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Reflection of Alfven waves in the solar windWe have revisited the problem of propagation of toroidal and linear Alfven waves formulated by Heinemann and Olbert (1980) to compare Wentzel-Kramers-Brillouin (WKB) and non-WKB waves and their effects on the solar wind. They considered two solar wind models and showed that reflection is important for Alfven waves with periods of the order of one day and longer and that non-WKB Alfven waves are no more effective in accelerating the solar wind than in WKB waves. There are several recently published papers that seem to indicate that Alfven waves with periods of the order of several minutes should be treated as non-WKB waves and that these non-WKB waves exert a stronger acceleration force than WKB waves. The purposse of this paper is to study the origin of these discrepancies by performing parametric studies of the behavior of the waves under a variety of different conditions. In addition, we want to investigate two problems that have not been addressed by Heinimann and Olbert, namely, calculate the efficieny of Alfven wave reflection by using the reflection coefficient and identfy the region of strongest wave reflection in different wind models. To achieve these goals, we investigate the influence of temperature, electron desity distribution, wind velocity, and magnetic field strength on te waves. The obtained results clearly demonstrate that Alfven wave reflection is strongly model dependent and that the strongest reflection can be expected in models with the base temperatures higher than 10(exp 6) K and with the base densities lower than 7 x 10(exp 7)/cu cm. In these models as well as in the models with lower temperatures and higher densities Alfven waves with periods as short as several minutes have negligible reflection so that they can be treated as WKB waves; however, for Alfven waves with periods of the order of one hour or longer reflection is significant, requiring a non-WKB treatment. We also show that non-WKB, linear Alfven waves are always less effective in accelerating the plasma than WKB Alfven waves. Finally, it is evident from our results that the region of strongest wave reflection is usually located at the base of the models and hence that interpretation of wave reflection based soley on the reflection coefficient can be misleading.
Document ID
19950048201
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Krogulec, M.
(Univ. of Alabama, Huntsville, AL United States)
Musielak, Z. E.
(Univ. of Alabama, Huntsville, AL United States)
Suess, S. T.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Nerney, S. F.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Moore, R. L.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
August 16, 2013
Publication Date
December 1, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: A12
ISSN: 0148-0227
Subject Category
Solar Physics
Accession Number
95A79800
Funding Number(s)
CONTRACT_GRANT: NSF ATM-91-19580
CONTRACT_GRANT: NSF INT-90-16514
CONTRACT_GRANT: NAG8-839
CONTRACT_GRANT: NAGW-2933
Distribution Limits
Public
Copyright
Other

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