Diffusion correction and thermal diffusion factors of ions in the ionosphere and plasmasphere

摘要

Diffusion equations determining ion diffusion velocities along magnetic field lines in the multicomponent ionosphere and plasma-sphere composed of ions, electrons, and neutral species are derived from Grad's 13-moment equations for average species velocities and heat flows. The general expressions for thermal diffusion and diffusion correction factors of an ion are simplified for the following cases of a multicomponent partially ionized plasma: (1) a major ion, a minor ion, electrons, and neutral species; (2) three major O~+, H~+, and He~+ ions, electrons, and neutral species; (3) two major O~+ and H~+ ions, a minor ion, electrons, and neutral species. The ion thermal diffusion and diffusion correction factors calculated for O+, H+, and He~+ ions of a fully ionized plasma are approximated by the analytical formulas as functions of [O~+]/[H~+] while changing the ratio of [He~+] to ([O~+] + [H~+] + [He~+]) between 0.01 and 0.9. A fully ionized plasma composed of two major ion species, O+ and H+, electrons, and a minor ion component, x, where x stands for NO+, N_2~+,O_2~+, H_2~+, N~+, O~(++), N~(++), Fe~+, Mg~+, Na~+, Ca~+, Al~+, and Si~+ is considered to calculate the thermal diffusion and diffusion correction factors of each minor ion. Analytical approximating relationships of these thermal diffusion and diffusion correction factors with the [O~+]/[H~+] ratio are presented for use in ionospheric models.