DYNAMICS OF HIGH ENERGY IONS AT A STRUCTURED COLLISIONLESS SHOCK FRONT

ABSTRACT Ions undergoing first-order Fermi acceleration at a shock are scattered in the upstream and downstream regions by magnetic inhomogeneities. For high energy ions this scattering is efficient at spatial scales substantially larger than the gyroradius of the ions. The transition from one diffu...

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Bibliographic Details
Published in:The Astrophysical journal 2016-07, Vol.825 (2), p.149-149
Main Authors: Gedalin, M., Dröge, W., Kartavykh, Y. Y.
Format: Article
Language:English
Subjects:
ACCELERATION
acceleration of particles
AMPLITUDES
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
FINE STRUCTURE
INCLINATION
Inhomogeneities
MAGNETIC FIELDS
OSCILLATIONS
Pitch angle
Reflection
SCATTERING
Shock fronts
SHOCK WAVES
TIME DEPENDENCE
Upstream
VELOCITY
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Summary:ABSTRACT Ions undergoing first-order Fermi acceleration at a shock are scattered in the upstream and downstream regions by magnetic inhomogeneities. For high energy ions this scattering is efficient at spatial scales substantially larger than the gyroradius of the ions. The transition from one diffusive region to the other occurs via crossing the shock, and the ion dynamics during this crossing is mainly affected by the global magnetic field change between the upstream and downstream region. We study the effects of the fine structure of the shock front, such as the foot-ramp-overshoot profile and the phase-standing upstream and downstream magnetic oscillations. We also consider time dependent features, including reformation and large amplitude coherent waves. We show that the influence of the spatial and temporal structure of the shock front on the dependence of the transition and reflection on the pitch angle of the ions is already weak at ion speeds five times the speed of the upstream flow.
ISSN:0004-637X
1538-4357
DOI:10.3847/0004-637X/825/2/149