Comparison of core and far-SOL tungsten measurements for opposing B_t direction during the SAS-VW campaign on DIII-D

A set of experiments conducted to study the effects of E×B drift direction on tungsten leakage from a closed slot divertor was successfully carried out during the SAS-VW campaign on DIII-D. Campaign empirical findings suggest that favorable B_t (ion B×▽B drift into slot) has higher core W concentration with fewer impurities reaching the far scrape-off-layer (SOL) while in unfavorable B_t the opposite trend occurs. W density estimations are made using soft X-ray (SXR) tomography in the core and impurity collector probe (CPs) measurements in the far-SOL. Two pairs of H-mode shots are considered, where each pair is similar except for the B_t direction. SXR data shows mean core W density and concentration are about 27% and 100% higher in the favorable B_t discharges relative to the unfavorable, respectively. Far-SOL W CP deposition is 110% higher in the unfavorable case relative to the favorable. Preliminary interpretive modeling will investigate the effects of E×B drifts, parallel flows, and divertor conditions to study how opposing B_t directions affect W SOL transport and core contamination. The effects of ELMs and pedestal conditions will also be examined, as the unfavorable cases could not reach the same pedestal temperatures as the favorable cases.