Numerical Simulation of Equilibrium Induction Plasma Flows in a Cylindrical Plasmatron Channel

Subsonic equilibrium air and argon plasma flows in the cylindrical discharge channel of an induction plasmatron are calculated over a wide range of the working parameters on the basis of a solution of the complete Navier-Stokes equations combined with a simplified equation for the high-frequency electric field. An effective method and the results of calculating the necessary transport coefficients of ionized multicomponent air and argon (including the plasma electrical conductivity) are given on the temperature interval 300–1500 K with allowance for the higher approximations in Sonine polynomials in the Chapman-Enskog method. The results of calculating the air and argon plasma flow and temperature field in the discharge channel of a 100 kW induction plasmatron are given. Two types of complex channel plasma flow vortex structures are detected.     

Plane Couette flow of binary gaseous mixture in the whole range of the Knudsen number

The Couette flow of binary gaseous mixtures is studied on the basis of the McCormack model of the Boltzmann equation, which was solved numerically by the discrete velocity method. The calculations were carried out for three mixtures of noble gases: neon–argon, helium–argon, and helium–xenon. The stress tensor and bulk velocity of both species were calculated for several values of the gas rarefaction in the range from 0.01 to 40 for three values of the molar concentrations: 0.1,0.5 and 0.9. The numerical solution together with an analytical solution based on the slip boundary condition cover the whole range of the gas rarefaction. It was showed that the Couette flow is weakly affected by the intermolecular interaction law.     

Kinetics of physical processes in pinch-discharge lasers

The kinetics of physical processes in pinch-discharge lasers is investigated. An analytic solution is proposed for the relaxation problem of the population of discrete levels of ionized argon (ArII) in rapid compression of a high-temperature nonequilibrium plasma. An expression for population inversion as a function of the parameters of the plasma and unit is obtained on the basis of the solution and also of a simplified model for the compression of a plasma column. Basic experimental dependences for pinch-discharge lasers are analyzed.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 4, pp. 14–21, July–August, 1974.     

The influence of radiation on the temperature profile of an induced discharge in argon at atmospheric pressure

This study presents a quantitative evaluation of the influence of radiation upon the parameters of a long induced discharge in argon at atmospheric pressure. Radiation heat transfer in the optically transparent tin plasma layers with thickness of the order of several centimeters) and reabsorption spectral intervals is examined. Experimental error produced by inaccurate knowledge of the transfer and optical characteristics of the plasma is evaluated. The effect of convection on radial temperature profile is evaluated.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiztki, No. 6, pp. 35–43, November–December, 1971.     

Condensation of an argon—monosilane mixture in a free jet

A mass–spectrometric study of the condensation of pure Ar and a 5% SiH₄ + 95% Ar mixture in a supersonic pulse free jet in a broad interval of stagnation pressures is performed. It is shown that a small content of monosilane in argon leads to the fact that condensation in the mixture begins at lower stagnation pressures than in pure argon; at high stagnation pressures, mixed argon—silane complexes are formed in the flow. The sequence of the stages of cluster formation in the mixture is determined.     

Electrical conductivity of an argon plasma in a stabilized arc

A method is described for determining the electrical conductivity cr as a function of the temperature T from measurements in extended plasma sources of radial symmetry. The accuracy and features of the method are analyzed in numerical examples. Measurements made for a stabilized argon arc and the (T) dependence determined from them are the argon plasma are reported. The results are analyzed and compared with theory and other experiments.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, Vol. 11, No. 2, pp, 153–161, March–April, 1969.In conclusion the authors thank Ya. M. Buzhdan for consultation in the writing of the computer program, and N. A. Rubtsov for interest in the study and valuable advice.     

On the conditions of formation of population inversion of atomic levels in a thermally heated recombining plasma

A theoretical investigation is made into the recombination of a thermally heated plasma of a monatomic gas which undergoes gas-dynamic cooling in a supersonic nozzle. A method of approximate analytic calculation makes it possible to determine the necessary conditions for the existence of an effective recombination regime of the flow out of the nozzle that makes possible population inversion of the excited electronic levels of the atom. The conditions of occurrence of inversion are studied as functions of the parameters characterizing the state of the plasma in the reservoir in front of the entrance to the nozzle, the shape of size of the nozzle, and the working substance. Use of the method of blocks of levels made it possible to calculate the degree of expansion needed for the formation of inversion between transitions with different wavelengths, and also to estimate the gain and the specific radiation energy in these transitions. Numerical estimates of the values of the parameters for the case of an argon plasma are given.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 91–97, November–December, 1979.We thank S. A. Losev for discussing the results and for helpful comments.     

The distribution function of atomic level populations in a plasma

An analytic form is obtained for the population distribution function in an atomic plasma as a series in successive time derivatives of the population of the first level. The first approximation includes the well-known method of a stationary sink. The quasistationary distribution obtained for hydrogen agrees well with numerical calculations of recombination and ionization, and for lithium, helium, and argon the quasistationary distribution gives qualitative agreement with numerical calculations.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 4, pp. 18–26, July–August, 1972.We should like to thank B. F. Gordiets for a helpful discussion.     

Investigation of unsteady flow structure during discharge of a shock-heated gas

This paper examines the structure of the near-gasdynamic section of a jet discharging into a rarefied volume. The experimental part of the article deals with unsteady discharge of a high-temperature gas. Discharge from a slot and from a circular aperture is investigated for air, nitrogen, CO₂, and argon with nonuniformities from 20–200. Approximate relations are obtained to describe the motion of the front of a discharging substance in dimensionless coordinates and the associated perturbation along the flow axis. It is established that the time for a steady geometric structure to form in the gasdynamic section of the jet is greater than the values obtained from data available in the literature.Translated from Zhurnal Prikladnoi Mekhaniki i Teoreticheskoi Fiziki, No. 5, pp. 34–40, September–October, 1973.     

Effect of an inhomogeneous magnetic field on the structure of an ionized gas flow

Results of an experimental study of the flow of an ionized gas produced by a shock wave through an inhomogeneous magnetic field are presented. Braking of the gas flow produced by the end currents is determined at two fixed sections of the magnetogasdynamic channel from the value of the isolated shock wave formed in the vicinity of the hemispherical model over which the flow passes. Maximum recorded reduction in Mach number was 30%, and with a magnetogasdynamic interaction parameter greater than 1.5, a transition of supersonic flow to infrasonic at the exit of the magnetic zone was observed. Experimental results were compared with a solution of a model problem which assumed one-dimensional flow in the flow core. The gas used was argon, with a maximum magnetic field induction of 1.5 T.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 174–178, September–October, 1976.     

Parameters of a closed arc stabilized by a longitudinal flow of argon

This article sets forth the results of an investigation of the temperature, velocity, dynamic head, and static pressure in high-current argon arcs used in plasma metallurgy. It is shown that the velocity and the amount of gas pumped through the column of the arc are determined by the current of the arc. A calculation is made and equations are presented which permit calculating this type of arc on the basis of a simplified equilibrium model. Experiment is compared with theory.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 1, pp. 66–74, January–February, 1973.     

Distribution of the electron concentration and wave processes in a pulsed discharge

A quantitative Schlieren method for measuring the electron-density gradient using a laser source in the infrared range is described, which guarantees measurement of densities above 10¹⁴ cm^–2; a detailed observation of the profile of the gas ionization in a pulsed discharge is likewise described. Certain results are presented of a study of the distribution of the electron concentration over the cross section of the discharge tube in a straight argon discharge during the flow of discharge current and also during the subsequent stages of the process. In order to perform time measurement of the electron-density gradients and to construct an overall picture of the plasma distribution, the Schlieren method with a CO₂ laser (10.6 ) as a light source was used. The measurements that were carried out revealed a complex picture involving the formation of a series of successive radial compression waves that exist during a fairly long period after completion of the discharge.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 15–20, March–April, 1971.     

Hall effect in the MHD model of plasma channel flow

The steady flow regime with quasi-radial electric current and nonequipotential boundaries is obtained in calculating axisymmetric plasma flow in a coaxial channel with an azimuthal self-magnetic field. The calculations were carried out using the MHD model with allowance for the Hall effect. The regime obtained describes the flow in the stream core of the channel of a modern quasi-steady heavy-current plasma accelerator outside thin near-electrode layers. Estimates of the Hall corrections relating to these layers are given.Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 5, pp. 56–65, September–October, 1995.     

Shock wave intersection in magnetohydrodynamics

The flow formed in the neighborhood of the discontinuity intersection point when shock waves collide at a nonzero angle is studied. The investigation can be directly applied to problems of shock wave interaction in the interplanetary plasma [9–12]. In magnetohydrodynamics the nature of the flow and its investigation are much more complex than in gas dynamics because of the greater number of possible waves and governing parameters.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 132–143, May–June, 1991.     

Experimental study of the possibility of reducing supersonic drag by employing plasma technology

The possibility of reducing the aerodynamic drag of a body by injecting plasma into the oncoming supersonic flow is confirmed experimentally.Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, pp. 177–182, March–April, 1996.     

Calculation of a wall-stabilized argon arc with account for radiative energy transfer

It was shown experimentally in [1, 2] and in a study by E. I. Asinovskii and A. V. Kirillin reported at the Scientific Technical Conference of the High-Temperature Scientific Research Institute held in 1964 that the heat transfer mechanism in a wall-stabilized argon arc was not purely purely conductive at gas temperatures greater than 11 000° K. Asinovskii and Kirillin also showed that radiative energy transfer is the reason why similarity is lost when the current-voltage characteristics are constructed in dimensionless form. The radiation of an argon arc has been studied experimentally by a number of authors [3–5], Dautov [6] calculated an argon arc without allowing for radiation.In this article an argon arc stabilized by the cooled duct walls is calculated with account for radiation using theoretically computed relationships describing the transport properties of argon plasma. A large portion of the radiated energy pertains to spectral lines whose role has been studied by L. M. Biberman. The authors have used I. T. Yakubov's data on argon radiation published in the journal Optics and Spectroscopy. A method of calculation and data on argon plasma radiation are also given in [7].Reference [8] deals with the problem of the role of radiation in an arc burning in nitrogen. In particular, the above-mentioned loss of similarity follows from the results of this work. However, the relationships used in this article to describe the transport properties of nitrogen plasma were obtained experimentally in [9].Notation r₀ arc radius (cm) - r variablesradius (cm) - T temperature (°K) - heat transfer coefficient (ergcm^–1sec^–1deg^–1) - E electric field intensity (g^1/2cm^–1/2sec^–1) - electrical conductivity (sec^–1) - q₁ heat flux density due to conduction - q₂ heat flux density due to radiation - u divergence of radiative energy flux density in the transparent part of the spectrum (ergcm^–3sec^–1) - u₂ same for part of the spectrum where reabsorption is taken taken into account - m₀ atomic mass - m_e electronic mass - Stefan-Boltzmann constant - h Planck constant - k Boltzmann constant - e electronic charge - p pressure - degree of ionization - N_e electron concentration (cm^–3) - n₀ neutral atom concentration - Q_0e electron-neutral collision cross section - Q_ie electron-ion collision cross section (cm²) - ₀ line center frequency (sec^–1) - ₊ line halfwidth (distance from line center to contour for ) due to effects giving dispersion contour - k _v absorption coefficient (cm^–1) - energy radiated by a hemispherical volume - emissivity of hemispherical volume - radius of hemispherical volume - S line intensity The authorS thank I. T. Yakubov for allowing them to use his data on arc plasma radiation.     

Investigation of the properties of a shock wave arising in a supersonic flow of plasma,passing through a transverse magnetic field

In a flow of plasma, set up by an ionizing shock wave and moving through a transverse magnetic field, under definite conditions there arises a gasdynamic shock wave. The appearance of such shock waves has been observed in experimental [1–4] and theoretical [5–7] work, where an investigation was made of the interaction between a plasma and electrical and magnetic fields. The aim of the present work was a determination of the effect of the intensity of the interaction between the plasma and the magnetic field on the velocity of the motion of this shock wave. The investigation was carried out in a magnetohydrogasdynamic unit, described in [8]. The process was recorded by the Töpler method (IAB-451 instrument) through a slit along the axis of the channel, on a film moving in a direction perpendicular to the slit. The calculation of the flow is based on the one-dimensional unsteady-state equations of magnetic gasdynamics. Using a model of the process described in [9], calculations were made for conditions close to those realized experimentally. In addition, a simplified calculation is made of the velocity of the motion of the above shock wave, under the assumption that its front moves at a constant velocity ahead of the region of interaction, while in the region of interaction itself the flow is steady-state.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 86–91, January–February, 1975.     

Calculation of supersonic heterogeneous flow directed against a barrier

A model describing a supersonic high-temperature gas flow containing powder particles is constructed. The flow characteristics associated with impingement on a target are analyzed, since such flows are widely used in plasma technology, in particular plasma deposition (see, for example, [1]). As distinct from [2, 3], flow against a target is considered rather than the flow past bodies of a stream of dusty gas homogeneous at infinity. The complex structure of the flow in the target zone makes the widely used one-dimensional and quasione-dimensional models inapplicable. However, in plasma deposition the flow usually retains its axial symmetry, which makes it possible to use axisymmetric two-dimensional problems for modeling purposes. Among a whole series of technological problems, attention is concentrated on the behavior of the powder particles in a supersonic jet of high-temperature gas.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. A, pp. 182–185, July–August, 1987.The authors wish to thank V. M. Fomin for useful discussions.     

Plasma flow accompanied by blowing and pumping of plasma across electrodes

The article discusses plane stationary slowly varying flows of a nonviscous plasma with good conductivity in a channel in a transverse magnetic field; the flows are accompanied by blowing in and pumping plasma across solid metallic electrodes. The Hall effect is taken into consideration. It is shown that the potential jump near the anode, which appears in an accelerated plasma flow in an ordinary channel with solid electrodes, can be eliminated in flows accompanied by blowing in (pumping) of plasma. It is also shown that flows are possible in which the velocity, density, and the transverse electric field increase in the direction of the accelerator cathode.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 6, pp. 26–34, November–December, 1970.     

Investigation of gas flows in a radial-type reactor for GaAs epitaxy

Argon and hydrogen flows for the epitaxy of GaAs from metal-organic compounds in a radial-type reactor are visualized by means of holographic interferometry methods. On the basis of the holographic interferograms the hydrogen temperature fields are calculated for various flow velocities. It is shown that an interpretation of the phenomena taking place in the gas phase, in terms of the dimensionless numbers Re and Ra, can be useful for qualitatively estimating and comparing various flow situations; a correlation of the interference patterns with the reactor geometry and gas flow velocity, which can be used to optimize the process parameters and reactor chamber structure, is described; the instability of Ar and H₂ flows is associated with the high-velocity turbulence and natural convection, the destabilizing effect of the buoyancy forces manifesting itself significantly more strongly in the argon flow. This means that it is incorrect to predict the nature of the flows on the basis of the complex Gr/Re².Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 6, pp. 118–124, November–December, 1996.