Fast magnetoacoustic waves in a randomly structured solar corona

The propagation of fast magnetoacoustic waves in a randomly structured sola r corona is considered in the linear and cold plasma limits. The random fie ld is assumed to be static and associated with plasma density inhomogeneiti es only. A transcendental dispersion relation for the fast magnetoacoustic waves which propagate perpendicularly to the magnetic field is derived in t he weak random field approximation. It is shown analytically that the fast magnetosonic waves experience acceleration, attenuation, and dispersion in comparison to the homogeneous case. These analytical findings are essential ly confirmed by numerical simulations for a wide-spectrum pulse, except tha t the waves were found decelerated. It is concluded that the coronal Moreto n waves can be applied to MHD seismology of the solar corona.