Transport in ITER-like plasmas in neoclassical, fluid and gyrokinetic descriptions

Turbulent and neoclassical transport in ITER-like plasmas is studied using a hierarchy of modelling tools. Transport from ITG/TEM instability is studied with nonlinear gyrokinetic simulations (using GYRO) and compared with results from an electrostatic fluid model. GYRO simulations include full kinetic ion (D,T,4He,C) and electron dynamics. Key issues ignored in standard transport modelling, such as D-T flow separation, as well as electromagnetic effects on electron transport, are considered and consistency of the ASTRA transport simulations is examined. Neoclassical transport of particles and energy is also computed using a new first-principles kinetic code with an advanced collision operator. Simulations are based on ITER-like profiles derived from ASTRA modelling. For the ASTRA profiles used in the simulations, the fluid and gyrokinetic simulations are in qualitative agreement, with inward particle flux is observed for all species. Importantly, we find that the ion and electron energy fluxes are significantly larger in the core than the values obtained by ASTRA in steady state. This implies that the ASTRA profiles may be overpredicting the ion temperature and thus the fusion power. (author)