Formation of Cold and Dense Divertor Plasma during Phases of Non-Inductive Current Ramp-Up and Recharging in Tokamak Fusion Reactor

Possibility of the formation of cold and dense divertor plasma is numerically studied during non-inductive current ramp-up and recharging phases in a Tokamak reactor. When the driving efficiency is high (e.g.∼0.3), the cold divertor plasma of 15–30 eV can be obtained consistent with the non-inductively driven current. In the case of low driving efficiency (e.g.∼0.1), it seems quite difficult to reduce the divertor plasma temperature below 30 eV within a realistic driving power. When the driving efficiency is improved with the main plasma temperature, the possibility to realize the cold divertor plasma is greatly enhanced. In the case of closed divertor geometry, more power is required in order to attain the same plasma temperature at the neutralizer plate.