G. S. Romanov

Thermodynamic and optical properties of gases in a wide range of parameters

Abstract This work describes calculational methods and the results of systematic calculations of the thermodynamic properties, composition, spectral and mean absorption coefficients for air, water, silicon dioxide and the atmosphere of Mars (0.965 CO 2 + 0.035 N 2 ). The range of the considered temperatures from 0.1 to 10 3 eV includes the molecular state of the substances, dissociative gas, low temperature plasma and multicharge plasma. The selected density range ϱ = 10 −9 -10 −2 g cm −3 includes the most interesting states for applications. The main mechanisms which determine the absorption coefficients of gases and plasma (inverse bremsstrahlung; photoionization from the ground and excited states of particles; photodissociation of molecules; photoionization from internal particle shells; electronic-vibrational transitions in molecules; line absorption by atoms and ions) were taken into account. Absorption coefficients were determined for photon energies e = 3 × 10 −2 -10 4 eV.

Databank on thermodynamic and optical properties of plasma

Methods of evaluation of thermodynamic and optical properties of multicomponent gases within a wide range of conditions are discussed. A databank on component composition, thermodynamic functions, spectral and group absorption coefficients, and Planck and Rosseland mean free paths of radiation for plasmas of air, water, silicon dioxide, and the Martian atmosphere (0.965 CO2+0.035 N2) is composed based on calculations.

Modeling of the impact dynamics of large meteoric bodies on the surface of the planet

We present a procedure for numerical modeling and the results predicted for dynamics of crater formation in asteroid impact on the ground in the approximation of two-dimensional gas dynamics in an axisymmetric formulation. Gas-dynamic equations are solved using a fully conservative difference scheme in Eulerian variables. Predictions are performed with both an analytic representation of the equation of state (according to Tillotson) and wide-range semiempirical equations of state with a phase transition into vapor and a more exact specification of cold compression. Consideration is given to impact at a velocity of 50 km/sec with body dimensions of the order of 1 km.

Integral transfer of radiation of the actual spectrum in problems of radiative plasmadynamics

Radiative energy transfer in plasma is investigated with account for its actual optical properties. Consideration is based on the spectrum-integral method of partial characteristics. Databanks on integral partial characteristics of a number of substances are composed on the basis of data on optical properties that include the molecular state of matter, weakly ionized plasma, and plasma with multicharge ions and the main processes that determine absorption of thermal radiation (bound-bound, free-free, and bound-free transitions in molecules, atoms, and ions). Calculations of plasma radiation by this method are compared with results of spectral description. Some generalizations of the given method for solving problems of radiative plasmadynamics are considered.

Dynamics of the z pinch with a light liner. II. Single-envelope liners and the anomalies of the cumulation stage

The results of calculations of the compression of single-envelope liners toward the axis in the one-dimensional magnetic radiative gas dynamics approximation are considered. A refinement is proposed for the method of calculating the cumulation stage, making it possible to obtain better agreement with experimental data.

Numerical simulation of gasdynamic processes and the dynamics of dust particles in catastrophic volcanic explosions by applying TVD schemes

We developed a physicomathematical model to predict volcanic explosion-induced gasdynamic phenomena and the dynamics of the distribution of particles of ash and dust that precipitate onto the earth’s surface and that remain in the atmotsphere. We investigated the factors and processes that exert an influence on the transport of dust particles in the atmosphere. On the basis of the physicomathematical model developed, numerical simulation of volcanic explosions of specified power and space scale is done, and results on the dynamics of gasdynamic flows of air and the distribution of dust particles for different instants of time are analyzed.

Quasi-equilibrium states of a low-temperature air plasma of reduced density

Quasistationary states of an air plasma of reduced density are considered on the basis of equations of chemical and ionization kinetics. The component composition and thermodynamic quantities are compared with data obtained in an equilibrium approximation.

Dynamics of sublimation and initial erosion plasma formation under the action of quasicontinuous laser radiation on metals

Onset times of sublimation and plasma production as well as of pressure on surfaces under the action of quasicontinuous Nd-laser radiation with a power density up to 10 MW/cm2 on metals are investigated experimentally. The results on sublimation onset time and dynamics are compared with a thermophysical action model that accounts for phase boundaries of melting and sublimation as well as for the temperature dependence of thermophysical characteristics of metals and the time dependence of the power density of laser radiation.

Dynamics of z-pinch with a light liner. 1. Description of the model and calculation of double-shell liners

The compression of a plasma by a plastic liner has been modeled computationally in the one-dimensional magnetic radiation gasdynamic approximation. The dynamics of the process has been considered with allowance for the deviation from local thermodynamic equilibrium.

Principles of dielectric material failure under the action of concentrated energy fluxes

The process of failure of silicate material under the action of energy fluxes of 2·106 –1·109 W/m2 is considered. Results of a numerical solution considering fusion, evaporation, and radiation are presented.