Regoli, L. H., Roussos, E., Feyerabend, M., Jones, G. H., Krupp, N., Coates, A. J., Simon, S., Motschmann, U. and Dougherty, M. K. (2016). Access of energetic particles to Titan's exobase: A study of Cassini's T9 flyby. Planet Space Sci., 130. S. 40 - 54. OXFORD: PERGAMON-ELSEVIER SCIENCE LTD. ISSN 0032-0633

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Abstract

We study how the local electromagnetic disturbances introduced by Titan affect the ionization rates of the atmosphere. For this, we model the precipitation of energetic particles, specifically hydrogen and oxygen ions with energies between 1 keV and 1 MeV, into Titan's exobase for the specific magneto spheric configuration of the T9 flyby. For the study, a particle tracing software package is used which consists of an integration of the single particle Lorentz force equation using a 4th order Runge-Kutta numerical Method. For the electromagnetic disturbances, the output of the A.I.K.E.F. hybrid code (kinetic ions, fluid electrons) is used, allowing the possibility of analyzing the disturbances and asymmetries in the access of energetic particles originated by their large gyroradii. By combining these methods, 2D maps showing the access of each set of particles were produced. We show that the access of different particles is largely dominated by their gyroradii, with the complexity of the maps increasing with decreasing gyroradius, due to the larger effect that local disturbances introduced by the presence of the moon have in the trajectory of the particles with lower energies. We also show that for particles with gyroradii much larger than the moon's radius, simpler descriptions of the electromagnetic environment can reproduce similar results to those obtained when using the full hybrid simulation description, with simple north-south fields being sufficient to reproduce the hybrid code results for O+ ions with energies larger than 10 keV but not enough to reproduce those for H+ ions at any of the energies covered in the present study. Finally, by combining the maps created with upstream plasma flow measurements by the MIMI/CHEMS instrument, we are able to estimate normalized fluxes arriving at different selected positions of the moon's exobase. We then use these fluxes to calculate energy deposition and non dissociative N-2 ionization rates for precipitating O+ and H+ ions and find differences in the ion production rates of up to almost 80% at the selected positions. All these results combined show that the electromagnetic field disturbances present in the vicinity of Titan significantly affect the contribution of energetic ions to local ionization profiles. (C) 2015 The Authors. Published by Elsevier Ltd.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Regoli, L. H.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Roussos, E.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Feyerabend, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Jones, G. H.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Krupp, N.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Coates, A. J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Simon, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Motschmann, U.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Dougherty, M. K.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-261834
DOI: 10.1016/j.pss.2015.11.013
Journal or Publication Title: Planet Space Sci.
Volume: 130
Page Range: S. 40 - 54
Date: 2016
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
Place of Publication: OXFORD
ISSN: 0032-0633
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
UPPER-ATMOSPHERE; IONOSPHEREMultiple languages
Astronomy & AstrophysicsMultiple languages
Refereed: Yes
URI: http://kups.ub.uni-koeln.de/id/eprint/26183

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