Adv. Space Res., 20, 221-224 1997
Abstract:
For near-isotropic distributions of energetic ions, the field-perpendicular
first order anisotropies which occur are due both to plasma flows
transverse
to B, and to field-perpendicular spatial gradients in the ion flux. A
technique has been developed to separate these by examining the variation
of
the anisotropy with ion energy. This has been applied to data obtained by
the
Anisotropy Telescopes instrument on the Ulysses spacecraft during the
Jupiter
fly-by in February 1992. Results are presented for a crossing through the
equatorial plasma sheet on the prenoon inbound pass, and for an interval of
transitions between the southern plasma sheet boundary and the outer
magnetosphere region on the dusk outbound pass. The velocity data show
that
the flow in the outer plasma sheet was directed sunward both inbound and
outbound at speeds 100-200 km s-1, while that in the outer magnetosphere
was directed antisunward at similar speeds. Flux gradient scale lengths
peak at ~0.5 RJ within the prenoon current sheet, and are ~0.2 RJ on the
outer
surface of the dusk plasma sheet.
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