THE SHEAR ALFVEN CONTINUUM IN AN ASYMMETRIC MAGNETOHYDRODYNAMIC EQUILIBRIUM

The Alfven continuum of an asymmetric plasma configuration that is an exact solution of the equilibrium equations of ideal magnetohydrodynam ics is treated. The equilibrium is parallel to an infinite straight ma gnetic axis about which the magnetic lines of force form closed magnet ic surfaces. Properties of the governing continuum equation for small plasma beta are explored, and the associated spectrum is determined. T he continuum has a localized component characterized by modes that dec ay to zero along magnetic field lines, and a non-localized component c haracterized by modes that approach non-zero constants at the plasma e nds. The localized component is restricted to real frequencies, while the non-localized component covers the entire complex frequency plane. The non-localized modes can be joined generally with those on neighbo ring field lines to form modes that smoothly cover the entire magnetic surface. The localized modes do not occur in symmetric plasmas. (C) 1 997 American Institute of Physics.