Continuous emission of argon,krypton and xenon plasmas

Emission coefficients of shock-tube plasmas have been measured as functions of the plasma parameters in the visible spectrum. The plasma state was determined by dual-wavelength interferometry and high accuracy of the ξ-factors was achieved. The results are compared with theoretical and other experimental data. In particular, the dependence of ξ on the plasma state is discussed.     

Collisional recombination in nonideal plasmas

We suggest a model that allows one to consider the kinetics of collisional recombination in a nonideal plasma and to calculate its rate by the molecular dynamics method. We have found that the dependence of the collisional recombination rate on the plasma coupling parameter differs significantly from the extrapolation of the three-body recombination rate to the nonideal region. The recombination rate in a strongly coupled plasma has been found to decrease with increasing coupling parameter. We have established that the effect of plasma nonideality increases with ion charge. The recombination kinetics is shown to depend significantly on how the ions are arranged in the medium. Collisional recombination transforms into three-body one as the coupling parameter of the medium decreases.     

Transport properties and weak non-ideality in xenon and argon plasmas of intermediate degree of ionization

Electron mobility and electric conductivity in xenon and argon plasmas of various degrees of thermal ionization are evaluated with the aid of a revised definition of the Debye radius permitting to treat these plasmas formally as weakly non-ideal. The analysis is carried out for temperatures ranging from 2 000 K to 20 000 K and for various initial pressures, equal to or smaller than the normal atmospheric pressure.     

Collisions and Langmuir waves in nonideal plasmas

Journal of Experimental and Theoretical Physics - Langmuir waves and particle-particle collisions in an equilibrium two-component plasma consisting of nondegenerate electrons and singly charged...     

Electron-ion Coulomb Bremsstrahlung in nonideal plasmas

The classical electron-ion Coulomb Bremsstrahlung process is investigated in nonideal plasmas. An effective pseudopotential model taking into account the plasma screening and collective effects is applied to describe the electron-ion interaction potential in a classical nonideal plasma. The classical straight-line trajectory method is applied to the motion of the projectile electron in order to visualize the variation of the differential Bremsstrahlung radiation cross-section (DBRCS) as a function of the scaled impact parameter, nonideal plasma parameter, projectile energy, photon energy, and Debye length. The results show that the DBRCS in ideal plasmas described by the Debye-Hückel potential is always greater than that in nonideal plasmas, i.e., the collective effects reduce the DBRCS for both the soft and hard photon cases. For large impact parameters, the DBRCS for the soft photon case is found to be always greater than that for the hard photon case. Received 1st December 1999     

Kinetics of ionization-recombination processes in nonideal hydrogen plasmas

The time evolution of the relative populations of excited atomic levels in a reacting dense H-plasma is studied on the basis of rate equations. Many-particle effects are taken into account via energy level shifts. It is found that the occupation of the bound state levels is essentially smaller than for the ideal case. It is shown that the mechanism of the relaxation to the thermal equilibrium depends on the density. Inversions of the level populations can be observed.     

Electron transfer in proton-hydrogen collisions in nonideal classical plasmas

Effects of nonideality of classical plasma on the reaction: p + H(1s) → H(nlm) + p has been investigated by carrying out fully quantum mechanical calculations within the framework of a first-order distorted wave method. Scattering amplitude is calculated conveniently by employing a simple, variationally determined wave function of hydrogen atom embedded in nonideal classical plasma. A detailed study is made on the changes in electron transfer cross sections due to the nonideality of plasma varying from 0 to 4 and the incident proton energy lying between 10 and 500 keV. It has been found that nonideality of plasma causes substantial change in capture cross section.     

Adsorption of argon and xenon on graphite

The microstructure of graphite surface is investigated, using the method developed earlier by the author.     

Nucleation in superheated argon,krypton and xenon liquids

The superheating of condensed noble gases (argon, krypton, xenon) was investigated by the techniques of continuous heating of liquid specimen in a glass capillary. Experiments covered the pressure range 1–35 bar at the nucleation rates ≈10⁵ cm^-3 s^-1. The superheating data obtained here were compared with the results of calculations based on the Volmer-Becker-Döring-Zeldovich-Frenkel homogeneous nucleation theory. A good agreement between theory and experiment as well as the thermodynamic similarity of the studied substances with respect to the fluctuation nucleation was found.     

Interpolation formula for the electrical conductivity of nonideal plasmas

On the basis of a quantum‐statistical approach to the electrical conductivity of nonideal plasmas we derive analytical results in the classical low‐density regime, in the degenerate Born limit, and for the contribution of the Debye‐Onsager relaxation effect. These explicit results are used to construct an improved interpolation formula of the electrical conductivity valid in a wide range of temperature and density which allows to compare with available experimental data of nonideal plasmas.     

Electron captures by positrons from hydrogenic ions in nonideal classical plasmas

In nonideal classical plasmas, the electron captures by positrons from hydrogenic ions are investigated. An effective pseudopotential model taking into account the plasma screening effects and collective effects is applied to describe the interaction potential in nonideal plasmas. The classical Bohr-Lindhard model has been applied to obtain the electron capture radius and electron capture probability. The modified hyperbolic trajectory method is applied to the motion of the projectile positron in order to visualize the electron capture probability as a function of the impact parameter, nonideal plasma parameter, projectile velocity, and plasma parameters. The results show that the electron capture probability in nonideal plasmas is always greater than that in ideal plasmas descried by the Debye-Hückel potential, i.e., the collective effect increases the electron capture probability. It is also found that the collective effect is decreased with increasing the projectile velocity. Received 21 January 2000 and Received in final form 27 April 2000     

Muonium formation in xenon and argon up to 60 atmospheres

Results of muon polarization studies in xenon and argon up to 60 atm are reported. In argon for pressures up to 10 atm, the muon polarization is best explained by an epithermalcharge exchange model. Above this pressure, the decrease inP _D and increase inP _L are ascribed to charge neutralization and spin exchange reactions, respectively, in the radiolysis track. Measurements with Xe/He mixtures with a xenon pressure of 1 atm indicate that the lost polarization in the pure xenon at this pressure is due to inefficient moderation of the muon. As the pressure in pure xenon is increased above 10 atm, we find thatP _L remains roughly constant andP _D begins to increase. The lost fraction may be due to the formation of a XeMu Van der Waals type complex, whileP _D is ascribed to XeMu⁺ formation. This suggests that spur processes appear to be less important in xenon than in argon.     

Stationary rarefaction wave in magnetized Hall plasmas

We demonstrate the existence of a stationary rarefaction wave in a current-carrying plasma. The result unexpectedly mismatches with the commonly accepted viewpoint about the impossibility of rarefaction shocks in gases or plasmas. The discovered wave may appear when the magnetic field has penetrated into the plasma and magnetized the electrons. At this stage, the wave front is formed at the cathode and propagates towards the anode through the magnetized quasineutral plasma. The case of low collisionality is investigated analytically. This phenomenon could explain the recent surprising experimental observations of a local plasma density drop in several laboratory plasmas.     

Dynamic plasma screening effects on low-energy bremsstrahlung emission in nonideal plasmas

The dynamic screening effects on the low-energy electron–ion bremsstrahlung process are investigated for both the soft and hard photon radiations in nonideal plasmas. The impact-parameter analysis is employed to obtain the bremsstrahlung radiation cross section as a function of the impact parameter, projectile energy, radiation photon energy, thermal energy, and Debye length. The results show that the dynamic screening effect on the bremsstrahlung radiation is found to be more significant for distant encounters. In addition, the dynamic screening effect is found to be more important for the soft photon radiation and decreases with increasing the radiation photon energy.     

Equilibrium properties of crystalline argon,krypton and xenon

By assuming an interaction energy for krypton and xenon of the same shape as that established for argon in an earlier paper and without introducing any adjustable parameters, values of the equilibrium properties of the crystals have been calculated which agree with the measured values to within the experimental accuracy or to within one per cent.     

应用Saha方程计算氩等离子体的Hugoniot物态方程

应用Saha模型加Debye-Huckel修正计算氩等离子体的Hugoniot物态方程,温度在10000-30000K之间,压力在0.0133-0.166GPa范围内,非理想参数Γ≈0.38.实验值和理论计算结果符合较好,说明Saha模型加Debye-Huckel修正能较好描述该热力学条件下氩等离子体的热力学行为.     

Electron state density and electron diffusion coefficient in energy space in nonideal nonequilibrium plasmas

We suggest a model for a hydrogenic low-temperature nonequilibrium nonideal plasma that allows the kinetic parameters of the plasma to be calculated by the method of molecular dynamics by taking into account the interparticle interaction. The charges interact according to Coulomb’s law; for unlike charges, the interaction is assumed to be equal to a constant at a distance smaller than several Bohr radii. For a system of particles, we solve the classical equations of motion under periodic boundary conditions. The initial conditions are specified in such a way that the electrons have a positive total energy. We consider the temperatures 1-50 K and densities n = 10⁹?10¹⁰ cm^?3 produced in an experiment through laser cooling and resonant excitation. We calculate the electron state density as a function of the plasma coupling parameter and the electron diffusion coefficient in energy space for highly excited (Rydberg) electron states close to the boundary of the discrete and continuum spectra.     

Calculation of radiative heat transfer in argon arc plasmas

Radiation emission and absorption in arc plasmas are important energy transfer processes. Exact calculations, though possible in principle, are usually impossible in practice because of the need to treat a large number of spectral lines and also the continuum radiation in the whole spectrum range. Recently, we have used an approximate method of partial characteristics to evaluate the radiation intensities, radiation fluxes and the divergence of radiation fluxes for SF₆ arc plasma with cylindrical symmetry. In this paper, we have extended our calculations toargon arc plasmas for the plasma pressures of 0.1, 0.5 and 1.0 MPa. We have calculated the coefficients of absorption for Ar plasmas at temperatures from 300 to 35 000 K, and have used these coefficients to calculate the partial characteristics. Both the continuum and the line spectra have been included in calculations. We have taken into account the radiative photo-recombination and bremsstrahlung for the continuous spectrum, and over 500 spectral lines for the discrete spectra.The method of partial characteristics has been applied to three-dimensional calculations of radiative heat transfer — i.e. radiation intensity, radiation flux and its divergence — in simplified temperature profiles. Conclusions have been made concerning validity and utilization of the method of partial characteristics in general gas dynamics problems.