Divertor modeling and design for a low-aspect-ratio tokamak transmutation reactor

The low aspect ratio tokamak has a wider scrape-off-layer, modeling of the SOL plasma in a low-aspect-ratio tokamak transmutation reactor is done in order to construct a database for the design of natural divertor in the reactor. B2 code is applied to modeling. Modeling results show that the wider SOL in low-A tokamak can reduce plasma temperature, density and energy flux on the target plate of natural divertor compared with thin SOL in convention tokamak, radiation gas puffed into room of the divertor can reduce energy flux on the target plate to very low level. Based on modeling and relative design experience of divertor, a new structure design of the natural divertor is proposed. The natural divertor consists of 16 modules, each module mainly includes cassette body, vertical target plate, energy dump target plate, wing and liner, dome, cooling tubes and so on, cold He gas puffing is applied to the design. Some key parameters for the design have been obtained.