Effect of velocity shear on flow driven resistive wall modes

The effect of velocity shear on the stability of resistive wall modes driven by a plasma flow is studied numerically in a slab model. It is shown that the sheared plasma flow can suppress the resistive wall instability if the velocity shear exceeds a critical value when a certain central velocity of the flow is lower than the Alfvén velocity. In comparison with the critical velocities in the uniform velocity case, it is found that the critical velocities of the sheared flow are always bigger than the former. Therefore the velocity shear is a stabilizing factor to the plasma flow driven resistive wall instability when the central velocity of the flow is lower than the Alfvén velocity.