Short wavelength electrostatic waves in the earth's magnetosheath

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6961696

Gallagher, D L

Recent observations with the ISEE-1 spacecraft have found electric field emissions in the dayside magnetosheath whose frequency spectrum is modulated at twice the spacecraft spin period. The upper frequency cutoff in the frequency-time spectrum of the emissions has a characteristic parabola shape or ''festoon'' shape. The low frequency cutoff ranges from 100 Hz to 400 Hz, while the high frequency limit ranges from about 1kHz to 4kHz. The bandwidth is found to minimize for antenna orientations parallel to these wave number vectors, requiring the confinement of those vectors to a plane which contains the geocentric solar eclilptic coordinate z-axis. The spacecraft observed frequency spectrum results from the spacecraft antenna response to the Doppler shifted wave vector spectrum which exists in the plasma. Imposed constraints on the plasma rest-frame wave vectors and frequencies indicate that the emissions occur within the frequency range from about 150 Hz to 1 kHz, with wavelengths between about 30 meters and 600 meters. These constraints strongly suggest that the festoon-shaped emissions are ion-acoustic waves. The small group velocity and k vector direction of the ion-acoustic mode are consistent with wave generation upstream at the bow shock and convection downstream to locations within the outer dayside magnetosheath.

• Research Organization: Iowa Univ., Iowa City (USA)
• OSTI ID: 6961696
• Country of Publication: United States
• Language: English

Related Subjects

640203* -- Atmospheric Physics-- Magnetospheric Phenomena-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
DOPPLER EFFECT
ELECTRIC FIELDS
EMISSION
FREQUENCY RANGE
HZ RANGE
ION ACOUSTIC WAVES
ION WAVES
KHZ RANGE
KHZ RANGE 01-100
MAGNETOSHEATH
PLASMA WAVES
SATELLITES
VELOCITY