Validation of the SOLPS Parallel Heat Transport Model

Recent SOLPS 2D fluid plasma/neutrals edge transport simulations have shown a consistent under-prediction of radiated power that when accounted for allows simulations to successfully match high resolution divertor and scrape-off-layer density ($n_e$) and temperature ($T_e$) measurements near detached conditions in DIII-D. The parallel heat transport model has been evaluated in simulations with the upstream $n_e$ and $T_e$ and divertor heat flux matched to experiments. Simulations of L-mode discharges near detachment onset require either increased carbon sources or hydrogenic recombination radiation to match measured radiative losses. With this increase, the poloidal $T_e$ profile shows good agreement with 2D divertor Thomson scattering data, including an extended region with very low $T_e$, which cannot be reproduced without the additional radiative loss. Similar scaling of the radiated power also results in agreement for the $T_e$ profile measured in H-mode experiments; however, in this case the plasma data show a poloidally extended region of high ne that is not captured in simulations.