Interaction of turbulence and magnetic islands

We have investigated the role of turbulence for two problems, the effect of the polarization current on the NTM and the effect of diamagnetic drifts on mode penetration. For the NTM problem, we find that the fluctuations exert a drag force on the island that results in a stabilizing slowdown in the propagation velocity. For the mode penetration problem, we have investigated the influence of polarization and diamagnetic rotation in the error field penetration threshold by comparing the results of electromagnetic simulations using a two-fluid model with theory. For rotation velocities between the ion and electron diamagnetic velocity, drift-waves are excited and the solution becomes delocalized. We find that the existing linear theories that neglect the drift wave radiation effect overestimate the penetration threshold.