Twisting & Bending Performance of a Subscale CORC Cable-in-Conduit-Conductor for Fusion and Detector Magnet Applications

Future magnetic confinement fusion machines and detector magnets will likely utilize high temperature superconducting (HTS) wire and/or tapes, configured in a Cable-in-Conduit-Conductor (CICC) to generate magnetic fields at temperatures above 4.2 K. As such, these CICCs will need to be twisted & bent to meet the design criteria for any given machine. We investigated the critical current (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub>) degradation of a subscale 6-around-1 CICC using Conductor-on-Round-Core<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> (CORC<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup>) wires after ever increasing deformation. A CORC<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> wire was inserted into one of six outer openings of an extruded aluminum conduit to form a sub-scale CICC, after which the CICC was twisted to ∼25 cm pitch and the whole assembly was then sequentially bent to nominal radii of ∼50 cm, ∼35 cm, and ∼25 cm. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> values at 77 K and self-field when straight and after each deformation step was measured. The CORC<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> wire <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> was robust to this type of “twisting + bending” deformation, with an overall degradation of ∼10% with respect to the straight, non-twisted wire. We also describe a CICC twisting process that potentially allows twisting of continuous-length CICCs after the CORC<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> wires are inserted. This method can lead to a scalable fabrication process of long-length CORC<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> CICCs that are required for manufacture of high-field fusion magnets and detector magnets for high-energy physics research.