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| Titel |
Origin of energetic ions observed in the terrestrial ion foreshock : 2D
full-particle simulations |
| VerfasserIn |
Philippe Savoini, Bertrand Lembège |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250126487
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| Publikation (Nr.) |
 EGU/EGU2016-6218.pdf |
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| Zusammenfassung |
| Collisionless shocks are well-known structures in astrophysical environments
which dissipate bulk flow kinetic energy and accelerate large fraction of
particle. Spacecrafts have firmly established the existence of the so-called
terrestrial foreshock region magnetically connected to the shock and filled
by two distinct populations in the quasi-perpendicular shock region (i.e.
for 45\r{ } $\le \quad \Theta _{Bn} \quad \le $ 90\r{ }, where $\Theta _{Bn}$
is the angle between the shock normal and the upstream magnetic field) : (i)
the field-aligned ion beams or ``~FAB~'' characterized by a gyrotropic
distribution\sout{,} and (ii) the gyro-phase bunched ions or ``~GPB~''
characterized by a NON gyrotropic distribution. The present work is based on
the use of two dimensional PIC simulation of a curved shock and associated
foreshock region where full curvature effects, time of flight effects and
both electrons and ions dynamics are fully described by a self consistent
approach.
Our previous analysis (Savoini et Lemb\`{e}ge, 2015) has evidenced that
these two types of backstreaming populations can originate from the shock
front itself without invoking any local diffusion by ion beam instabilities.
Present results are focussed on individual ion trajectories and evidence
that "FAB" population is injected into the foreshock mainly along the shock
front whereas the "GPB" population penetrates more deeply the shock front.
Such differences explain why the "FAB" population loses their gyro-phase
coherency and become gyrotropic which is not the case for the
"GPB". The impact of these different injection features on
the energy gain for each ion population will be presented in d\'{e}tails.
Savoini, P. and B. Lemb\`{e}ge (2015), ``~Production of nongyrotropic and
gyrotropic backstreaming ion distributions in the quasi-perpendicular ion
foreshock r\'{e}gion~'', \textit{J. Geophys. Res.}, 120, pp 7154-7171, \textit{doi = 10.1002/2015JA021018}. |
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