Stability of force-free axisymmetric spherical plasma with flow

A stationary equilibrium of force-free spheromak-like plasma with a plasma flow inside and a mass flow outside is obtained. The plasma translates in a neutral gas along the axisymmetric axis with a constant velocity, when the outside mass fluid is at rest. Its stability is discussed for internal modes and free boundary modes as Rosenbluth and Bussac did for the spheromak and Sudan for the cusp-shaped plasma with plasma flow. Further we use the sufficient stability condition of plasmas with flow derived by Frieman and Rotenberg. Moreover we refer to the paper by Finn and Antonsen in which the comparison of the stability conditions between the use of δW for the ideal MHD state and δ2E* for the Taylor state is described. (author) 5 refs., 2 figs