Closed corner divertor with B × ∇B away from the divertor: a promising divertor scenario for tokamak power exhaust

A major challenge facing the steady-state operation of tokamak fusion reactors is to develop a viable divertor solution with order-of-magnitude increase in power handling capability as compared with present experience. A recently developed divertor concept for this end has been tested recently on EAST tokamak through combining the effects of a closed divertor corner and E × B drifts. The E × B drifts in the divertor move particles towards the outer divertor corner area in the scrape-off layer for B × ∇B directed away from the divertor, which can significantly enhance the particle concentration there, facilitating divertor detachment. In recent EAST experiments, the effects have been demonstrated where the lowest electron temperature at the divertor plate is obtained with strike point located close to the corner in the horizontal target and with B × ∇B away from the divertor. These experimental results are in reasonable agreement with SOLPS-ITER simulations including drift effects, suggesting that the new divertor concept potentially provides a promising divertor solution for long-pulse operations of future tokamak fusion reactors with much higher power fluxes.