Nested shell superconducting magnet designs

A novel concept for manufacturing the toroidal field coil is described. In the nested shell concept, the conductor is layer-wound in grooves in a shell that lies in the toroidal direction. This simplifies substantially the winding process, both in laying down the conductor and in reducing the number of joints in the graded case. An entire row (of the same grade) is wound on the shell. The minimum number of joints per coil would be equal to the number of grades. If coupled to a bucking cylinder and modest structural caps, the coils are able to support the normal out-of-plane coils without the need for a large intercoil structure, increasing the accessibility and maintainability of the reactor. The magnet configuration is described and the advantages explored. Structural analysis of the concept is performed using the ARIES tokamak reactor parameters. The effectiveness of a structural cap, placed above and below the toroidal field coils and used only to balance opposing torques generated in different places of the coil, is quantified