24th IAEA Fusion Energy Conference - IAEA CN-197

PD/1-1: State-of-the- art Neoclassical Tearing Mode Control in DIII-D Using Real-Time Steerable Electron Cyclotron Current Drive Launchers

12 Oct 2012, 14:00

4h 45m

Poster Room (Area F-B)

Poster Poster: P8

Speaker

Mr Egemen Kolemen (USA)

Description

Real time steerable electron cyclotron current drive (ECCD) has been demonstrated to reduce the power requirements and time needed to remove 3/2 and 2/1 neoclassical tearing modes (NTM) in the DIII-D tokamak. In a world first demonstration of the techniques required in ITER, the island formation onset is detected automatically, gyrotrons are turned on, and the real-time steerable ECCD launcher mirrors are moved promptly to drive current at the location of the islands; the modes are shrunk and suppressed well before saturation with the use of real-time motional Stark effect (MSE) constrained equilibria reconstruction with advanced feedback and search algorithms. For ITER, this method will reduce the ECCD energy requirement and so raises Q by keeping the EC system off when the NTM is not present. Further, in the experiments with accurate tracking of pre-emptive ECCD to resonant surfaces, both 3/2 and 2/1 modes are prevented from appearing with up to 5 times less ECCD power.