Sources of electron pitch angle anisotropy in the magnetotail plasma sheet. Issue 10 (1st October 2013)

• Record Type: Journal Article
• Authors: Walsh, Andrew P.; Fazakerley, A. N.; Forsyth, C.; Owen, C. J.; Taylor, M. G. G. T.; Rae, I. J.
• Is Part Of: Journal of geophysical research. Volume 118:Issue 10(2013:Oct.)
• Page Start: 6042
• Page End: 6054
• Publication Date: 2013-10-01
• Subjects: Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/jgra.50553
• Languages: English
• ISSNs: 2169-9380

Abstract

<abstract abstract-type="main" id="jgra50553-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p id="jgra50553-para-0001">[1] We survey the properties of electron pitch angle distributions in the magnetotail plasma sheet at a distance between 15 and 19 <italic>R</italic>_{<italic>E</italic>} from the Earth, using data from the Plasma Electron and Current Experiment (PEACE) instrument. We limit our survey to those pitch angle distributions measured when the interplanetary magnetic field (IMF) had been steadily northward or steadily southward for the previous 3 h. We find that, at sub‐keV energies, the plasma sheet electron pitch angle distribution has an anisotropy such that there is a higher differential energy flux 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 to the large‐scale field‐aligned current systems that couple the magnetosphere and ionosphere.</p> </abstract>