Winding mandrel design for the wide cable SSC dipole

The 50-mm coil (i.d.) Superconducting Super Collider (SSC) dipole magnets use wider cables to give a greater operational margin between the quench field and the operating field. The cable used for the inner coil has 30 strands of the same size (0.808 mm) instead of 23, the outer has 36 strands of the same size (0.648 mm) instead of 30, and the cable widths are increased in proportion. Although the inner diameter of the coil has been increased from 40 mm, the coil ends are noticeably harder to wind. The authors describe the computational and experimental effort to design winding mandrels or center posts for the constant-perimeter ends.