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 βN = (1.4–2.2) and βN = (1.4–2). Global analysis of these dedicated experiments exhibits a strong unfavourable β scaling as Bτth ∝ β−0.9. This tendency is confirmed by a local analysis which shows an increase in the thermal heat diffusivity with increasing β as χeff/B ∝ β0.65. These results are discussed and compared with studies made in DIII-D, JET and JT-60U.