Predictions of finite Larmor radius reduced magnetohydrodynamics for Rayleigh-Taylor unstable plasmas

Finite Larmor radius magnetohydrodynamics (FLR MHD), being valid when the ion Larmor radius is of the order of the characteristic length scale, predicts a Rayleigh-Taylor instability in an inhomogeneous plasma with unfavorable field line curvature. It is shown that the FLR MHD equations can be reduced to a set of two scalar field equations for the pressure and the electrostatic potential in the flute approximation and the large aspect ratio limit. Using a Galerkin approximation with a few dominating modes, the simple model reproduces previous numerical simulations based on the full FLR MHD equations. (C) 1998 American Institute of Physics. [S1070-664X(98)04207-4]