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Energy balance and cascade in MHD turbulence in the solar corona

Published online by Cambridge University Press:  01 September 2008

Francesco Malara ,
Giuseppina Nigro  and
Pierluigi Veltri
Francesco Malara
Affiliation:
Dipartimento di Fisica, Università della Calabria, via P. Bucci, I-87036, Rende (CS), Italy email: malara@fis.unical.it, nigro@fis.unical.it, veltri@fis.unical.it
Giuseppina Nigro
Affiliation:
Dipartimento di Fisica, Università della Calabria, via P. Bucci, I-87036, Rende (CS), Italy email: malara@fis.unical.it, nigro@fis.unical.it, veltri@fis.unical.it
Pierluigi Veltri
Affiliation:
Dipartimento di Fisica, Università della Calabria, via P. Bucci, I-87036, Rende (CS), Italy email: malara@fis.unical.it, nigro@fis.unical.it, veltri@fis.unical.it
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Abstract

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The dynamics of fluctuations in a closed coronal structure is regulated both by resonance with motions at bases that stores energy in the structure in form of discrete eigenmodes, and by nonlinear couplings that move this energy along the spectrum to smaller scales. The energy balance is evaluated both analytically and, numerically, using an hybrid shell model. The input energy flux is independent of nonlinear effects and is determined by slow (DC) perturbations. Coherent eigenmode couplings determine the nonlinear energy flux and, consequently, the level of fluctuations at large scales. The estimated velocity fluctuation level is in agreement with measures of nonthermal velocity in corona. The resulting turbulence spectrum contains both a pre-inertial range where coherent interactions dominate, and a standard inertial range where the turbulence behaves as in an unbounded system.

Keywords

Sun: corona(magnetohydrodynamics:) MHDturbulencewaves
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 4 , Symposium S257: Universal Heliophysical Processes , September 2008 , pp. 543 - 553
Copyright
Copyright © International Astronomical Union 2009

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