Isee 3 Magnetic Field Observations in the Mgnetotail: Implications for Reconnection
- 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
Siscoe, G. L., Sibeck, D. G., Slavin, J. A., Smith, E. J., Tsurutani, B. T. and Jones, D. E. (1984) Isee 3 Magnetic Field Observations in the Mgnetotail: Implications for Reconnection, in Magnetic Reconnection in Space and Laboratory Plasmas (ed E. W. Hones), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM030p0240
- Published Online: 19 MAR 2013
- Published Print: 1 JAN 1984
Print ISBN: 9780875900582
Online ISBN: 9781118664223
- Magnetic field observations;
- Magnetometer measurements;
- Plasma sheet
ISEE 3 explored the magnetotail to a distance of 220 RE during its first two tail orbits. The characteristic cross-sectional structure of the tail near the earth was recognizable to apogee. The field strength in the lobes and the Bz component in the plasma sheet decreased systematically with distance. The frequency of occurrence of negative Bz Increased with distance. Beyond 210 RE, the average Bz was slightly negative. The observations suggest the existence of an x-type neutral line located on average near 200 RE.
In addition to the systematic variations with distance, three types of transient events were recorded. The first type, which the spacecraft encountered on more than 30 occasions, is a discrete magnetic structure of 5 to 20 minutes duration distinguished by strong diamagnetism, a bipolar north-to-south Bz signature, hot plasma, high energy particles and increased wave activity. These events occur during intervals of geomagnetic activity. Hones has Identified these structures as tailward moving plasmoids produced by reconnection within the tail.
The second type of discrete magnetic structures consists of solitary compressions of the lobe field. The compressions have amplitudes from 2 to 6 nT and last 5 to 30 minutes. These events are closely correlated with substorm onsets. They appear to be peripheral encounters with the plasmoids that make up the first class of events.
The third type of transient features are best described by how they differ from plasmoids. Whereas plasmoids cause a bipolar signature in Bz and have a weak field at their center, events of the new class have bipolar signatures in either Bz or By and have strong fields at their center. Whereas the axis of a plasmoid is y-aligned, the axis of the new kind of structures is x-aligned. They have the characteristics of magnetic flux ropes lying parallel to the tail.