Microwave heating and current drive for performance optimisation in magnetically confined fusion plasmas

The use of microwaves in the 100 GHz range for heating and current drive in magnetically confined fusion plasmas is reviewed with emphasis on application to performance optimisation. Recent progress in this field has shown that both confinement and stability properties of such plasmas can be favourably altered by the application of localised heating and current drive at the electron cyclotron frequency. Examples for optimisation of confinement are the generation of internal transport barriers for heat losses in both tokamak and stellarators or the control of particle confinement by applying ECRH or ECCD. Stability optimisation includes the tailoring of the sawtooth instability and the suppression of neoclassical tearing modes in tokamak plasmas.