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Étude des phénomènes d'accélération de particules dans les régions aurorales des magnétosphères

Abstract : Particle acceleration is a topic of general astrophysical interest
which can be studied in a convenient natural laboratory: the Earth's
magnetosphere and, more widely, the magnetospheres of magnetised planets.
In particular, numerous physical processes occur in the auroral regions,
for example the northern and southern auroras, which are very
spectacular but rather imperfectly understood phenomena. Numerous
satellite measurements have shown the existence of highly energetic
populations of particles flowing towards the Earth, and this implies the
existence of a strong electric potential difference which most of the
proposed models fail to predict. Generally speaking, an understanding of
this acceleration is necessary to explain the dynamic coupling between
the magnetosphere, where the energy is released during substorms, and
ionosphere where the energy is dissipated. The study of the dissipation,
which takes place on short spatial and temporal scales, constitutes the
main theme of the present work. We consider as electromagnetic
perturbation an Alfvén wave propagating along the geomagnetic field
lines. Its interaction, in the auroral zones, with the highly
inhomogeneous structures known as plasma cavities, leads to the
formation of parallel electric fields able to accelerate particles, as
well as to a significant energy transfer from the waves to the
electrons. Finally, this study enables us to suggest a new scenario for
the formation of auroral arcs. This work was conducted both analytically
and numerically using a "particles in cell" code.
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Contributor : Vincent Génot <>
Submitted on : Friday, October 7, 2005 - 1:08:49 PM
Last modification on : Monday, April 5, 2021 - 2:26:07 PM
Long-term archiving on: : Thursday, March 24, 2011 - 11:59:49 AM

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Vincent Génot. Étude des phénomènes d'accélération de particules dans les régions aurorales des magnétosphères. Astrophysique [astro-ph]. Université de Versailles-Saint Quentin en Yvelines, 1999. Français. ⟨tel-00010474⟩

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