Magnetospheric Plasma Studies Using Data from the Dynamics High and Low Altitude Plasma Instruments.
Abstract
Plasma data from the High and Low Altitude Plasma Instruments aboard the Dynamics 1 and 2 (DE-1 and DE-2) satellites have been analyzed to investigate high latitude plasma characteristics. DE-1 hot plasma observations in the mid-altitude polar cusp have shown evidence of a significant velocity filtering phenomenon which is consistent with a latitudinally narrow region of plasma injection located at a geocentric distance of about 8 earth radii (RE). This velocity filtering effect allows the measurement of much smaller flow velocities (about km/s) than have heretofore been possible with plasma measurements. Observations at altitudes of 2-3 RE indicate two distinct types of counterstreaming electron events. The type 1 event is characterized by two Maxwellian distribution functions, an isotropic high-temperature component and a field-aligned low temperature component. Type 1 events appear to involve wave-particle interactions while type 2 events imply direct acceleration by oppositely-directed electric fields pointing toward the satellite along magnetic field lines. The data indicate that cold ionospheric electrons, which carry the downward region-1 Birkeland currents on the morning side, are accelerated upward by potential drops of tens of eV at altitudes of several thousand kilometers. This acceleration process allows spacecraft above those altitudes to measure routinely the charge carriers of both downward and upward current systems.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 15, 1983
- Accession Number
- ADA131793
Entities
People
- J. N. Barfield
Organizations
- Southwest Research Institute