Ion composition in interchange injection events in Saturn's magnetosphere

M. F. Thomsen; D. B. Reisenfeld; R. J. Wilson; M. Andriopoulou; F. J. Crary; G. B. Hospodarsky; C. M. Jackman; X. Jia; K. K. Khurana; C. Paranicas; E. Roussos; N. Sergis; R. L. Tokar

doi:10.1002/2014JA020489

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Ion composition in interchange injection events in Saturn's magnetosphere

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Ion composition in interchange injection events in Saturn's magnetosphere

M. F. Thomsen, D. B. Reisenfeld, R. J. Wilson, M. Andriopoulou, F. J. Crary, G. B. Hospodarsky, C. M. Jackman, X. Jia, K. K. Khurana, C. Paranicas, …

Journal of geophysical research. Space physics, Vol.119(12), pp.9761-9772

12/2014

DOI: 10.1002/2014JA020489

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Abstract

Interchange injection events are commonly observed by the Cassini spacecraft in the region between about 6 and 12 R-s (1 R-s = 60,268 km) and even frequently beyond. In this study, 13 examples of interchange injection events are identified in Cassini/Cassini Plasma Spectrometer data under special conditions such that time-of-flight (TOF) mass spectra could be obtained from entirely within the events. Using the TOF data to separate the main ion species H+, H-2(+), and W+, approximate densities of each species are calculated under the assumption that all distributions were isotropic. The light-ion density ratios, H-2(+)/H+, in the injection events are not discernibly different from those ratios in control intervals from the ambient plasma. However, the water-group ratio, W+/H+, is significantly lower than ambient. The comparison of the measured density ratios with the range of values observed throughout Saturn's magnetosphere indicates that the values of W+/H+ that are as low as those observed within the injection events are found primarily beyond L similar to 14 (where L is the equatorial crossing distance, in Saturn radius, of a dipole field line), indicating that the injection events are delivering plasma from the outer magnetosphere at times traveling at least 6 R-s.

Physical Sciences

Astronomy & Astrophysics

Science & Technology

Details

Title: Subtitle: Ion composition in interchange injection events in Saturn's magnetosphere
Creators: M. F. Thomsen - Planetary Science Institute
D. B. Reisenfeld - University of Montana
R. J. Wilson - Laboratory for Atmospheric and Space Physics
M. Andriopoulou - Austrian Academy of Sciences
F. J. Crary - Laboratory for Atmospheric and Space Physics
G. B. Hospodarsky - University of Iowa
C. M. Jackman - University of Southampton
X. Jia - University of Michigan
K. K. Khurana - University of California, Los Angeles
C. Paranicas - Johns Hopkins University Applied Physics Laboratory
E. Roussos - Max Planck Institute for Solar System Research
N. Sergis - Academy of Athens
R. L. Tokar - Planetary Science Institute
Resource Type: Journal article
Publication Details: Journal of geophysical research. Space physics, Vol.119(12), pp.9761-9772
DOI: 10.1002/2014JA020489
ISSN: 2169-9380
eISSN: 2169-9402
Publisher: Amer Geophysical Union
Number of pages: 12
Grant note: ST/L004399/1 / STFC; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC) 1243218 / NASA Cassini program through JPL ST/L004399/1 / Science and Technology Facilities Council; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC) Southwest Research Institute
Language: English
Date published: 12/2014
Academic Unit: Physics and Astronomy
Record Identifier: 9984455269702771

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