Effects of neon seeding location and E × B drift on plasma detachment in EAST

Optimizing impurity seeding locations is important for achieving divertor detachment with minimal impurity injection and maintaining core plasma performance. The effects of gas puffing at the scrape-off layer (GP@SOL) and private-flux region (GP@PFR) sides in the divertor, as well as the role of E × B drift, are investigated by Experimental Advanced Superconducting Tokamak experiments and SOLPS-ITER simulations. The study shows that GP@SOL is more effective in reducing the divertor electron temperature and heat flux and promoting plasma detachment, while not resulting in a higher core Ne content than GP@PFR. GP@SOL produces a higher Ne ion density in the outer divertor region than GP@PFR, resulting in stronger radiative energy loss there. Meanwhile, E × B drift further modifies the transport of Ne and D ions, affecting the relative detachment performance of GP@SOL and GP@PFR under different Bt conditions. After detachment, the changes in the electric fields modify the E × B transport of deuterium ions, leading to opposite radial shifts of the ion saturation current density peak under favorable and unfavorable Bt conditions.