3D Numerical Analysis of Radiative Edge Cooling in Wendelstein 7-X Island Divertor Scenarios

Radiative edge cooling is a promising method for mitigation of high heat and particle fluxes in the 3D field geometry of Wendelstein 7-X. A new high mirror island configuration is investigated featuring a more uniform distribution of heat and particle fluxes on horizontal and vertical divertor targets. For an upstream density of $n_{up}=2\times$10$^{19}$m$^{-3}$ at $P_{ECRH}$=8MW maximum heat loads up to $q_{max}\approx$7.2MWm$^{-2}$ are calculated with the 3D fluid and kinetic edge transport Monte Carlo Code EMC3-EIRENE. Carbon eroded from the divertor targets is predicted to serve as effective intrinsic radiator enabling detached operational regimes at higher densities ($n_{up}>4\times$10$^{19}$m$^{-3}$). The feasibility of active control of heat and particle flux levels by impurity seeding (C$_{x}$H$_{y}$, N$_{2}$, Ne) will be discussed for the new island geometry. Impurity line radiation tends to concentrate in the islands for lower densities and causes a drop of flux levels correlated to the power loss fraction, $\Delta q\propto \frac{P_{rad}}{P_{SOL}}$. $\beta$-effects are taken into account based on the 3D MHD-equilibrium code HINT.