Acceleration of ions in Jovian plasmoids: does turbulence play a role?

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Title: Acceleration of ions in Jovian plasmoids: does turbulence play a role?
Authors: Kronberg, EA
Grigorenko, EE
Malykhin, A
Kozak, L
Petrenko, B
Vogt, M
Roussos, E
Kollmann, P
Jackman, C
Kasahara, S
Malova, KV
Tao, C
Radioti, A
Masters, A
Item Type: Journal Article
Abstract: The dissipation processes which transform electromagnetic energy into kinetic particle energy in space plasmas are still not fully understood. Of particular interest is the distribution of the dissipated energy among different species of charged particles. The Jovian magnetosphere is a unique laboratory to study this question because outflowing ions from the moon Io create a high diversity in ion species. In this work, we use multispecies ion observations and magnetic field measurements by the Galileo spacecraft. We limit our study to observations of plasmoids in the Jovian magnetotail, because there is strong ion acceleration in these structures. Our model predicts that electromagnetic turbulence in plasmoids plays an essential role in the acceleration of oxygen, sulfur, and hydrogen ions. The observations show a decrease of the oxygen and sulfur energy spectral index γ at ∼30 to ∼400 keV/nuc with the wave power indicating an energy transfer from electromagnetic waves to particles, in agreement with the model. The wave power threshold for effective acceleration is of the order of 10 nT2Hz−1, as in terrestrial plasmoids. However, this is not observed for hydrogen ions, implying that processes other than wave‐particle interaction are more important for the acceleration of these ions or that the time and energy resolution of the observations is too coarse. The results are expected to be confirmed by improved plasma measurements by the Juno spacecraft.
Issue Date: 27-Jun-2019
Date of Acceptance: 8-Jun-2019
ISSN: 2169-9380
Publisher: American Geophysical Union
Journal / Book Title: Journal of Geophysical Research: Space Physics
Copyright Statement: ©2019. American Geophysical Union. All Rights Reserved.
Sponsor/Funder: The Royal Society
Funder's Grant Number: UF150547
Publication Status: Published online
Embargo Date: 2019-12-27
Online Publication Date: 2019-06-27
Appears in Collections:Space and Atmospheric Physics
Faculty of Natural Sciences

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