Ambipolar Diffusion in Meteor Trails

Abstract

Ambipolar diffusion and the formulation of the equations of continuity for a diffusing cloud of electrons and ions are briefly discussed. A numerical method for the solution of the equations is outlined and the solutions are presented in graphical form. The results indicate that, for concentrations higher than a critical value, electrons and ions diffuse at the same rate and that the major part of the radio echo from a meteor trail will occur under conditions of ambipolar diffusion. However, a sheath of electrons is to be expected surrounding the diffusing cloud. The ratio mobility: diffusion coefficient is shown to be an important parameter in controlling the transition from ambipolar to free diffusion.