Investigation of Divertor Detachment in EAST by `Two-Point' Model

Abstract

Divertor plasma detachment offers one of the most promisingoperating modes for fusion devices because of low target powerloading. In this article a `two-point' model is used to investigatethe formation of detachment and explore the route to detachment inEAST, in order to find an ideal operation window. The simulationresults show that impurity radiation and ion-neutral friction arethe main causes of divertor plasma detachment at the target plates.Raising the safety factor and reducing the upstream power densityprovide effective means to achieve the detachment due to theincreased radiation power fraction. Puffing Ar and Ne impurities andraising the safety factor can bring the upstream high plasmatemperature region (above 100 eV) and the low target plasmatemperature region (below 10 eV) close to each other in terms ofthe separatrix density. But it is difficult to find a commonoperating region which satisfies both conditions. High recycling anddetached regimes provides an ideal operation window because of thesteady upstream condition and low target power load.