High Resolution Substorm Energetic Electrons seen in the Magnetotail by all 4 
CLUSTER satellites

Wu, P., Fritz, T.A., Reed, R.S., Friedel, R., Reeves, G., Baker, D., Daly, P. 


We report our examination of the 3-D pitch angle distributions (PAD) of
energetic electrons as the Cluster satellites cross the earth's plasma sheet
near their apogee in the nightside magnetosphere during the tail season (July,
August, September, October) of year 2005. We identified several energetic
electron injections in the tail plasma sheet associated with substorm events.
Those events are all associated with continual switching of PADs from field
aligned to the peak at 90 degree, which indicated to us that those energetic
electrons are accelerated in different manners and they form different
populations. The study of the evolution of the PAD gave us an impression that
the Fermi and betatron accelerations play different roles along the tail. They
compete with each other, depend on the radial distance. However, this idea needs
to be further verified with the study of more events. The large separations of
the 4 Cluster satellites in this tail season of 2005 provide a good opportunity
for us to identify more energetic electron bursts events with better spatial and
temporal clarity. Comparing the observation from these 4 different satellites
will allow us to visualize the picture in many more dimensions and avoid
vagueness as much as we can. Together with our collaboration with LANL and LASP,
including more satellite data (e.g. Geosynchronous satellites, POLAR, IMAGE), we
will report on a more integrated picture of the magnetotail energetic electron
dynamics.

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Fall Meeting, American Geophysical Union, San Francisco, U.S.A., 
5-9 December 2005