Numerical simulation of coronal heating by resonant absorption of Alfvén waves
Abstract
The heating of coronal loops by resonant absorption of Alfvén waves is studied in compressible, resistive magnetohydrodynamics. The loops are approximated by straight cylindrical, axisymmetric plasma columns and the incident waves which excite the coronal loops are modelled by a periodic external driver. The stationary state of this system is determined with a numerical code based on the finite element method. Since the power spectrum of the incident waves is not well known, the intrinsic dissipation is computed. The intrinsic dissipation spectrum is independent of the external driver and reflects the intrinsic ability of the coronal loops to extract energy from incident waves by the mechanism of resonant absorption. The numerical results show that resonant absorption is very efficient for typical parameter values occurring in the loops of the solar corona. A considerable part of the energy supplied by the external driver, is actually dissipated Ohmically and converted into heat. The heating of the plasma is localized in a narrow resonant layer with a width proportional to η ^{1/3}. The energy dissipation rate is almost independent of the resistivity for the relevant values of this parameter. The efficiency of the heating mechanism and the localization of the heating strongly depend on the frequency of the external driver. Resonant absorption is extremely efficient when the plasma is excited with a frequency near the frequency of a socalled ‘collective mode’.
 Publication:

Solar Physics
 Pub Date:
 March 1989
 DOI:
 10.1007/BF00150014
 Bibcode:
 1989SoPh..123...83P
 Keywords:

 Computerized Simulation;
 Coronal Loops;
 Magnetohydrodynamic Waves;
 Magnetohydrodynamics;
 Solar Corona;
 Absorption;
 Acoustic Propagation;
 Energy Dissipation;
 Finite Element Method;
 Plasma Heating;
 Solar Heating;
 Solar Physics