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Ann. Geophys., 24, 1957-1968, 2006
www.ann-geophys.net/24/1957/2006/
© European Geosciences Union 2006
Alternating bursts of low energy ions and electrons near the substorm onset
T. V. Kozelova1, L. L. Lazutin2, B. V. Kozelov1, N. Meredith3, and M. A. Danielides4
1Polar Geophysical Institute, Apatity, Murmansk region, 184209, Russia
2Russia Space Science Division, Scobeltsyn Institute for Nuclear Physics of Moscow State University, Russia
3Mullard Space Science Laboratory, University College, London, UK
4Space Physics Group, University of Oulu, Finland
Abstract. The substorm associated behavior of the low energy particles (30 eV–28.5 keV)
near the earthward edge of the plasma sheet is examined using data from
CRRES during the late growth and early expansion phases of a substorm on
12 March 1991 and their significance for the substorm onset mechanism is
discussed. In this substorm, the CRRES was located on L ~6.3 and
~20° westward of the substorm onset and observed the sequence of
the alternating bursts of the low energy ions and electrons. The bursts of
the 0.633–9.6 keV ions occurred 1–2 min before the (7.31–21.7 keV)
electron bursts. The first ion burst happened 2min before the substorm
onset, at the moment of weak brightening of the most equatorial pre-breakup
arc near the latitude ~62°. The alternation of the ion and
electron bursts may be a signature of a drift-Alfvén ballooning
instability on the inner edge of the plasma sheet near substorm onset.
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