Development and Testing of the First REBCO Racetrack Model Coils at CERN

This is the authors' abstract. We don't add key points for this paper.

One of the goals of the High Field Magnet (HFM) Program at CERN is to explore High-Temperature Superconducting (HTS) magnet technology for accelerator applications that go beyond the limits of low-temperature superconductors such as Nb3Sn. This offers a pathway for the development of higher energy and more sustainable particle accelerators operating at temperatures above 1.9 K or even 4.5 K. As a stepping-stone to achieve these goals, CERN has launched the development of model coils in racetrack geometry that can be scaled up for use in common coil-type magnets. The model coils were used to validate winding tooling, a newly developed cable insulation application method, instrumentation placement, conductor performance, and other key design choices with a short iteration cycle that allows for rapid development. We detail the coil electromagnetic design, and several lessons learned during the progression from single-layer to double-layer coils with an internal layer jump that allows for a modular magnet design approach. Additionally, the results from liquid nitrogen tests and preliminary findings from liquid helium testing are discussed.