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Ion cyclotron bands in VLF saucersIn the wideband VLF data obtained by the polar orbiting DE-1 satellite over the polar night ion trough region of the upper ionosphere, conspicuous frequency-band structures are found to occur both in absorption and emission, particularly associating with VLF saucers. The attenuation bands indicate that the ions of atomic hydrogen from the polar ionosphere are accelerated by the ac electric fields of VLF waves oscillating normal to the static magnetic field, analogous to a cyclotron accelerator. The observed frequencies of the cyclotron harmonics suggest that the acceleration is taking place in the layer below the satellite at a geocentric distance of less than about 1.5 earth radii. This example indicates the existence of upward propagating hiss at those altitudes inside the auroral zone. On the other hand, the frequency shifts of the emission bands are attributed to a combination of two different types of Doppler shift, one due to the orbital motion of the satellite and the other due to the upward motion of the medium at the emission source. This indicates the existence of an upward plasma flow at the source, with a velocity of the order of 20 km/s inside the saucer. The amount of this frequency shift decreases with increasing harmonic order, indicating a higher phase velocity for the electrostatic waves of higher harmonic order.
Document ID
19900048325
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Maeda, Kaichi
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Fung, Shing F.
(Atlantic Research Corp. Landover, MD, United States)
Calvert, Wynne
(Iowa, University Iowa City, United States)
Date Acquired
August 14, 2013
Publication Date
April 1, 1990
Publication Information
Publication: Planetary and Space Science
Volume: 38
ISSN: 0032-0633
Subject Category
Geophysics
Accession Number
90A35380
Funding Number(s)
CONTRACT_GRANT: NAGW-1206
CONTRACT_GRANT: NAGW-1488
CONTRACT_GRANT: NAG5-310
Distribution Limits
Public
Copyright
Other

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