At ASDEX Upgrade the influence of triangularity on the H-mode performancehas been studied intensively. It has been found that confinement increaseswith δ for a fixed line-averaged density. Though confinement decreaseswith increasing density for all analysed values of δ, H-factors(ITERH-98P) at the Greenwald density could be raised to 1 for the highestδ values achieved so far. The H-mode density limit could be increasedby ≈20%. There is a scatter of about 30% on the confinement data,which is anti-correlated to the average density in the scrape-off layer or theneutral fluxes outside the plasma. For nearly all discharges analysed so far,the temperature profiles are self-similar. This indication of profilestiffness could be verified by changing the heat-flux profile by changing thebeam-voltage of the neutral-beam injection (NBI) at high density. At lowdensity, first results indicate a deviation from this stiff behaviour.
Confinement studies in L and H-type Asdex discharges