Critical Current Measurements of Prototype REBCO Round Cables at 77 K

High temperature superconducting (HTS) cables are necessary for next-generation high-field accelerator magnets, and various types of HTS cables have been developed worldwide. We have started the development of HTS cables in which rare-earth barium copper oxide (REBCO) coated conductors are spirally wound around a flexible multi-wire core. In this study, we constructed five sample cables with a 2-mm-wide coated conductor and a 1.8-mm-diameter multi-wire core. The transport critical current (I-c) of the coated conductors used for the sample cables was measured at 77 K and 4.2 K. At 4.2 K, the I-c was measured in a perpendicular magnetic field from 1 T to 18 T. The transport I-c and bending properties of the sample cables were characterized at 77 K. The cable I-c degraded 10-16% due to the cable construction and 10% after bending the cable with a radius of 20 mm. The cable current density (J(e)) at 20 T and 4.2 K was estimated as a function of the cable diameter.