Modeling of Plasma Fuelling and Nitrogen Seeding of JET Discharges with the COREDIV code
In view of possible realistic predictions for ITER-relevant scenarios with impurity seeding, JET discharges with nitrogen injection have been numerically simulated in recent years using the self-consistent transport code COREDIV. The coupled core-edge code COREDIV (1-D radial transport in the core, 2-D poloidal and radial transport in the SOL, self- consistent with respect both to the interaction core-SOL and main plasmaimpurities) has been developed and benchmarked against JET discharges, proving its capability of reproducing - with the diagnostic and modeling uncertainties - the main features of JET seeded plasmas, as the electron temperature and density profiles, the total radiated power, Prad, and the ionic effective charge, In the core, the electron and ion energy fluxes are defined by a local transport model which, for a given profile of the transport coefficients (usually parabolic), reproduces a prescribed energy confinement law (enhancement factor, H98P(y,2)). A simple slab geometry (poloidal and radial directions) with classical parallel and anomalous radial transport (order of 0.5m2 s-1) is used for the SOL. Chemical and physical sputtering together with sputtering by seeded nitrogen account for the fluxes of the intrinsic carbon and recycling is a free parameter. Zeff. It should be noted that COREDIV, although intrinsically time dependent, has been used so far to analyze only steady state plasmas (average values for ELMy discharges).