Effects of triangularity on confinement, density limit and profile stiffness of H-modes on ASDEX upgrade

At ASDEX Upgrade the influence of triangularity on the H-mode performance h as been studied intensively. It has been found that confinement increases w ith delta for a fixed line-averaged density. Though confinement decreases w ith increasing density for all analysed values of delta. H-factors (ITERH-9 8P) at the Greenwald density could be raised to 1 for the highest delta val ues achieved so far. The H-mode density limit could be increased by approxi mate to 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 the n eutral fluxes outside the plasma. For nearly all discharges analysed so far , the temperature profiles are self-similar. This indication of profile sti ffness could be verified by changing the heat-flux profile by changing the beam-voltage of the neutral-beam injection (NBI) at high density. At low de nsity, first results indicate a deviation from this stiff behaviour.