A rotation-transport threshold model of neoclassical tearing modes (NTMs) issuggested. It is assumed that weakening of the bootstrap currenteffect is determined by competition of perpendicular transportand island rotation, which is in contrast to the known transportthreshold models dealing with the parallel transport or parallelconvection instead of island rotation. It is shown that forsufficiently strong island rotation the perpendicular transportdoes not lead to decreasing the bootstrap current contributioninto the island width evolution equation. It is explained that theisland rotation can prevail over the parallel transport/convectionmainly for the case of ion contribution into the bootstrapcurrent effect. Interrelation between the rotation-transportthreshold model and the known ones is discussed. A generalizedtransport threshold model of NTMs describing the competition ofthe perpendicular transport with the island rotation, paralleltransport and parallel convection is formulated. It is shown thatthe perpendicular transport can lead to weakening the bootstrapdrive contribution only if it overpowers all the competitive effects.
Influence of rotation on the (m, n) = (3, 2) neoclassical tearing mode threshold in the ASDEX Upgrade
Experimental evidence for the bootstrap current in a tokamak