The polarization drifts arising from the acceleration of plasma flowing alongside a magnetic island are shown to be destabilizing. A critical island width is found above which the polarization drifts (inertial forces) defeat the stabilizing effect of the viscous forces and prevent islands from being unlocked by increasing the plasma rotation.

• Received 15 October 1996

DOI:https://doi.org/10.1103/PhysRevLett.78.1703