Survey of Thermal Plasma Composition in Saturn's Magnetosphere Using Time-of-Flight Data From Cassini/CAPS

Felici, M. and Arridge, C.S. and Wilson, R.J. and Coates, A.J. and Thomsen, M. and Reisenfeld, D. (2018) Survey of Thermal Plasma Composition in Saturn's Magnetosphere Using Time-of-Flight Data From Cassini/CAPS. Journal of Geophysical Research: Space Physics, 123 (8). pp. 6494-6513. ISSN 2169-9380

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Abstract

The Cassini spacecraft orbited Saturn from 2004 to 2017, and in 2006 it started exploring the deep magnetotail, reaching distances of about 68 RS (where RS is the equatorial radius of Saturn). Since Cassini covered a broad area of Saturn's magnetosphere, this raises the question of what is the typical and atypical plasma composition in different regions of Saturn's environment. In this paper, we present a survey of the bulk plasma composition using time-of-flight data from the Plasma Spectrometer/Ion Mass Spectrometer instrument on Cassini, from 2004 through 2012. This is the most comprehensive study ever made of relative abundances of thermal plasma at Saturn, maximizing the use of Cassini's orbital coverage in Saturn's magnetosphere during those years, and, therefore, the sensitivity to seasonal or natural variability of the system. We studied the ratio of counts between ions with E/q≃1.19–21,300 eV/q and mass per charge equal to 2 (either H+ 2 or He++) and ionized hydrogen ([(m/q = 2)]/[H+]), and a mixture of ions (H2O+, H3O+, OH+, and O+), known as the water group (W+) and ionized hydrogen ([W+]/[H+]). We present the data as a function of position in the magnetosphere, radial distance and local time, and distance from the planet and longitude with respect to the moons Enceladus, Dione, Rhea, and Titan. We found that the plasma composition in Saturn's magnetosphere presents significant local time asymmetries and variability. ©2018. American Geophysical Union. All Rights Reserved.

Item Type:
Journal Article
Journal or Publication Title:
Journal of Geophysical Research: Space Physics
Additional Information:
An edited version of this paper was published by AGU. Copyright 2018 American Geophysical Union. Felici, M., Arridge, C. S., Wilson, R. J., Coates, A. J., Thomsen, M., & Reisenfeld, D. (2018). Survey of thermal plasma composition in Saturn's magnetosphere using time‐of‐flight data from Cassini/CAPS. Journal of Geophysical Research: Space Physics, 123, 6494–6513. https://doi.org/10.1029/2017JA025085 To view the published open abstract, go to http://dx.doi.org and enter the DOI.
ID Code:
129453
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Deposited On:
10 Jan 2019 10:06
Refereed?:
Yes
Published?:
Published
Last Modified:
20 Sep 2020 05:15