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| Titel |
Injection of heavy ions into shock acceleration |
| VerfasserIn |
A. Sandroos, R. Vainio |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250026081
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| Zusammenfassung |
| Solar energetic particle events are commonly divided into gradual and impulsive events, with
diffusive shock acceleration (DSA) and acceleration in resonant wave processes in solar flares
as the main acceleration mechanisms, respectively. The gradual events typically have much
larger particle intensities and coronal elemental abundances, while impulsive events typically
show higher mean ionic charges, enhanced 3He/4He ratio, and enhanced heavy ion
abundances.
However, gradual events have been shown to be highly variable in their heavy ion
statistics at the highest energies, with some events showing characteristics typical to
impulsive events. One proposed solution to this variability is a selective acceleration at shock
waves driven by coronal mass ejections, and a compound seed population consisting of
coronal / solar wind plasma and ions preaccelerated by flares.
The idea of selective shock acceleration is sensitive to the injection threshold, i.e., to the
factors that determine whether or not a given incident ion is picked up by the DSA
mechanism. Such factors are, for example, speed of the incident ion, shock obliquity angle,
and the level of turbulence in the electromagnetic field.
We have previously studied the injection of heavy ions using Monte Carlo simulations,
which confirm the idea of selective ion injection. However, in these simulations,
self-consistent modeling of particle transport perpendicular to the mean magnetic field is not
included. In the present work, we use a self-consistent quasi-neutral hybrid simulation to
study the injection problem. Results from the two numerical approaches are compared and
their similarities and differences discussed. |
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