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The electron swarm parameters and electron energy distribution function (EEDF) are necessary, especially on understanding quantitatively plasma phenomena and ionized gases. The EEDF and electron swarm parameters including the reduce effective ionization coefficient (α-η)/N (α and η are the ionization and attachment coefficient, respectively), electron drift velocity, electron mean energy, characteristic energy, density normalized longitudinal diffusion coefficient, and density normalized electron mobility in tetrafluoromethane (CF4) which was analyzed and calculated using the two-term approximation of the Boltzmann equation method at room temperature, over a range of the reduced electric field strength (E/N) between 0.1 and 1000 Td (1Td=10-17 V.cm2), where E is the electric field and N is the gas density of the gas. The calculations required cross-sections of the electron beam, thus published momentum transfer, vibration, electronic excitation, ionization, and attachment cross-sections for CF4 were used, the results of the Boltzmann equation in a good agreement with experimental and theoretical values over the entire range of E/N. In all cases, negative differential conductivity regions were found. It is found that the calculated EEDF closes to Maxwellian distribution and decreases sharply at low E/N. The low energy part of EEDF flats and the high-energy tail of EEDF increases with increase E/N. The EEDF found to be non-Maxwellian when the E/N> 10Td, having energy variations which reflect electron/molecule energy exchange processes. In addition, limiting field strength (E/N)limit has been calculated from the plots of (α-η)/N, for which the ionization exactly balances the electron attachment, which is valid for the analysis of insulation characteristics and application to power equipment.

Starting from the kinetic approach for a mixture of reacting gases whose particles interact through elastic scattering and a bimolecular reversible chemical reaction, the equations that govern the dynamics of the system are obtained by means of the relevant Boltzmann-like equation. Conservation laws are considered. Fluid dynamic approximations are used at the Euler level to obtain a close set of PDEs for six unknown macroscopic fields. The dispersion relation of the mixture of reacting gases is explicitly derived in the homogeneous equilibrium state. A set of ODE that governs the propagation of a plane travelling wave is obtained using the Galilei invariance. After numerical integration some solutions, including the well-known Maxwellian and the hard spheres cases, are found for various meaningful interaction laws. The main macroscopic observables for the gas mixture such as the drift velocity, temperature, total density, pressure and its chemical composition are shown. [Copyright &y& Elsevier]

Relaxation-time approximations of the collisional operator of the Boltzmann transport equation are used for simulating carrier transport in silicon semiconductors. Solutions of these kinetic models are obtained through the use of exact-integral representations in the stationary and homogeneous regime. Some properties of these solutions have been discussed and their validity have been assessed by Monte Carlo simulations in bulk silicon. [Copyright &y& Elsevier]

This paper develops a procedure, based on methods of extended thermodynamics, to design nonlinear hydrodynamical models for charge transport in metals or in semiconductors, neglecting viscous phenomena. Models obtained in this way allow the study of the motion of electric charges in the presence of arbitrary external electric fields and may be useful when one wishes to study phenomena in a neighborhood of a stationary nonequilibrium process: indeed, the drift velocity of the charge gas with respect to the crystal lattice is not regarded as a small parameter. [Copyright &y& Elsevier]

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Onsager-type transport equations, as were derived in a previous paper by the authors, are applied to the diffusion of test particles near the interface of a scattering medium with a perfect absorber. Temperature and density profiles are obtained for different types of scattering cross-section. [ABSTRACT FROM AUTHOR]

The Fokker-Planck equation describing a beam of charged particles entering a homogeneous medium is solved here for a stationary case. Interactions are taken into account through Coulomb cross-section. Starting from the charged-particle distribution as a function of velocity and penetration depth, some important kinetic quantities are calculated, like mean velocity, range and the loss of energy per unit space. In such quantities the energy straggling is taken into account. This phenomenon is not considered in the continuous slowing-down approximation that is commonly used to obtain the range and the stopping power. Finally the well-known Bohr or Bethe formula is found as a first-order approximation of the Fokker-Planck equation. [ABSTRACT FROM AUTHOR]

Following a procedure which is typical of linear (neutron) transport theory, a multigroup approach is proposed for the non-linear extended Boltzmann equation in the presence of removal, a background medium, an external source and an external force field. The relevant multigroup equations, corresponding to a discretization of the speed variable only, are derived and discussed, especially in connection with the so-called semi-discrete models recently introduced in kinetic theory. [ABSTRACT FROM AUTHOR]

The first paper in this series investigated, from the mathematical point of view, several aspects of the thermodynamic fluid theories (of divergence type). The object of this second paper is to present a simple example of such a theory. Here the Grad moment method is applied to a classical Boltzmann equation to obtain a determined system of the quasi-linear, first-order partial differential equations for the evaluation of the usual hydrodynamic variables and the stress deviator. As demonstrated already by Loose and Hess ( Phys. Rev. A, 37, 2099 (1988)), these equations provide valuable information about the shear-rate dependence of the viscosity coefficients and on other non-Newtonian properties of the pressure tensor. Accidentally, for the above-mentioned choice of independent gas-state variables, the truncation scheme of Grad not only leads to a symmetric hyperbolic system of differential equations, but also is in complete agreement with the variational approach to Maxwell's equations of transfer. Thus the proposed method enables one to obtain the supplementary balance law, interpreted as the equation of balance of entropy, satisfied by a certain function h of the original variables. This function, which in the present case can be calculated explicitly, is referred to as the specific entropy (per unit mass). The resulting non-linear expression for h is investigated with a view to a deeper understanding of a status of the extended Gibbs relation. Due to the existence of this relation, one easily arrives at the natural definitions of temperature, pressure, and thermodynamic potentials for gaseous systems «not infinitesimally near to equilibrium». [ABSTRACT FROM AUTHOR]

Using an efficient Monte Carlo simulation algorithm and a multiterm code, we verify the observation of Braglia et al. concerning the inadequacy of the two-term approximation for the description of electron transport in argon. The implications of this observation for the analysis of swarm experiments are discussed. We comment on truncation methods employed by a number of multiterm solutions and point out a possible source of confusion that may arise when comparing methods. A discussion of the presentation and labelling of transport coefficients is also given. [ABSTRACT FROM AUTHOR]

The viscosity coefficient entering sound wave attenuation is evaluated for the liquid alkali metals in an ion-electron plasma approach. It is shown that the contribution from electrical conduction, though small, is by no means negligible. The calculated longitudinal viscosity is very close to the measured shear viscosity contribution, the bulk viscosity being expected to be small in the present approach. [ABSTRACT FROM AUTHOR]

The present paper describes a direct method of obtaining are expression of the distribution function of charged particles which diffuse in a plasma. The distribution function in velocity, angle and time is presented starting from the Fokker-Planck equation. Temperature, average velocity and energy of charged particles (electron or ions) have also been calculated as functions of time. [ABSTRACT FROM AUTHOR]

A 3×3 semi-linear hyperbolic system arising in extended kinetic theory is studied. Direct solutions to such system are discussed in a systematic way, and for various physical situations. [ABSTRACT FROM AUTHOR]

The approximate conservation laws for a binary gas mixture with quadratic interactions can be written as a system of two semilinear hyperbolic equations. By using the method of characteristics the study of this system is reduced to the study of a system of nonlinear ordinary differential equations, for which we find several classes of exact solutions. Exact integrability conditions are found for ODE systems of generalized Lotka-Volterra type. Some situations are also considered, in which the characteristic method cannot be applied and exact solutions are obtained via an operator method. [ABSTRACT FROM AUTHOR]

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Copyright of Il Nuovo Cimento della Societa Italiana di Fisica: D is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento della Societa Italiana di Fisica: D is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento della Societa Italiana di Fisica: D is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento della Societa Italiana di Fisica: D is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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The discrete-velocity models of the extended kinetic equations are analysed for the case of a gas of test particles scattering between themselves and absorbed or generated by a background medium. Exact analytical solutions to the set of hyperbolic semilinear first-order PDE governing the components of the particle distribution function are investigated. Particular solutions of different type satisfying special initial conditions are determined or discussed. [ABSTRACT FROM AUTHOR]

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