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Proton temperature anisotropies in the plasma environment of Venus

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Proton temperature anisotropies in the plasma environment of Venus. / Bader, Alexander; Stenberg Wieser, Gabriella; André, Mats et al.
In: Journal of Geophysical Research: Space Physics, Vol. 124, No. 5, 01.05.2019, p. 3312-3330.

Research output: Contribution to Journal/MagazineJournal articlepeer-review

Harvard

Bader, A, Stenberg Wieser, G, André, M, Wieser, M, Futaana, Y, Persson, M, Nilsson, H & Zhang, T 2019, 'Proton temperature anisotropies in the plasma environment of Venus', Journal of Geophysical Research: Space Physics, vol. 124, no. 5, pp. 3312-3330. https://doi.org/10.1029/2019JA026619

APA

Bader, A., Stenberg Wieser, G., André, M., Wieser, M., Futaana, Y., Persson, M., Nilsson, H., & Zhang, T. (2019). Proton temperature anisotropies in the plasma environment of Venus. Journal of Geophysical Research: Space Physics, 124(5), 3312-3330. https://doi.org/10.1029/2019JA026619

Vancouver

Bader A, Stenberg Wieser G, André M, Wieser M, Futaana Y, Persson M et al. Proton temperature anisotropies in the plasma environment of Venus. Journal of Geophysical Research: Space Physics. 2019 May 1;124(5):3312-3330. doi: 10.1029/2019JA026619

Author

Bader, Alexander ; Stenberg Wieser, Gabriella ; André, Mats et al. / Proton temperature anisotropies in the plasma environment of Venus. In: Journal of Geophysical Research: Space Physics. 2019 ; Vol. 124, No. 5. pp. 3312-3330.

Bibtex

@article{38c8bb2ff13b4c2d82831db47fa09378,
title = "Proton temperature anisotropies in the plasma environment of Venus",
abstract = "Velocity distribution functions (VDFs) are a key to understanding the interplay between particles and waves in a plasma. Any deviation from an isotropic Maxwellian distribution may be unstable and result in wave generation. Using data from the ion mass spectrometer IMA (Ion Mass Analyzer) and the magnetometer (MAG) onboard Venus Express, we study proton distributions in the plasma environment of Venus. We focus on the temperature anisotropy, that is, the ratio between the proton temperature perpendicular (T ⊥) and parallel (T ‖) to the background magnetic field. We calculate average values of T ⊥ and T ‖ for different spatial areas around Venus. In addition we present spatial maps of the average of the two temperatures and of their average ratio. Our results show that the proton distributions in the solar wind are quite isotropic, while at the bow shock stronger perpendicular than parallel heating makes the downstream VDFs slightly anisotropic (T ⊥/T ‖ > 1) and possibly unstable to generation of proton cyclotron waves or mirror mode waves. Both wave modes have previously been observed in Venus's magnetosheath. The perpendicular heating is strongest in the near-subsolar magnetosheath (T ⊥/T ‖≈3/2), which is also where mirror mode waves are most frequently observed. We believe that the mirror mode waves observed here are indeed generated by the anisotropy. In the magnetotail we observe planetary protons with largely isotropic VDFs, originating from Venus's ionosphere. ",
author = "Alexander Bader and {Stenberg Wieser}, Gabriella and Mats Andr{\'e} and Martin Wieser and Yoshifumi Futaana and Moa Persson and Hans Nilsson and Tielong Zhang",
year = "2019",
month = may,
day = "1",
doi = "10.1029/2019JA026619",
language = "English",
volume = "124",
pages = "3312--3330",
journal = "Journal of Geophysical Research: Space Physics",
issn = "2169-9402",
publisher = "Blackwell Publishing Ltd",
number = "5",

}

RIS

TY - JOUR

T1 - Proton temperature anisotropies in the plasma environment of Venus

AU - Bader, Alexander

AU - Stenberg Wieser, Gabriella

AU - André, Mats

AU - Wieser, Martin

AU - Futaana, Yoshifumi

AU - Persson, Moa

AU - Nilsson, Hans

AU - Zhang, Tielong

PY - 2019/5/1

Y1 - 2019/5/1

N2 - Velocity distribution functions (VDFs) are a key to understanding the interplay between particles and waves in a plasma. Any deviation from an isotropic Maxwellian distribution may be unstable and result in wave generation. Using data from the ion mass spectrometer IMA (Ion Mass Analyzer) and the magnetometer (MAG) onboard Venus Express, we study proton distributions in the plasma environment of Venus. We focus on the temperature anisotropy, that is, the ratio between the proton temperature perpendicular (T ⊥) and parallel (T ‖) to the background magnetic field. We calculate average values of T ⊥ and T ‖ for different spatial areas around Venus. In addition we present spatial maps of the average of the two temperatures and of their average ratio. Our results show that the proton distributions in the solar wind are quite isotropic, while at the bow shock stronger perpendicular than parallel heating makes the downstream VDFs slightly anisotropic (T ⊥/T ‖ > 1) and possibly unstable to generation of proton cyclotron waves or mirror mode waves. Both wave modes have previously been observed in Venus's magnetosheath. The perpendicular heating is strongest in the near-subsolar magnetosheath (T ⊥/T ‖≈3/2), which is also where mirror mode waves are most frequently observed. We believe that the mirror mode waves observed here are indeed generated by the anisotropy. In the magnetotail we observe planetary protons with largely isotropic VDFs, originating from Venus's ionosphere.

AB - Velocity distribution functions (VDFs) are a key to understanding the interplay between particles and waves in a plasma. Any deviation from an isotropic Maxwellian distribution may be unstable and result in wave generation. Using data from the ion mass spectrometer IMA (Ion Mass Analyzer) and the magnetometer (MAG) onboard Venus Express, we study proton distributions in the plasma environment of Venus. We focus on the temperature anisotropy, that is, the ratio between the proton temperature perpendicular (T ⊥) and parallel (T ‖) to the background magnetic field. We calculate average values of T ⊥ and T ‖ for different spatial areas around Venus. In addition we present spatial maps of the average of the two temperatures and of their average ratio. Our results show that the proton distributions in the solar wind are quite isotropic, while at the bow shock stronger perpendicular than parallel heating makes the downstream VDFs slightly anisotropic (T ⊥/T ‖ > 1) and possibly unstable to generation of proton cyclotron waves or mirror mode waves. Both wave modes have previously been observed in Venus's magnetosheath. The perpendicular heating is strongest in the near-subsolar magnetosheath (T ⊥/T ‖≈3/2), which is also where mirror mode waves are most frequently observed. We believe that the mirror mode waves observed here are indeed generated by the anisotropy. In the magnetotail we observe planetary protons with largely isotropic VDFs, originating from Venus's ionosphere.

U2 - 10.1029/2019JA026619

DO - 10.1029/2019JA026619

M3 - Journal article

VL - 124

SP - 3312

EP - 3330

JO - Journal of Geophysical Research: Space Physics

JF - Journal of Geophysical Research: Space Physics

SN - 2169-9402

IS - 5

ER -