Increasing positive ion number densities below the peak of ion-electron pair production in titan's ionosphere

E. Vigren, M. Galand, O. Shebanits, J. E. Wahlund, W. D. Geppert, P. Lavvas, V. Vuitton, Roger Yelle

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

We combine derived ion-electron pair formation rates with Cassini Radio Plasma Wave Science Langmuir Probe measurements of electron and positive ion number densities in Titan's sunlit ionosphere. We show that positive ion number densities in Titan's sunlit ionosphere can increase toward significantly lower altitudes than the peak of ion-electron pair formation despite that the effective ion-electron recombination coefficient increases. This is explained by the increased mixing ratios of negative ions, which are formed by electron attachment to neutrals. While such a process acts as a sink for free electrons, the positive ions become longer-lived as the rate coefficients for ion-anion neutralization reactions are smaller than those for ion-electron dissociative recombination reactions.

Original languageEnglish (US)
Article number69
JournalAstrophysical Journal
Volume786
Issue number1
DOIs
StatePublished - May 1 2014

Fingerprint

Titan
pair production
positive ions
ionospheres
ionosphere
electron
ion
ions
electrons
recombination coefficient
recombination reactions
recombination
electron attachment
low altitude
electrostatic probes
plasma waves
mixing ratios
sinks
negative ions
free electrons

Keywords

  • molecular processes
  • planets and satellites: individual (Titan)

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Increasing positive ion number densities below the peak of ion-electron pair production in titan's ionosphere. / Vigren, E.; Galand, M.; Shebanits, O.; Wahlund, J. E.; Geppert, W. D.; Lavvas, P.; Vuitton, V.; Yelle, Roger.

In: Astrophysical Journal, Vol. 786, No. 1, 69, 01.05.2014.

Research output: Contribution to journalArticle

Vigren, E. ; Galand, M. ; Shebanits, O. ; Wahlund, J. E. ; Geppert, W. D. ; Lavvas, P. ; Vuitton, V. ; Yelle, Roger. / Increasing positive ion number densities below the peak of ion-electron pair production in titan's ionosphere. In: Astrophysical Journal. 2014 ; Vol. 786, No. 1.
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AU - Geppert, W. D.

AU - Lavvas, P.

AU - Vuitton, V.

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