Radial Diffusion Coefficient for Electrons at 1.76 < <i>L</i> < 5

TitleRadial Diffusion Coefficient for Electrons at 1.76 < L < 5
Publication TypeJournal Article
Year of Publication1968
AuthorsNewkirk, LL, Walt, M
JournalJournal of Geophysical Research
Pagination7231 - 7236
Date Published12/1968
KeywordsRadial Transport
AbstractRadial diffusion by nonconservation of the third adiabatic invariant of particle motion is assumed in analyzing experiments in which electrons appeared to move across field lines. Time-dependent solutions of the Fokker-Planck diffusion equation are obtained numerically and fitted to the experimental results by adjusting the diffusion coefficient. Values deduced for the diffusion coefficient vary from 1.3 × 10−5 RE²/day at L = 1.76 to 0.10 RE²/day at L = 5. In the interval 2.6 < L < 5, the coefficient varies as L10±1. Assuming a constant electron source of arbitrary magnitude at L = 6 and the above diffusion coefficients, the equatorial equilibrium distribution is calculated for electrons with energies above 1.6 Mev. The calculation yields an outer belt of electrons whose radial distribution is in good agreement with the observed belt. The calculated distribution also exhibits an inner belt at L ≈ 1.5. However, the calculated intensity of the inner belt relative to the outer belt is several orders of magnitude smaller than the experimental ratio.

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