Plasma and energetic particle properties of dispersionless substorm injections at geosynchronous orbit

J. Birn, M. F. Thomsen, J. E. Borovsky, G. D. Reeves, D. J. McComas, R. D. Belian

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Using a full year of geosynchronous spacecraft data, we survey the substorm-associated behavior of the thermal plasma (30 eV < E < 40 keV) in the plasma sheet in relation to energetic particle injections (E > 50 keV). Five classes of injection events are found, well ordered by their average local times: Ion injections without accompanying electron injection at ∼21 LT, ion injections followed a few minutes later by an electron injection at ∼22 LT, simultaneous ion and electron injections close to midnight, electron injections that are followed by an ion injection at ∼1 LT, and finally pure electron injections at ∼2 LT. The thermal electrons show a significant increase in temperature (from ∼1 keV to ∼2 keV) and pressure at substorm onset, while the density and the thermal ion signatures (below ∼30 keV) are typically weak. However, energetic ions (above ∼30 keV) contribute significantly to the total ion pressure and temperature, leading to a rise in the total temperature from ∼10 keV to ∼16 keV. Preexisting perpendicular anisotropies in the thermal electrons and ions are reduced during the substorm growth phase but become enhanced again after onset, sometimes after a brief period of parallel anisotropy.

Original languageEnglish (US)
Pages (from-to)321-326
Number of pages6
JournalEuropean Space Agency, (Special Publication) ESA SP
Issue number389
StatePublished - Dec 1 1996
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Space and Planetary Science

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