RF current drive by electron cyclotron waves in the presence of magnetic islands

The influence of the presence of magnetic islands, and the consequent modif ication of the tokamak magnetic surface topology, on electron cyclotron cur rent drive is analysed. To this end, a new three-dimensional Fokker-Planck code has been developed, taking into account the modifications of the magne tic equilibrium topology owing to the presence of the islands. Significant differences between the electron cyclotron current drive efficiency with an d without islands inside the plasma are found, particularly in the case of interaction with locked modes.