Steady-state Superconducting Advanced Spherical Tokamak Reactor (SASTR)

A concept for a Steady-state Superconducting Advanced Spherical Tokamak Reactor (SASTR) with a slim-CS is proposed. This is a spherical tokamak (ST) with an internal transport barrier (ITB) and superconducting magnets. The ITB allows for sufficient bootstrap (BS) current to sustain the plasma. The feasibility of a self-sustained SASTR is investigated by using a set of plasma burning equations. We find that the toroidal magnetic field and the confinement enhancement factor are key parameters to meet the beta limit and density limit criteria, respectively. We estimate the dependence of the cost of electricity (COE) on the aspect ratio and reactor size. We present a conceptual design of a 0.8 GWe SASTR power reactor with a major radius of 4.5 m, an aspect ratio of 1.8, a toroidal field of 2.67 T generated by Nb3Sn superconducting magnets, and a plasma current of 24.5 MA driven fully by the BS current.