  A 14-moment maximum-entropy system of equations is applied to the description
of non-equilibrium electrons in crossed electric and magnetic fields and in the
presence of low collisionality, characteristic of low-temperature plasma
devices. The flexibility of this formulation is analyzed through comparison
with analytical results for steady-state non-equilibrium velocity distribution
functions and against particle-based solutions of the time-dependent kinetic
equation. Electric and magnetic source terms are derived for the 14-moment
equations, starting from kinetic theory. A simplified BGK-like collision term
is formulated to describe the collision of electrons with background neutrals,
accounting for the large mass disparity and for energy exchange. An
approximated expression is proposed for the collision frequency, to include the
effect of the electrons drift velocity, showing good accuracy in the considered
conditions. The capabilities of the proposed 14-moment closure to capture
accurately non-equilibrium behaviour of electrons for space homogeneous
problems under conditions representative of those found in Hall thrusters is
demonstrated.
