Toroidal field magnet system utilizing normal metal trimming coils

A conceptual design of a tokamak toroidal field (TF) magnet system with trimming coils to reduce field ripple throughout the plasma region is presented. The number and size of superconducting TF coils is reduced from conventional designs to provide more access for maintenance, blanket cooling, vacuum pumping and plasma heating schemes and to improve the operating economics. The resulting large toroidal field ripple is trimmed with normal copper coils located close to the plasma. Saddle shaped and ring shaped trimming coils are described. In addition to its primary function of trimming, a ring shaped normal coil also can be used to supply a fair amount of magnetic field strength to augment the maximum fields available from the superconducting coils. The cooling scheme, material selection, number, size, shape and placement of the superconducting coils and the trimming coils are discussed