Uniformization of the density in reacting magnetohydrodynamic flows

Ionization and recombination provide a transfer between species in a partially ionized plasma. These phenomena modify the continuity equation for each species by linking them together in a common system. The consequences are specially clear when the velocities of ions and neutrals coincide and the flow is weakly compressible: the densities along each trajectory tend to a definite limit depending only on the initial total density and not on the ion/neutral rate. For the general case a weaker global estimate on the final rate between species may be proved.