Comparative evaluation of existing concepts for a 10 tesla FED toroidal field coil

The existing design concept options for FED toroidal field coils have been studied and evaluated by General Atomic Company as part of the FED/INTOR Critical Magnetic Issues effort for 1982. The various design concepts studied are: (1) forced flow cooled NbTi cabled conductor, (2) He-II bath cooled NbTi cabled conductor, and (3) He-I bath cooled Nb3Sn-NbTi hybrid with cabled conductor. These design concepts are evaluated based upon their relative merits, including technological maturity, operational reliability, overall reactor compatability, maintainability, and cost. An important aspect of this study was the normalization of each design concept to meet similar operational requirements. The critical issues in the TF coil design, including the structural role of the helium vessel, quench protection, accommodation of neutronic and eddy current heating, credible fault criteria, and the possibility of prototype coil demonstration are discussed. The consequences and implications of extending the peak field in the range from 8 to 10 tesla was also studied.