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Magnetic helicity in magnetohydrodynamic turbulence with a mean magnetic field

Abstract
A computational investigation of magnetic helicity of the fluctuatingmagnetic fieldHm in ideal and freely decaying three‐dimensional (3‐D) magnetohydrodynamics (MHD) in the presence of a uniform mean magnetic field is performed. It is shown that for ideal 3‐D MHDHm, which is a rugged invariant in the absence of a mean magnetic field [Frisch et al., J. Fluid Mech. 77, 796 (1975)], decays from its initial value and proceeds to oscillate about zero. The decay of Hm is shown to result from the presence of a new ‘‘generalized’’ helicity invariant, which includes contributions from the uniform magnetic field. The loss of invariance of Hm will diminish the effects of inverse transfer of Hm on freely decaying turbulence. This is demonstrated in a discussion of the selective decay relaxation process.
Type
Journal Article
Type of thesis
Series
Citation
Stribling, T., Matthaeus, W. H., & Oughton, S. (1995). Magnetic helicity in magnetohydrodynamic turbulence with a mean magnetic field. Physics of Plasmas, 2(5), 1437.
Date
1995
Publisher
American Institute of Physics
Degree
Supervisors
Rights
© 1995 American Institute of Physics