UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Access of energetic particles to Titan's exobase: A study of Cassini's T9 flyby

Regoli, LH; Roussos, E; Feyerabend, M; Jones, GH; Krupp, N; Coates, AJ; Simon, S; ... Dougherty, MK; + view all (2016) Access of energetic particles to Titan's exobase: A study of Cassini's T9 flyby. Planetary and Space Science , 130 pp. 40-53. 10.1016/j.pss.2015.11.013. Green open access

[thumbnail of Regoli_1-s2.0-S0032063315003621-main.pdf]
Preview
Text
Regoli_1-s2.0-S0032063315003621-main.pdf

Download (4MB) | Preview

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 1keV and 1MeV, into Titan's exobase for the specific magnetospheric 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 10keV 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 N2 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.

Type: Article
Title: Access of energetic particles to Titan's exobase: A study of Cassini's T9 flyby
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.pss.2015.11.013
Publisher version: http://dx.doi.org/10.1016/j.pss.2015.11.013
Language: English
Additional information: Copyright © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Keywords: Titan, Exobase, Tracing software, Precipitation, Hybrid code, Energy deposition
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/1474815
Downloads since deposit
Loading...
0Downloads
Download activity - last month
Loading...
Download activity - last 12 months
Loading...
Downloads by country - last 12 months
Loading...

Archive Staff Only

View Item View Item