Simulation studies of tungsten impurity behaviors during neon impurity seeding with tungsten bundled charge state model using SOLPS-ITER on EAST

An investigation into tungsten (W) impurity behaviors with the update of the EAST lower W divertor for H-mode has been carried out using SOLPS-ITER. This work aims to study the effect of external neon (Ne) impurity seeding on W impurity sputtering with the bundled charge state model. As the Ne seeding rate increases, plasma parameters, W concentration ($C_{\mathrm{W}}$), and eroded W flux (${\mathrm{\Gamma }}_{\mathrm{W}}^{\mathrm{Ero}}$) at both targets are compared and analyzed between the highly resolved bundled model 'jett' and the full W charge state model. The results indicate that 'jett' can produce divertor behaviors essentially in agreement with the full W charge state model. The bundled scheme with high resolution in low W charge states (< W²⁰⁺) has no obvious effect on the Ne impurity distribution and thus little effect on W sputtering by Ne. Meanwhile, parametric scans of radial particle and thermal transport diffusivities ($D_{\perp }$ and ${\chi }_{\mathrm{e},\mathrm{i}}$) in the SOL are simulated using the 'jett' bundled model. The results indicate that the transport diffusivity variations have significant influences on the divertor parameters, especially for W impurity sputtering.