Alternative current losses of superconductor corc cables with copper former

High temperature superconductors from REBCO (RE = rare earth) family reached industrial production and their performance is continuously enhancing. However, cabling technology using these conductors for high-current (kA-range) cables for magnet (coil) technology is still challenging and there are only few cable concepts (CORC®, Roebel cable, twisted stack cable). Each of them exhibits different characteristics. In this study we experimentally investigate CORC® cable produced in house utilizing copper tube former. Such former offers central cooling channel for partial or complete cable cooling by forced flow of coolant. We focused mainly on AC loss due to transport AC current, external applied AC magnetic field and their simultaneous action. In case of transport AC current we have found indications that large part of total loss has origin in eddy current due to axial magnetic field. For magnetization AC loss investigation we prepared several samples with different configurations. In this case we found direct evidence of AC loss increase due to loss in former. However, we have also found that at low field amplitudes magnetization AC loss of the complete cable is lower than loss in bare former. This is caused by shielding of the magnetic field by superconductor, which was also confirmed by numerical simulations.