Konstantin Vladimirovich Khishchenko

This work is devoted to the description of the thermodynamics of the condensed states of the rare-earth metal europium under intense mechanical and thermal loading in shock waves. A new model of the equation of state for metallic materials is proposed based on the characteristic function of entropy with volume and internal energy (per unit mass) as variables. Within the framework of this model, calculations of the thermodynamic characteristics of europium at high pressures and specific entropies were carried out, the results of which are presented in comparison with the available data from shock-wave experiments. The developed equation of state for this material can be effectively applied to the modeling and simulation of various dynamic processes at high energy densities.

The thermodynamics of substances in the vicinity of the critical point of the liquid–vapor phase transition has been studied. Using the scaling theory of critical phenomena, the properties of sulfur hexafluoride at the boundary of the evaporation region have been calculated. Agreement between the calculation results and the available experimental data has been achieved.

The present theoretical work is devoted to the construction of a model of the equation of state for matter, where the specific volume is used as the thermodynamic potential, and the entropy and the thermal part of the internal energy act as thermodynamic variables. Based on the proposed model, called STEC, calculations were carried out for aluminum in the region of high internal energies and entropies. A comparison of the calculated shock adiabats with the available data from shock-wave experiments indicates that the constructed equation of state describes well the thermodynamic properties of aluminum up to a shock compression pressure of about 1 TPa. The proposed STEC equation-of-state model can be used in numerical simulations of various processes under extreme conditions at high energy densities.

This work is dedicated to the theoretical description of the thermodynamic characteristics of the hafnium–zirconium alloy at high pressures and temperatures under shock compression. A simple model is proposed for the thermal and caloric equations of state of the alloy components. Assuming equal temperatures and pressures in the components, a calculation of the shock adiabat for the hafnium–zirconium alloy was performed. The results are compared with available experimental data on shock waves. The obtained equations of state for hafnium, zirconium, and their alloy can be used to model the dynamics of various processes under high energy densities.

A two-time-layer scheme has been developed for solving the simplified kinetic Fokker–Planck equation related to the transport of charged products of thermonuclear reactions, which includes an interpolation procedure in four-dimensional grid space. Instabilities in the scheme were detected at low particle velocities and for a specific choice of particle deceleration in the ion field, which enters the kinetic equation as a parameter. It was shown that the thermalization condition, which prohibits solving the kinetic equation for particles with energy lower than the average ion energy, significantly limits the number of thermonuclear reactions where instability can manifest. The scheme was tested on the problem of relaxation to a stationary state and on a problem with a prescribed time-dependent thermonuclear reaction rate, for which an exact solution to the kinetic equation can be found.

A two-level time scheme for solving the simplified Fokker–Planck kinetic equation is created as applied to the transport of charged products of a thermonuclear reaction, which includes an interpolation procedure in a four-dimensional grid space. The instability of this scheme is discovered at low values of the particle velocity and a special choice of the particle deceleration rate in the ion field, which is included in the kinetic equation as a parameter. It is shown that the thermalization condition, which prohibits solving the kinetic equation for particles with an energy less than the average ion energy significantly limits the number of thermonuclear reactions in which instability can manifest itself. This scheme is tested on the problem of relaxation to a stationary state and on the problem with a given time dependence of the thermonuclear reaction rate, for which an exact solution to the kinetic equation can be found.

An equation of state for titanium is proposed in the form of an analytical function of pressure on the specific volume and specific internal energy. Comparison of the results of calculating the shock adiabats for samples of different initial densities with the available data from shock-wave experiments indicates an adequate description of the thermodynamic properties of the bcc phase and melt of this metal in the high-pressure region. The developed equation of state can be used in modeling various adiabatic processes in matter under intense pulse effects.

This paper describes the thermodynamic properties of zirconium in a high-pressure region. The available experimental data on isothermal and shock compression of this metal are summarized in the form of a simple model that specifies a pressure function of the specific volume and specific internal energy. The results of calculations of the thermodynamic characteristics of the body-centered cubic crystalline phase and zirconium melt are presented in comparison with the available experimental data in the studied range of thermodynamic parameters. The resulting equation of state can be used in the numerical modeling of adiabatic processes at high energy concentrations.

A simple analytical function of pressure versus specific volume and specific internal energy is proposed for describing thermodynamic properties of tantalu

The processes in a flat palladium target irradiated with an intense picosecond laser pulse are studied. In the experiment, the parameters of the irradiating pulse, as well as the depth of the spall cavity formed as a result of the complex flow of compression and expansion waves through the substance are determined. The interaction dynamics of these waves are modeled using a new equation of state for palladium over a wide range of densities and pressures. Based on the results of the experiment and numerical simulation, the maximum tensile stress in the spall plane at a high tensile rate is estimated.