Development of the transport-code framework for self-consistent predictions of rotation and the radial electric field

Abstract

A toroidal momentum solver, which calculates the evolution of the toroidal angular momentum density summed over thermal species, is modelled and integrated into the 1.5D integrated transport code TOPICS. A non-iterative scheme to uniquely determine the radial electric field Er is developed. It is also used to compute the parallel and toroidal flows for each species based on the neoclassical transport theory. The combination of TOPICS and the orbit-following Monte Carlo code OFMC enables us to self-consistently predict the evolution of not only the density, temperature and safety factor but also the toroidal momentum and Er. The framework developed has been tested against JT-60U experiments and showed the predictive capability of toroidal rotation. Several time-dependent simulations in which toroidal rotation and Er play an important role are carried out, showing that the H-mode confinement considerably depends on the direction of toroidal rotation via the change in Er, as observed in JT-60U. Rapid toroidal rotation can be hardly expected in ITER if rotation is solely driven by neutral beam (NB) injection, whereas the residual stress may potentially generate the torque comparable to or greater than that by NBs.