Short-time development of swarms-approach to hydrodynamic regime for charged particles in neutral gases

Abstract

The initial value problem for the spatial moments of the phase space distribution for charged particles in neutral gases is formally solved. The approach to the hydrodynamic regime is studied by defining time-dependent transport coefficients. An ambiguity in previous formulations is resolved by reference to some properties of these equations and contact is made with the equations of hydrodynamic regime. It is shown that all such transport coefficients are independent of the initial values of the number density and approach their constant asymptotic values in the same characteristic time.