Nature of energetic ion transport by ion temperature gradient driven turbulence and size scaling

Energetic ion transport has been studied using a global gyrokinetic nonlinear simulation in the presence of ion temperature gradient (ITG) driven turbulence. The measured transport and its nature show dependence on the system size of the tokamak expressed as the ratio of plasma minor radius (a) to the thermal ion Larmor radius (σi). It increases with system size initially and then tends to saturate at larger system size. The nature of transport, on the other hand, exhibits nondiffusive character for smaller system size which eventually becomes diffusive one as the system size becomes larger.