Predicted Impacts of Proton Temperature Anisotropy on Solar Wind Turbulence

Abstract

Particle velocity distributions measured in the weakly collisional solar wind are frequently found to be non-Maxwellian, but how these non-Maxwellian distributions impact the physics of plasma turbulence in the solar wind remains unanswered. Using numerical solutions of the linear dispersion relation for a collisionless plasma with a bi-Maxwellian proton velocity distribution, we present a unified framework for the four proton temperature anisotropy instabilities, identifying the associated stable eigenmodes, highlighting the unstable region of wavevector space, and presenting the properties of the growing eigenfunctions. Based on physical intuition gained from this framework, we address how the proton temperature anisotropy impacts the nonlinear dynamics of the \Alfvenic fluctuations underlying the dominant cascade of energy from large to small scales and how the fluctuations driven by proton temperature anisotropy instabilities interact nonlinearly with each other and with the fluctuations of the large-scale cascade. We find that the nonlinear dynamics of the large-scale cascade is insensitive to the proton temperature anisotropy, and that the instability-driven fluctuations are unlikely to cause significant nonlinear evolution of either the instability-driven fluctuations or the turbulent fluctuations of the large-scale cascade.

27 pages, 9 figures, Published in Physics of Plasmas

References in corpus (5)

• Anisotropic scaling of magnetohydrodynamic turbulence
• Whistler mode waves and the electron heat flux in the solar wind: Cluster observations
• Validity of the Taylor Hypothesis for Linear Kinetic Waves in the Weakly Collisional Solar Wind
• Physical Interpretation of the Angle Dependent Magnetic Helicity Spectrum in the Solar Wind: The Nature of Turbulent Fluctuations near the Proton Gyroradius Scale
• The Quasilinear Premise for the Modeling of Plasma Turbulence

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• Observations of heating along intermittent structures in the inner heliosphere from PSP data
• General dispersion properties of magnetized plasmas with drifting bi-Kappa distributions. DIS-K: DIspersion Solver for Kappa plasmas
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• Linear Stability in the Inner Heliosphere: Helios Reëvaluated
• Wave-particle energy transfer directly observed in an ion cyclotron wave
• Ion-Driven Instabilities in the Inner Heliosphere I: Statistical Trends
• The Velocity-Space Signature of Transit-Time Damping
• Ion-Driven Instabilities in the Inner Heliosphere II: Classification and Multi-Dimensional Mapping
• Isolation and Phase-Space Energization Analysis of the Instabilities in Collisionless Shocks
• Modeling hot, anisotropic ion beams in the solar wind motivated by the Parker Solar Probe observations near perihelia
• Evolution of an Alfvén Wave-Driven Proton Beam in the Expanding Solar Wind
• Non-Maxwellian rate coefficients for electron and ion collisions in Rydberg plasmas: implications for excitation and ionization
• AHKASH: a new Hybrid particle-in-cell code for simulations of astrophysical collisionless plasma
• Unveiling the Velocity-Space Signature of Ion Cyclotron Damping Using Liouville Mapping
• Observing Particle Energization above the Nyquist Frequency: An Application of the Field-Particle Correlation Technique