Design of a steady-state tokamak device with superconducting coils for a volumetric neutron source

We designed a volumetric neutron source for testing large-scale blanket components, based on a steady-state tokamak device with superconducting coils. It is found that a neutron flux of approximately 1.0 MW m^-2 is available in the medium-size device (R = 4.5 m, a = 1.0 m, κ = 1.8, I_p = 5.6 MA) under the conditions of H ∼ 2 and β_N ∼ 3 with a neutral beam injection (NBI) power of about 60 MW. We demonstrate the controllability of the current profiles required for high-beta plasma up to β_N = 3-3.8 with the combination of bootstrap current and NB-driven current (E_b = 1.0 MeV). If an advanced performance scenario such as a reversed shear configuration is available, a neutron flux of 1.4 MW m^-2 is achievable. We install the breeding blanket of Li-Pb only at outboard and upper regions, and find that a local tritium breeding ratio (TBR) of 1.5 is achievable and a net TBR of 0.8 could be available. The analysis of shielding materials at the inboard region shows that the proper combination of tungsten, steel and boric water yields a reduction of the nuclear irradiation of TF coil by a factor of approximately 10.