Minor ion diffusion in the F2-region of the ionosphere
1970; Elsevier BV; Volume: 18; Issue: 9 Linguagem: Inglês
10.1016/0032-0633(70)90142-x
ISSN1873-5088
AutoresR. W. Schunk, James C. G. Walker,
Tópico(s)Atomic and Subatomic Physics Research
ResumoWe have evaluated ionospheric diffusion coefficients to the second approximation of Chapman and Cowling in order to check the first approximation values which are currently in use. We find that the first approximation to the ambipolar diffusion coefficient is quite accurate, but that similar diffusion coefficients for the minor ions are in error by as much as a factor of 2. Coulomb collisions couple minor ion drift velocities closely to the velocity of the O+ ions. Consequently, minor ion densities in the F-region are very sensitive to fluxes of ionization into or out of the ionosphere. To illustrate this sensitivity we present solutions of the continuity equations for O+, H+, He+ and N+ ions in the F-region for a range of topside boundary conditions. We find that H+ densities are significantly reduced if the upward O+ flux approaches 9 × 108 cm −2 sec−1 or if the upward H+ flux approaches 2·5 × 107 cm−2 sec−1. For He+ the corresponding limits are 4 × 108 cm−2 sec−1 of O+ or 4.3 × 106 cm−2 sec−1 of He+, and for N+ the limits are 2 × 108 cm−2 sec−1 of O+ or 9.5 × 105 cm−2 sec−2 of N+.
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