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Observations of interplanetary plasma waves, spacecraft noise, and sheath phenomena on Imp 7The Imp 7 plasma wave instrument measures electric and magnetic wave components of plasma oscillations over the frequency range from 10 Hz to 100 kHz. The instrumentation and relevant external characteristics of the spacecraft that appear to be responsible for some in-flight disturbance effects are briefly described. It is shown that as each one of the 16 solar panel flats rotates into shadow or sunlight, the array transients produce fluctuating magnetic fields that are detected on the magnetic loop mounted 3.4 m from the spacecraft. These transients occur 16 times per spin period, and the corresponding magnetic noise has a high frequency on the rapidly spinning Imp 7 spacecraft. The analysis suggests that some Imp magnetic threshold levels measured 3-4 m from the spacecraft are determined by the solar array current transient effects associated with the discrete 16-sided geometry of the spacecraft. The geometry also influences the response of the electric dipole antenna by modulating the sheath.
Document ID
19740035610
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Scarf, F. L.
Fredricks, R. W.
Green, I. M.
Crook, G. M.
(TRW Systems Group Redondo Beach, Calif., United States)
Date Acquired
August 7, 2013
Publication Date
January 1, 1974
Publication Information
Publication: Journal of Geophysical Research
Volume: 79
Subject Category
Space Sciences
Accession Number
74A18360
Funding Number(s)
CONTRACT_GRANT: NAS5-11384
CONTRACT_GRANT: NAS5-23150
Distribution Limits
Public
Copyright
Other

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