Tungsten peaking is predicted in the core of a WEST plasma with total-f gyrokinetic simulations, including both collisional and turbulent transport. This prediction is validated with a synthetic diagnostic of the bolometry. Although nitrogen impurities are shown to reduce the neoclassical peaking of tungsten on-axis, the overall tungsten peaking increases when nitrogen impurities are present, as they reduce the turbulence screening off-axis. This finding is important for the plasma current ramp-up phase of ITER, where light impurities seeding will be desirable to achieve low temperatures at the plasma-facing components and reduce tungsten sputtering. It provides further argument for applying early ECRH heating to maintain margins on the core power balance. The neoclassical peaking factor is cross-verified between XGC and FACIT. The heat flux at separatrix and the heat load width are modeled by XGC and compared to WEST data.
This paper predicts the peaking of tungsten in the core of a WEST plasma, including both collisional and turbulent transport. It shows that while nitrogen impurities reduce neoclassical peaking, they also reduce turbulence screening off-axis, leading to overall increased tungsten peaking. This finding is important for ITER's plasma current ramp-up phase, where light impurities seeding will be desirable.