A quasi-moment description of the evolution of an electron gas towards a state dominated by a reduced transport equation

For electrons in electric and magnetic fields which collide elastically with neutral atoms or molecules, a minute evolution study is made using the multiple time-scale method. In this study a set of quasi-moment equations is used which is derived from the Boltzmann equation by taking appropriate quasi-moments, i.e. velocity moments where the integration is performed only over velocity angles. In a systematic way we reveal the evolution in a transient regime where processes take place on time-scales related to the electron-atom collision frequency and electron cyclotron frequency and show how the evolution enters a regime where it is governed by a reduced transport equation. This work has relevance to the theory of evolution of gases of charged particles in general and to non-neutral plasmas and partially ionized gases in particular.