Assessment of Tokamak Plasma Operation Modes as Fusion Power Plants: the Starlite Study

During the past several years, the ARIES/Starlite Team has investigated the feasibility and potential features of tokamak fusion power plants. The research also has aimed at identifying both the trade-offs that lead to the optimal regime of operation for a tokamak power plant and the critical plasma physics and technology issues. During the initial phase of the Starlite study, an assessment of various tokamak plasma operation modes as candidates for fusion power plants was made. Five different regimes of operation were considered: (1) steady-state operation in the first-stability regime, e.g., ARIES-I, (2) pulsed-plasma tokamak operation, e.g., Pulsar, (3) steady-state operation in the second-stability regime, e.g., ARIES-II and ARIES-IV, (4) steady-state operation with reversed-shear profile, and (5) low-aspect ratio tokamaks (spherical tokamaks). The extent of the plasma physics data base as well as performance as a power plant were considered. Based on the above analysis, the Starlite project has chosen reversed-shear operation for its reference design. This paper summarizes the results of this assessment,