AC Loss Reduction in REBCO Coated Conductors using the Hexagonal Arrangement Cabling Method

High-temperature superconducting (HTS) rare-earth barium copper oxide (REBCO) coated conductors with outstanding critical current density under high fields can help realize a high-field path toward magnetic-confinement fusion. REBCO cabling methods such as conductor on round core (CORC) cables, twisted stacked tape conductor (TSTC) cables, and Rutherford cables are based on the cable-in-conduit conductor (CICC) developed for low-temperature superconducting (LTS) Nb3Sn and Nb-Ti conductors. However, the REBCO coated conductor has challenges in achieving current transposition by twisting due to its ceramic-like mechanical behavior. In addition, it is more sensitive to external perpendicular magnetic fields with its rectangular cross-section than metallic LTS superconductors. In order to solve these issues, a hexagonal arrangement REBCO cabling method with the inherent advantage of mechanical protection and inductance balance is proposed in this paper. The electromagnetic behavior of REBCO coated conductors in the cable is evaluated using H-formulation and T-A formulation-based finite element methods. Results show that AC losses can be reduced using the hexagonal arrangement method compared with non-twisted cables and TSTC cables, which makes it a potentially helpful cabling method for ultra-high-field large-scale applications with high-level inductance balance requirements, especially the central solenoid coils of thermonuclear fusion reactors.