The effect of heat load on divertor target by pumping in HL-2A Tokamak

Background The energy produced by nuclear fusion on a Tokamak device is mainly exhausted through the divertor, its service life is directly affected by the interaction between huge heat flux from core and the divertor target. The large amount of impurity produced by the heat flux hitting the target leads to the reduction of the plasma confinement performance whilst pumping is an important means to control plasma density and impurity density. Purpose This study aims to investigate the influence of pumping on the heat load of the target plate which is of reference significance for the future experiment. Methods Based on the experimental parameters of the HL-2A Tokamak, SOLPS-ITER code was used to study the effect of pumping on the heat load of the divertor target under different upstream electron densities. Analysis was performed through density scanning to find the sensitive threshold whilst and atom-molecular collision process was applied to the effect of pumping on the distribution of plasma and neutral particle parameters in divertor region at different upstream electron density. Results Density scanning results show that pumping near the detachment threshold ( T e t O S P ~5 eV) has a greater effect on the thermal load of the target plate. When the pumping rate is 12 m3·s-1, 36 m3·s-1 and 96 m3·s-1 respectively, the miss threshold and thermal load peak of outer target plate are 1.11, 1.24, 1.39 and 1.37, 1.96, 2.54 times of those without pumping respectively. Conclusion It is found that the decreases of deuterium molecular density results in the energy of the collision reaction power decreases when the upstream electron density exceeds the detachment threshold, leads to the increase of the temperature and energy flow of the plasma in the target plate.