Superconducting toroidal field magnet for an experimental tokamak

We have studied a TOKAMAK equipped with superconducting toroidal field coils, to be used for plasma physics experiments. The torus is characterized by a radius of 1.7 m, a magnetic field of 3T and a small aspect ratio R/a = 2.6. These parameters require a conductor with a high current density. The fast rise time of the plasma current, 0.15 s, causes serious losses in the toroidal field coils, introducing additional problems. We describe in the following the main conductor, the mechanical structure, the refrigeration system and the protection scheme.