Preliminary integrated core-SOL-divertor modelling for DTT tokamak with liquid metal divertor targets

Abstract

The I-DTT tokamak has been analyzed by means of the integrated COREDIV code simulations when either Li or Sn are used as liquid divertor target materials. It has been found that power to divertor can be strongly mitigated with LMD. The reason is that the solution is determined by the LM divertor properties, leading to the requirements that the heat load to the liquid target is reduced below a threshold value. The threshold is due to the limits to the plasma contamination by the evaporated material. In the case of Li target, the limit is set to ∼8 MW/m2 and is achieved by strong Li radiation in the divertor (vapor shielding). For Li, there is a low density limit and solution is only achievable if the plasma density is high enough. The low density operation might be recovered if Kr seeding is applied.For the tin liquid divertor, H-mode operation is possible with efficient reduction of the heat flux to the divertor (∼11 MW/m2) in the evaporation efficiency reduced mode of operation and with the separatrix density high enough. The heat load reduction can be even more efficient (∼2.5 MW/m2) in the regime with strong evaporation but in this case the H-mode operation might be a problem. It appears that Ne seeding can hardly solve the H-mode operation problem but Li seeding seems to be better solution. The operation with higher edge plasma densities alleviates difficulties with the H-mode operation of liquid tin divertor.