Round Conductor With Low AC Loss Made From High-Temperature Superconducting Tapes

The second generation of high-temperature superconductor tape exhibits rapidly progressing electric transport capacity. However, its use as a conductor in magnet technology is somewhat held up by the strip-like geometry. Possible solution is the helical layout of parallel tapes on a flexible round former (recently called the Coated Conductor on Round Core or CORC). We present the study of AC properties of single-layer CORC conductors made from tapes with non-magnetic substrate. When subjected to AC magnetic field, single-layer CORC conductors exhibit negligible coupling currents because the tapes are fully transposed. On top of this the hysteresis loss can be reduced by the tape striation. Numerical simulations of magnetization loss for CORC conductors are in good agreement with experimental data. Prediction of AC loss in a coil made from CORC is compared to that calculated for a classical double pancake one made from the same amount of tape. Result indicate that the CORC-made coil produces lower losses at AC current amplitudes approaching the critical current.