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Ulysses observations of electron and proton components in a magnetic cloud and related wave activityIn addition to a smooth rotation of the magnetic field vector, magnetic clouds have a low proton temperature T(sub p). Their expansion in the solar wind leads to depletion and therefore the ion component cools down. It has been shown recently that the electron component in magnetic clouds behaves differently: when the cloud expands, electron temperature Te anti correlates with density and therefore Te increases in the cloud, creating favorable conditions for the rise of ion-acoustic waves. For the magnetic cloud observed by Ulysses on June 10 - 12, 1993 at 4.64 AU at S 32.5 deg, we present observations for both electron and proton components and related plasma wave activity. Our results confirm the anti correlation between T(sub e) and electron density and also exhibit a high ratio of T(sub e)/T(sub P) in the cloud. Since Landau damping is not effective for T(sub e)/T(sub p) much greater than 1, Doppler shifted ion acoustic waves are expected in the cloud. Calculation of ion acoustic wave frequencies in the cloud and comparison with observed wave activity confirm this expectation. As in our previous work, we show that the electron component in the cloud obeys a polytropic law with gamma is less than 1 (gamma approximately equals 0.3-0.4). The dynamics of the magnetic cloud are determined to a large degree by the dominating electron pressure.
Document ID
19960021488
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Osherovich, V. A.
(Hughes STX, Inc. Greenbelt, MD United States)
Fainberg, J.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Stone, R. G.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
MacDowall, R. J.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Phillips, J. L.
(Los Alamos National Lab. NM United States)
Balogh, A.
(Imperial Coll. of Science and Technology London, United Kingdom)
Date Acquired
August 17, 2013
Publication Date
June 30, 1995
Publication Information
Publication: International Solar Wind 8 Conference
Subject Category
Astrophysics
Accession Number
96N24884
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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