ALFVEN RESONANCE EXCITATION AND FAST-WAVE PROPAGATION IN MAGNETOSPHERIC WAVE-GUIDES

Magnetic pulsations are a robust feature of the Earth's magnetosphere. It has been suggested recently that the magnetosphere is sometimes be tter modeled as a waveguide rather than a cavity. This paper presents numerical simulations of linear magnetohydrodynamic (MHD) waves in an inhomogeneous, low-beta waveguide. Several features predicted by recen t theoretical studies are confirmed in our simulations, notably that A lfven resonances are driven at frequencies corresponding to the natura l frequency of the fast waveguide modes with V(g) almost-equal-to 0 (k (y) almost-equal-to 0).