TOWARD A THEORY OF ASTROPHYSICAL PLASMA TURBULENCE AT SUBPROTON SCALES

Journal Article · Fri Nov 01 00:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/777/1/41· OSTI ID:22270659

Boldyrev, Stanislav; Horaites, Konstantinos; Xia, Qian ^[1]; Perez, Jean Carlos ^[2]

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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)

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.

• OSTI ID: 22270659
• Journal Information: Astrophysical Journal, Vol. 777, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

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