The fine-scale structure of the outer plasmasphere
- Florida Institute of Technology, Melbourne (Australia)
- Los Alamos National Lab., NM (United States); and others
The density and temperature structure of the low-energy ion population in the outer plasmasphere is examined by using data from Los Alamos National Laboratory`s three-dimensional magnetospheric plasma analyzer at synchronous orbit. The authors define the {open_quotes}outer plasmasphere{close_quotes} as regions of dense, cold plasma observed at synchronous orbit, with no attempt to distinguish between the main plasmasphere or detached plasma regions existing beyond the plasmapause. They find that for moderate to high levels of geomagnetic activity the outer plasmasphere typically has a fine-scale density structure. The amount of variability in the density generally increases with increasing geomagnetic activity, as indicated by Kp, and the most variable intervals are associated with substorm activity. The dense (>10 ions cm{sup {minus}3}), cold ({approx}1 eV), plasmaspherelike plasma is adjacent to, and often interspersed with, low-density (1-10 ions cm{sup {minus}3}), warm (2-10 eV), {open_quotes}troughlike{close_quotes} plasma regions. They find that occasionally these two temperature populations can coexist, but that most often they do not. The scale size of the fine-scale structure in the dense, cold plasma regions often is of the order of 1000 km or less. These observations suggest that fine-scale density structure in the dusk sector of the outer plasmasphere is imposed by penetrating substorm electric fields. 35 refs., 12 figs.
- OSTI ID:
- 207240
- Journal Information:
- Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A5 Vol. 100; ISSN JGREA2; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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