Simultaneous measurements of energetic ion ( ge 50 keV) and electron ( ge 220 keV) activity upstream of earth's bow shock and inside the plasma sheet: Magnetospheric source for the November 3 and December 3, 1977 upstream events

Journal Article · Sun Nov 01 04:00:00 EST 1987 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA092iA11p12083· OSTI ID:5940090

Sarris, E T; Anagnostopoulos, G C ^[1]; Krimigis, S M ^[2]

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1. Demokritos Univ. of Thrace, Xanthi (Greece)
2. Johns Hopkins Univ., Laurel, MD (United States)

Simultaneous observations of energetic ions ({approx gt}50 keV) and electrons ({approx gt}220 keV) by the IMP 7 and 8 spacecraft, carrying identical instruments and located within the distant ({approximately}37 R{sub E}) magnetotail and upstream from the bow shock, have been employed to separate temporal variations from spatial variations during the upstream ion events observed on December 3, 1977 and November 2-3, 1977, in order to determine the source of these particles. The IMP data, when compared with those from ISEE 1 and 2, have also made possible the determination of field-aligned and flux-tube intensity gradients in the upstream region, thus enabling the test of specific predictions of the Fermi acceleration model for such events. The analysis of these three-spacecraft observations and comparison with theory have revealed the following: (1) For each of the observed upstream enhancements, energetic ions and electrons were simultaneously present inside the plasma sheet - successive increases were in excellent time coincidence with substorm injection events seen on ground-based magnetograms; (2) The low-energy ({approx gt}50 keV) ion intensity profile inside the plasma sheet was relatively flat, while at higher ({approx gt}300 keV) energies there was considerable variability, with one case exhibiting an inverse velocity dispersion profile; (3) Relativistic electron bursts were seen inside the plasma sheet and also upstream of the shock but at substantially reduced intensities; (4) The ion energy spectrum for the December 3 event, extended to energies {approximately}2 MeV, was identical in form within the plasma sheet and upstream of the shock and can be described well by dj/dE {proportional to} E{sup {minus}5.5}; (5) Ion anisotropies exhibited typically large dawn-dusk or dusk-dawn gradients, depending on spacecraft location, and showed large (up to 20:1) field-aligned streaming away from the bow shock.

• OSTI ID: 5940090
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 92:A11; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACCELERATION
ANISOTROPY
CHARGED PARTICLES
COLLISIONLESS PLASMA
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRONS
ELEMENTARY PARTICLES
ENERGY SPECTRA
FERMIONS
INTERACTIONS
INTERPLANETARY MAGNETIC FIELDS
IONS
LEPTONS
MAGNETIC BAYS
MAGNETIC FIELDS
MAGNETOTAIL
ORIGIN
PLASMA
PLASMA SHEET
SATELLITES
SHOCK WAVES
SOLAR ACTIVITY
SOLAR WIND
SPECTRA
VARIATIONS