Regensburg 2007 – wissenschaftliches Programm
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EP: Fachverband Extraterrestrische Physik
EP 7: Solar-Terrestrische Beziehungen
EP 7.2: Vortrag
Dienstag, 27. März 2007, 16:45–17:00, H46
Cluster observations of energy conversion in the plasma sheet — •Octav Marghitu1,2, Maria Hamrin3, Berndt Klecker1, and Kjell Rönnmark3 — 1Max-Planck-Institut für extraterrestrische Physik, Garching, Germany — 2Institute for Space Sciences, Bucharest, Romania — 3Physics Department, Umeå University, Umeå, Sweden
The Cluster mission provides, for the first time, a platform for the
in-situ investigation of energy conversion in key
magnetospheric regions. Cluster data can be used to infer the electric
field and current density vectors, E, J, and
further to evaluate the power density, E·J.
When E·J<0 the plasma behaves as a generator,
and mechanical energy is converted into electromagnetic energy. When
E·J>0 the plasma behaves as a load and the
conversion sense is reversed. We present preliminary results of a
search for energy conversion events, using plasma sheet Cluster data
from the summer and fall of 2001. As expected, the North–South
spacecraft crossings, at about 18RE, show most of the time a large
scale load character. Concentrated loads with high power densities can
be located around the neutral sheet, in particular close to midnight.
Both concentrated load and generator regions, with low to moderate
power densities, are observed in the plasma sheet boundary layer.
Energy conversion appears to be always associated with the
intensification of the bulk plasma flow, and sometimes with
temperature anisotropy.