Downward flowing ions and evidence for injection of ionospheric ions into the plasma sheet

Journal Article · Mon Oct 01 04:00:00 EDT 1979 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA084iA10p05781· OSTI ID:5728718

Ghielmetti, A G; Sharp, R D; Shelley, E G; Johnson, R G

Energetic (keV) protons and O/sup +/ ions with field aligned pitch angle distributions and peak fluxes up to approx.7 x 10/sup 7/ (cm/sup 2/ s sr keV)/sup -1/ have been observed streaming downward in the high altitude (approx.1R/sub E/) auroral ionosphere. In two examples described in detail, the correlations observed between the downward flowing and coincident trapped ion populations suggest a common origin. Downward flowing ion events are a much less frequent phenomenon than upward flowing ion events in the auroral region. The significant difference implies that the energetic upward flowing ions from the auroral ionosphere are commonly injected into the trapped population of the plasma sheet, and furthermore that parallel electric fields involving potential drops of > or approx. =500 V are directed preferentially upward in the altitude range from 2000 km to approx.3R/sub E/. Spatially localized regions of enhanced hot (approx.keV) plasma density were frequently observed in the low L portion of the plasma sheet. The statistical location of these 'plasma clouds' correlates well with the substorm injection boundary near dusk inferred by Mcllwain (1974) and with the upward flowing ion events observed at approx.1R/sub E/ altitude (Ghielmetti et al., 1978a,b). The downward flowing ion events occurred preferentially within such 'plasma clouds.' The results described in this paper suggest that upward flowing ions from the auroral acceleration regions are responsible for both the downward flowing ions anf for at least some of the plasma clouds. A significant fraction of the equatorial substorm injected plasma clouds may thus result from this ionospheric source region.

• Research Organization: Lockheed Palo Alto Research Labaoratory, Palo Alto, California 94304
• OSTI ID: 5728718
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 84:A10; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
CATIONS
CHARGED PARTICLES
CHARGED-PARTICLE PRECIPITATION
EARTH ATMOSPHERE
ENERGY RANGE
HOT PLASMA
HYDROGEN IONS
HYDROGEN IONS 1 PLUS
IONOSPHERE
IONS
KEV RANGE
OXYGEN IONS
PLANETARY IONOSPHERES
PLASMA
PLASMA DENSITY
PLASMA SHEET
TRAPPING