Investigation of divertor detachment in EAST by 'two-point' model

Divertor plasma detachment offers one of the most promising operating modes for fusion devices because of low target power loading. In this article a 'two-point' model is used to investigate the formation of detachment and explore the route to detachment in EAST, in order to find an ideal operation window. The simulation results show that impurity radiation and ion-neutral friction are the main causes of divertor plasma detachment at the target plates. Raising the safety factor and reducing the upstream power density provide effective means to achieve the detachment due to the increased radiation power fraction. Puffing Ar and Ne impurities and raising the safety factor can bring the upstream high plasma temperature region ( above 100 eV) and the low target plasma temperature region (below 10 eV) close to each other in terms of the separatrix density. But it is difficult to find a common operating region which satisfies both conditions. High recycling and detached regimes provides an ideal operation window because of the steady upstream condition and low target power load.