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Simulations and Observations of Heating of Auroral Ion BeamsIn the auroral zone, quasi-static parallel electric fields produce beams of ionospheric ions (e.g., H(+), He(+) and 0(+)), which flow outward into the magnetosphere, providing a significant source of ions for the ring current and plasma sheet. Because the velocities to which these beams are accelerated is dependent on the mass of the ions, differential flows between the various ion species can develop which are unstable to an ion-ion streaming instability. Particle simulations and observations from DE 1 are used to investigate the heating of the ion beams produced by this instability. It is shown that there is net transfer of energy from the light ions to the heavy ions, with the heavy ions reaching maximum velocities near the beam velocity of the light ions. Bulk heating of the heavy ions occurs when their relative density is low while high-energy tails are produced when their relative density is high. The heating is primarily parallel to the magnetic field if the difference in the heavy and light ion beam velocities is subsonic while both perpendicular and parallel heating can occur if it is supersonic. In the latter case, very strong heating of an intermediate ion's species such as He(+) can also occur. Comparison with observations shows features consistent with heating via the ion-ion instability including perpendicular heating in the supersonic regime and parallel heating in the subsonic regime and a change in the heating between these regimes as the ratio of the H(+) beam speed to the local sound speed is observed to decrease. This heating is, however, not always observed in association with enhanced wave emissions. This lack of waves is attributed to reabsorption of the waves as the ions become heated.
Document ID
19970030284
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Winglee, R. M.
(Colorado Univ. Colorado Springs, CO United States)
Dusenbery, P. B.
(Colorado Univ. Colorado Springs, CO United States)
Collin, H. L.
(Lockheed Missiles and Space Co. Palo Alto, CA United States)
Lin, C. S.
(Southwest Research Inst. San Antonio, TX United States)
Persoon, A. M.
(Iowa Univ. Iowa City, IA United States)
Date Acquired
August 17, 2013
Publication Date
July 1, 1989
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 94
Issue: A7
ISSN: 0148-0227
Subject Category
Geophysics
Report/Patent Number
NASA-CR-204422
Paper-88JA04139
NAS 1.26:204422
Accession Number
97N72337
Funding Number(s)
CONTRACT_GRANT: NASw-998
CONTRACT_GRANT: NsG-7287
CONTRACT_GRANT: NSF ATM-83-18203
CONTRACT_GRANT: NAS5-28711
CONTRACT_GRANT: NAS5-28710
CONTRACT_GRANT: NAGw-91
CONTRACT_GRANT: NAG5-310
CONTRACT_GRANT: NSF ATM-87-19371
Distribution Limits
Public
Copyright
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