Predictive multi-channel integrated modeling of a reversed magnetic shear H-mode discharge with internal transport barrier in EAST

A reversed magnetic shear high plasma performance H-mode discharge with internal transport barrier (ITB) has been realized and modeled on experimental advanced superconducting tokamak (EAST) in deuterium (D) plasmas with an ITER-like tungsten (W) upper divertor. In this shot (#71326), the dimensionless parameter G () can reach to 0.25 (H89 ⩽ 2, βN ⩽ 2, q95 ∼ 4, Ip ⩽ 450 kA, BT ⩽ 1.6 T). The ITB has been observed in the channels of particle (electron density ne), electron and ion temperature (Te and Ti) and toroidal rotation velocity (Vt). However, in the formation process of Vt and ne ITBs, the heavy impurities accumulate in the core plasmas, which may be one of the most important reasons for the limitation of the improvement of plasma performance. A time slice (t = 4.65 s) of the high plasma performance phase with ne, Ti and Vt ITBs has been analyzed. It is found that the position of minimum safety factor (qmin) is at about normalized radius ρ = 0.4 where may be the location of ion ITB foot, during equilibrium reconstruction from EFIT using external magnetic and internal polarimeter-INTferometer (POINT) measurement constraints. Based on this equilibrium, the source is self-consistently calculated by ONETWO and NUBEAM. Then the ne, Te, Ti and Vt have been modeled predictively and simultaneously by TGYRO utilizing the reconstructed equilibrium, the self-consistent source and the experimental radiated power for the first time in EAST. This modeling well reproduces the experimental ne and Ti profiles in the reversed magnetic shear plasmas. In addition, it is shown that reversed magnetic shear rather than shear of radial electric field (Er) mainly produced by Vt plays a key role to the formation of ne and Ti ITBs. The reasons for central accumulation of W impurity are also clarified by computing both neoclassical and turbulent transport components of W. It turns out that the neoclassical transport dominates over turbulent transport for W and neoclassical pinch of W causes its central accumulation.