Re-Analysis of the Cassini RPWS/LP Data in Titan's Ionosphere: 2. Statistics on 57 FlybysShow others and affiliations
2021 (English)In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 126, no 8, article id e2020JA028413Article in journal (Refereed) Published
Abstract [en]
The ionosphere of Titan hosts a complex ion chemistry leading to the formation of organic dust below 1,200 km. Current models cannot fully explain the observed electron temperature in this dusty environment. To achieve new insight, we have re-analyzed the data taken in the ionosphere of Titan by the Cassini Langmuir probe (LP), part of the Radio and Plasma Wave Science package. A first paper (Chatain et al., 2021) introduces the new analysis method and discusses the identification of four electron populations produced by different ionization mechanisms. In this second paper, we present a statistical study of the whole LP dataset below 1,200 km which gives clues on the origin of the four populations. One small population is attributed to photo- or secondary electrons emitted from the surface of the probe boom. A second population is systematically observed, at a constant density (similar to 500 cm(-3)), and is attributed to background thermalized electrons from the ionization process of precipitating particles from the surrounding magnetosphere. The two last populations increase in density with pressure, solar illumination and Extreme ultraviolet flux. The third population is observed with varying densities at all altitudes and solar zenith angles (SZA) except on the far nightside (SZA > similar to 140 degrees), with a maximum density of 2,700 cm(-3). It is therefore certainly related to the photo-ionization of the atmospheric molecules. Finally, a fourth population detected only on the dayside and below 1,200 km reaching up to 2000 cm(-3) could be photo- or thermo-emitted from dust grains.
Place, publisher, year, edition, pages
AMER GEOPHYSICAL UNION American Geophysical Union (AGU), 2021. Vol. 126, no 8, article id e2020JA028413
Keywords [en]
Titan ionosphere, dusty plasma, Langmuir probe, electron population, electron temperature, electron density
National Category
Fusion, Plasma and Space Physics Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:uu:diva-456141DOI: 10.1029/2020JA028413ISI: 000691018000040OAI: oai:DiVA.org:uu-456141DiVA, id: diva2:1603466
Funder
Swedish National Space BoardSwedish National Space Board, 135/13Swedish Research Council, 621-2013-4191EU, European Research Council, 6368292021-10-152021-10-152024-01-15Bibliographically approved