RCM-E simulation of ion acceleration during an idealized plasma sheet bubble injection

In this paper, we investigate the role of plasma sheet bubbles in the ion flux variations at geosynchronous orbit during substorm injections by using the Rice Convection Model with an equilibrated magnetic field model (RCM‐E). The bubble is initiated in the near‐Earth plasma sheet with a localized r...

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Bibliographic Details
Published in:Journal of Geophysical Research: Space Physics 2011-05, Vol.116 (A5), p.n/a
Main Authors: Yang, J., Toffoletto, F. R., Wolf, R. A., Sazykin, S.
Format: Article
Language:English
Subjects:
Atmospheric sciences
Bubbles
Fluctuations
Injection
Magnetic fields
Magnetism
Plasma
plasma sheet bubble
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Summary:In this paper, we investigate the role of plasma sheet bubbles in the ion flux variations at geosynchronous orbit during substorm injections by using the Rice Convection Model with an equilibrated magnetic field model (RCM‐E). The bubble is initiated in the near‐Earth plasma sheet with a localized reduction in entropy parameter PV5/3 following a substorm growth phase. In the expansion phase, characteristic features of substorm injections are reproduced; that is, there is a prominent dispersionless flux increase for energetic protons (>40 keV) and a flux decrease for lower‐energy protons near midnight geosynchronous orbit while there is dispersive flux enhancement near the dusk sector. We find that the injection boundary is well coincident with the earthward boundary of the bubble, inside which the depletion of plasma content causes the magnetic field dipolarization, and in return, the magnetic field collapse energizes particles and alters the drift paths dramatically. Our results also show that a high‐PV5/3 island is pushed ahead of the fast earthward propagating bubble, and a dipolarization front forms between them. Within the high‐PV5/3 island, the diamagnetic effect makes the plasma pressure increase and the strength of the magnetic field decrease to a local minimum. We suggest that plasma sheet bubbles are elementary vehicles of substorm time particle injections from the main plasma sheet to the inner magnetosphere. Key Points We quantitatively calculate particle flux variations at GEO orbit using RCM‐E We reproduce characteristic features, and find what a injection boundary is Plasma sheet bubbles are elementary vehicles of substorm particle injections
ISSN:0148-0227
2169-9380
2156-2202
2169-9402
DOI:10.1029/2010JA016346