A conceptual design of a spherical tokamak power plant

The spherical tokamak (ST) has a very low aspect ratio, typically below sim ilar to1.8, which allows operation at high beta. The ST also offers stabili ty at high elongation which permits operation at high bootstrap current fra ction leaving only a modest external current drive requirement. Results fro m START indicate the ST has resilience to disruptions and low halo currents when disruptions are triggered. In order to explore these potential advant ages, a conceptual design of a steady-state ST power plant is being develop ed for which the thermodynamic, neutronic and mechanical design of the plan t have been iterated, together with the plasma parameters, to give a consis tent design. The baseline design uses water cooled copper for the centre ro d and return limbs of the toroidal held (TF) coils with minimal steel shiel ding around the rod giving a simple coil design. A helium cooled ceramic pe bble bed blanket with beryllium multiplier is used to generate the required tritium and achieve a high thermal efficiency. (C) 2000 Elsevier Science B .V. All rights reserved.