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| Titel |
Multi-step electron acceleration in magnetotail reconnection |
| VerfasserIn |
Alessandro Retino, Rumi Nakamura, Bertalan Zieger, Andris Vaivads, Yuri Khotyaintsev, Fouad Saharoui |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250055784
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| Zusammenfassung |
| Magnetic reconnection plays a key role for particle acceleration. Important examples in the
solar system are flares and planetary substorms. Numerical simulations for the magnetotail
show that the reconnection electric field can accelerate ions and electrons to very high
energies and this prediction has been verified by in-situ observations. However these studies
also indicate that the flux of accelerated particles is rather small compared to the total, raising
the question if reconnection itself is indeed efficient as accelerator. The same question has
been raised for the solar corona, where the estimated number of particles accelerated by the
reconnection field seem not sufficient to explain flare observations (the so-called number
problem). Recent models and simulations suggest that acceleration in the magnetotail is
rather a multi-step process, where particle are initially accelerated by the reconnection field
and further energized by other mechanisms away from the reconnection site. Here
we use Cluster multi-point observations for one event to try testing such scenario
for electrons. Preliminary results show that the hardest spectra are found when
the current sheet is very thin and electric fields are strongest, possibly close to the
reconnection site, and that fluxes increase and spectra become softer when the current sheet
becomes thicker and has a more dipolar topology, consistent with a two-step scenario. |
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