Convection Electric Fields and the Diffusion of Trapped Magnetospheric Radiation

TitleConvection Electric Fields and the Diffusion of Trapped Magnetospheric Radiation
Publication TypeJournal Article
Year of Publication1969
AuthorsBirmingham, TJ
JournalJournal of Geophysical Research
Pagination2169 - 2181
Date Published05/1969
KeywordsRadial Transport
AbstractWe explore here the possible importance of time-dependent convection electric fields as an agent for diffusing trapped magnetospheric radiation inward toward the earth. By using a formalism (Birmingham, Northrop, and Fälthammar, 1967) based on first principles, and by adopting a simple model for the magnetosphere and its electric field, we succeed in deriving a one-dimensional diffusion equation to describe statistically the loss-free motion of mirroring particles with arbitrary but conserved values of the first two adiabatic invariants M and J. Solution of this equation bears out the fact that reasonable electric field strengths, correlated in time for no longer than the azimuthal drift period of an average particle, move particles toward the earth at a rate at least an order of magnitude faster than electric fields whose source is a fluctuating current on the magnetopause.

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