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Coronal heating by the resonant absorption of Alfven waves - Importance of the global mode and scaling lawsNumerical simulations of the MHD equations for a fully compressible, low-beta, resistive plasma are used to study the resonance absorption process for the heating of coronal active region loops. Comparisons with more approximate analytic models show that the major predictions of the analytic theories are, to a large extent, confirmed by the numerical computations. The simulations demonstrate that the dissipation occurs primarily in a thin resonance layer. Some of the analytically predicted features verified by the simulations are (a) the position of the resonance layer within the initial inhomogeneity; (b) the importance of the global mode for a large range of loop densities; (c) the dependence of the resonance layer thickness and the steady-state heating rate on the dissipation coefficient; and (d) the time required for the resonance layer to form. In contrast with some previous analytic and simulation results, the time for the loop to reach a steady state is found to be the phase-mixing time rather than a dissipation time. This disagreement is shown to result from neglect of the existence of the global mode in some of the earlier analyses. The resonant absorption process is also shown to behave similar to a classical driven harmonic oscillator.
Document ID
19930072484
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Steinolfson, Richard S. (Southwest Research Inst. San Antonio, TX, United States)
Davila, Joseph M. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 16, 2013
Publication Date
September 20, 1993
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 415
Issue: 1
ISSN: 0004-637X
Subject Category
SOLAR PHYSICS
Funding Number(s)
PROJECT: RTOP 370-04-01
CONTRACT_GRANT: NAGW-2087
CONTRACT_GRANT: NSF ATM-90-15705
Distribution Limits
Public
Copyright
Other