Scaling of the marginal  pof neoclassical tearing modes during power ramp-down experiments in ASDEX Upgrade

Based on the models describing the behaviour of neoclassical tearing modes (NTMs), fits for the seed-island triggered excitation and disappearance of these modes at small β-values have been tested for an extended parameter range in the ρ pi *– ii plane in ASDEX Upgrade. The disappearance of NTMs at the marginal β p ,marg during power ramp-down phases provides input for a direct comparison with models without the influence of the seed-island size. It has been found that for low q 95 the NTM remains present until the HL-transition, whereas for higher q 95 the mode decays well in H-mode. Scalings for the onset and the marginal β p for the (3/2)-NTM and the analysis of marginal β p for the (2/1)-NTM are presented.