Stability properties of magnetohydrodynamic cylindrical flows

Abstract Results are reported from a normal-mode linear stability analysis of a cylindrical magnetic equilibrium configuration with flow, using a theoretical model developed to simulate extragalactic jets. The general form of the stability equations is derived; the specific boundary conditions and eigenvalue problem are given; and numerical results for longitudinal flow and flow parallel to the magnetic field are presented in graphs. The existence of equilibrium configurations which are stable for both types of flow is demonstrated, with stability guaranteed if the flow velocity and azimuthal magnetic field are small. Significant linear instabilities appear at super-Alfvenic velocities and/or large azimuthal magnetic fields.