Study on the Impact of Ne Impurity Injection Combined with Open and Closed Divertors in HL-2A on Pedestal and Divertor Plasmas Performance

The SOLPS-ITER code was employed to systematically investigate the effects of neon （Ne） impurity injection on the plasma characteristics in the pedestal and divertor regions of the HL-2A tokamak device under both open and closed divertor configurations. The results demonstrate that under the investigated background plasma parameters and closed divertor condition, the pedestal plasma pressure and temperature are higher than those observed under the open divertor configuration. This finding indicates that within the studied parameter range, the pedestal performance of the closed divertor is superior to that of the open divertor, and impurity injection under the closed divertor condition leads to an increase in ion temperature and plasma pressure. It is found that under the closed divertor condition, the ion parallel energy flux exhibits backflow in the vicinity of the X-point, and this backflow is further enhanced following impurity injection. This phenomenon is presumably responsible for the higher ion temperature at the core boundary of the closed divertor. Additionally, it is observed that the particle and energy fluxes incident on the target plate under the open divertor condition are lower than those under the closed divertor condition. This discrepancy is primarily attributed to the fact that the neutral particle density in the closed divertor region is significantly higher than that in the open divertor region, thereby providing a more intense ionization source.