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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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