Speaker
Description
High quality materials are essential to the success of large magnet projects. National High Magnetic Field Laboratory (NHMFL) has been funded by the US National Science Foundation to design a 40 T superconducting magnet which uses REBCO coated conductor tapes for the insert coil winding co-wound with copper and stainless-steel tapes. Characterization and incoming quality assurance (QA) testing for these materials are obviously critical to the success of test coils in this project.
The critical current (Ic) of commercial REBCO tapes is typically characterized by the vendors at 77 K. But Ic at 4.2 K, the temperature the 40 T magnet is designed for, and many other important properties are not tested by the vendors. Therefore, we carry out a comprehensive QA sub-project. The following tests are performed on each spool of the received tapes: transport Ic at 4.2 K in magnetic field up to 15 T; Ic versus field angle using torque magnetometry at 4.2 K up to 15 T; residual-resistance-ratio (RRR) of copper stabilizer; thickness profile across tape width; REBCO ab plane tilt angle; peel strength; and lap joint resistivity at 77 K. In addition, the electromagnetic property such as Ic versus longitudinal tensile strain, and tensile fatigue properties are measured every 10 spools at 77 K. The mechanical properties of copper and stainless-steel co-wind tapes are characterized as well.
In this talk, we present results from these comprehensive QA tests of over 150 spools of REBCO tapes (total of >20 km). Important experiences of carrying out these incoming QA measurements will be shared.
Acknowledgment
This work was performed at the National High Magnetic Field Laboratory, which is supported by National Science Foundation Cooperative Agreement No. DMR- 2128556, DMR- 2131790, and the State of Florida, and by DMR-1644779 through User Collaborations Grants Program.
