Investigating the effect of transverse compressive loads on the electromagnetic performance of superconducting CORC^® cables

Abstract

High-temperature superconductor (Re)Ba2Cu3Ox (ReBCO) conductor on round core cable (CORC®) has a large current carrying capacity for high field magnets. Lorentz forces acting on CORC conductors, cause a reduction of the critical current, or even permanent degradation of their performance when exceeding critical values. Transverse compressive stress is one of the principal mechanical stresses when CORC cables are bundled to CICC conductors capable of operating at currents up to 100 kA in magnetic fields of up to 20 T. In this research, a mechanical-electromagnetic model is developed to study the effect of transverse compressive loads on the electromagnetic performance of CORC cables. A mechanical transverse load on the cable is implemented to simulate the electromagnetic force. A comparison of numerical simulations with experiments for a three-layer CORC cable is first performed to validate the model's reliability, with particular attention to critical current reduction during the transverse compression process. A novel feature of this paper is that the model developed can analyze both mechanical response under transverse compressive loads and electromagnetic performance under applied AC magnetic fields with low amplitudes. On this basis, the model investigates the effects of winding parameters on the axial strain and critical current reduction of the ReBCO layer in a single-layer CORC cable. The numerical analysis shows that increasing the winding angle can reduce the axial strain and critical current reduction of the ReBCO layer in the contact area. Subsequently, a detailed comparative study is carried out studying the axial strain of the ReBCO layer in the non-contact area with and without taking the winding core into account. In addition, a sudden increase of the magnetization loss is explained when the transverse compressive load reaches a certain level. Finally, a six-layer CORC cable's electromagnetic analysis is performed, and each tape layer's critical current reduction is investigated and discussed. The comparison of magnetization loss and current density between six- and single-layer CORC cables in the no-strain case is also given. This FE model can guide optimizing a cable design for specific application conditions.

Influence of HTS tape arrangement on the transverse compression performance of copper former CORC cables

“…The first study of this performance is carried out by Van Der Laan et al and it is found that parameters such as the former size, the gap between HTS tpaes, and the thickness of copper laminating of the tape have a significant effect on the transverse compression performance of CORC cables [31]. Yan et al found that the winding angle of HTS tape also has a significant impact on the transverse compression performance of CORC cables [32]. Whereas, the current research on the transverse compression performance of CORC cables is not comprehensive enough, and the influence of many factors on the transverse compression performance of CORC cables is still blank.…”

CORC Cables: Numerical Characterization of the Critical Current After Bending

“…In [8] a detailed parametric analysis, validated through experiments, aimed at defining the stress-strain state for the determination of the critical strain that may cause the breakage of the YBCO layer, considering the bending of the cable. In [21] and in [22], electromechanical simulation, based on T −A formulation, were performed to predict the strain state and the critical current degradation for straight CORC ® cables. The thermal behavior was not considered in those models and the current was imposed without any possibility of redistributing, if necessary, due to uneven strain in different tapes.…”

Performance test of REBCO CICC sub-cables with 10 kA current under 20 T background field

“…Experiments show that REBCO cables are capable of maintaining high current-carrying capability under a high electromagnetic (EM) load [23]. However, the mechanical performance of the conductor on round core (CORC) cables is associated with the tape specifications [24], winding parameters [25], screening current [26] and so on. Moreover, degradation was caused by the deformation of the cables during bending and EM cycling in modeling and experimental tests [27,28].…”