Blocks-in-Conduit: REBCO Cable for a 20T@20K Toroid for Compact Fusion Tokamaks

Blocks-in-Conduit is a novel approach to cable, coil, and splice technologies with unique benefits for a high-current-density toroid winding to operate at 20 T at 20 K. Blocks of REBCO tape are cabled in conduit, with a laminated structure and thin-wall center-tube that provides twist along the cable, spring-loaded stress management within the cable, and cross-flow cooling throughout a thick toroid winding. The coil technology utilizes a co-wound armor structure that integrates stress management, cross-flow cooling and bypass of coil stress to protect the BIC. An interleaved splice joint enables low-resistance demountable splices within the winding pack. These provisions yield maximum current density in the winding pack, maximum stability of the REBCO tape blocks, and minimum conductor cost for a tokamak toroid.