NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Growing 'Alfvenic' modes in the upstream region of SaturnRecent studies of low-frequency electromagnetic waves upstream of the Saturn bow shock have shown that these waves, in contrast to those at Earth, are observed not in one, but in at least two, distinct frequency bands. The results of wave mode identification based on the Hall-magnetohydrodynamic (MHD) model of plasma and observed wave polarization suggested that these waves propagate in the high beta intermediate mode. However, the underlying instability was not unambiguously determined. In the present paper we use the full electromagnetic dispersion relation derived from linear Vlasov theory in order to examine which of the plasma modes, with observed properties, are unstable in an isotropic Maxwellian plasma in the presence of backstreaming proton beams consistent with Voyager 2 observations at Saturn. As a result we find that the unstable 'Alfvenic' beam mode, as well as resonant and non-resonant fast magnetosonic modes have properties consistent with the data. Moreover, we find that in contrast to the Earth's upstream waves, at Saturn no 'kinetic' normal mode can account for the observed magnetic polarization.
Document ID
19950038004
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Orlowski, D. S.
(University of California, Los Angeles, CA United States)
Russell, C. T.
(University of California, Los Angeles, CA United States)
Krauss-Varban, D.
(University of California, San Diego, CA United States)
Omidi, N.
(University of California, San Diego, CA United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: A1
ISSN: 0148-0227
Subject Category
Astrophysics
Accession Number
95A69603
Funding Number(s)
CONTRACT_GRANT: NAGW-2139
CONTRACT_GRANT: NAGW-2886
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available