Numerical and experimental studies on the current capacity of VIPER high temperature superconducting cable

Abstract Growing demands for superconducting cables with high current density and excellent stability in nuclear fusion, high energy physics, and smart grids have rendered high temperature superconducting (HTS) cables based on REBCO coated conductors a critical technical route for next generation high field magnets. The Vacuum Impregnated Pressurized Roebel (VIPER) cable inherits the advantages of Twisted Stacked-Tape Cable (TSTC) and Cable-in-Conduit Conductor (CICC), constituting a novel HTS conductor architecture with high current carrying capacity and structural stability. To systematically investigate the influence of tape stacking number on the self-field current carrying performance of VIPER cables, three three dimensional electromagnetic models corresponding to 5 slot 8 layer, 5 slot 9 layer, and 5 slot 10 layer configurations were developed and simulated at temperature 77 K using Ansys Maxwel.The results demonstrate that the relative errors between simulated and experimental critical currents for all three configurations are within an acceptable range of 5%. As the number of stacked layers increases, the total current-carrying capacity rises from 3810.8 A (8 layers) to 4156.0 A (9 layers) and 4515.2 A (10 layers), while the inter-slot current distribution deviation decreases from 7.35% to 1.55%. Nevertheless, the self-field superposition effect intensifies, with a maximum value of approximately 0.433 T. The average current carried by a single tape decreases from 95.3 A to 90.3 A, and its ratio to the self-field critical current of an individual tape (195 A) declines from 48.9% to 46.3%. The local critical current of the tapes gradually reduces from approximately 183.6 A at the innermost layer to 94.96 A at the outermost layer, yielding a current-sharing efficiency of only 62.2%–63.2%, substantially lower than the theoretical upper limit under ideal full current sharing (6130–7149 A). The measured total current of the 10-layer cable reaches 95.1% of the conservative weakest-link limit (4748 A). The marginal gain drops from 9.1% for the transition from 8 to 9 layers to 8.6% for the transition from 9 to 10 layers, indicating diminishing returns when further increasing the layer count under self-field limitation, proposes optimal parameters based on theoretical and data analysis This study provides fundamental data and quantitative references for optimizing the stacking layer number of VIPER cables.