Observations of Bi-directional Field Aligned Electrons and Solitary Waves in the Plasma Sheet

M. O. Fillingim1, G. K. Parks1, R. P. Lin1, S. D. Bale1, and L.-J. Chen2

1Space Sciences Laboratory, University of California, Berkeley
2Department of Physics and Astronomy, University of Iowa, Iowa City

Presented at the 2003 EGS-AGU-EUG Joint Assembly, Nice, France, April 6 - 11, 2003


Abstract

Observations of narrowly collimated field aligned bi-directional electron distributions measured by the WIND spacecraft in the plasma sheet at radial distances of 10 to 20 Earth radii in the midnight sector are presented. At energies below about 1 keV, the parallel flux is about one order of magnitude larger than the perpendicular flux. At higher energies up to 30 keV, the anisotropy is much smaller, closer to a factor of 2. Typically the distributions are flat-topped; however, occasionally well defined counter streaming electron beams are observed. Through out these time intervals, magnetic field mapping suggests that the footprint of WIND is in the region of intense auroral emission as indicated by Polar/UVI images. The beams are inferred to be of ionospheric origin. Coincident with the field aligned electron observations, plasma wave measurements show the presence of solitary structures. We suggest that the presence of counter streaming electron beams and their mutual interactions are responsible for the generation of the observed solitary structures.



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Matt Fillingim
matt at ssl dot berkeley dot edu
University of California, Berkeley
Space Sciences Laboratory # 7450
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