Publication Date:
2013-09-13
Description:
[1] We survey the properties of electron pitch angle distributions in the magnetotail plasma sheet at a distance between 15 and 19 R E from the Earth, using data from the Cluster PEACE instrument. We limit our survey to those pitch angle distributions measured when the IMF had been steadily northward or steadily southward for the previous three hours. We find that, at sub-keV energies the plasma sheet electron pitch angle distribution has an anisotropy such that there is a higher differential energyflux of electrons in the (anti-) field-aligned directions. Fitting the measured pitch angle distributions with both a single and two component kappa distribution reveals that this anisotropy is the result of the presence of a second, cold, component of electrons that is observed more often than not, and occurs during both the northward and southward IMF intervals. We present evidence that suggests the cold electron component has an ionospheric, rather than magnetosheath, source and is linked tothe large scale field aligned current systems that couple the magnetosphere and ionosphere.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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