Fluid simulations of the boundary of fusion plasmas predict the formation of an electric potential well in the vicinity of the X-point in detached divertor conditions with Bt in the unfavorable direction for H-mode access. This potential well arises when the parallel current in the divertor is dominated by Pfirsch-Schlüter currents and is closely related to previously reported potential hill formation in favorable Bt direction. A simple analytic model describes its dependence on plasma shape and divertor conditions. The poloidal particle transport in the divertor is dominated by the parallel flow, while cross-field particle transport in the vicinity of the separatrix is argued to be E × B-dominated, even in the presence of turbulence. With a potential well, the E × B-flow differs qualitatively from the classic drift pattern with the near-SOL poloidal E × B-flux enhanced and reversed while radially widening/compressing the outer/inner divertor leg, respectively.
In–out asymmetry of divertor particle flux in H-mode with edge localized modes on EAST