Nonequilibrium macroscopic descriptions of electrons in weakly ionized gases

In this paper a nonequilibrium description of the dynamics of electrons in a background gas under the influence of space-time varying fields is presented. It is obtained by interpolating between a kinetic and a moment formulation. To achieve this, the moment equations have been ordered by using characteristic scales. The ordering is then used to derive, from the kinetic equation, a new equation valid only in the scale of the moment equations. This equation and a finite set of moment equations form a closed system which can be used to describe the dynamics of electrons under various nonequilibrium conditions. Comparisons are presented between results obtained with this formulation and those obtained from a kinetic model.