Bibliography
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O + Ion Conic and Plasma Sheet Dynamics Observed by Van Allen Probe Satellites during the 1 June 2013 Magnetic Storm
Author | Burke, W.; Erickson, P.; Yang, J.; Foster, J.; Wygant, J.; Reeves, G.; Kletzing, C.; |
Keywords | oxygen ion conics; plasma sheet dynamics; Van Allen Probes |
Abstract | The Van Allen Probe satellites were near apogee in the late evening local time sector during the 1 June 2013 magnetic storm\textquoterights main phase. About an hour after crossing the ring current\textquoterights \textquotedblleftnose structure\textquotedblright into the plasma sheet, the satellites encountered a quasi-periodic sequence of 0.08 - 3 keV O+ ions. Pitch angle distributions of this population consistently peaked nearly anti-parallel to the local magnetic field. We interpret this population as O+ conics originating in the northern ionosphere. Sequences began as fairly steady state conic fluxes with energies in the ~ 80 to 100 eV range. Over about a half hour build-up phase, O+ energies peaked near 1 keV. During subsequent release phases lasting ~ 20 minutes, O+ energies returned to low-energy starting points. We argue these observations reflect repeated formations and dissolutions of downward, magnetically aligned electric fields (ε||) layers trapping O+ conics between mirror points within heating layers below and electrostatic barriers above [Gorney et al., 1985]. Nearly identical variations were observed at the locations of both satellites during 9 of these 13 conic cycles. Phase differences between cycles were observed at both spacecraft during the remaining events. Most \textquotedblleftbuild-up\textquotedblright to \textquotedblleftrelease\textquotedblright phase transitions coincided with AL index minima. However, in situ magnetometer measurements indicate only weak dipolarizations of tail-like magnetic fields. The lack of field-aligned reflected O+ and tail-like magnetic fields suggest that both ionospheres may be active. However, southern hemisphere origin conics cannot be observed since they would be isotropized and accelerated during neutral sheet crossings. |
Year of Publication | 2016 |
Journal | Journal of Geophysical Research: Space Physics |
Volume | |
Number of Pages | |
Section | |
Date Published | 05/2016 |
ISBN | |
URL | http://doi.wiley.com/10.1002/2015JA021795 |
DOI | 10.1002/2015JA021795 |