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Title: Particle distributions in a two-dimensional reconnection field geometry

Journal Article · · Journal of Geophysical Research; (United States)
;  [1]
  1. Univ. of Iowa, Iowa City (United States)

Particle trajectories in a two-dimensional steady state reconnection field geometry are studied in order to understand phase space density variations near the magnetopause and in the geomagnetic tail. The inflow regions for the dayside magnetopause are the magnetosheath and the closed field lines inside the magnetosphere. The inflow regions for the magnetotail are the lobes north and south of the central plasma sheet. Using Liouville's theorem and known distribution functions in the source regions, the distribution function at the spacecraft can be calculated. Unlike previous studies of remote sensing, this one is in two dimensions and includes a perpendicular electric field. The question of whether trapped distribution functions can exist on open field lines on the dayside magnetopause is examined as well as the signatures of reconnection in the geomagnetic tail. The authors find that trapped distributions which have a peak at or near 90{degree} pitch angle can exist on topologically open field lines. Thus the observations of such distributions in the low-latitude boundary layer do not establish that this layer is on closed field lines. In the tail the omnidirectional flux of keV ions should show a minimum in the center of the plasma sheet at distances up to about 25 R{sub E} earthward of the neutral line. Since no such minimum is apparent in the ISEE data, they conclude that the neutral line in the tail is generally tailward of 50 R{sub E}. They also find that adiabatic theory cannot be used as a means for visualizing or predicting the orbits of charged particles in these complex magnetic field topologies.

OSTI ID:
5941100
Journal Information:
Journal of Geophysical Research; (United States), Vol. 94:A1; ISSN 0148-0227
Country of Publication:
United States
Language:
English