Read Full Article    Cited by

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 98, NO. A12, PAGES 21,253–21,264, 1993

Electron Distributions in the Inner Jovian Magnetosphere: Voyager 1 Observations

G. Ye

Department of Physics and Astronomy, University of Kansas, Lawrence

T. P. Armstrong

Department of Physics and Astronomy, University of Kansas, Lawrence

Abstract

Using several improvements in the analysis of the observations of the Low Energy Charged Particle (LECP) experiment on Voyager 1, electron phase space densities in the inner Jovian magnetosphere (5-10 R_J ) were first calculated at constant first and second invariants (represented by µ and K, respectively), based on the LECP measurements. The calculated electron phase space density profiles show that in the inner Jovian magnetosphere there exist evident time and longitude variations, energetic electron injections, and present radial transport and distributed losses. To study the radial and pitch angle diffusions of Jovian electrons, we have calculated the phase space densities in the K-L space. It is found that the electron population in the inner Jovian magnetosphere seems to consist of two components: electrons radially diffusing from a main external source and electrons generated from local sources. The radially diffusing electrons have a relatively time stationary and isotropic distribution, while the locally created electrons mainly concentrate around the equatorial plane and have relatively lower energies, in comparison with the inward diffusing electrons. Consequently, the sources of precipitation losses to the ionosphere must be primarily electrons transported from outer sources, and the major precipitations occur in the inner magnetosphere (L < 7.5 R_J ). In the inner Jovian magnetosphere (L = 5 ∼ 10 R_J ) it is estimated that for electrons with magnetic moment µ = 300 MeV/G, the diffusion coefficient D is roughly 10⁻⁸ ∼ 10⁻⁶ R_J ² s⁻¹, and the lifetime against the diffusion losses is of the order of 10⁴ ∼ 10⁶ s.

Received 2 March 1992; accepted 16 June 1993.

Read Full Article    Cited by

Citation: Ye, G., and T. P. Armstrong (1993), Electron Distributions in the Inner Jovian Magnetosphere: Voyager 1 Observations, J. Geophys. Res., 98(A12), 21,253–21,264.

Copyright 1993 by the American Geophysical Union.