Blocks-in-Conduit: REBCO cable for a 20T@20K toroid for compact fusion tokamaks

TL;DR

This paper introduces a novel REBCO cable design called Blocks-in-Conduit for high-current-density, high-field toroidal coils in compact fusion tokamaks, emphasizing improved stability, cooling, and cost efficiency.

Contribution

It presents a new cable and coil technology that enhances current density, stability, and cooling in high-field fusion magnets, with innovative splice and stress management features.

Findings

Achieves maximum current density in winding pack

Provides enhanced stability of REBCO tape blocks

Enables low-resistance demountable splices

Abstract

Blocks-in-Conduit is a novel approach to cable, coil, and splice technologies with unique benefits for a high-current-den-sity toroid D winding to operate at 20 T, 20 K. Blocks of REBCO tape are cabled in conduit, with a thin-wall center-tube spring that provides transposition, stress management at the cable level, and cross-flow cooling of a thick-coil toroid winding. The coil technology utilizes a co-wound armor structure that integrates stress manage-ment and cross-flow cooling and bypasses coil stress to protect the BIC. An interleaved splice joint enables low-resistance demountable splices of the windings. 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.