Study of the β dependence of confinement and heat transport in ASDEX Upgrade

First β scan experiments have been made in ASDEX Upgrade in H-mode plasmas with type-I ELMs. Two sets of discharges, performed in different density ranges, scan β between β N = (1.4–2.2) and β N = (1.4–2). Global analysis of these dedicated experiments exhibits a strong unfavourable β scaling as B τ th ∝ β −0.9 . This tendency is confirmed by a local analysis which shows an increase in the thermal heat diffusivity with increasing β as χ eff / B ∝ β 0.65 . These results are discussed and compared with studies made in DIII-D, JET and JT-60U.