The unique structure of conductors on round core (CORC) cable leads to symmetrical electromagnetic properties and excellent mechanical performance. However, it is quite a big challenge to analyze the mechanical properties of CORC cables, due to the unpredictable initial residual stress generated during the fabrication process of both tape and cable. In this paper, the mechanical model of CORC cable consists of several individual models representing the tape fabrication, cable fabrication, CORC cable bending and cooling process. The numerical model is verified by experimental results of both superconducting tapes and CORC cables. On basis of this, the numerical model is used to explain the mechanism of performance degradation during bending process. Moreover, the effects of winding angle on critical bending diameter are analyzed from the aspect of critical current degradation and physical extrusion. And simulation results are used to determine the principle critical bending diameter of CORC cable. Conclusions in this paper can be useful for design of CORC cables in applications where small bending diameter is needed.

High temperature superconducting (HTS) conductor on round core (CORC) cable is considered as a potential technology for power applications, because of its high current-carrying capacity, compactness, and strong mechanical properties. As the main component of CORC cable, center core is used to support the HTS conductors. However, for metal center core, eddy current induced in the core under alternating electromagnetic field is unneglectable, which will lead to extra AC loss in power applications. This paper focuses on the selection of center core of CORC cable. AC losses of CORC cable using different core materials are evaluated by both numerical and experimental methods, in which copper, stainless steel, fiberglass epoxy and nickel have been chosen as the core. Results illustrate that AC loss of CORC cable has a correspondingly increase with the conductivity of core material. Significant frequency dependence of AC loss indicates that for single layer CORC cable, proper core material should be chosen to minimize the eddy current loss. Besides, CORC cable with core of nickel shows a quite different AC performance due to its ferromagnetic characteristics. Conclusions obtained from this paper will provide essential data for future optimization on the design of CORC cables.

Conductor on round core (CORC) cables with the features of flexibility and a high engineering current density have been a potential candidate for high magnetic field magnets and accelerator magnets. In these applications, reducing the magnetization loss generated in superconductors is essential in the process of design. CORC cables fabricated by multifilament-coated conductor (CC) tapes have been proved to have a low magnetization loss. However, the degradation of the critical current (I _c ) and additional coupling losses significantly affects the performance of CORC cables. In this article, ultraviolet laser cutting technology is used to scribe both the superconducting layer and copper stabilization layers into narrow filaments. First, the magnetization loss of a single tape with different numbers of filaments was measured by a calibration-free method. Then, based on the testing results of a single tape, two typical CORC cables are wound by 10-mm-wide and 4-mm-wide CC tapes. The magnetization loss of cables made of striated tapes was discussed by both experimental and numerical methods. It is found that the magnetization loss significantly decreases with an increasing number of filaments under a high background magnetic field. The magnetization losses decrease in CORC cables made of striated CC tape. Due to the reduced coupling loss and attenuated shielding effect, there is not much difference between the two values of the magnetization loss reduction rates in CORC cables and single tapes. The conclusions obtained in this article will be instructive for the future design of CORC cables.

Striation has been proved to be effective in reducing the magnetization losses of Conductor on Round Core (CORC®) cables assembled with REBCO coated conductors. In this study, we present numerical models of CORC® cable with striated strands considering the inter-filamentary coupling by using 3D ${T-A}$ formulation. Calculated magnetization losses were compared against experimental data to confirm the validity of our models, including 3×2 CORC® cables with straited and non-striated strands. Frequency dependence of magnetization losses and the electromagnetic coupling effect were demonstrated and analyzed. The coupling loss fits well with analytical function. And the coupling time constant characteristics was found almost in proportion to the square of pitch length.

Implement of low-resistive and compact terminal between superconducting cables and bus-bars is one of the most important challenges for industrial application of conductor on round core (CORC) cables. In this paper, a three-dimensional numerical model capable of simulating the terminal resistance and joint resistance of CORC cables is developed and validated by experimental data. On basis of this, the effect of different current injection methods on terminal resistance and the effect of trimming of HTS tapes on current distribution are discussed in this paper. Results shows a wide range of variation in terminal resistance and the homogeneity of current distribution. We expect conclusions obtained from this paper could provide guidelines for commercial and practical terminal fabrication of CORC cables.