Dynamo action in dissipative, forced, rotating MHD turbulence

Journal Article · Wed Jun 15 04:00:00 EDT 2016 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4954817· OSTI ID:22598936

Shebalin, John V. ^[1]

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1. Astromaterials Research Office, NASA Johnson Space Center, Houston, Texas 77058-3696 (United States)

Magnetohydrodynamic (MHD) turbulence is an inherent feature of large-scale, energetic astrophysical and geophysical magnetofluids. In general, these are rotating and are energized through buoyancy and shear, while viscosity and resistivity provide a means of dissipation of kinetic and magnetic energy. Studies of unforced, rotating, ideal (i.e., non-dissipative) MHD turbulence have produced interesting results, but it is important to determine how these results are affected by dissipation and forcing. Here, we extend our previous work and examine dissipative, forced, and rotating MHD turbulence. Incompressibility is assumed, and finite Fourier series represent turbulent velocity and magnetic field on a 64{sup 3} grid. Forcing occurs at an intermediate wave number by a method that keeps total energy relatively constant and allows for injection of kinetic and magnetic helicity. We find that 3-D energy spectra are asymmetric when forcing is present. We also find that dynamo action occurs when forcing has either kinetic or magnetic helicity, with magnetic helicity injection being more important. In forced, dissipative MHD turbulence, the dynamo manifests itself as a large-scale coherent structure that is similar to that seen in the ideal case. These results imply that MHD turbulence, per se, may play a fundamental role in the creation and maintenance of large-scale (i.e., dipolar) stellar and planetary magnetic fields.

• OSTI ID: 22598936
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 6 Vol. 23; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
79 ASTRONOMY AND ASTROPHYSICS
ASTROPHYSICS
ASYMMETRY
ENERGY SPECTRA
GRIDS
HELICITY
INJECTION
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
THREE-DIMENSIONAL CALCULATIONS
TURBULENCE
VELOCITY
VISCOSITY