Development of CORC® Wires for use in Canted Cosine Theta Accelerator Magnets

Accelerator magnets that are currently being used in high-energy physics experiments are limited to a maximum magnetic field of less than 20 T because superconductivity in the low- temperature superconductors from which the magnets are constructed breaks down at higher fields. The next generation of accelerator magnets needs to be made from high-temperature superconducting magnet cables. Such cables with sufficient performance are unavailable. This proposal seeks to develop high-temperature superconducting CORC® magnet wires that would enable the next generation of accelerator magnets that operate at 20 T and above. They will be tailored for use in canted cosine theta accelerator magnets, which is a design in which the stresses on the conductor are effectively managed to a safe level for the conductor. During Phase I of the program, we’ve demonstrated the feasibility of winding CORC® wires with a high current density into canted cosine theta magnet structures and demonstrated the their performance didn’t degrade significantly when bent to a diameter of less than 40 mm. During Phase II of the program, we will develop commercial high performance CORC® wires to enable canted cosine theta insert magnets that can operate inside an outsert made from low temperature superconductors, with the goal to increase the total magnetic field to at least 20 T. The CORC® wire performance will be increased to 600 A/mm2 at 20 T, while their flexibility is improved to allow bending diameters of less than 30 mm. Several prototype subscale canted cosine theta insert magnets will be constructed and tested during Phase II of the program. High-temperature superconducting magnet wires that have a high current density at 20 T, while being bendable to diameters less than 30 mm, will enable some of the next generation of high- energy physics magnets, proton cancer treatment facilities, practical fusion magnets, and scientific magnets. These magnets will also benefit superconducting magnetic energy storage systems for use in the power grid and for application within the Department of Defense. The development of high current density magnet wires made from high-temperature superconductor and magnets wound from these wires is necessary for the US to maintain their leadership position in superconductivity research, materials science, medical applications and high-energy physics research.