Effect of magnetic geometry on divertor asymmetry and access to high confinement mode in EAST

The basic in-out divertor asymmetry with respect to ion B × ∇B direction has been examined in EAST by changing the divertor configuration from upper single null (USN) to lower single null (LSN) during the same discharge without reversing BT. It is remarkable that the in-out asymmetry is reversed when moving from USN to LSN. However, modeling with SOLPS, taking into account classical drifts, shows little difference. The divertor magnetic configuration also affects the access to H-modes, favoring DN or near-DN divertor configurations on EAST. ELMs further enhance the in-out divertor asymmetry, leading to greater particle and heat deposition on the outer target with a broader footprint, presumably arising from enhanced ELM transport in the outboard region.