NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Shell Models of RMHD Turbulence and the Heating of Solar Coronal LoopsA simplified nonlinear numerical model for the development of incompressible magnetohydrodynamics in the presence of a strong magnetic field B|| and stratification, nicknamed 'Shell-Atm,' is presented. In planes orthogonal to the mean field, the nonlinear incompressible dynamics is replaced by two-dimensional shell models for the complex variables u and b, allowing one to reach large Reynolds numbers while at the same time carrying out sufficiently long integrations to obtain good statistics at moderate computational cost. The shell models of different planes are coupled by Alfve'n waves propagating along B||. The model may be applied to open or closed magnetic field configurations where the axial field dominates and the plasma pressure is low; here we apply it to the specific case of a magnetic loop of the solar corona heated by means of turbulence driven by photospheric motions, and we use statistics for its analysis. The Alfven waves interact nonlinearly and form turbulent spectra in the directions perpendicular and, through propagation, also parallel to the mean field. A heating function is obtained and shown to be intermittent; the average heating is consistent with values required for sustaining a hot corona and is proportional to the aspect ratio of the loop to the -1.5 power, and haracteristic properties of heating events are distributed as power laws. Crosscorrelations show a delay of dissipation compared with energy content.
Document ID
20080032363
Acquisition Source
Jet Propulsion Laboratory
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Buchlin, E.
(Florence Univ. Italy)
Velli, Marco C.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 24, 2013
Publication Date
June 10, 2007
Publication Information
Publication: The Astrophysical Journal
Publisher: American Astronomical Society
Volume: 662
Subject Category
Solar Physics
Funding Number(s)
CONTRACT_GRANT: SHP04-0000-0150
CONTRACT_GRANT: HPRN-CT-2001-00310
Distribution Limits
Public
Copyright
Other
Keywords
corona
turbulence
flares
magnetohydrodynamics

Available Downloads

There are no available downloads for this record.
No Preview Available