 |
| Titel |
Origin of energetic ions in the polar cusp inferred from ion composition measurements by the Viking satellite |
| VerfasserIn |
G. Kremser, J. Woch, K. Mursula, P. Tanskanen, B. Wilken, R. Lundin |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 13, no. 6 ; Nr. 13, no. 6, S.595-607 |
| Datensatznummer |
250011880
|
| Publikation (Nr.) |
 copernicus.org/angeo-13-595-1995.pdf |
|
|
|
|
|
| Zusammenfassung |
| The magnetospheric ion composition
spectrometer MICS on the Swedish Viking satellite provided measurements of the
ion composition in the energy range 10.1 keV/e\leqE/Q\leq326.0 keV/e.
Data obtained during orbit 842 were used to investigate the ion distribution in
the northern polar cusp and its vicinity. The satellite traversed the outer ring
current, boundary region, cusp proper and plasma mantle during its poleward
movement. H+ and He++ ions were encountered in all of
these regions. He+ ions were present only in the ring current. The
number of O+ and O++ ions was very small. Heavy
high-charge state ions typical for the solar wind were observed for the first
time, most of them in the poleward part of the boundary region and in the cusp
proper. The H+ ions exhibited two periods with high intensities. One
of them, called the BR/CP event, appeared at energies up to 50 keV. It started
at the equatorward limit of the boundary region and continued into the cusp
proper. Energy spectra indicate a ring current origin for the BR/CP event. Pitch
angle distributions show downward streaming of H+ ions at its
equatorward limit and upward streaming on the poleward side. This event is
interpreted as the result of pitch angle scattering of ring current ions by
fluctuations in the magnetopause current layer in combination with poleward
convection. The other of the two periods with high H+ ion
intensities, called the accelerated ion event, was superimposed on the BR/CP
event. It was restricted to energies \leq15 keV and occurred in the poleward
part of the boundary region. This event is regarded as the high-energy tail of
magnetosheath ions that were accelerated while penetrating into the
magnetosphere. The cusp region thus contains ions of magnetospheric as well as
of magnetosheath origin. The appearance of the ions depends, in addition to the
ion source, on the magnetic field configuration and dynamic processes inside and
close to the cusp. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|