Amplification of critical velocity ionization by associative ionization

Journal Article · Wed Apr 01 04:00:00 EST 1992 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/91JA02656· OSTI ID:5509130

Lai, S T; Murad, E ^[1]; McNeil, W J ^[2]

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1. Phillips Lab., Hanscom AFB, MA (United States)
2. Radex Inc., Bedford, MA (United States)

Space experiments to verify the critical ionization velocity (CIV) theory have for the most part involved the release of barium in the ionosphere. It is suggested in this paper that associative ionization (Al) reactions involving barium (i.e., Ba + O {yields} BaO + e) may occur in these experiments, and since the products would be indistinguishable from those generated by electron impact ionization (CIV), it is likely that AI-generated ions may be mistaken for those generated by CIV. The electrons formed in AI and by electron impact may be energized by the ion beams, generated by both CIV and AI. The energized electrons may ionize, enhancing the CIV process. In this way, the AI-CIV double process could amplify CIV. The amplification is especially important for sustaining CIV when the CIV energy budget is tight or when the ionization rate due to CIV alone is too low to satisfy Townsend's criterion. The result may have significant implications for the results observed in recent CIV space experiments using barium jets. The AI-CIV double process may offer a plausible explanation for the observed long distance of Ba{sup +} ionization. Any other ion beam formation mechanism, such as charge exchange, stripping and reflected ambient ions, can also amplify CIV in a manner similar AI, although comparison of the relative magnitudes of several of these processes indicates that AI may be the most significant. The authors suggest an AI-assisted experiment in which a samarium beam could undergo AI, promoting CIV in an accompanying xenon beam.

• OSTI ID: 5509130
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 97:A4; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATOM COLLISIONS
BARIUM IONS
BEAMS
CHARGE EXCHANGE
CHARGED PARTICLES
COLLISIONS
DIAGNOSTIC TECHNIQUES
EARTH ATMOSPHERE
ELECTRON COLLISIONS
INSTABILITY
ION BEAMS
ION COLLISIONS
ION-ATOM COLLISIONS
IONIZATION
IONOSPHERE
IONS
PLANETARY IONOSPHERES
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
TWO-STREAM INSTABILITY
VELOCITY
VERIFICATION