DC performance test of twisted stacked slotted-core CICC prototype under 80 kA current and 10.85 T background field

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Abstract
The development of high-field superconducting magnets for next-generation fusion devices requires robust, high-current cable-in-conduit conductors (CICCs) that withstand combined electromagnetic, thermal, and mechanical loads. In this work, a 2.8 m-long full-size prototype of a twisted stacked-tape rare-earth barium copper oxide (REBCO) CICC with a lateral support structure was designed, fabricated, and tested at the SULTAN facility. The prototype comprises three twisted stacked slotted-core sub-cables (336 REBCO tapes total), vacuum-solder consolidated onto a slotted copper former, wrapped with copper and 316 l tape and compacted into a CHSN01 stainless-steel jacket. Baseline tests at 77 K and self-field obtained a critical current ( I c ) of 16.6 ± 0.3 kA and an n -value of approximately 27. At a magnetic field of 10.85 T and operating currents of 60 kA and 70 kA, the measured current sharing temperature ( T cs ) values were approximately 23.5 K and 19.6 K, respectively, deviating within 1.0 K of the predicted average for REBCO tapes. Under electromagnetic cycling conditions with currents reaching 75–80 kA and a background field of 10.85 T, the prototype exhibited only a 1.3% reduction in T cs after the 53rd cycle, and remained stable throughout subsequent cycles, demonstrating excellent capability to withstand high-field electromagnetic loads. This represents the successful operation of a twisted stacked-tape conductor-type high-temperature superconducting (HTS) CICC under an electromagnetic load of ∼830 kN·m −1 . The results confirm that vacuum soldering combined with a lateral support structure can effectively enhance the capability of HTS CICC to prevent the degradation under high transverse electromagnetic loads, providing crucial engineering experience for the future development of high-field HTS conductors for fusion magnet applications.
Funding Information
  • Comprehensive Research Facility for Fusion Technology Program of China (2018-000052-73-01-001228)
  • National Natural Science Foundation of China (52307035)

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