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Please use this identifier to cite or link to this item: http://hdl.handle.net/2014/40968

Title: Coronal heating, weak MHD turbulence, and scaling laws
Authors: Rappazzo, A. F.
Velli, M.
Einaudi, G.
Dahlburg, R. B.
Keywords: corona
magnetic fields
Sun
Issue Date: 1-Mar-2007
Publisher: American Astronomical Society
Citation: The Astrophysical Journal Letters, 657: L47–L51, 2007 March 1
Abstract: Long-time high-resolution simulations of the dynamics of a coronal loop in Cartesian geometry are carried out, within the framework of reduced magnetohydrodynamics (RMHD), to understand coronal heating driven by the motion of field lines anchored in the photosphere. We unambiguously identify MHD anisotropic turbulence as the physical mechanism responsible for the transport of energy from the large scales, where energy is injected by photospheric motions, to the small scales, where it is dissipated. As the loop parameters vary, different regimes of turbulence develop: strong turbulence is found for weak axial magnetic fields and long loops, leading to Kolmogorovlike spectra in the perpendicular direction, while weaker and weaker regimes (steeper spectral slopes of total energy) are found for strong axial magnetic fields and short loops. As a consequence we predict that the scaling of the heating rate with axial magnetic field intensity B, which depends on the spectral index of total energy for given loop parameters, must vary from B3/2 for weak fields to B2 for strong fields at a given aspect ratio. The predicted heating rate is within the lower range of observed active region and quiet-Sun coronal energy losses.
URI: http://hdl.handle.net/2014/40968
Appears in Collections:JPL TRS 1992+

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