Numerical SOLPS-ITER study of the effect of fueling on ionization and neutral density profiles in EDA H-modes on Alcator C-Mod

The effect of plasma edge opacity to neutrals on density pedestal structure was evaluated in experiments on Alcator C-Mod, in H-mode regimes approaching ITER-like edge opacities. Perturbative gas puffs of varying magnitude were applied to these high-density, high power EDA H-modes at high plasma current along with discharges at reduced current and density and thus opacity. In order to assess the role of fueling versus transport at the plasma edge, we use the SOLPS-ITER code suite to first calculate the radial and poloidal neutral density profiles for both a discharge at high opacity as well as one at low opacity. We match the upstream experimental radial fluxes as well as density and temperature profiles by varying the radial transport coefficients using SOLPS-ITER. We will study the effect of varying the relative ratio of the diffusion and pinch contributions upon the neutral and electron density profiles. By comparing the simulations and experimental observations of two discharges at different opacity we can address the relative role of transport versus fueling in determining the local electron density in the Scrape-Off Layer and pedestal region.