Design description of the helical field coils for the Advanced Toroidal Facility

The Helical Field (HF) Coils for the Advanced Toroidal Facility will consist of two coils, which wrap around the plasma six times. The major radius of the coils will be 2.1 m with a minor radius of 45.75 cm to the coil current center. The coils will be positioned at assembly to within a 2 mm diameter around the winding law, Theta = 1/6 Phi. The coils will be fabricated as a set of 24 identical segments, 12 upper segments and 12 lower segments. These segments will be joined into continuous coils at the installation site by means of field assembled joints at the horizontal centerline of the machine. One special joint on each coil will contain the coil leads. The HF coils will consist of 14 copper turns and a structural member of stainless steel which has a cross section in the shape of a T. These pieces will be fabricated in accordance with the winding law Theta = 1/6 Phi. The copper turns will be water cooled and formed from CDA 101 or 102 copper. The 14 copper turns will be positioned such that 7 turns will be placed on each side of the structural tee. The structural tee will be fabricated from 44.45 mm thick stainless steel with a minimum yield strength of 205 MPa and a tensile strength of 485 MPa