Quantifying Wave-Particle Interactions in Collisionless Plasmas: Theory and Its Application to the Alfven-mode Wave

Article Astronomy & Astrophysics

Electromagnetic Proton Beam Instabilities in the Inner Heliosphere: Energy Transfer Rate, Radial Distribution, and Effective Excitation

Wen Liu et al.

Summary: This study explores proton beam instability in the solar wind, revealing that proton beams can efficiently drive various instabilities and proposing an effective growth length for estimating the excitation of instability.

ASTROPHYSICAL JOURNAL (2021)

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Article Astronomy & Astrophysics

Determining Threshold Instrumental Resolutions for Resolving the Velocity-Space Signature of Ion Landau Damping

J. L. Verniero et al.

Summary: This study demonstrates the use of kinetic numerical simulations of plasma turbulence to create synthetic spacecraft data, which can then be used to determine instrumental requirements to achieve scientific goals related to plasma heating and particle acceleration in turbulent heliospheric plasmas. The research provides an important scientific methodology for identifying specific particle energization mechanisms.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS (2021)

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Article Astronomy & Astrophysics

On Stochastic Heating and Its Phase-space Signatures in Low-beta Kinetic Turbulence

S. S. Cerri et al.

Summary: The study revisited the theory of stochastic ion heating in kinetic turbulence of the low-beta solar wind, emphasizing the role of Hall and thermoelectric effects in electric-field fluctuations. Analyzing phase-space signatures using hybrid-kinetic simulations, it was found that energization of ions perpendicular to the magnetic field dominates, with approximately 75% and 40% of turbulent energy going into ion heating at beta(i) = 0.3 and beta(i) ≈ 0.1 respectively. The findings are consistent with Landau-resonant collisionless damping and a combination of ion-cyclotron and stochastic heating, demonstrating good agreement with the scale-dependent theory.

ASTROPHYSICAL JOURNAL (2021)

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Article Astronomy & Astrophysics

Anisotropy of Solar Wind Turbulence in the Inner Heliosphere at Kinetic Scales: PSP Observations

Die Duan et al.

Summary: The study presents observations of anisotropy at kinetic scales in the slow, Alfvenic solar wind in the inner heliosphere using measurements from the Parker Solar Probe. It finds evidence of anisotropy with k(perpendicular to) >> k(parallel to) in both transition and kinetic ranges, indicating a power anisotropy P-perpendicular to/P-parallel to > 10 in the kinetic range. Spectral index and wavevector anisotropy exhibit specific variations in the transition and kinetic ranges.

ASTROPHYSICAL JOURNAL LETTERS (2021)

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Article Astronomy & Astrophysics

Electron Heat Flux Instabilities in the Inner Heliosphere: Radial Distribution and Implication on the Evolution of the Electron Velocity Distribution Function

Heyu Sun et al.

Summary: This study investigates the electron heat flux instability in the inner heliosphere, finding that both electron acoustic waves and oblique whistler waves are unstable under conditions of large relative drift speed. It is proposed that electron heat flux can effectively drive oblique whistler waves in anisotropic electron velocity distribution. Additionally, lower-hybrid waves are observed to be stronger than oblique Alfven waves in the solar atmosphere.

ASTROPHYSICAL JOURNAL LETTERS (2021)

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Article Physics, Fluids & Plasmas