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Neutral cloud theory of the Jovian nebula: Anomalous ionization effect of superthermal electronsThe standard model of the Jovian nebula postulates that its particle source is the extended cloud of neutral sulfur and oxygen atoms that escape from the satellite Io and become ionized through electron impact from the corotating plasma. Its energy source is the gyroenergy acquired by newly formed pickup ions as they are swept up to corotation velocity by the planetary magnetic field. Elastic collisions between plasma ions and electrons cool the ions and heat the electrons, while inelastic collisions cool the electrons and excite the ions to radiate intense line emission, which is the primary energy-loss mechanism for the plasma. This neutral cloud theory of the Io plasma torus, as it has come to be known, has been the subject of recent critcism which asserts that the theory cannot account for the observed charge state of the plasma which features O(+) and S(2+) as the dominant ions. It is shown in this work that the inclusion of a small population of super-thermal electrons is required to achieve the correct ion partitioning among various charge states. It is also argued that the anomalous ionization effect of the superthermal electrons is responsible for the overall spatial bifurcation of the nebula into a hot multiply charged plasma region outside of 5.7 Jovian radii and a cool singly ionized plasma inside this distance.
Document ID
19950049394
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Barbosa, D. D.
(Univ. of California, Los Angles, CA United States)
Date Acquired
August 16, 2013
Publication Date
July 20, 1994
Publication Information
Publication: The Astrophysical Journal, Part 1
Volume: 430
Issue: 1
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A80993
Funding Number(s)
CONTRACT_GRANT: NAGW-3190
CONTRACT_GRANT: NAGW-1810
Distribution Limits
Public
Copyright
Other

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