Overview of ASDEX upgrade results

During the last two years on ASDEX Upgrade the physics base for ITER operation was significantly extended in both the foreseen standard H-mode scenario as well as the stationary improved H-mode scenario with enhanced performance. For anomalous transport (energy, particles, toroidal momentum) a multi-faceted picture of mode dominance in different plasma parameter regimes of ITG, TEM and ETG turbulence is evolving based on detailed measurements including fluctuation reflectometry and gyrokinetic calculations. Similar structures were found for natural and pellet induced, mitigated type I-ELMs. They develop to outward drifting helical filaments which are seen as footprints on plasma phasing components. New insights were gained on the interaction of energetic particles (driven by NBI and ICRH) with large scale instabilities (TAEs, NTMs, ELMs) based on new diagnostic and theoretical tools. The unexpected broadening of NBI driven currents beyond a certain heating power can be explained by a fast particle diffusion driven by small-scale turbulence. The active control of MHD instabilities (sawteeth, NTMs) concentrates on ECCD as proposed for ITER. NTMs were completely stabilized with very localized deposition of dc ECCD in improved H-modes, while for the deposition widths larger than the marginal island size as in ITER modulated injection phased with the island O-point was demonstrated to be advantageous. The tungsten coverage of the vessel interior was further extended up to 85%, where the highest erosion occurs at the LFS poloidal limiters, where it is dominated by ICRF accelerated impurities and fast particles from NBI. The W concentration can be kept at an acceptable level by ELM pace-making (using pellets) and by tailored central heating. The stationary improved H-mode extends ITER operation beyond its standard H-mode performance for confinement and beta with H-98(y,H-2)beta(N)/q(95)(2) up to 0.4 (ITER reference value 0.2). Based on ASDEX Upgrade kinetic profiles it promises either a fusion performance up to ignition at full current or long pulses of up to I h at reduced current (hybrid scenario). This operation mode extends well into the ITER dimensionless parameter range except for rho*. Besides the development of discharge scenarios, the influence of the edge pedestal on confinement and of the flat central q-profile on MHD and confinement was documented.