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Title: Nonlinear mean field electrodynamics of turbulent dynamos

Abstract

Mean field electrodynamics of turbulent dynamos taking into account Lorentz forces of the generated magnetic fields is derived and studied. Small-scale magnetic fields that are much stronger than the mean field {ital B}{sub 0} modify the fluid turbulence in such a way as to suppress the {alpha} effect: {alpha}={alpha}{sub 0}(1+{ital R}){sup {minus}1}, where {alpha}{sub 0} is the kinematic value, and the reduction factor is proportional to the magnetic Reynolds number {ital R}{sub {ital m}}, {ital R}={ital R}{sub {ital mB{sup 2}{sub 0}}}/(4{pi}{rho}{ital v}{sup 2}), and {ital v} is the characteristic turbulent velocity. In two dimensions the analog is turbulent magnetic diffusivity suppression. Suppression becomes noticeable at very low values of the mean magnetic field, {ital B}{sup 2}{sub 0}{approximately}{rho}{ital v}{sup 2}/{ital R}{sub {ital m}}. The modification of turbulence by the small-scale magnetic fields is discussed. {copyright} {ital 1996 American Institute of Physics.}

Authors:
;  [1]
  1. Department of Physics, University of California at San Diego, La Jolla, California 92093-0319 (United States)
Publication Date:
Research Org.:
University of California
OSTI Identifier:
280171
DOE Contract Number:  
FG03-88ER53275
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 3; Journal Issue: 5; Other Information: PBD: May 1996
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION; EARTH MAGNETOSPHERE; ELECTRODYNAMICS; LORENTZ FORCE; TURBULENCE; MAGNETIC REYNOLDS NUMBER; MAGNETOHYDRODYNAMICS; ALFVEN WAVES; PLANETARY MAGNETOSPHERES; GEOMAGNETIC FIELD; MEAN-FIELD THEORY; DYNAMO THEORY

Citation Formats

Gruzinov, A.V., and Diamond, P.H. Nonlinear mean field electrodynamics of turbulent dynamos. United States: N. p., 1996. Web. doi:10.1063/1.871981.
Gruzinov, A.V., & Diamond, P.H. Nonlinear mean field electrodynamics of turbulent dynamos. United States. doi:10.1063/1.871981.
Gruzinov, A.V., and Diamond, P.H. Wed . "Nonlinear mean field electrodynamics of turbulent dynamos". United States. doi:10.1063/1.871981.
@article{osti_280171,
title = {Nonlinear mean field electrodynamics of turbulent dynamos},
author = {Gruzinov, A.V. and Diamond, P.H.},
abstractNote = {Mean field electrodynamics of turbulent dynamos taking into account Lorentz forces of the generated magnetic fields is derived and studied. Small-scale magnetic fields that are much stronger than the mean field {ital B}{sub 0} modify the fluid turbulence in such a way as to suppress the {alpha} effect: {alpha}={alpha}{sub 0}(1+{ital R}){sup {minus}1}, where {alpha}{sub 0} is the kinematic value, and the reduction factor is proportional to the magnetic Reynolds number {ital R}{sub {ital m}}, {ital R}={ital R}{sub {ital mB{sup 2}{sub 0}}}/(4{pi}{rho}{ital v}{sup 2}), and {ital v} is the characteristic turbulent velocity. In two dimensions the analog is turbulent magnetic diffusivity suppression. Suppression becomes noticeable at very low values of the mean magnetic field, {ital B}{sup 2}{sub 0}{approximately}{rho}{ital v}{sup 2}/{ital R}{sub {ital m}}. The modification of turbulence by the small-scale magnetic fields is discussed. {copyright} {ital 1996 American Institute of Physics.}},
doi = {10.1063/1.871981},
journal = {Physics of Plasmas},
number = 5,
volume = 3,
place = {United States},
year = {1996},
month = {5}
}