Tearing-mode stability in a cylindrical plasma with equilibrium flows

The effect of a sheared equilibrium mass flow on the resistive tearing mode is studied numerically by calculating Δ‧. Both stabilizing and destabilizing effects are found, depending on the velocity and magnetic field profiles. Specifically, when q₀ ≈ 1, the flow is strongly stabilizing for centrally peaked current profiles, whereas the flow has a strongly destabilizing effect for flatter current profiles. While the extreme effects are more pronounced for larger flows, a smaller flow may have more influence on marginal stability. The case where the flow speed becomes comparable to the Alfvén speed is also examined. It is found that this may lead to the equations being singular at points other than a rational surface, drastically changing the behaviour of the mode.