SuperCIC: Enhanced Winding Current Density for Hybrid Windings of Tokamaks

• Published in: IEEE transactions on applied superconductivity 2020-06, Vol.30 (4), p.1-7
• Main Authors: McIntyre, Peter, Breitschopf, Jeff, Brown, Tom E., Chavez, Daniel, Kellams, Joshua N., Sattarov, Akhdiyor
• Format: Article
• Language: English
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Armor; Aspect ratio; Bismuth strontium calcium copper oxide; Cable shielding; Coils (windings); Current density; Electron tubes; Extrusion; fusion; hybrid windings; Kerf; Sheaths; Superconducting cable; Superconducting cables; Superconducting magnets; tokamak; Tokamak devices; Tokamaks; Winding; Windings; Wires
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2020.2971195

The design is presented for a new approach to cable-in-conduit (SuperCIC) for use in the high-field windings of tokamaks. Two layers of high-field superconductor wires are cabled onto a thin-wall perforated center tube. An overwrap is applied and the cable is inserted as a loose fit into a sheath tube. The sheath tube is drawn down onto the cable to compress the wires onto the center tube and immobilize them. The SuperCIC is then co-wound with a high-strength armor extrusion, which is kerf-cut so that the co-winding onto a coil mandrel can be made without deformation within the armor or the CIC. SuperCIC facilitates hybrid windings, in which sub-windings of NbTi are used where B < 7 T, Nb 3 Sn where B < 14 T, and Bi-2212 where B > 14 T to minimize superconductor cost. Demountable splices are used to interconnect layers. A conceptual design has been prepared for a tokamak with aspect ratio A ∼2.0, magnetic field of 17.4 T at the inner windings and 6.7 T at the plasma, and winding current density ∼140 A/mm 2 - sufficient for optimizing the fusion power density in a compact spherical tokamak