Study on divertor oscillations during detachment experiment with impurity seeding on EAST

Divertor oscillations accompanied by abrupt changes in electron temperature present a significant challenge for achieving a stable detached divertor in magnetic confinement fusion. In EAST, these oscillations exhibit a strong correlation with radiation power. To elucidate the underlying physics, a novel interpretive model based on local power balance near the divertor target has been developed. By using the key local target parameters—the electron temperature and particle flux—as inputs, the model calculates the ion and electron densities, as well as radiative power losses near the divertor target. The model’s calculations show favorable agreement with experimental measurements from the EAST tokamak, successfully elucidating the mechanism behind the radiation-driven oscillations and the associated sharp collapse of temperature. Based on this mechanism, a stable detachment control strategy is proposed and experimentally verified. The divertor oscillations are suppressed successfully by setting a sufficiently low feedback target temperature. This study provides a fundamental understanding of radiation-driven divertor oscillations and offers a practical approach for their avoidance in future fusion devices.