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Nonthermal ions and associated magnetic field behavior at a quasi-parallel earth's bow shockAttention is given to ion and magnetic field measurements at the earth's bow shock from the AMPTE-UKS and -IRM spacecraft, which were examined in high time resolution during a 45-min interval when the field remained closely aligned with the model bow shock normal. Dense ion beams were detected almost exclusively in the midst of short-duration periods of turbulent magnetic field wave activity. Many examples of propagation at large elevation angles relative to the ecliptic plane, which is inconsistent with reflection in the standard model shock configuration, were discovered. The associated waves are elliptically polarized and are preferentially left-handed in the observer's frame of reference, but are less confined to the maximum variance plane than other previously studied foreshock waves. The association of the wave activity with the ion beams suggests that the former may be triggered by an ion-driven instability, and possible candidates are discussed.
Document ID
19930046822
Document Type
Reprint (Version printed in journal)
Authors
Wilkinson, W. P. (Queen Mary and Westfield College London, United Kingdom)
Pardaens, A. K. (Sheffield Univ. United Kingdom)
Schwartz, S. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Burgess, D. (Queen Mary and Westfield College London, United Kingdom)
Luehr, H. (Braunschweig, Technische Univ. Germany)
Kessel, R. L. (National Space Science Data Center Greenbelt, MD, United States)
Dunlop, M. (Imperial College of Science, Technology, and Medicine London, United Kingdom)
Farrugia, C. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 16, 2013
Publication Date
March 1, 1993
Publication Information
Publication: Journal of Geophysical Research
Volume: 98
Issue: A3
ISSN: 0148-0227
Subject Category
GEOPHYSICS
Funding Number(s)
CONTRACT_GRANT: SERC-GR/F/85017
Distribution Limits
Public
Copyright
Other