Simulation study of the effect of magnetic curvature drift on tungsten impurity transport in the edge plasma region of EAST Tokamak

Magnetic field drift, caused by magnetic field inhomogeneity or curvature, is proportional to the particle mass and thus more pronounced for high-Z impurities. At present, the magnetic drift effect of high-Z impurities has not received sufficient attention in edge transport studies, and systematic investigations are still lacking. In this work, the impurity transport code IMPEDGE is upgraded to investigate the impact of magnetic curvature drift on tungsten impurity transport in the EAST Tokamak under a lower single-null forward Bt configuration. The upgraded code incorporates the magnetic curvature drift effect and applies a heat flux limiter factor to correct the parallel heat flux in non-local conditions to avoid overestimation of thermal force. The focus is placed on the influence of magnetic curvature drift on the radial transport of tungsten impurities under different scrape-off layer (SOL) collisionality conditions. The results show that, without thermal force correction, the overestimation of impurity parallel velocity leads to a pronounced magnetic curvature drift effect, which substantially reduces the core tungsten density. The mechanism of impurity screening by magnetic curvature drift lies in the outward radial convective velocity generated at the outer divertor entrance. Even with thermal correction force taken into account, magnetic curvature drift still suppresses tungsten core accumulation, but its impact becomes relatively weaker due to the reduction of impurity parallel velocity. The study further finds that the influence of magnetic curvature drift on tungsten transport also depends on the SOL collisional frequency . The effect of on core tungsten impurity density exhibits a non-monotonic trend with increasing . Specifically: when > 25 s−1, the curvature drift velocity is small and its influence on impurity transport is negligible; when 10 s−1 < < 25 s−1, curvature drift induces a significant outward radial convective velocity (∼30 m s−1) near the outer divertor entrance, suppressing core accumulation (the core tungsten density is reduced by ∼20% in this simulation); when < 10 s−1, the competing E× B drift effect weakens the influence of magnetic curvature drift. This study demonstrates that incorporating the thermal correction is crucial for accurately predicting impurity parallel velocity and the influence of magnetic field curvature drift, while also revealing that the strength of the magnetic curvature drift effect strongly depends on .