Simultaneous measurements of magnetotail dynamics by IMP spacecraft

Journal Article · Sun Mar 01 04:00:00 EST 1981 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA086iA03p01396· OSTI ID:6315746

Fairfield, D H; Lepping, R P; Hones, Jr, E W; Bame, S J; Asbridge, J R

Eleven traversals of the magnetotail at 30-40 R/sub E/ by the IMP 7 and IMP 8 spacecraft ocurred while IMP 6 was making magnetotail measurements inside 33 R/sub E/. Combined magnetic field and plasma data from these spacecraft provide the first demonstration of pressure balance between the high ..beta.. plasma of the plasma sheet and the strong magnetic fields of the tail lobes. The time variations of this pressure support the view that a southward interplanetary magnetic field enhances the accumulation of energy in a magnetotail energy reservoir. Sometimes the accumulated magnetic energy is rapidly dissipated during a magnetospheric substorm. At other times the dissipation can occur more gradually during ongoing magnetic activity. At such times the energy supplied by the solar wind may even exceed that being dissipated, thus causing the tail energy to increase. In addition to plasma sheet thinnings seem prior to substorm onsets inside approx.15 R/sub E/ a gradual decrease in plasma ..beta.. is detected in the deep tail which precedes onset and the more prominent plasma disappearance that typically accompanies it. The frequency of thinnings and the regions over which they occur indicate that drastic changes in plasma sheet thickness are common features of substorms which occur at all locations across the tail. Several magnetically quiet periods correspond to thick plasma sheets with enhanced B/sub Z/ components and gradually cooling plasmas.

• Research Organization: Planetary Magnetospheres Branch, Laboratory for Extraterrestrial Physics, NASA Goddard Space Flight Center, Greenbelt, Mayland 20771
• OSTI ID: 6315746
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 86:A3; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640203* -- Atmospheric Physics-- Magnetospheric Phenomena-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
EARTH ATMOSPHERE
HIGH-BETA PLASMA
INTERPLANETARY MAGNETIC FIELDS
MAGNETIC BAYS
MAGNETIC FIELDS
MAGNETOSPHERE
MAGNETOTAIL
PLASMA
PLASMA PRESSURE
PLASMA SHEET
SOLAR ACTIVITY
SOLAR WIND