Abstract Body

High magnetic fields of up to 20 T in tokamak-type fusion devices require High-Temperature Superconductors (HTS). The large Lorentz forces occurring under these operating conditions may locally generate very high values of mechanical stress, which can irreversibly degrade the critical current of the superconductor. For this reason, detailed structural finite element analysis (FEA) of cables based on accurate material electromagnetic and mechanical properties under relevant electromagnetic load levels is essential.

Full-scale 3D FE models have been developed and validated at the University of Twente (UT) for 50 kA/20 T class, full-size ReBCO Cable In Conduit Conductors (CICC) based on Conductors On Round Core (CORC®)-like cables, proposed for the Central Solenoids of the European DEMO and the Chinese BEST fusion reactors. The CICC samples designed, built and further developed within a collaboration between ASIPP (China) and UT (NLD) are experimentally tested in SULTAN. In one design concept, the six CORC®-like cables are placed into the grooves of a twisted-shaped copper structure, which mechanically decouples the cables while in a second concept, the CORC®-like cables are in direct contact with each other, albeit protected by surrounding copper tubes. The full-scale FE model aims to evaluate the stress-strain state of the various tape layers in the full-size CICC CORC®-like cables as a function of the manufacturing, thermal and Lorentz loads, including detailed design and material properties. Therefore, the electrical and mechanical material properties of the used superconducting tapes are experimentally determined and simulated as nonlinear homogenous materials. The model predictions are well in agreement with experimental results and are being used to predict quantitively which configurations can best withstand Lorentz load and what the impact is of proposed geometric and material design optimisations.

References

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Acknowledgment

This work was in part supported by the EUROfusion (EU), Chinese Academy of Sciences, ASIPP (CN) and the University of Twente. The views and opinions expressed herein do not necessarily reflect those of any of the above-acknowledged parties.