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Title: 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 Alfvénic 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.

Authors:
 [1]
  1. Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242 (United States)
Publication Date:
OSTI Identifier:
22408225
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 3; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ANISOTROPY; COLLISIONLESS PLASMA; DISPERSION RELATIONS; EIGENFUNCTIONS; FLUCTUATIONS; MATHEMATICAL SPACE; NONLINEAR PROBLEMS; NUMERICAL SOLUTION; PROTON TEMPERATURE; SOLAR WIND; TURBULENCE; VELOCITY

Citation Formats

Klein, K. G., E-mail: kristopher.klein@unh.edu, and Howes, G. G. Predicted impacts of proton temperature anisotropy on solar wind turbulence. United States: N. p., 2015. Web. doi:10.1063/1.4914933.
Klein, K. G., E-mail: kristopher.klein@unh.edu, & Howes, G. G. Predicted impacts of proton temperature anisotropy on solar wind turbulence. United States. https://doi.org/10.1063/1.4914933
Klein, K. G., E-mail: kristopher.klein@unh.edu, and Howes, G. G. 2015. "Predicted impacts of proton temperature anisotropy on solar wind turbulence". United States. https://doi.org/10.1063/1.4914933.
@article{osti_22408225,
title = {Predicted impacts of proton temperature anisotropy on solar wind turbulence},
author = {Klein, K. G., E-mail: kristopher.klein@unh.edu and Howes, G. G.},
abstractNote = {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 Alfvénic 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.},
doi = {10.1063/1.4914933},
url = {https://www.osti.gov/biblio/22408225}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 3,
volume = 22,
place = {United States},
year = {Sun Mar 15 00:00:00 EDT 2015},
month = {Sun Mar 15 00:00:00 EDT 2015}
}