Increasing Positive Ion Number Densities Below the Peak of Ion-Electron Pair Production in Titan's Ionosphere
2014 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 786, no 1, 69- p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2014. Vol. 786, no 1, 69- p.
molecular processes, planets and satellites: individual (Titan)
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:uu:diva-227261DOI: 10.1088/0004-637X/786/1/69ISI: 000335810700069OAI: oai:DiVA.org:uu-227261DiVA: diva2:731736