Nonlinear resonant absorption of fast magnetoacoustic waves due to coupling into slow continua in the solar atmosphere

¹ Space & Atmosphere Research Center, Department of Applied Mathematics, University of Sheffield, S3 7RH, Sheffield, UK
² Center for Plasma-Astrophysics, K.U. Leuven, Celestijnenlaan 200B, 3001 Heverlee, Belgium

Corresponding author: R. Erdélyi, Robertus@sheffield.ac.uk

Received: 28 July 2000
Accepted: 12 January 2001

Abstract

Nonlinear resonant absorption of fast magnetoacoustic (FMA) waves in inhomogeneous weakly dissipative, isotropic and anisotropic plasmas in static and steady equilibria is studied. Both isotropic and anisotropic plasmas are considered and for the background equilibrium state 1D planar static and steady models are used. The equilibrium configuration consists of three layers, where an inhomogeneous magnetised plasma slab is surrounded by two homogeneous magnetised semi-infinite plasma regions. The propagating FMA waves are partly absorbed due to coupling to local nonlinear slow magnetohydrodynamic (MHD) waves in the inhomogeneous layer, and are partly reflected. The coefficient of wave energy resonant absorption is derived using two simplifying assumptions (i) weak nonlinearity and (ii) the thickness of the inhomogeneous layer is small compared to the wavelength of the waves, i.e. the so-called long-wavelength approximation is used.