Jonathan Roeltgen, UT-Austin

"Modeling non-Coronal Impurity Radiation in the Tokamak Divertor with Emphasis on Shallow Field Line Angles"

Abstract: Through SOLPS-ITER simulations of DIII-D and MAST-U, an Xdivertor (XD) on DIII-D and a super X-divertor (SXD) on MAST-U were shown to have increased carbon emissivity (PRad/nenI) than corresponding standard divertors (SD) at similar degrees of partial detachment. The reasons behind the increased emissivity in the DIII-D XD and SXD are analyzed using a simple 0D transport model. The input power (Pin) was varied from 1 to 18MW which showed an increase in the XD’s emissivity with higher emissivity.

A 1D model was used to extrapolate the increased emissivity of the XD at high power to ITER. It supports the proposition that a major cause of the increased emissivity is due to a shorter impurity confinement time (τ ). It is also used to explain the basic geometrical reasons for the increased emissivity of the XD over the SD as well as its increase with Pin. Similar reasons of increased emissivity for different impurities is also shown.