HR: 13:40h
AN: NG33A-01    [Abstracts]
TI: Measurement of Energy Cascade Rate and Dissipation Rate in the Solar Wind: Theoretical Approach Based on Third Order Moments in Axisymmetric MHD Turbulence
AU: Forman, M A
EM: maforman@notes.cc.sunysb.edu
AF: Department of Physics and Astronomy, State University of New York, Stony Brook, NY 11794, United States
AU: * Podesta, J J
EM: j.podesta@unh.edu
AF: Space Science Center, University of New Hampshire, Durham, NH 03824, United States
AU: Smith, C W
EM: Charles.Smith@unh.edu
AF: Space Science Center, University of New Hampshire, Durham, NH 03824, United States
AB: The energy dissipation rate of solar wind turbulence has recently been measured by a technique based on Politano and Pouquet's law for incompressible MHD turbulence. Politano and Pouquet's law is valid for isotropic turbulence but not for anisotropic turbulence in magnetized plasmas such as the solar wind. A generalization of Politano and Pouquet's law to anisotropic incompressible magnetohydrodynamic (MHD) turbulence is used to develop a theory for the measurement of the turbulent cascade rates of energy and cross-helicity assuming that the turbulence is statistically axisymmetric about the mean magnetic field. The theory is based on measurements of third order moments of the velocity and magnetic field fluctuations at two points separated by a distance r (two point measurements). In the inertial range the third order moments are proportional to the separation r and to the energy cascade rate \varepsilon. For axisymmetric MHD turbulence the third order moments are also functions of the angle θ between the displacement vector \bm r and the mean magnetic field \bm B₀ and the dependence on this angle must be measured to determine the cascade rates from experimental data. The theory provides a relationship between the cascade rates and the angular dependence of the third order moments.
DE: 2149 MHD waves and turbulence (2752, 6050, 7836)
DE: 2159 Plasma waves and turbulence
DE: 4490 Turbulence (3379, 4568, 7863)
DE: 7839 Nonlinear phenomena (4400, 6944)
DE: 7863 Turbulence (4490)
SC: Nonlinear Geophysics [NG]
MN: 2007 Fall Meeting