Speaker
Description
REBCO coated conductors are produced nowadays in lengths long enough for first demonstrative applications. Due to that also several HTS cable concepts are being developed, as Roebel Assembled Coated Conductor (RACC) cable, Coated Conductor on Round Core (CORC) cable and diverse stack cable concepts.
Approaching demonstrative applications, middle lengths of the RACC cable need to be assembled and supplied. Going from short length (couple of meter) to intermediate lengths (∼ 30 m) is a significant development step due to coated conductor geometrical inhomogeneity’s and strand forming technology issues. Up to now in the HTS cable development the focus is mostly on critical current (Ic) requirements. Thinking about long length not only Ic criteria but also geometrical homogeneity and superconducting properties homogeneity across and along the tape need to be taken into account.
Thanks to EU project EuCARD2 and its ‘’future magnets’’, development task for HTS magnets for accelerator use the cable development is pushed forward. Such accelerator focused demonstrators need customized intermediate HTS cable length which were prepared by advanced routes and supplied for coiling.
The crucial steps from short lengths of the RACC cable (below 6 m) towards intermediate lengths (∼ 30 m) will be addressed in this contribution. Geometrical irregularities of the coated conductor will be quantified, qualified and compared with RACC strand inconsistency. Internal tape inequalities of the critical current will be quantified and qualified using transport methods as well as induction measurement methods. A new punching tool for strand preparation in collaboration with CERN designed on basis of the collected experience led to significantly improved strand performance. First results with the impact on the cable performance will be shown.