Energy spectrum, dissipation, and spatial structures in reduced Hall magnetohydrodynamic

We analyze the effect of the Hall term in the magnetohydrodynamic turbulence under a strong externally supported magnetic field, seeing how this changes the energy cascade, the characteristic scales of the flow, and the dynamics of global magnitudes, with particular interest in the dissipation. Nume...

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Bibliographic Details
Published in:Physics of plasmas 2012-05, Vol.19 (5), p.052305-052305-6
Main Authors: Martin, L. N., Dmitruk, P., Gomez, D. O.
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
COMPUTERIZED SIMULATION
ENERGY LOSSES
ENERGY SPECTRA
ENERGY TRANSFER
HALL EFFECT
IONS
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
NUMERICAL ANALYSIS
THREE-DIMENSIONAL CALCULATIONS
TURBULENCE
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Summary:We analyze the effect of the Hall term in the magnetohydrodynamic turbulence under a strong externally supported magnetic field, seeing how this changes the energy cascade, the characteristic scales of the flow, and the dynamics of global magnitudes, with particular interest in the dissipation. Numerical simulations of freely evolving three-dimensional reduced magnetohydrodynamics are performed, for different values of the Hall parameter (the ratio of the ion skin depth to the macroscopic scale of the turbulence) controlling the impact of the Hall term. The Hall effect modifies the transfer of energy across scales, slowing down the transfer of energy from the large scales up to the Hall scale (ion skin depth) and carrying faster the energy from the Hall scale to smaller scales. The final outcome is an effective shift of the dissipation scale to larger scales but also a development of smaller scales. Current sheets (fundamental structures for energy dissipation) are affected in two ways by increasing the Hall effect, with a widening but at the same time generating an internal structure within them. In the case where the Hall term is sufficiently intense, the current sheet is fully delocalized. The effect appears to reduce impulsive effects in the flow, making it less intermittent.
ISSN:1070-664X
1089-7674
DOI:10.1063/1.4717728