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Title: TOWARD A THEORY OF ASTROPHYSICAL PLASMA TURBULENCE AT SUBPROTON SCALES

Abstract

We present an analytical study of subproton electromagnetic fluctuations in a collisionless plasma with a plasma beta of the order of unity. In the linear limit, a rigorous derivation from the kinetic equation is conducted focusing on the role and physical properties of kinetic-Alfvén and whistler waves. Then, nonlinear fluid-like equations for kinetic-Alfvén waves and whistler modes are derived, with special emphasis on the similarities and differences in the corresponding plasma dynamics. The kinetic-Alfvén modes exist in the lower-frequency region of phase space, ω << k v{sub Ti} , where they are described by the kinetic-Alfvén system. These modes exist both below and above the ion-cyclotron frequency. The whistler modes, which are qualitatively different from the kinetic-Alfvén modes, occupy a different region of phase space, k v{sub Ti} << ω << k{sub z}v{sub Te} , and they are described by the electron magnetohydrodynamics (MHD) system or the reduced electron MHD system if the propagation is oblique. Here, k{sub z} and k are the wavenumbers along and transverse to the background magnetic field, respectively, and v{sub Ti} and v{sub Te} are the ion and electron thermal velocities, respectively. The models of subproton plasma turbulence are discussed and the results of numericalmore » simulations are presented. We also point out possible implications for solar-wind observations.« less

Authors:
; ;  [1];  [2]
  1. Department of Physics, University of Wisconsin-Madison, Madison, WI 53706 (United States)
  2. Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States)
Publication Date:
OSTI Identifier:
22270659
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 777; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALFVEN WAVES; ASTROPHYSICS; BETA RATIO; COLLISIONLESS PLASMA; COMPUTERIZED SIMULATION; CYCLOTRON FREQUENCY; ELECTRONS; FLUCTUATIONS; KINETIC EQUATIONS; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; NONLINEAR PROBLEMS; PHASE SPACE; PLASMA FLUID EQUATIONS; SOLAR WIND; TURBULENCE; WHISTLER INSTABILITY

Citation Formats

Boldyrev, Stanislav, Horaites, Konstantinos, Xia, Qian, and Perez, Jean Carlos. TOWARD A THEORY OF ASTROPHYSICAL PLASMA TURBULENCE AT SUBPROTON SCALES. United States: N. p., 2013. Web. doi:10.1088/0004-637X/777/1/41.
Boldyrev, Stanislav, Horaites, Konstantinos, Xia, Qian, & Perez, Jean Carlos. TOWARD A THEORY OF ASTROPHYSICAL PLASMA TURBULENCE AT SUBPROTON SCALES. United States. https://doi.org/10.1088/0004-637X/777/1/41
Boldyrev, Stanislav, Horaites, Konstantinos, Xia, Qian, and Perez, Jean Carlos. Fri . "TOWARD A THEORY OF ASTROPHYSICAL PLASMA TURBULENCE AT SUBPROTON SCALES". United States. https://doi.org/10.1088/0004-637X/777/1/41.
@article{osti_22270659,
title = {TOWARD A THEORY OF ASTROPHYSICAL PLASMA TURBULENCE AT SUBPROTON SCALES},
author = {Boldyrev, Stanislav and Horaites, Konstantinos and Xia, Qian and Perez, Jean Carlos},
abstractNote = {We present an analytical study of subproton electromagnetic fluctuations in a collisionless plasma with a plasma beta of the order of unity. In the linear limit, a rigorous derivation from the kinetic equation is conducted focusing on the role and physical properties of kinetic-Alfvén and whistler waves. Then, nonlinear fluid-like equations for kinetic-Alfvén waves and whistler modes are derived, with special emphasis on the similarities and differences in the corresponding plasma dynamics. The kinetic-Alfvén modes exist in the lower-frequency region of phase space, ω << k v{sub Ti} , where they are described by the kinetic-Alfvén system. These modes exist both below and above the ion-cyclotron frequency. The whistler modes, which are qualitatively different from the kinetic-Alfvén modes, occupy a different region of phase space, k v{sub Ti} << ω << k{sub z}v{sub Te} , and they are described by the electron magnetohydrodynamics (MHD) system or the reduced electron MHD system if the propagation is oblique. Here, k{sub z} and k are the wavenumbers along and transverse to the background magnetic field, respectively, and v{sub Ti} and v{sub Te} are the ion and electron thermal velocities, respectively. The models of subproton plasma turbulence are discussed and the results of numerical simulations are presented. We also point out possible implications for solar-wind observations.},
doi = {10.1088/0004-637X/777/1/41},
url = {https://www.osti.gov/biblio/22270659}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 777,
place = {United States},
year = {2013},
month = {11}
}