REBCO coated conductors maintain high engineering current density above 16 T at 4.2 K. That fact will significantly impact markets of various magnet applications including high-field magnets for high-energy physics and fusion reactors. One of the main challenges for the high-field accelerator magnet is the use of multitape REBCO cables with high engineering current density in magnet development. Several approaches developing high-field accelerator magnets using REBCO cables are demonstrated. In this paper, we introduce an alternative concept based on the canted cos θ (CCT) magnet design using Conductor on Round Core (CORC R) wires that are wound from multiple REBCO tapes with a Cu core. We report the development and test of double-layer three-turn CCT dipole magnets using CORC R wires at 77 K and 4.2 K. The scalability of the CCT design allowed us to effectively develop and demonstrate important magnet technology features such as coil design, winding, joints and testing with minimum conductor lengths. The test results showed that the CCT dipole magnet using CORC R wires was a viable option in developing REBCO accelerator magnet. One of the critical development needs is to increase the engineering current density of the 3.7 mm diameter CORC R wire to 540 A mm −2 at 21 T, 4.2 K and to reduce the bending radius to 15 mm. This would enable a compact REBCO dipole insert magnet to generate a 5 T field in a background field of 16 T at 4.2 K.

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Abstract-We report on the progress in our R&D program, targeted to develop the technology for the application of Bi2Sr2CaCu2Ox (Bi-2212) in accelerator magnets. The program uses subscale coils, wound from insulated cables, to study suitable materials, heat treatment homogeneity, stability, and effects of magnetic field and thermal and electro-magnetic loads. We have addressed material and reaction related issues and report on the fabrication, heat treatment, and analysis of subscale Bi-2212 coils. Such coils can carry a current on the order of 5000 A and generate, in various support structures, magnetic fields from 2.6 to 9.9 T. Successful coils are therefore targeted towards a hybrid Nb3Sn-HTS magnet which will demonstrate the feasibility of Bi-2212 for accelerator magnets, and open a new magnetic field realm, beyond what is achievable with Nb3Sn.

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