Numerical study of divertor detachment on TCV H-mode scenarios

The numerical simulation of TCV H-mode scenarios has been performed through SOLEDGE-EIRENE transport code. The simulation results show good agreement with available experimental data. An extensive scan has been applied based on the basic case with a fixed pedestal temperature, giving possibilities to understand the impact of impurities and baffle closure in a quantitative way. The results show that the detachment can have easier access by increasing neutral pressure and impurities concentration in the divertor. More closed divertor and nitrogen seeding can make plasma detach with lower upstream separatrix density (up to 50%) and lower target heat flux (about 30%). When nitrogen concentration in the divertor is high enough (about 10%), the effects caused by the reduction in baffle closure can be largely mitigated. The detachment threshold in target temperature can be higher with increasing impurity concentration. The RHS value which considered the joint effect of neutral pressure and impurity concentration has a consistent detachment threshold for the cases with variated baffle closure and impurities concentration in the divertor. Some parameters are found to be highly related to detachment and show the potential to be used as indicators for detachment control in the future