Controlling of tungsten (W) impurity core accumulation is of great significance for the steady-state operation of tokamaks. This work mainly investigates the effect of neoclassical transport on the core accumulation of W impurities by using STRAHL code. The study focuses on the HL-3 device, which will use tungsten divertor and conduct research under argon gas injection discharge conditions. In the simulation, the edge and core background plasma parameters are obtained by SOLPS-ITER and OMFIT simulations, respectively. The distribution of tungsten impurities in the boundary region is simulated using the IMPEDGE code. The edge anomalous transport coefficient in STRAHL is adjusted accordingly, and the simulation results are compared with those from the IMPEDGE to ensure consistency in impurity distribution between the core and edge. In the core region, a numerical scan is performed to adjust the simulation results so that the energy radiation matches the setting values, thereby determining the specific turbulence convection velocity. By setting the coefficients for both the core region and the boundary region, a complete distribution of W impurities from boundary to the core is obtained. To account for the neoclassical transport effects, the neoclassical transport coefficients are calculated using the subroutine NEOART and applied to the impurity transport simulation, and the simulation region is set from $ \rho =0 $ to 0.9. On this basis, the transport of W impurities with and without neoclassical convection is simulated. The simulation results show that without neoclassical convection, anomalous transport dominates the impurity transport, which is inward and enhances impurity accumulation in the core, and the core impurity density reaches $ 1.1\times {10}^{16}\;{{\mathrm{m}}}^{-3} $. After introducing neoclassical convection which is outward, it can offset the inward anomalous convection and significantly reduces the W impurity density in the core, thereby significantly reducing the core tungsten impurity density to $ 4.0\times {10}^{15}\;{{\mathrm{m}}}^{-3} $. In addition, the neoclassical convection in the region of $ \rho$ = 0.72–0.90 plays a more important role in reducing the core impurity density. Further analysis of the components of neoclassical convection shows that the Pfirsche-Schlüter (PS) component dominates the neoclassical convection term, which is mainly driven by the ion temperature gradient term. Therefore, experimentally, plasma heating can be used to enhance the temperature gradient and suppress impurity core accumulation.
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