First power exhaust experiments in DIII-D's new V-shaped Small Angle Slot divertor

Initial DIII-D experiments in the new V-shaped SAS-VW slot divertor reveal a more abrupt cliff-like transition to dissipative conditions compared to the legacy flat-end SAS slot divertor, for ion B×B drift into the slot, whereas the dependence of dissipation on strike point position in the slot is similar to SAS. DIII-D modified its original Small Angle Slot (SAS) divertor into a V-shaped slot (SAS-VW). Recent H-mode experiments studied its basic power exhaust properties. Outer strike point (OSP) sweeps at fixed plasma density reveal that, for ion B×B drift into the slot, the OSP T_e is ~50% lower if the OSP is on the inner compared to the outer slant. In contrast, for ion B×B drift out of the slot, the OSP T_e is ~50% lower if the OSP is on the outer compared to the inner slant. Such geometric dependence is consistent with SAS data and SOLPS-ITER drift modeling. Plasma density ramps at fixed OSP, for ion B×B drift into the slot, show that, at low density, the near-SOL T_e is higher in SAS-VW compared to SAS but, for increasing density, it drops at a faster rate in SAS-VW, causing an abrupt cliff-like transition to dissipative conditions (~5-10 eV) at densities similar to SAS. Advanced data analysis and SOLPS-ITER drift modeling are carried out to interpret these results.