REBCO Coated Conductor Cables for Accelerator Magnets

Accelerator magnets that are currently being used in high-energy physics experiments are limited to a maximum magnetic field of about 20 T because superconductivity in the low- temperature superconductors (LTS) from which the magnets are constructed breaks down at higher fields. The only way to build the next generation of more powerful accelerator magnets is by using high-temperature superconductors (HTS) that can operate at magnetic fields of 20 T and above. There is currently no feasible method to bundle HTS into high-current cables that have an overall current density of at least 150 A/mm2 at 20 T that is required for the next generation of accelerator magnets. This proposal seeks to develop HTS cables that have a high current density needed for the next generation of superconducting accelerator magnets that operate at fields of 20 T and above. During Phase I, we demonstrated the feasibility of raising the critical current density at 20 T of conductor on round core (CORC) cables that were invented by the PI towards 200 A/mm2. During Phase II we will commercialize CORC cables that have a critical current density of at least 300 A/mm2 at 20 T from which the next generation of accelerator magnets can be built. We will accomplish this by optimizing the cable layout when using superconducting tapes that have thin layers of copper and contain thin substrates. Commercial Applications and Other Benefits: High-temperature superconducting magnet cables with high current densities will enable the next generation of accelerator magnets for high-energy physics, proton cancer treatment facilities, and practical fusion magnets. These cables will also benefit superconducting magnetic energy storage systems for use in the power grid and for application within the Department of Defense.