Upgoing ion beams: 1. Microscopic analysis

Journal Article · Wed Dec 01 04:00:00 EST 1982 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA087iA12p10487· OSTI ID:5987521

Kaufmann, R L; Kintner, P M

The stability of electrostatic waves with frequencies near the hydrogen cyclotron frequency is investigated for an auroral plasma containing an ion beam. The energetic portion of the model distribution function is based on measurements made by Aerospace ion and electron detectors on the S3-3 satellite at an altitude of 1 R/sub E/. Parameters describing unmeasured cold background species are varied, and the resulting wave growth rates are compared with measurements from the Berkeley AC electric field experiment. The events studied in this report involve waves that peak just above the hydrogen cyclotron frequency. These waves are seen only when an upgoing ion beam is present. We conclude that of the wave modes investigated, only electrostatic hydrogen ion cyclotron waves can be driven by the existing plasma. The waves can be produced either by drifting electrons or by the ion beam. Although we cannot exclude the possibility that electrons are drifting and contributing to wave growth, we find that many features of the measurements are a natural consequence of instabilities generated by ion beams. In this model, ion beams are seen with their observed temperatures because they have evolved to a weakly unstable configuration in which the wave growth length is comparable to the width of the beam region. Waves are well confined to the beams because they are damped rapidly in the adjacent plasma. The mirror effect can maintain a weak instability over a considerable altitude range. The above explanation is consistent only if we make two assumptions concerning unmeasured particles. First, hydrogen ions that are too cold to be measured by the S3-3 detectors must be present to sustain the hydrogen cyclotron waves and to produce a second peak in the ion distribution function.

• Research Organization: Department of Physics, University of New Hampshire, Durham, New Hampshire 03824
• OSTI ID: 5987521
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 87:A12; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACCELERATION
BEAMS
EARTH ATMOSPHERE
ELECTRIC FIELDS
INSTABILITY GROWTH RATES
ION BEAMS
ION TEMPERATURE
IONOSPHERE
PLANETARY IONOSPHERES
PLASMA ACCELERATION
PLASMA WAVES
SATELLITES