coals for the main thermotechnical parameters. During torrefaction moisture is removed from initial material and the partial thermal decomposition of its components appears. The final torrefied product can be recommended for utilization in existing coal-fired boilers without their major reconstruction. Thus torrefaction technology enables the partial or complete replacement of fossil coal. At JIHT RAS, a torrefaction pilot plant is developed. As heat transfer medium the gas-piston engine exhaust gases were used. Results of researching and proposals for further development are showed in this paper.

This paper is devoted to calculation of yearly energy production, demanded area and capital costs for first Russian 5 MW grid-tie photovoltaic (PV) plant in Altay Republic that is named Kosh-Agach. Simple linear calculation model, involving average solar radiation and temperature data, grid-tie inverter power-efficiency dependence and PV modules parameters is proposed. Monthly and yearly energy production, equipment costs and demanded area for PV plant are estimated for mono-, polycrystalline and amorphous modules. Calculation includes three types of initial radiation and temperature data—average day for every month from NASA SSE, average radiation and temperature for each day of the year from NASA POWER and typical meteorology year generated from average data for every month. The peculiarities for each type of initial data and their influence on results are discussed.

The analysis of the response of dense plasma to electromagnetic waves of moderate intensity can be used as a tool to investigate the validity of the physical models describing the behavior of matter under extreme conditions. Within this work the new experimental data on oblique incidence of polarized electromagnetic wave are presented. The study of polarized reflectivity properties of nonideal xenon plasma was accomplished using laser light at ν_las = 2.83 × 10¹⁴ s^-1 (λ_las = 1064 nm) and ν_las = 5.66 × 10¹⁴ s^-1 (λ_las = 532 nm). The measurements of polarized reflectivity coefficients of explosively driven dense plasmas have been carried out at incident angles up to θ = 78°. The plasma composition was calculated within a chemical picture. The integration of Maxwell equations to construct the spatial profile of the density of charge carriers of plasmas was based on an interpolation formula for DC conductivity.

We provide theoretical analysis of the reflectance of shock compressed plasmas and warm dense matter for normal incidence of laser radiation as well as for the dependence of s- and p-polarized reflectivity on incidence angle. We use density functional theory approach for the calculation of the dielectric function and reflectivity. The Kohn-Sham set of equations with the projector augmented wave (PAW) potential is solved for valent electrons. Due to the nonlocality of the PAW potentials, the longitudinal expression for the imaginary dielectric function is used. The real part is obtained by the Kramers-Kronig transformation. Quantum molecular dynamics simulation and VASP is used. Comparison with the experimental data for shock compressed xenon is performed. Three wavelengths are considered.

Ion recombination is considered in a wide range of medium properties in dense gases. A dependence of the ion recombination rate on background gas density is found. Three ranges of different recombination kinetics regimes are defined: collisional, diffusion and intermediate. Their borders are defined. A dependence of the recombination rate on the ion Coulomb nonideality is established, contrary to the idea that there is no such dependence, though it is weaker than in the collisional regime. The dependence can be interpolated as exponentially drop-down curves in the whole range the nonideality parameter values. The slope of the decay decreases with an increase of the background gas density, in other words, with the decrease of the ion free path. Extrapolation of this trend to high densities permits to suggest that the dependence is of no importance in liquids. However, the effect can be remarkable in the range of gas pressures from one up to several dozen atmospheres.

In this work, using recently obtained expansion of the dielectric function in the long wave length limit by Moldabekov et al (2015 Phys. Plasmas 22 102104), we extended previously obtained formulas for the equation of state of the semiclassical dense plasma from Ramazanov et al (2015 Phys. Rev. E 92 023104) to the quantum case. Inner energy and contribution to the pressure due to plasma non-ideality derived for both Coulomb pair interaction and quantum pair interaction potentials. Obtained analytical result for the equation of state reproduces the Montroll-Ward contribution, which corresponds to the quantum ring sum. It was shown that the obtained results are consistent with the Thomas-Fermi approximation with the first order gradient correction. Additionally, the generalization of the quantum Deutsch potential to the case of the degenerate electrons is discussed. Obtained results will be useful for understanding of the physics of dense plasmas as well as for further development of the dense plasma simulation on the basis of the quantum potentials.

In this paper, dense non-ideal, non-isothermal plasma is considered. Effective screened interaction potentials taking into account the quantum-mechanical diffraction effect have been used. Pair correlation functions were studied in the exponential approximation. Thermodynamic properties for hydrogen plasma were calculated using the analytical expressions derived from these effective potentials.

The new numerical version of the Wigner approach to quantum mechanics for treatment thermodynamic properties of the strongly interacting systems of particles has been developed for extreme conditions, when there are no small physical parameters and analytical approximations used in different kind of perturbation theories can not be applied. The new path integral representation of the quantum Wigner function in the phase space has been developed for canonical ensemble. Explicit analytical expression of the Wigner function has been obtained in linear and harmonic approximations. The new quantum Monte-Carlo method for calculations of average values of arbitrary quantum operators has been proposed. Preliminary calculations of the momentum distribution function of the Coulomb systems of particles have been carried out. Comparison with classical Maxwell-Boltzmann distribution shows the significant influence of quantum effects on the high energy asymptotics ("tails') of the calculated momentum distribution functions, which resulted in appearance of sharp oscillations.

We offer a metal model suitable for the description of fast electrophysical processes in conductors under influence of powerful electronic and laser radiation of femto- and picosecond duration, and also high-voltage electromagnetic pulses with picosecond front and duration less than 1 ns. The obtained dynamic equations for metal in approximation of one quasineutral liquid are in agreement with the equations received by other authors formerly. New wide-range expressions for the electronic conduction in strong electromagnetic fields are obtained and analyzed.

The influence of boundary conditions on results of the classical molecular dynamics simulations of nonideal electron-ion plasma is analyzed. A comprehensive study is performed for the convergence of per-particle potential energy and pressure with the number of particles using both the nearest image method (periodic boundaries) and harmonic reflective boundaries. As a result an error caused by finiteness of the simulation box is estimated. Moreover the electron oscillations given by the spectra of the current autocorrelation function are analyzed for both types of the boundary conditions. Nonideal plasmas with the nonideality parameter in range 0.26-2.6 is considered. To speed up the classical molecular dynamics simulations the graphics accelerators code is used.

Theory of a weakly non-ideal Bose gas in the canonical ensemble is developed without assumption of the C-number representation of the creation and annihilation operators with zero momentum. Instead of this assumption, we use the assumption on the C-number nature of the density operator N₀ = a^†₀a₀ with zero momentum. It is shown that the pole of the "density-density" Green function (DDGF), as well as the pole of the single-particle Green function (SPGF), exactly coincide with the Bogoliubov phonon-roton spectrum of excitations for both assumptions. This spectrum, as is known confirmed by many neutron and x-ray experimental measurements of the dynamic structure factor in He II, is straightly related to the DDGF. At the same time, we show that in the other case under consideration, when neither N₀ nor a^†₀ and a₀ are C-numbers, a gap can exist in SPGF. This gap in SPGF excitations is straightly related to the density of particles in the "condensate". Therefore, the spectra of excitations for the DDGF and SPGF in the last case under consideration are different, in contrast to the Bogoliubov-type theory where these spectra are identical.

The current-pressure (I-P) characteristics of dc magnetron discharge in inert gases (Ar, Kr and Xe) for various constant discharge voltages were measured. Under certain conditions on I-P characteristic, the nonmonotonic region of local maximum followed by a minimum is observed. It is found that increasing mass of the working gas ions results in a shift of the local maximum to lower pressures. The spatial distribution of ions in the plasma was studied by optical emission spectroscopy. Transformation of the discharge spatial structure with pressure was observed. A qualitative model of the observed trends is presented. It takes into account the pressure dependence of the discharge spatial structure, the capturing of secondary electrons by the cathode and charge exchange effects.

We present the results from a two-dimensional computational investigation of the intersection of a streamer with solid particles and density fluctuations and gas bubbles filled with air and immersed in liquids. We consider the evolution of a streamer propagating along the vector of the applied external electric field. The clusters of particles in air or bubbles in liquids have a symmetric form with branches elongated either in horizontal or vertical direction. The orientation of the cluster determines the branching patterns. We show that clusters having the prevailing horizontal branches facilitate streamer branching in liquids, while clusters in gases with vertical branches promote the splitting or reinitiating of a discharge filament. The phenomenon is mainly due to different polarization patterns of vertical or horizontal clusters in air and liquids and the ratio of dielectric permittivity of medium/particle or medium/bubble.

Current paper is devoted to study new plasma actuator type—plasma synthetic jet actuator, based on the magnetohydrodynamic flow acceleration. Gas is accelerated inside the planar channel by the pulsed arc with current ∼ 300 A, moving in the external magnetic field of 1.2 T. The channel is opened at both sides. The asymmetric jet, formed at one of the channel ends is studied by means of shadow imaging and particle image velocimetry. The total thrust of the system is estimated by integrating velocity field and by direct measurement of the recoil force.

The paper is devoted to the study of high speed flow control around the airfoil by means of the Lorentz force. The latter is formed by creating the pulsed arc filament, moving in the magnetic field along the upper airfoil surface. The research was performed for the NACA23012 airfoil model at flow velocities up to 60 m/s (134 mph). The dynamic measurement of the aerodynamic forces on the airfoil was made. Changes up to 5% in an average value of lift and pitching moment were obtained at pulse repetition frequency up to 13 Hz and average discharge power less than 200 W. The amplitude of lift force oscillation was obtained as high as 10%, with the integration time of the balance 30 ms. The dynamic flow visualization of an airfoil model after a single discharge ignition was performed. It is shown that interaction of the main flow with the arc-induced disturbance leads to the dramatic changes in the flow structure. It was shown that the upstream movement of the arc channel (I = 40-700 A) leads to the local flow separation and simultaneously to the formation of a high pressure region above the model surface. Current paper presents investigation of previous work.

An experimental study of the flow around a circular cylinder model with magnetohydrodynamic (MHD) actuator was carried out in subsonic wind tunnels (M < 0.2). Combined (high frequency and pulsed-periodic) electrical discharge was used in this MHD actuator. This intense pulsed-periodic discharge had the following characteristics: voltage amplitude up to 15 kV, current amplitude up to 16 A and frequency up to 1 kHz. Permanent magnets with an induction of B = 0.1 T on the model surface were placed inside the cylindrical model. Annular electrodes were situated on the surface of the cylindrical model. The Lorentz force causes the rotation of the electric arc on the model surface. In turn, the movement of the arc discharge induces the rotation of the gas near the surface of the model. In this experiment were carried out the measurement of the flow velocity profile near the surface of the model on the following operational modes: with plasma and without plasma. A parametric study of the aerodynamic performance of the model was fulfilled with respect to the discharge parameters and the flow velocity. To measure the velocity profile was used particle image velocimetry method.

The possibility of significant improvement transmission conditions of microwave radiation passing through a homogeneous quasi-neutral plasma layer in the constant magnetic field B₀ is considered. The study based on 1D analysis was conducted for layers with concentration N_p = 10¹⁷-10¹⁹ m^-3 and collision frequency of electrons with molecules ν = 10¹⁰-10¹¹ s^-1 in the wavelength range λ = 1-10 cm. For different values of plasma parameters N_p and ν the dependences of the magnetic induction values B₀(λ, α, |D|_cr), reducing a transmitted wave amplitude attenuation to a specified level (in this case, |D|_cr = 3 dB) were obtained. Analyzed the influence of the angle between vectors B₀ and k (wave vector) on the amplitude A_T and, hence, on the value of B₀(λ, α, |D|_cr), revealed the optimal conditions of the field B₀ orientation relative to the direction of electromagnetic waves propagation. Experimentally investigated the influence of a constant magnetic field B₀ on the attenuation degree of microwave radiation (f = 13 GHz) in a various types plasma structures and in the plasma layers. The experiments were carried out in air at pressures P = 70-500 Torr. A marked increase in the amplitude of the transmitted wave in presence of constant magnetic field was indicated.

One of the promising applications of magneto-plasma compressor (MPC) may be the use of plasma jets generated by MPC for experimental study of hypersonic flow around the models. For the study the MPC was developed with a caliber of 24 mm with internal initiation of discharge, working in "submerged" mode. The maximum operating value of the discharge current in this MPC corresponds 29 kA, the duration of the current pulse is not less than 90 μs. Jet quasi-stationary mode is set when the discharge current reaches of about 12-15 kA, that gives an estimate of the jet lifetime about 55-60 μs. To estimate the abilities of MPC the tests were conducted with Teflon conic models with a diameter of 10 mm and a height of 30 mm at a distance from the edge of the cone to the MPC nozzle exit 30-50 mm. Experiments have shown that the studied type of the MPC could serve as a basis for creation of the experimental stand for the radio physical researches of the processes in hypersonic flows in the ranges of pressures and flow rates of interest.

In this paper, an approach to solve conjugate heat- and mass-transfer problems is considered to be applied to hypersonic vehicle surface of arbitrary shape. The approach under developing should satisfy the following demands. (i) The surface of the body of interest may have arbitrary geometrical shape. (ii) The shape of the body can change during calculation. (iii) The flight characteristics may vary in a wide range, specifically flight altitude, free-stream Mach number, angle-of-attack, etc. (iv) The approach should be realized with using the high-performance-computing (HPC) technologies. The approach is based on coupled solution of 3D unsteady hypersonic flow equations and 3D unsteady heat conductance problem for the thick wall. Iterative process is applied to account for ablation of wall material and, consequently, mass injection from the surface and changes in the surface shape. While iterations, unstructured computational grids both in the flow region and within the wall interior are adapted to the current geometry and flow conditions. The flow computations are done on HPC platform and are most time-consuming part of the whole problem, while heat conductance problem can be solved on many kinds of computers.

Previously, a two-component pseudopotential "shelf Coulomb" plasma model has been developed. A Monte-Carlo study of canonical NVT ensemble with periodic boundary conditions has been performed to find gas-liquid critical point in the model. In present work additional calculations have been carried out using hybrid Gibbs statistical ensemble Monte- Carlo technique. New data for 15kT shelf has been obtained and presented in this paper. More accurate simulations confirmed the melting curve position and triple point estimations of the model (T* ≈ 0.0476, ν* ≈ 6 × 10^-4).

Phase diagrams for the "shelf Coulomb" and the modified pseudopotential plasma models developed in our previous works are compared. Qualitative agreement is observed between gas-liquid phase transition region of "shelf Coulomb" model and liquid-gas structure region of modified pseudopotential one. The possibility of experimental finding of the phase transition in nonequilibrium ultracold Rydberg plasma is considered. Parameters (density, temperature, levels of Rydberg atoms) for such a transition are estimated. Conclusion is made that "shelf Coulomb" model phase transition is practically impossible to observe in equilibrium strongly coupled plasmas due to high neutral atoms density at low temperatures: T_crit ≈ 0.076.

Kinetic processes taking place after injection of antiprotons in cold positron cloud are discussed. Mixture of antiparticles is considered as low temperature non neutral weakly coupled plasma. Simple estimations of energy of antihydrogen atoms that may be formed due to three body recombination in the system are made. Dependence of atom energy on initial particles temperatures and influence of strong confining magnetic field are discussed.

Heating of protons in cold electron gas in strong magnetic field is studied. Calculations of heating process are preformed using molecular dynamics method. Estimations of heating rate depending on initial proton energies and electron gas temperatures are made.

The applicability of the van der Waals potential approximation (C₆/R⁶) is limited by its smallness in comparison with the distance to the nearest undisturbed level of the system of two interacting atoms. It is shown that this condition should be taken into account in the study of interaction of Rydberg atoms. The calculation of the interaction potential for one of Δ-term system of two ⁷Li atoms in the 5d state is given. It is shown that at the violation of the specified conditions, the dependence of the potential 1/R⁶ is replaced by the linear dipole interaction dependence 1/R³, resulting from the solution of the secular equation.

The physical model of the particle system describing the thermodynamics of mixtures of ultracold Rydberg gases with different levels of excitation are proposed. In our model system of particles is a mixture of atoms in S-state and atoms in the P-state. To calculate the thermodynamic of the mixture Rydberg gases the method of Monte-Carlo was used. Computational results of the spatial correlations of dipoles depending on the coupling parameter are presented. At some value of the nonideality parameter the dipole chains are formed.

Energy spectra of ultracold Rydberg lithium atoms are discussed. Our technique has been used for the experimental observation of coherent and non-coherent components of two-step excitation in Rydberg states. The high sensitivity of the technique has allowed us to record narrow coherent resonance at 2P-41D. The width of this resonance is 3 times less than width of non-coherent resonance. The coherent resonance is observed when the laser is detuned by ±803.5 MHz from the atomic transition 2P_3/2.

Using recently developed diagnostic technique we measured the frequency intervals between Rydberg states nF and nD (n = 38-48) of lithium-7 atoms. The obtained value of the quantum defect δ_F for Rydberg states nF is 0.000478(24).

We have developed an effective spectroscopic method for measure the energy spectra of highly excited ultracold atoms using the registration of resonance fluorescence of atoms in magneto-optical trap during two-step cw excitation of Rydberg states by uv laser. Using this method it was obtained the value of the quantum defect was determined for Rydberg states nD of lithium-7 atoms δ = 0.00192(17).

A mathematical model of the rf plasma flow at 13.3-133 Pa in transition regime at Knudsen number values 8 × 10^-3 ≤ Kn ≤ 7 × 10^-2 and the nozzle pressure ratio n = 10 for the carrier gas is described. The model based on both the statistical approach to the neutral component of the rf plasma and the approach to the continuum model for electron and ion components. The results of plasma flow calculations performed both for an undisturbed flow and for the stream with a sample at a prescribed electric field are described. The effect of a warming up of a stream in a mixture zone confirmed by comparison of numerical results with experimental ones is found.

Metallic coatings were deposited onto glass spheres having diameters from several to one hundred micrometers by the magnetron sputtering. Two different experimental schemes were exploited. One of them had the traditional configuration where a magnetron sputter was placed at one hundred millimeters from particles. In this scheme, continuous mechanical agitation in a fluidized bed was used to achieve uniformity of coatings. In the second scheme the treated particles (substrates) levitated in a magnetron rf plasma over a sputtered rf electrode (target) at the distance d of few mm from it and at gas pressure p values of 30-100 mTorr. These parameters are essentially different from those in the traditional sputtering. Agitation due to the features of a particle confinement in dusty plasma was used here to obtain uniform coatings. Thickness and morphology of the obtained coatings were studied. As it is known, film growth rate and structure are determined by the substrate temperature, the densities of ion and neutral atom fluxes to the substrate surface, the radiation flux density, and the heat energy produced due to the surface condensation of atoms and recombination of electrons and ions. These parameters particularly depend on the product of p and d. In the case of magnetron rf dusty plasma, it is possible to achieve the pd value several times lower than the lowest value proper to the first traditional case. Completely different dependencies of the film growth rate and structure on the pd value in these sputtering processes were observed and qualitatively explained.

Interaction of two charged pointlike macroparticles located at nodes of simple cubic (sc), body-centered cubic (bcc) and face-centered cubic (fcc) lattices in an equilibrium plasma is studied within the linearized Poisson-Boltzmann model. It is shown that the boundary shape has a strong influence on the electrostatic interaction between two macroparticles, which switches from repulsion at small interparticle distances to attraction as it approaches the halflength of a computational cell. It is found that in a case of dust particles arranged in the nodes of the sc, bcc and fcc lattices, the electrostatic force acting on them is equal to zero and the nature of the interaction changes from repulsion to attraction; hence, the infinite sc, bcc and fcc lattices of charged dust particles are thermodynamically stable at rather low temperatures.

The self-consistency and basic openness of dusty plasma, charge fluctuations, high dissipation and other features of dusty plasma system lead to the appearance of a number of unusual and unique properties of dusty plasma. "Anomalous" heating of dusty particles, anisotropy of temperatures and other features, parametric resonance, charge fluctuations and interaction potential are among these unique properties. Study is based on analytical approach and numerical simulation. Mechanisms of "anomalous" heating and energy transfer are proposed. Influence of charge fluctuations on the system properties is discussed. The self-consistent, many-particle, fluctuation and anisotropic interparticle interaction potential is studied for a significant range of gas temperature. These properties are interconnected and necessary for a full description of dusty plasmas physics.

Dust particles under certain conditions can acquire kinetic energy of the order of 10 eV and higher, far above the temperature of gas and temperatures of ions and electrons in the discharge. Such heating can be explained by the energy transfer between degrees of freedom of a dusty plasma system. One of the mechanisms of such energy transfer is based on parametric resonance. A model of dust particles system in gas discharge plasma including fluctuations of dust particles charge and features of near-electrode layer is presented. Molecular dynamics simulation of the dust particles system is performed. Conditions of the resonance occurrence are obtained for a wide range of parameters.

Particles interaction and value of the screening length in dusty plasma systems are of great interest in dusty plasma area. Three inter-particle potentials (Debye potential, Gurevich potential and interaction potential in the weakly collisional regime) are used to solve equilibrium equations for two dusty particles suspended in a parabolic trap. The inter-particle distance dependence on screening length, trap parameter and particle charge is obtained. The functional form of inter-particle distance dependence on ion temperature is investigated and compared with experimental data at 200-300 K in order to test used potentials applicability to dusty plasma systems at room temperatures. The preference is given to the Yukawa-type potential including effective values of particle charge and screening length. The estimated effective value of the screening length is 5-15 times larger than the Debye length.

Features of the first-order phase transitions in complex (dusty, colloid etc) plasma are under discussion. The basis for consideration is the well-known phase diagram of dusty plasma as a Debye system from Hamaguchi et al (1997 Phys. Rev. E 92 4671) in Γ-κ plane (Γ is a Coulomb non-ideality parameter, κ is a screening parameter). The initial Γ -κ phase diagram from Hamaguchi et al (1997 Phys. Rev. E 92 4671) is converted in standard thermodynamic variables in temperature-density planes. Here 2-component electroneutral systems of macro- and microions (+Z, -1) and (-Z, +1) are considered as thermodynamically equilibrium ensembles of classical Coulomb particles. An extensive area for negative compressibility of the system was revealed at the phase diagram in a fluid state of the initial Debye system when one considers the system as equilibrium two-component electroneutral mixture of macro- and microions (+Z, -1) (or (-Z, +1)) under equations of state from Hamaguchi et al (1997 Phys. Rev. E 92 4671) and Khrapak et al (2014 Phys. Rev. E 89 023102). This means thermodynamic instability of the simplified Debye system in this domain. Non-linear screening and an unavoidable existence of additional phase transitions of gas-liquid and gas-crystal type are proposed as hypothetical resolution of discussed thermodynamic instability problem.

A new kind of dusty plasma instability was observed in the joint Russian-European "Plasma Kristall-4" space experiment on board of the International Space Station. An elongated cylindrical dust particle cloud of 0.9 cm diameter with a length of 20 cm was formed in the uniform positive column of a dc discharge operating in a polarity switching mode (dc/ps-mode). The discharge was operated in a glass tube of 3 cm inner diameter with a total length of 85 cm filled by argon at a pressure of 0.5 mbar. The dc/ps discharge was operated at 1 mA with a polarity switching frequency of 500 Hz. During the experiment, all the dust particles vibrated synchronized in the same phase in the direction perpendicular to the tube axis with a frequency of 24 Hz and peak-to-peak amplitude of 0.2 mm. The vibration was attended by discharge glow fluctuation. The nature of the cloud vibration is discussed.

It is shown that for consideration of dust particle release from the lunar surface one has to take into account (among other effects) both adhesion and meteoroid impacts. The effect of surface roughness on the adhesion intensity on the Moon is discussed. The rate of meteoroid impacts with the lunar surface per unit area is determined. The strength of the regolith due to the adhesion effect is estimated. The processes occurring when a high-speed meteoroid impacts with the lunar surface are described. In particular, the characteristic parameters of zones of evaporation of the substance, its melting, destruction of particles constituting lunar regolith, their irreversible deformations, and elastic deformation of the regolith substance are found. A possibility of the rise of micrometer-sized dust particles above the lunar surface is shown. It is demonstrated that most of the particles rising over lunar surface due to the meteoroid impact originates from the elastic deformation zone. The number of dust particles raised over the lunar surface as result of meteoroid impacts is calculated. The size-distribution function of particles released from the lunar surface due to meteoroid impacts is determined. It is noted that micrometeoroid impacts can result in rise of dust particles of the size of a few μm up to an altitude of about 30 cm that explains the effect of "horizon glow" observed by Surveyor lunar lander.

In the paper, the particle dynamics in two-dimensional (2D) Yukawa systems were studied numerically. New data on a density of the thermal fluctuations of pair-interaction forces have been obtained for non-ideal systems in a wide range of their parameters. Comparisons of these thermal fluctuations with the internal energy density were performed. For the first time we have found, that for strongly correlated fluid 2D Yukawa systems the dielectric constant is inversely proportional to the second derivative of a pair potential at the mean inter-particle distance.

In this article, the possibility of nanoparticle confinement by electrodynamic Paul trap is shown. The areas of nanoparticle confinement as the dependencies of particle charge density on voltage frequency and geometry of the trap are found. The nanoparticle charge density for its confinement should be of order (10¹³-10¹⁴)e/m².

In this article, the possibility of particle separation by alternating electric fields of quadrupole type was demonstrated. It was shown that by varying the parameters of the trap (the distance between electrodes, the magnitude and frequency of alternating voltage) it is possible to separate both specific types of particles from the polydisperse powder as well as spatially separate them inside the trap.

Conditions of the charged particles confinement in a vertically oriented microparticle electrodynamic ion trap have been determined experimentally. The experiment included two stages. At the first stage, charge-to-mass ratio of the trapped particle was measured by its position in a non-uniform electric field while at the second stage the ac voltage frequency was varied until the particle fell out of the trap. This frequency was taken as the boundary of particle confinement.

The microparticle dynamics in linear electrodynamic trap with different numbers of electrodes (8, 12 and 16) was theoretically studied. The regions of particle confinement as the dependencies of frequency of alternating voltage on particle charges and number of electrodes were determined. Amplitudes of particle oscillations decreases with the growth of the frequency as well as with the growth of the number of trap electrodes.

The formation of structures consisted of dusty clusters in plasma at the discharge tube cooling to a temperature of liquid nitrogen was discovered. The dependence of the reduced electric field in the positive column of a discharge on gas temperature was experimentally measured. Depending on the pressure of neon were observed the different structural transitions in the regions of growing current-voltage characteristics at low discharge currents ≤ 1 mA. It was found that the regions of existence of structured clusters and the regions of structural transitions were characterized by the higher values of the reduced electric field than the regions of destruction of ordered structures.

The electrical characteristics of the positive column of glow discharge were measured and simulated in pure neon and in plasma with micron size particles. The increment of the longitudinal electric field strength caused by the presence of dust structures was measured. Simulation was based on the diffusion-drift model of the positive column of glow discharge. Simulation was carried out using the measured values of dusty structure parameters and discharge characteristics. It was shown, that a dust structure maintained in a dc discharge represents a plasma trap for ions with ion concentrations more than three times higher than in a free discharge. The results can be used to calculate the traps for confinement of ions and dust particles in gas-discharge plasma.

Pulse electrical breakdown in 15% water solution of Isopropyl alcohol with air microbubbles from a pointed anode has been studied experimentally. It is shown, that the breakdown is always initiated from the bright region near the anode (anode "spot"). Detailed investigation into dynamic current-voltage characteristics and synchronized images reveals that it is thermal instability in the near anode region that causes spark channel initiation and development. The breakdown voltage, spark channel propagation speed and short-circuit current increase when the microbubbles are presented in the solution. The spark channel propagation speed is about 4-12 m/s and grows along with microbubbles concentration.

The system of electro-hydrodynamic equations at a pre-breakdown liquid insulator is given. The influence of electric field on the partial dissociation molecules rate is taken into account. The stationary and non-stationary solutions for electric potential and hydrodynamic velocity distributions are obtained. The numerical results of electro-hydrodynamic flows are compared with the experiment data.

The present paper discusses the issues of implementation of high-pressure ignition plasma torch in terms of discharge phenomena in compressed gases, dense nitrogen plasma properties and stable arcing power requirements. Contact ignition has been tested in a pressure range p = 1-25 bar and has proved to be a reliable solution for pilot arc burning.

Experimental results for discharge in hydrogen with current amplitude up to 1 MA, current rise rate of ∼ 10¹⁰ A/s, and at initial pressure up to 30 MPa are presented. A series of channel contractions was observed at a current rise stage. Estimation of plasma channel parameters was made for equilibrium state at the channel diameter oscillations. The speed of the discharge channel contraction was determined by the specially developed magnetic- probe technique. Comparison of these magnetic probe measurements with high-speed optical photostreaks was carried out.

The experimental data of energy deposition distribution along discharge chamber of lightning protection multichamber system in initial stage of discharge process aimed to model lightning current impulse up to 10 kA is presented. A multichamber system is a series connection of discharge chambers. According to our experiments the shock wave formation occurs during the breakdown phase between electrodes located at the bottom of discharge chamber. The consequent energy deposition during discharge development goes in the whole volume bounded by shock wave front.

The results of investigations of high-current dc and ac arc discharges of atmospheric pressure emerging above the free surface of liquid metal (In-Ga-Sn eutectic alloy) are presented in the paper. The mechanism of the arc formation due to pinch-effect is discussed here.

Ceramic composite reinforced with plaits of carbon nanotubes have been fabricated by the reaction bonded silicon carbide method. Carbon nanotubes (CNTs) are produced using a 35 kW dc plasma torch and C₂H₂ as carbon precursor. Effective methods of CNTs adding and dispersing in the preform volume have been found. The optimal content and operational technological parameters have been determined for ceramic matrix. Physico-mechanical properties of the reinforcing ceramic matrices with nanomaterials have been investigated.

Diffuse vacuum arc with hot cathode is one of the perspective plasma sources for the development of spent nuclear fuel plasma reprocessing technology. Experimental data is known for such type of discharges on metal cathodes. In this work discharge with cerium dioxide hot cathode was studied. Cerium dioxide properties are similar to uranium dioxide. Its feature as dielectric is that it becomes conductive in oxygen-free atmosphere. Vacuum arc was studied at following parameters: cathode temperatures were between 2.0 and 2.2 kK, discharge currents was between 30 and 65 A and voltages was in range from 15 to 25 V. Power flows from plasma to cathode were estimated in achieved regimes. Analysis of generated plasma component composition was made by radiation spectrum diagnostics. These results were compared with calculations of equilibrium gaseous phase above solid sample of cerium dioxide in close to experimental conditions. Cerium dioxide vacuum evaporation rate and evaporation rate in arc were measured.

Present the results of numerical simulation of the formation of a crater on the surface of the cathode during the explosion of micro tip. The simulation was performed using the two-dimensional magnetohydrodynamic program, which used wide-range equation of state and the table of conductivity of the metal, based on experimental data. It is shown that the electric explosion of micro tip with parameters typical unit ecton may form on the cathode surface of the crater with a radius of a few microns.

The aim of this work is investigation of the influence of high-energy plasma impact on composite multi-layer coating (NiAl as a sublayer and Al₂O₃ as a top coat) on meteoroid shielding element. In order to reach this goal qausi-stationary plasma accelerator with impulse gas feeding was used. Experiments were conducted with use of helium and hydrogen gas mixture and nitrogen as plasma forming substance. Plasma accelerator generates plasma jet with electron temperature ≈ 150 kK and electron density (2.5-4) × 10¹⁶ cm^-3. Visual examination, photography and spectral measurements were made through special vacuum chamber optical windows.

In the article, the two-phase flow of electric arc gas heater of the linear scheme is studied. The power of the plasma torch can be varied from 200 to 1500 kW. For stabilization of the electric arc a magnetic coil is used. The operation of the plasma torch took place at overpressure in the discharge chamber. Injection of the powder was made near the exit of the nozzle. A powder of SiO₂ was used as a disperse phase. The size of the particles was not more than 50 microns. The dispensing device was used for the powder injection. The technique of velocity measurement in high-temperature heterogeneous flow from the registration of flow by the high-speed camera is presented. The results of measurements indicate that the speed of the particles much lower than the speed of the gas. The results of measuring the heat flux along the axis of the plasma torch are presented. The heat flux was measured by means of regular mode uncooled sensors with tablet type calorimeters.

The paper reports on experiments to investigate how the quality of surface finish, i.e., surface roughness, influences the plasma formation in a skin explosion of conductors. The experiments were performed on a MIG terawatt generator with a current amplitude of up to 2.5 MA and current rise time of 100 ns. The plasma formation at the conductor surface and the evolution of the plasma boundary was recorded using a four-frame optical camera with an exposure time of 3 ns per frame. It is shown that the quality of surface finish little affects the onset of plasma formation in a skin explosion of stainless steel and St3 steel conductors at a magnetic field of up to 400 T.

Results of the experimental investigation of surface dielectric barrier discharge's energy dependence on frequency of applied sinusoidal voltage varying from 0.6 to 40 kHz at atmospheric pressure are presented in the paper for disk electrodes of 20, 50 and 150 μm thick. It is shown that surface dielectric barrier discharge's energy dependence on applied voltage frequency represents an U-shaped curve with a distinct minimum. The value and position of energy minimum are related with thickness of the generating plasma electrode, the barrier material and supply voltage. Increase of plasma heat dissipation owing to selection of the dielectric barrier material changes significantly a trend of the U-shaped curve.

Spent nuclear fuel plasma separation method approbation implies the use of model substances. Thus it is necessary to solve the problem of material conversion into a cold plasma flow, as well as the problem of deposition on collectors. For this purpose, we carried out a kinetic and hydrodynamic simulation of the discharge with hot cathode in the lead vapor (lead vapor was injected into the interelectrode gap). Dependencies of the ionization efficiency, electrostatic potential distribution, density distribution of ions and electrons in the discharge gap on the discharge current density and the model substance vapor concentration were obtained. The simulation results show that at discharge current density of about 3.5 A/cm² and the lead vapor concentration of 2 × 10¹² cm^-3, the ionization efficiency is close to 60%. Experimental research of the discharge with a hot cathode in the lead vapor was carried out. We also carried out the research of the Pb condensation coefficients on various substrates. For experimental data analysis the numerical model based on Monte Carlo method was used. The research results show that deposition coefficients at medium temperatures of substrates near 70 °C do not drop lower than 75%.

Presented results have been obtained to develop the concept of spent nuclear fuel plasma separation. The main task is to calculate trajectories of ions of the substance imitating spent nuclear fuel in crossed electric and magnetic fields. The 3D calculations have been made by the KARAT code in a single-particle approximation. The calculations have been performed for a number of combinations of azimuthal and axial magnetic fields and different electric fields configurations. Magnetic field is produced by 2 main coils with the characteristic field strength up to 1.4 kG and in several series with additional coil with the characteristic field strength up to 1.6 kG. Electric field is produced by 2 electrodes with electric potential up to 1 kV. The characteristic linear size of the calculation area is 100 cm. The characteristic size of injection region is 1 cm (up to 10 cm along main axis). Spatial position of the injection region and axis of the injection direction are varied. Injected particles are single-charged ions with energies from 0.2 to 3 eV with atomic masses A = 150 and 240, spreading angle is 60°. Calculations have revealed several options to realize a spatial separation of spent nuclear fuel ions.

In this paper the numerical model of direct current gas discharge in drift-diffusion approximation is considered. For two-component plasma the processes of the gas discharge development in the reflex geometry with ring cathodes at a helium pressure of 35 mTorr are studied. We investigate the influence of: (a) the boundary conditions on the dielectric, (b) the electron temperature and (c) the coefficient of the secondary ion-electron emission on the I–U curve of the discharge. In a magnetic field of 50 Gauss the impact of the discharge voltage U = 300–700 V on the evolutionary process of the discharge is examined. The effect of diffusion on maintaining steady state discharge is researched. The parameters of the existence of a high-current (tens of μA) and low voltage (tens of mA) discharge modes are defined.

It has been experimentally shown that highly ionized He arc plasma does not achieve local thermodynamic equilibrium expected for plasmas with electron concentrations above 1 × 10¹⁶ cm^-3 like argon plasma. We have found that the reason for this deviation is strong nonisotropy of plasma. Triple electron recombination with temperatures of 2.5-3 eV is almost absent. Charged particles move from the arc (r = 1 mm) to chamber walls due to ambipolar diffusion creating ionization nonequilibrium over the excited states rendering Boltzmann distribution and Saha equation inapplicable for determining electron temperature. A method for determining electron temperature is suggested that is based on using the relative intensities of the atomic and ion lines. Its advantage lies in an energy gap between these lines' states over 50 eV that reduces the influence of nonequilibrium on the result. This influence can be taken into account if the ionization energies of emitting states of atom and ion have close values. The suggested method can be expanded for any media including those with dimensional nonisotropy that have both atomic and ion lines in their emission spectra.

Experimental study of helium plasma in the state of quasistationary heating under atmospheric pressure was made. The plasma state is shown to fail to be described by Saha- Boltzmann approximation at high ionization levels α_i = 0.5-0.9, temperatures 2.5-4.0 eV and electron concentrations about 10¹⁷ cm^-3. The deviation from the equilibrium state of the plasma is caused by lack of spatial uniformity due to charged particles loss by ambipolar diffusion. In order to thoroughly study the temporal changes of plasma radiation characteristics, spectroscopic analysis was carried out with DFS-452 spectrometer and high-speed CMOS camera Andor iStar attached to its output. The system yields the spatial resolution of 30-50 μm and temporal resolution of 5-50 μs. Electron concentration n_e was measured from the half-width of the local Hei spectrum line contours having dominant quadruple Stark effect with well-known constants. In order to determine the temperature of heavy particles, Doppler component of He_I line triplet at 1083 nm was studied. The temporal evolution of the following important characteristics has been determined for helium plasma during pulsed heating: current power, intensities of a number of He_I and He_II spectral lines, electron temperatures and concentrations.

The results of spectroscopic studies of the initial section of the supersonic plasma jet created by a pulsed discharge in the capillary with the ablative wall are presented. Features of the spatial distribution of the electron density and the intensity of the spectral components, which, in particular, caused by the high electron temperature in the hot central zone, exceeding the "normal" temperature, as well as significant non-isobaricity at the initial section of supersonic jet are revealed. The presence of the molecular components exhibiting their emission properties at the plasma jet periphery permit us to estimate the parameters of the plasma in the spatial domain, where "detached" shock waves of the supersonic jet are created.

To study the breakdown of transformer oil with gas bubbles an experimental setup was created that allows to determine electrical and optical properties of the discharge. Oil was sparged with air and sulfur hexafluoride gas. It was found that sparging oil with gas lowers the breakdown voltage of the oil. When a gas bubble is present between the electrodes at a considerable distance from the electrodes at first there is a spherically shape flash observed, resulting in the discharge gap overlapping by a conductive channel. These leads to discharges forming in the discharge gap with the frequency of hundreds Hz and higher. Despite the slightly lower breakdown voltage of oil sparged with sulfur hexafluoride the advantage of this medium to clean oil can serve as a two-phase medium damping properties, which may be sufficient to prevent the destruction of the body in the breakdown of oil-filled equipment.

A new generator of high enthalpy (H₀ > 40 kJ/g), chemically active nitrogen and air plasmas was designed and constructed. Main feature of the generator is an expanding channel of an output electrode; the generator belongs to the class of DC plasma torches with thermionic cathode with an efficiency of 80%. The generator ensures the formation of a slightly divergent plasma jet (2α = 12°) with a diameter of D = 10-12 mm, an electric arc maximum power of 20-50 kW, plasma forming gas flow rate 1.0-2.0 g/s, and the average plasma temperature at an outlet of 8000-11000 K.

An experimental automated system was designed and constructed for studying the parameters and characteristics of non-stationary interacting system high-enthalpy-plasma stream-investigated sample: enthalpy of plasma in the incident stream; speed and temperature of plasma stream; temperature of electrons and heavy particles, ionic composition and their spatial distribution; heat flux incident on the sample (kW/cm²); surface temperature of the sample; ablation of the sample material, and others. Measurements of achievable plasma heat flux levels are carried out by calorimetry of plasma streams incident on the surface of multisection copper calorimeter. Determination of acceleration characteristics for profiled plasma torch nozzle, as well as the gas flow rate is produced by measuring the total pressure using the Pitot tube. Video visualization of interacting system is carried out using synchronized high-speed cameras. Micropyrometry of the selected zone on the sample surface is carried out by high-speed, three-wavelength pyrometer. To measure the rate of mass loss of the sample, in addition to the weighing method of evaluation the methods of laser knife and two-position stereoscopy are used. Plasma and sample emission characteristics are performed with two separate spectrometers.