Abstract. A self-consistent theory for the role of the polarisation current in magnetic island evolution is presented, which suggests that it can, under certain circumstances, provide a threshold island width for growth of neoclassical tearing modes. However, at high coupling to an unstable resistive wall mode (RWM) removes this threshold, and would limit the achievable plasma pressure. Techniques for stabilising the RWM using a rotating shell are described, thus providing the possibility of high operation.
IAEA 2001