STABILITY OF MAGNETIC VORTICES WITH FLOW IN ANISOTROPIC MAGNETOHYDRODYNAMICS

The eigenvalue problem for linear stability of concentric radial profi les of current and vorticity in reduced forms of three-dimensional mag netohydrodynamics is solved numerically. Arbitrary relative amplitudes of the velocity and magnetic fields are considered. Vorticity profile s are unstable if nonmonotonic, but are stabilized by a poloidal magne tic field when the on-axis vertical current is at least as large as th e on-axis vertical vorticity. Nonmonotonic current profiles are less e fficient at stabilization. When the neutral modes have vertical struct ure, an added poloidal magnetic field does not stabilize the mode unle ss the vertical held is also moderately strong. Current profiles in wh ich the integrated current changes sign, although spectrally stable, a re shown to be nonlinearly unstable via both numerical solution and Ly apunov techniques. (C) 1996 American Institute of Physics.