Design status of the ITER ECH upper launcher steering mirror mechanism

The ITER ECRH upper port antenna (or launcher) will be used to drive current locally for stabilising the neoclassical tearing mode (NTM)) by depositing mm-wave power inside of the island which forms on the q=3/2 or 2 rational magnetic flux surfaces and control the sawtooth instability by driving current near the q=1 surface. This requires the launcher to be capable of steering the focused beam deposition location across the resonant flux surface over the range where the q=1, 3/2 and 2 surfaces are expected to be found (roughly the outer half of the plasma) [4].