Radar observations of the onset of current-driven instabilities in the topside ionosphere

Technical Report · Mon Feb 01 04:00:00 EST 1988

OSTI ID:6798873

Foster, J C; Pozo, C; Groves, K

Milestone Hill radar spectra exhibit pronounced spectral asymmetries in the presence of field-aligned currents in the topside ionosphere. The enhanced, often intense, returns associated with the current-driven growth of the ion-acoustic mode exhibit the characteristics of hard-target backscatter suggesting that many satellite echoes observed by UHF radars at high latitudes might be caused by this mechanism. A large current density (>100 microamp/sq.m) is calculated for the conditions observed, consistent with that seen in intense earthward-directed current filaments. These observations indicate that the ion-acoustic mode grows toward instability with increasing altitude. Backscatter observed from the unstable region at higher altitudes is characteristically at the ion plasma frequency consistent with the unstable growth of the acoustic mode for large ratios of electron-to-ion temperature.

• Research Organization: Haystack Observatory, Westford, MA (USA)
• OSTI ID: 6798873
• Report Number(s): AD-A-194821/5/XAB
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALTITUDE
ASYMMETRY
BACKSCATTERING
CHARGED PARTICLES
CURRENT DENSITY
EARTH ATMOSPHERE
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
INSTABILITY
ION ACOUSTIC WAVES
ION WAVES
IONOSPHERE
IONS
LEPTONS
MEASURING INSTRUMENTS
PLANETARY IONOSPHERES
PLASMA INSTABILITY
PLASMA WAVES
RADAR
RANGE FINDERS
SCATTERING
SPECTRA
STABILITY
TARGETS