Beta‐Dependent Constraints on Ion Temperature Anisotropy in Jupiter’s Magnetosheath

Bandyopadhyay, R.; Begley, L. J.; Maruca, Bennett A.; McComas, D. J.; Szalay, J. R.; Allegrini, F.; Ebert, R. W.; Gershman, D. J.; Connerney, J. E. P.; Bolton, S. J.

doi:10.1029/2022gl098053

Cited by 4 publications

(1 citation statement)

References 52 publications

(103 reference statements)

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“…Similar observational evidence for the action of proton temperature anisotropy instabilities has also been found in Earth's magnetosheath (Anderson et al 1994;Phan et al 1994;Gary et al 1997;Tan et al 1998) and magnetosphere (Gary et al 1995;Anderson et al 1996). Most recently, the (β ∥p , R p ) relationship has been identified in Jupiter's magnetosheath (Bandyopadhyay et al 2022). Taken collectively, these studies strongly suggest that kinetic microinstabilities provide ubiquitous constraints on proton temperature anisotropy across space plasmas.…”

Section: Introductionsupporting

confidence: 67%

Alpha Particle Temperature Anisotropy in Earth’s Magnetosheath

DeWeese

Maruca

Qudsi

et al. 2022

ApJ

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In magnetized plasmas, temperature anisotropy manifests as distinct temperatures (T ⊥j , T ∥j ). Numerous prior studies have demonstrated that as plasma beta (β ∥j ) increases, the range of temperature anisotropy (R j = T ⊥j /T ∥j ) narrows. This limiting effect is conventionally taken as evidence that kinetic microinstabilities are active in the plasma, and has been previously observed for protons in the magnetosheath. This study is the first to use data from the Magnetic Multiscale Mission to investigate these instability-driven limits on alpha particle (ionized helium) anisotropy in Earth’s magnetosheath. The distribution of data over the (β ∥j , R j ) plane was plotted and shows the characteristic narrowing in the range of R j -values as β ∥j increases. The contours of the data distribution align well with the contours of the constant growth rate for the ion cyclotron, mirror, parallel firehose, and oblique firehose instabilities, which were calculated using linear Vlasov theory.

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Section: Introductionsupporting

confidence: 67%

Alpha Particle Temperature Anisotropy in Earth’s Magnetosheath

DeWeese

Maruca

Qudsi

et al. 2022

ApJ

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Turbulent Energy Conversion Associated With Kinetic Microinstabilities in Earth's Magnetosheath

Lewis,

Stawarz,

Matteini

et al. 2024

Geophysical Research Letters

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Plasma in Earth's magnetosheath rarely experiences interparticle collisions, so kinetic microinstabilities are thought to contribute to regulating the plasma thermodynamics. Instabilities excite waves and redistribute free energy in velocity space, reducing free energy in the velocity distribution function (VDF). Using 24 hr of data spread over 163 intervals of in situ magnetosheath observations by Magnetospheric Multiscale (MMS), we investigate signatures of energy conversion where the turbulent dynamics have locally distorted the VDFs into non‐Maxwellian shapes, in the context of electron and ion temperature anisotropy driven instabilities. We find enhanced average energy conversion into the particles along instability boundaries, suggesting turbulence plays a role in redistributing free energy. In so doing, we quantify the energetics associated with unstable conditions for both species. This work provides insight into the open question of how specific plasma processes couple into the turbulent dynamics, ultimately leading to energy dissipation and particle energization in collisionless plasmas.

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Applicability of Bernoulli's theorem to upstream and downstream of the bow shock

Ren,

Shen,

et al. 2024

Physics of Fluids

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In this research, the validity of Bernoulli's theorem for the solar wind crossing the Earth's bow shock has been investigated based on space explorations. Using solar wind plasma and interplanetary magnetic field data from the OMNI database, along with magnetosheath plasma and magnetic field data measured by the magnetospheric multiscale satellite in 2016 and 2018, 95 events were selected to study the Bernoulli invariant from the upstream to the downstream of Earth's bow shock (from the unshocked solar wind region to the shocked magnetosheath region). Statistical investigations show that the differences in the characteristic energy of plasmas between the solar wind region and the magnetosheath region are less than 5%, regardless of the upstream solar wind speed and the satellite's location in the magnetosheath. These results quantitatively support the generalization of Bernoulli's equation to the solar wind flowing through the bow shock, including the contribution of magnetic field energy.

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Beta‐Dependent Constraints on Ion Temperature Anisotropy in Jupiter’s Magnetosheath

Cited by 4 publications

References 52 publications

Alpha Particle Temperature Anisotropy in Earth’s Magnetosheath

Alpha Particle Temperature Anisotropy in Earth’s Magnetosheath

Turbulent Energy Conversion Associated With Kinetic Microinstabilities in Earth's Magnetosheath

Applicability of Bernoulli's theorem to upstream and downstream of the bow shock

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