Magnetosheath plasma precipitation in the polar cusp and its control by the interplanetary magnetic field
- Swedish Inst. of Space Physics, Kiruna (Sweden)
Magnetosheath particle precipitation in the polar cusp region is studied based on Viking hot plasma data obtained on meridional cusp crossings. Two distinctively different regions are commonly encountered on a typical pass. One region is characterized by high-density particle precipitation, with an ion population characterized by a convecting Maxwellian distribution. Typical magnetosheath parameters are inferred for the spectrum of the source population. The spectral shape of the ion population encountered in the second region suggests that here the magnetosheath ions have been energized by about 1 keV, corresponding to an ion velocity gain of about twice the magnetosheath Alfven velocity. The location of the region containing the accelerated plasma is dependent on the IMF B{sub z} component. For southward IMF the acceleration region is bounded by the ring current population on the equatorward side and by the unaccelerated magnetosheath plasma precipitation on the poleward side. For northward IMF the region is located at the poleward edge of the region with unaccelerated precipitation. The accelerated ion population is obviously transported duskward (dawnward) for a dawnward (duskward) directed IMF. These observations are interpreted as evidence for plasma acceleration due to magnetopause current sheet disruptions/merging of magnetospheric and interplanetary magnetic flux tubes.
- OSTI ID:
- 5361639
- Journal Information:
- Journal of Geophysical Research; (United States), Vol. 97:A2; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
POLAR CUSP
CHARGED-PARTICLE PRECIPITATION
ACCELERATION
GEOMAGNETIC FIELD
INTERPLANETARY MAGNETIC FIELDS
MAGNETIC FLUX
MAGNETOPAUSE
MAGNETOSHEATH
PLASMA DENSITY
PLASMA DRIFT
SATELLITES
MAGNETIC FIELDS
661320* - Auroral
Ionospheric
& Magnetospheric Phenomena- (1992-)