Toroidal Field Strength Requirements in Tokamak Reactors

A survey has been made of the toroidal magnetic field strength requirements in a tokamak reactor as a function of size, confinement, temperature, safety factor, aspect ratio, and cross-sectional shape. The maximum field strengths consistent with reasonable limitations on the wall-loading and plasma-driving system and the minimum field strengths necessary for predicted confinement were determined along with the associated power output and an indication of the magnet cost. It was found that a maximum toroidal field at the coil of 80 kG (8 T) may be adequate for large-scale reactors. Fields in excess of 100 kG (10 T) would only be required for reactors in the intermediate-size range (major radius ∼7 m).