Plasma size scaling of avalanche-like heat transport in tokamaks

Jolliet, S.*; Idomura, Yasuhiro   

The influence of plasma size on global ion temperature Gradient turbulence is studied with the full- Eulerian code GT5D. The gyrokinetic model includes a consistent neoclassical electric field as well as a fixed-power source operator, enabling long-time simulations with self-consistent turbulent transport and equilibrium profiles. The effects of plasma size are studied by scaling the minor radius and the input power. For the first time, worse-than-Bohm scaling is observed in experimentally realistic conditions. For all plasma sizes, avalanches propagate over significant radii but their propagation depends on the radial electric shear. It is found that this quantity does not scales with the size due to the building up of intrinsic momentum. These simulations therefore suggest that intrinsic momentum reduces heat transport.