Similarity law for kinetic coefficients of hot electrons in atomic liquids with molecular impurities

A straightforward similarity law is proposed in the framework of the Lekner-Cohen theory which makes it possible to estimate the effect of the impurities on the kinetic coefficients of electrons in liquids with molecular additions.     

Enskog-Landau kinetic equation for multicomponent mixture. Analytical calculation of transport coefficients

The Enskog-Landau kinetic equation is considered to describe non-equilibrium processes of a mixture of charged hard spheres. This equation has been obtained in our previous papers by means of the non-equilibrium statistical operator method. The normal solution of this kinetic equation found in the first approximation using the standard Chapman-Enskog method is given. On the basis of the found solution the flows and transport coefficients have been calculated. All transport coefficients for multicomponent mixture of spherical Coulomb particles are presented analytically for the first time. Numerical calculations of thermal conductivity and thermal diffusion coefficient are performed for some specific mixtures of noble gases of high density. We compare the calculations with those ones for point-like neutral and charged particles. Received 10 June 1999 and Received in final form 15 October 1999     

Emission characteristics and electron kinetic coefficients of the plasma of a transverse volume discharge initiated in a mixture of heavy inert gases with chlorine molecules

The results of studying the radiation due to argon, krypton, and xenon monochloride bands, as well as to the bands of chlorine molecules, from the plasma of a transverse Ar-Kr-Xe-Cl₂ volume discharge are reported. The working mixture of a pulse radiation source is optimized with regard to its pressure and elemental composition and parameters of an excitation system. By numerically solving the Boltzmann kinetic equation for the electron energy distribution function, the transport characteristics of plasma electrons and discharge power specific losses are found for different values of the reduced electric field strength. The plasma parameters are simulated for the quaternary mixture, which is most appropriate for a multiwave UV-VUV source. Qualitative analysis is conducted for the most important electron processes in the multicomponent plasma that govern the joint formation of argon, krypton, and xenon monochlorides in the transverse discharge.     

Distribution of electron flows over the cathode surface in a discharge with oscillating electrons

The mechanisms governing the distribution of the longitudinal electron flows over the cathode surface in a discharge with oscillating electrons are studied experimentally. The influence of the discharge gap length on the magnitude and distribution of the electron flows is investigated. It is shown that intense longitudinal electron flows in a tube of diameter d _a =31 mm can form only with short anodes of length l _a =2.5–3.5 cm. The distributions of the electron current over the cathode surface at various discharge conditions are determined.     

An analytical approach to the distribution function of electrons in the molecular oxygen discharge

Analytical expressions for the electron distribution function and the kinetic coefficients in the molecular oxygen glow discharge are given. The relative importance of the various collisional processes in evaluation of some experimentally measured quantities is discussed as well as the validity of the present results.     

Thermal expansion and kinetic coefficients of crystals

Electrical (ρ) and thermal (W) resistivities and thermal expansion coefficient (β) of Cu, Zn, Al, Pb, Ni, β-brass, Al₂O₃, NaCl, Si, SiO₂(∥), and SiO₂(⊥) were simultaneously measured with standard four-probe, absolute steady-state, and quartz dilatometer techniques. Measurements of Ni and β-brass were performed at temperatures from 300 to 1100 K and measurements of all other samples were made between 90 and 500 K. This temperature range includes the range below and above the Debye temperature (T_D). The total uncertainties of the specific electrical and thermal resistivities and thermal expansion coefficient (TEC) measurements are 0.5%, 3.0%, and (1.5-4.0%), respectively. The universal linear relationship between the electrical and thermal resistivities and βΤ over the wide temperature range was found experimentally. Using the Landau criterion for convection development for ideal phonon and electron gases in the solids, the universal relations, ρ^ph/ρ^*≡βT and W^ph/W^*≡βT (where ρ^ph is the phonon electrical resistivity, is the characteristic electrical resistivity, W^ph is the phonon thermal resistivity, and W^*=k_BG/qc_p is the characteristic thermal resistivity) between relative phonon electrical and phonon thermal resistivities and βΤ were derived. The derived universal relations provide a new method for estimating the kinetic coefficients (electrical and thermal resistivities) from TEC measurements.     

On relativistic kinetic gas theory: XIV. Transport coefficients of a binary mixture. General expressions

A relativistic method to calculate transport coefficients is developed for a binary mixture with arbitrary particle interaction. The heat conductivity, the diffusion coefficient, the thermal-diffusion coefficient, the shear viscosity and the volume viscosity are expressed in terms of relativistic omega integrals.     

Electron transport coefficients in a helium-xenon mixture

Electron drift characteristics in a helium-xenon mixture under an electric field strength E/N = 1 ? 100Td are calculated and analyzed taking into account inelastic collisions. It was shown that a minor xenon additive to helium, beginning with percent fractions, has a significant effect on the discharge, in particular, on the characteristics of inelastic processes. The effect of the percentage of helium and xenon on electron drift, i.e., the diffusion and mobility coefficients, ionization frequency, etc. is studied.     

Distribution functions of electrons with respect to energy,in a high-frequency electrode discharge at reduced pressures

This paper considers the question concerning the applicability of the well-known theory of positive column contraction of a direct current discharge to a high-frequency discharge in nitrogen at reduced pressures. Measurements of the electron energy distribution function and other parameters of the plasma are carried out by probe methods along the radius of a high-frequency discharge. Comparison is made between the experimental and theoretical results.     

Glow discharge in rare-gas and metal vapour mixture

Conclusion The results are summarized in the form of graphs which illustrate the dependence of the rate coefficients on three parameters: E/N (electric field over total neutral concentration) x_e (ionization degree) and n₁ (relative concentration of cadmium). In such a way, we have tried to point out the main feature of the collisional rates under the conditions of steady-state, weakly ionized plasma. The use of the maxwellian distribution function for an evaluation of the rate coefficients would yield the results which differ substantially from ours. This concerns, particularly, the excitations from the ground state of atom efficacy of which depends on the high energy distribution tail. Since the true distribution function from Ref. [1] was employed in our calculations, it can be inferred that the main source of the inaccuracy in the rate coefficients is essentially given by the cross-sections used. It is believed that the present results can serve for a more quantitative understanding or for obtaining insight into the microscopic phenomena occurring in the positive column of the discharge.     

Glow discharge in rare-gas and metal vapour mixture

Applying the Boltzmann equation to a He-Cd mixture discharge the electron energy distribution functions, kinetic coefficients and collision frequencies are numerically calculated. Calculations are made for a homogeneous and stationary discharge plasma subjected to an externally applied electric field. The collision processes which have been taken into account are elastic and inelastic collisions of electrons with He and Cd atoms as well as mutual encounters of electrons. In this case the electron energy distribution and all the quantities calculated from it are dependent on the reduced electric field, the ionization degree and the relative cadmium concentration.     

Distribution function and diffusion of electrons in the Rydberg energy space in a nonideal ultracold plasma

The distribution functions and diffusion coefficient of electrons in the Rydberg energy space in an ultracold plasma are obtained as functions of temperature by numerically solving a system of kinetic balance equations. As the initial conditions, the results obtained in previous papers by the molecular dynamics method are used. From calculation of Rydberg electron fluxes, the temperature dependence of the recombination coefficient is obtained, in good agreement with the recombination coefficient calculated previously by the molecular dynamics method.     

Mean energy of electrons in the oxygen discharge plasma

The mean energy of electrons in the homogeneous form of the positive column in an oxygen discharge is determined. The mean energy of electrons is calculated from double-probe characteristics under the assumption of a Druyvesteyn distribution using volt-equivalents of the electron temperature. The relation between the mean energy of electrons andE/p is compared with the theoretical results of another author. As a result of this comparison it can be concluded that for some discharge conditions the energy distribution of electrons is very close to a Druyvesteynian. We also analyze the influence of the negative ions on the double-probe characteristics.The author is obliged to Dr. O.tirand, Dr. L.Pekárek and Dr. J.Skála for their support of this work and helpful comments.     

Barnett kinetic coefficients in dense charged and neutral media

An approach based on the nonlinear response theory is proposed for determining nonlinear transport properties of nonideal multielement charged and neutral media. A version of this theory developed for describing these properties involves the comparison of phenomenological conservation equations for dense media in the Barnett approximation and microscopic equations for operators of dynamic variables. The Mori algorithm used for formulating the microscopic equations makes it possible to obtain these equations for non-ideal media in the form of generalized nonlinear Langevin equations. As a result, macroscopic expressions are derived for nonlinear kinetic coefficients in the second order in thermal perturbations (of temperature, mass velocity, etc.). The expressions for nonlinear and linearized Barnett kinetic coefficients are compared.     

Trapped and free electrons in the near-anode region of a striated discharge

Spatial potential profiles and electron energy distribution functions are measured in the near-anode region of a striated neon glow discharge. It is discovered that potential wells of small depth adjacent to the anode appear on the spatial potential profiles at certain moments in time. The distribution functions measured in the potential wells have a pronounced maximum of slow electrons, which sharply distinguishes them from the distribution functions in the striation phases where there are no wells. The mechanism which shapes the electron distribution function for electrons trapped in a potential well is analyzed. A perturbing effect of the anode on the electron distribution function as the anode is approached is discovered experimentally, and an interpretation of this effect is given. Zh. Tekh. Fiz. 68, 25–32 (March 1998)     

Determining the energy distribution function of electrons in the negative-luminescence plasma of a glow discharge from the line intensities

The energy distribution function of electrons (EDFE) in the negative luminescence of a glow discharge is found using, as well as the probe method, calculation from measured spectralline intensities. The measurements are made in a weakly anomalous discharge in helium at a pressure of 0.5 mm Hg. In the energy range from 0 to 35 eV, EDFE is determined by the second-derivative method, and in the range from 23 to 69 eV by derivation from the helium spectral-line intensities. Note that the nonmonotonic behavior of the distribution function due to inelastic collisions of electrons with gas atoms is clearly reflected both in the probe characteristics and in the radiation spectrum.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 71–76,. May, 1979.     

Nonlinear hyperbolicity in kinetic theory of a gas mixture

Summary A system of nonlinear hyperbolic conservation equations, arising in the study of an evolution problem of a mixture of gases of interacting particles in the presence of only removal effects, is illustrated. Explicit analytical solutions to such system are obtained and commented on both mathematical and physical grounds.

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Riassunto Nel presente lavoro si illustra un sistema di equazioni iperboliche non lineari di conservazione, che si incontra nello studio di un problema di evoluzione per una miscela di gas di particelle interagenti in presenza di soli effetti di rimozione. Soluzioni analitiche esplicite di tale sistema sono costruite e commentate su base sia matematica che fisica.

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Резюме Рассматривается система нелинейных гиперболических уравнений сошранения, возникающих при исследовании проблемы эволюции смеси газов взаимодействующих частиц в присутствии зффектов удаления. Получаются точные аналитические решения для такой системы. Проводится обсуждение полученных результатов с математической и физической точек зрения