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| Titel |
Self-consistent kinetic PIC simulations of collisionless supercritical shocks in astrophysical plasmas with multiple ion species |
| VerfasserIn |
Vegard L. Rekaa, Sandra C. Chapman, Richard O. Dendy |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250088671
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| Publikation (Nr.) |
 EGU/EGU2014-2808.pdf |
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| Zusammenfassung |
| Supernova remnant and heliopause termination shock plasmas may contain significant
populations of minority heavy ions such as alpha-particles, with relative number densities
nα-ni up to 50%. Fully self-consistent kinetic simulations of quasi-perpendicular,
supercritical shocks can show non-steady, reforming solutions with consequences for ion
acceleration local to the shock. We present the first set of particle-in-cell simulations that
span the entire range of values of nα-ni from zero to one, where the two ion species and
electrons are all treated fully self-consistently. These ’1.5D’ simulations evolve the full three
dimensional particle trajectories and electromagnetic vector fields as a function of one space
co-ordinate and time. The simulated supercritical (Mach number ~ 8) shocks have
perpendicular geometry, plasma β = 0.15, upstream magnetic field B1 = 10-7T and particle
density n - 107m-3. Crucial to the time evolving phenomenology of the shocks and
particles at different nα-ni are the interplay between the differing characteristic
gyroscales of the two ion species. Ions can gain energy both directly by acceleration in
the electromagnetic foot-ramp region of the shock, and in the strongly fluctuating
fields downstream. The downstream field fluctuations are driven by the free energy
that both ion species gain in their initial interaction with the shock. The details of
all these processes, and their efficiency for energization, are found to depend on
nα-ni.
Disclaimer: This work was partly funded by the UK Engineering and Physics Sciences
Research Council under grant EP/G003955 and by The European Communities under
the contract of association between Euratom and CCFE. The views and opinions
expressed herein do not necessarily represent those of the European Communities. |
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