Experimental test of the electromagnetic ion cyclotron instability within the earth's magnetosphere

Journal Article · Wed Oct 01 04:00:00 EDT 1980 · Phys. Fluids; (United States)

DOI:https://doi.org/10.1063/1.862873· OSTI ID:5071338

Mauk, B H; McPherron, R L

The ATS-6 geostationary satellite has observed many examples of propagating, electromagnetic Alfven/ion cyclotron waves in both plasma particle and magnetic field data. These waves have been viewed predominantly near the afternoon and dusk regions of the earth's magnetosphere with normalized frequencies (..omega../..cap omega../sub H//sup +/) ranging between 0.05 and 0.5. Viewed from an average geomagnetic latitude of +10/sup 0/, the waves have only been observed to propagate northward, suggesting that they are generated within the equatorial or minimum BETA regions. Two wave events have been chosen for detailed analysis. Both events appeared coincidentally with the encounter of cool plasma populations (5 eV) which joined the hot populations already present (10--40 keV). These coincidences suggest the popular, yet largely untested, electromagnetic ion cyclotron instability as the wave generation mechanism. As a test of this hypothesis, ion cyclotron amplification profiles are obtained by evaluating the linear growth rate integrals under the measured, anisotropic hot ion distributions. The measured frequencies for both of the chosen events are in good agreement with the quite restricted values which correspond to the peaks of the amplification profiles. As a result of magnetic field inhomogeneities, the interactions remain within the linear regime.

• Research Organization: Space Sciences Division, Geophysics Program, University of Washington, Seattle, Washington 98195
• OSTI ID: 5071338
• Journal Information: Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 23:10; ISSN PFLDA
• Country of Publication: United States
• Language: English

Related Subjects

640203* -- Atmospheric Physics-- Magnetospheric Phenomena-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALFVEN WAVES
ATS SATELLITES
CHARGED PARTICLES
CYCLOTRON FREQUENCY
DISTRIBUTION FUNCTIONS
DOPPLER EFFECT
EARTH ATMOSPHERE
FUNCTIONS
HYDROMAGNETIC WAVES
INSTABILITY
ION WAVE INSTABILITY
IONS
MAGNETOMETERS
MAGNETOSPHERE
MEASURING INSTRUMENTS
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
PLASMA WAVES
SATELLITES