Multiple Discrete-Energy Ion Features in the Inner Magnetosphere: Polar Observations
Abstract
The Polar satellite traverses the inner magnetosphere twice in 18 h. On many traversals of the inner magnetosphere, multiple-peaked spectra are observed by the ion composition sensors (CAMMICE/MICS and TIMAS) with peaks in the energy ranges near 2-5, 10-20, 35-50, and 90-120 keV as Polar moves from high L to cross the equator near L = 2.5-3.5. The multi-peaked spectra are observed most often on the dayside (6-18 MLT), and the peaks appear as traces that extend from large to small L values. They are similar to classic "nose" events except for the multiplicity of discrete energy peaks or "traces" that extend over a wide L range. For example, on February 9, 1998, the MICS observed such traces extending from L = 7 to 3.5 that had at least 5 discrete energy peaks in H+ near 3.5, 18, 32, 65, and 90 keV/q at L = 3.5. The three lowest energy peaks were also observed in He and O+. These were well below the ^ L(-3) trace corresponding to the peak energy of the quiet time ring current, which had a broad spectral peak in the H+ near 400 keV at L^ 3.5. These discrete energy traces may be consistent with the motion of ions inward from the magnetotail during a period that had a fluctuating cross polar cap electric field. However, standard particle tracing in combined model electric and magnetic fields can only explain some but not all these discrete energy traces. The lowest energy ion features appear to correspond to "banana" type closed drift shells near the Earth as predicted bY standard particle trajectory calculations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 20, 1998
- Accession Number
- ADA385323
Entities
People
- James Roeder
- Joseph F. Fennell
- K. J. Trattner
- Mingwei Chen
- W. K. Peterson
Organizations
- The Aerospace Corporation