The QSF Divertor Configuration and Its Impurity Seeding Experiments on EAST

Abstract

The divertor overheated damage caused by the plasma heat and particle fluxes has been a difficult challenge to the magnetic fusion reactors. The radiative divertor and the snowflake (SF) divertor can optimize the divertor heat load, but for the future fusion reactors with higher discharge parameters, the integration of various methods for reducing divertor heat load is necessary. EAST develops the advanced divertor configuration suitable for the superconducting tokamak, quasi-SF (QSF) to optimize the SOL magnetic topology. QSF plasma can reduce the divertor heat load and particle flux effectively, and the divertor electron temperature (T $_{e,t}$ ) is lower than the regular single-null (SN) shape. The radiative feedback control by the impurity seeding has been implemented for the first time under QSF configuration. With the increment of the radiated power, T $_{e,t}$ and the tungsten line emission (WUTA) are reduced effectively. The stable operation of QSF with low divertor heat load and low tungsten sputtering is built by the integration of QSF shape control and the radiative feedback control, which will have important application value in the future.