A Plasmoid Release Mechanism That Could Explain the Substorm'S Impulsive Earthward Diversion of Cross-Tail Current
- Edward W. Hones Jr.
Published Online: 19 MAR 2013
Copyright 1984 by the American Geophysical Union.
Magnetic Reconnection in Space and Laboratory Plasmas
How to Cite
Bratenahl, A. and Baum, P. J. (1984) A Plasmoid Release Mechanism That Could Explain the Substorm'S Impulsive Earthward Diversion of Cross-Tail Current, in Magnetic Reconnection in Space and Laboratory Plasmas (ed E. W. Hones), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM030p0347
- Published Online: 19 MAR 2013
- Published Print: 1 JAN 1984
Print ISBN: 9780875900582
Online ISBN: 9781118664223
- Double inverse pinch device (DIPD);
- Plasmoid release mechanism;
- Polar electrojet (PEJ);
- Reconnection substorm model
The sudden interruption and earthward diversion of cross-tail current in association with substorms is a concept of long standing, but the detailed mechanism which causes it has remained unclear. This uncertainty, which helps prolong the debate over just what it is that causes substorms, might be resolved along with the debate itself, if greater theoretical attention were given the subject of time-dependent reconnection. Be that as it may, an elementary and perhaps obvious deduction is that whenever the reconnection rate increases, current is diverted into two types of propagating wave systems, rarefaction upstream, compressive downstream. Laboratory reconnection experiments have demonstrated a sudden and large amplitude process of this kind, and it is now reasonably certain that it is the result of an abrupt decrease in the density of inflowing plasma. In the Hones model of magnetotail dynamics, plasmoid detachment occurs when the reconnection process progresses through the last closed field line of the plasma sheet boundary, i.e., from the high density plasma sheet into the low density tail lobes. To the extent the laboratory evidence may be relevant we would have to conclude that the substorm is a result of the plasmoid detachment process. In this case, the impulsive current diversion would drive a blast wave earthward and forcibly eject the plasmoid tailward. Propagation of the large amplitude rarefaction waves into the tail lobes would be caused by the extraction of the magnetic energy needed to drive the earthward and tailward processes. But the essential question remains: What has theory to say about the effect of sudden density decreases on the rate of reconnection?