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

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

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.

energy transformation, ion acceleration, Jovian magnetopshere, Jovian magnetotail, plasmoid, turbulence
2169-9380
Kronberg, E. A.
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Grigorenko, E. E.
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Malykhin, A.
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Kozak, L.
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Petrenko, B.
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Vogt, M. F.
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Roussos, E.
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Kollmann, P.
e8028cc0-a696-4475-8836-c67ae718bb14
Jackman, C. M.
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Kasahara, S.
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Malova, Kh V.
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Tao, C.
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Radioti, A.
0451be9e-9800-44fb-bb31-abb5fe00958a
Masters, A.
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Kronberg, E. A.
1de51184-0fa8-4fb9-9c83-60fb9e21be2c
Grigorenko, E. E.
d5f856df-b3e8-4b07-bc06-416327636ec3
Malykhin, A.
37e08ab8-b3e3-4dd4-a93a-356488584520
Kozak, L.
a1f28eb9-4c29-47d6-9b6d-abe331d62148
Petrenko, B.
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Vogt, M. F.
7a00094d-e760-44eb-bf65-4135d218932b
Roussos, E.
6b85b964-976c-4bd0-b1aa-b2ba918482da
Kollmann, P.
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Jackman, C. M.
9bc3456c-b254-48f1-ade0-912c5b8b4529
Kasahara, S.
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Malova, Kh V.
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Tao, C.
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Radioti, A.
0451be9e-9800-44fb-bb31-abb5fe00958a
Masters, A.
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Kronberg, E. A., Grigorenko, E. E., Malykhin, A., Kozak, L., Petrenko, B., Vogt, M. F., Roussos, E., Kollmann, P., Jackman, C. M., Kasahara, S., Malova, Kh V., Tao, C., Radioti, A. and Masters, A. (2019) Acceleration of ions in Jovian plasmoids: Does turbulence play a role? Journal of Geophysical Research: Space Physics. (doi:10.1029/2019JA026553).

Record type: 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.

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Kronberg_et_al-2019-Journal_of_Geophysical_Research__Space_Physics - Version of Record
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Accepted/In Press date: 8 June 2019
e-pub ahead of print date: 27 June 2019
Keywords: energy transformation, ion acceleration, Jovian magnetopshere, Jovian magnetotail, plasmoid, turbulence

Identifiers

Local EPrints ID: 432863
URI: https://eprints.soton.ac.uk/id/eprint/432863
ISSN: 2169-9380
PURE UUID: 0a39cefc-0c7c-4c99-a066-445cfeb8e565
ORCID for C. M. Jackman: ORCID iD orcid.org/0000-0003-0635-7361

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Date deposited: 31 Jul 2019 16:30
Last modified: 13 Dec 2019 01:31

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Contributors

Author: E. A. Kronberg
Author: E. E. Grigorenko
Author: A. Malykhin
Author: L. Kozak
Author: B. Petrenko
Author: M. F. Vogt
Author: E. Roussos
Author: P. Kollmann
Author: C. M. Jackman ORCID iD
Author: S. Kasahara
Author: Kh V. Malova
Author: C. Tao
Author: A. Radioti
Author: A. Masters

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