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Bulk properties and velocity distributions of water group ions at Comet Halley - Giotto measurementsIn the region upstream of Comet Halley, pickup heavy ions of cometary origin were directly observed by the implanted ion spectrometer on Giotto. Diffusion of this population in pitch angle and in energy, during the approach to the comet and on the outbound leg is discussed. The two data sets are compared and qualitative ideas on scattering timescales are inferred. In addition the bulk parameters of these distributions have been computed and a comparison of the observed speed in the solar wind frame and the observed density with expectations is presented. Pitch angle scattering occurs more slowly than expected with filled shells appearing at 2,500,000 km, and significant energy diffusion does not occur until the bow shock region. Also the shell distributions downstream of the shock flow at the bispherical bulk speed (related to the Alfven speed) along the magnetic field with respect to the solar wind in accordance with conservation of energy between the pickup ions and the wave turbulence.
Document ID
19900054425
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Coates, A. J.
(University Coll. Dorking, United Kingdom)
Johnstone, A. D.
(London, University College, Dorking, United Kingdom)
Wilken, B.
(University Coll. Dorking, United Kingdom)
Jockers, K.
(Max-Planck-Institut fuer Aeronomie Katlenburg-Lindau, Federal Republic of Germany, United States)
Glassmeier, K.-H.
(Koeln, Universitaet Cologne, Federal Republic of Germany, United States)
Date Acquired
August 14, 2013
Publication Date
July 1, 1990
Publication Information
Publication: Journal of Geophysical Research
Volume: 95
ISSN: 0148-0227
Subject Category
Astrophysics
Accession Number
90A41480
Funding Number(s)
CONTRACT_GRANT: BMFT-01-OF-112-4
CONTRACT_GRANT: NAS5-27442
CONTRACT_GRANT: NASA ORDER W-15164
Distribution Limits
Public
Copyright
Other

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