Publication
The ITER ECH upper launcher is devoted to directing up to 8 2NM beams per port plug over half of the plasma cross section. A focusing mirror is used to achieve a very narrow deposition profile to stabilize MHD activity such as the neoclassical tearing modes (NTMs) and the sawtooth oscillation. The beam deposition location is changed via a steering mirror with up to +/-7 deg (+/-14 deg beam), which allows access from inside mid radius out to nearly the plasma edge. The steering mechanism uses a frictionless backlash free system to avoid sticking, thus increasing the reliability.