HR: 0800h
AN: SH51C-0284    [Abstracts]
TI: Anisotropic MHD/EMHD Turbulence in the Solar Wind and the Interstellar Medium
AU: Germaschewski, K
EM: kai.germaschewski@unh.edu
AF: Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Morse Hall, 39 College Road, Durham, NH 03824 United States
AU: * Ng, C
EM: chung-sang.ng@unh.edu
AF: Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Morse Hall, 39 College Road, Durham, NH 03824 United States
AU: Bhattacharjee, A
EM: amitava.bhattacharjee@unh.edu
AF: Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Morse Hall, 39 College Road, Durham, NH 03824 United States
AB: The solar wind and the interstellar medium is permeated by large-scale magnetic fields that render magnetohydrodynamic (MHD) turbulence anisotropic. In the weak-turbulence limit in which three-wave interactions dominate, analytical and high-resolution numerical results based on random scattering of shear-Alfv\'en waves propagating parallel to a large-scale magnetic field demonstrate rigorously an anisotropic energy spectrum that scales as $k_{\perp}^{-2}$, instead of the famous Iroshnikov-Kraichnan spectrum of $k^{-3/2}$ for the isotropic case. Even in the absence of a background magnetic field, when the energy spectrum is globally isotropic, anisotropy is found to develop with respect to the local magnetic field. Collisionless turbulence is studied in electron magnetohydrodynamics (EMHD), where whistler waves mediate the anisotropic energy cascade. Comparisons are made with MHD turbulence, especially with respect to global and local anisotropy in both inertial and dissipation ranges. The anisotropy of the energy cascade necessarily implies anisotropy of turbulent heating. Scalings of collisional and collisionless energy spectrum and dissipation rate will be discussed.
DE: 7863 Turbulence
DE: 2149 MHD waves and turbulence
DE: 2164 Solar wind plasma
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting