LORENTZIAN ION EXOSPHERE MODEL

Citation
V. Pierrard et J. Lemaire, LORENTZIAN ION EXOSPHERE MODEL, J GEO R-S P, 101(A4), 1996, pp. 7923-7934
Citations number
48
Categorie Soggetti
Geosciences, Interdisciplinary","Astronomy & Astrophysics","Metereology & Atmospheric Sciences
Journal title
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
ISSN journal
21699380 → ACNP
Volume
101
Issue
A4
Year of publication
1996
Pages
7923 - 7934
Database
ISI
SICI code
2169-9380(1996)101:A4<7923:LIEM>2.0.ZU;2-B
Abstract
Since observed velocity distributions of particles in the magnetospher e generally have a suprathermal tail instead of an exponential one, we propose to recalculate the density and temperature distributions in a nonrotating ion exosphere with a Lorentzian velocity distribution fun ction (VDF) instead of a Maxwellian. The number density, the flux of p articles, parallel and perpendicular pressures, and energy flux of the different classes of particles in the exosphere have been determined for any value of the index kappa characterizing the Lorentzian VDF. Th e barometric density and temperature distributions for a Maxwellian VD F and for a Lorentzian VDF are compared. It is shown that for particle s in an attractive potential, the barometric density decreases more sl owly with altitude for the Lorentzian VDF. Furthermore, the temperatur e increases with altitude in this case, while for a Maxwellian VDF, it is independent of altitude. It is suggested that positive gradients o f the ion and electron temperatures observed between the topside ionos phere and the outer plasmasphere can be explained by this effect, that is, a non-Maxwellian VDF with an enhanced suprathermal tail.