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Evidence for ion transport and molecular ion dominance in the Venus ionotailWe present analyses from the five Pioneer Venus Orbiter plasma experiments and the plasma wave experiment when a patch of plasma with enhanced densities was encountered in the near-Venus ionotail during atmospheric entry at an altitude of approximately 1100 km in the nightside ionosphere. Our analyses of the thermal and superthermal ion measurements in this plasma feature provides the first evidence that at times molecular ions in the 28-32 amu mass range are dominant over atomic mass species thus yielding evidence for a transport mechanism that reaches into the lower ionosphere. Analysis of plasma analyzer (OPA) observations at this time indicates the presence of ions measured in the rest frame of the spacecraft at approximately 27 and 37 volt energy per unit charge steps. In the rest frame of the planet these superthermal ions are flowing from the dawn direction at speeds (assuming they are O2(+)) of approximately 8 km/s and with a flow component downward (perpendicular to the ecliptic plane) at speeds of approximately 2 km/s. OPA analyses also determine the ion number flux, energy, flow angles, and angular distributions. Plasma wave bursts appear to indicate that plasma density decreases within and on the equatorward edge of the patch of enhanced plasma densities are associated with ion acoustic waves and relative ion streaming.
Document ID
19950057071
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Intriligator, D. S.
(Carmel Research Center Santa Monica, CA, United States)
Brace, L. H.
(University of Michigan, Ann Arbor, MI United States)
Cloutier, P. A.
(Rice University Houston, TX, United States)
Grebowsky, J. M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hartle, R. E.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kasprzak, W. T.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Knudsen, W. C.
(Knudsen Geophysical Research, Monte Sereno, CA United States)
Strangeway, R. J.
(University of California, Los Angeles, CA United States)
Date Acquired
August 16, 2013
Publication Date
September 1, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: A9
ISSN: 0148-0227
Subject Category
Astrophysics
Accession Number
95A88670
Funding Number(s)
CONTRACT_GRANT: NAS2-12912
CONTRACT_GRANT: NASW-4815
Distribution Limits
Public
Copyright
Other

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