Additional particle control methods, such as gas puffing, may lead to changes in the ratio between the separatrix electron density and the pedestal electron density (), and lead to the relative shift between the density and temperature profiles. And the changes in and the relative shift could result in the change of pedestal structure. In this paper, a new version of REPED model has been developed and used to study the effect of density profile on the pedestal structure in EAST. Modeling results show that pedestal pressure has a positive correlation observed with meaning that pedestal pressure height and width increase with the increase of . Study of the relative shift shows that the pedestal pressure increases as the pedestal density shifts inward which also leads to higher pedestal gradient and higher bootstrap current at the pedestal region which is beneficial for the ballooning mode. Analysis by the ELITE code shows that the PBM boundary gradually moves inward as the density shifts outward. Furthermore, the new REPED model is applied to predict the pedestal structure in EAST experiment which has relative density shift, and the predicted pedestal height shows good agreement with experimental measurement. The REPED model also predicts that the ITER pedestal increases/decreases by 10% with a density inward/outward shift of 0.02. The simulations indicate that the relative shift at the pedestal needs to be considered in future and current pedestal predictions and pedestal model development.
This paper investigates how changes in the ratio between the separatrix electron density and the pedestal electron density, as well as the relative shift between the density and temperature profiles, can affect the pedestal structure in the EAST tokamak. The study uses a new version of the REPED model to predict the impact of these factors on the pedestal pressure, gradient, and bootstrap current, which are important for plasma stability.