First performance test of the iron-based superconducting racetrack coils at 10 T

Abstract

Iron-based superconducting (IBS) racetrack coils were firstly fabricated by using 100-m 7-filamentary Ba1-xKxFe2As2 (Ba122) tapes at the Institute of High Energy Physics, Chinese Academy of Sciences (IHEP, CAS). The IBS tape was wound in parallel with stainless steel tape to withstand the high tensile hoop stress under high magnetic field. After the heat treatment, the coils were impregnated with epoxy resin. Then the IBS coils were tested in a low-temperature superconducting Common-Coil dipole magnet which provided a maximum background field of 10 T at 4.2 K. Most importantly, the best IBS racetrack coil quenched at 4.2 K and 10 T with an operating current of 65 A, which is still as high as 86.7% of critical current of the short sample at 10 T. The details of the fabrication process and performance test results were presented in this paper. The performance test demonstrated the IBS conductor is a promising candidate for the application of high field magnets especially for future high-energy accelerators.

Fabrication of small superconducting coils using (Ba,A)Fe2As2 (A: Na, K) round wires with large critical current densities

“…For example, the transport I c of the pancake coil achieved 35 and 25 A under magnetic fields of 100 and 240 kOe at 4.2 K, respectively [55]. A racetrack coil was also fabricated, and it quenched at 100 kOe at 4.2 K near the operating current of 65 A, which is as large as 86.7% of I c of the short sample at the same condition [57].…”

Superconducting materials: Challenges and opportunities for large-scale applications

“…In 2020, by using 100-meter 7-filament Ba-122 tapes provided by IEECAS, IBS racetrack coils were firstly fabricated at the Institute of High Energy Physics, Chinese Academy of Sciences (IHEPCAS). The racetrack coils were tested in a low-temperature superconducting common-coil dipole magnet which provided a maximum background field of 10 T at 4.2 K. One of the best IBS racetrack coil quenched at 4.2 K and 10 T showed an operating current of 65 A, which is still as high as 86.7% of the I c of short samples at 10 T ( Zhang et al, 2021 ). As presented in Figure 8 , these results demonstrate that the IBS conductor is a promising candidate for the application of high field magnets, especially for future high-energy accelerators.…”

“…At present, a conceptual design study of 12 T dipole magnets is ongoing with the IBS technology to fulfill the requirements and need of a large-scale superconducting accelerator proposed by IHEPCAS ( The CEPC Study Group, 2018 ).

Figure 8 Iron-based superconducting coils Pancake coils ( Wang et al, 2019 ; Qian et al, 2021 ) and racetrack coils ( Zhang et al, 2021 ) were made with iron-based superconductors and their in-field critical currents, which show weak field dependence up to 30 T and 12 T, respectively.

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“… Pancake coils ( Wang et al, 2019 ; Qian et al, 2021 ) and racetrack coils ( Zhang et al, 2021 ) were made with iron-based superconductors and their in-field critical currents, which show weak field dependence up to 30 T and 12 T, respectively. …”

High-Frequency ac Susceptibility of Iron-Based Superconductors

“…Since 2006, when iron-based superconductors (IBSs) were discovered [ 1 ], they raised great interest both from a fundamental point of view and for application-oriented research [ 2 , 3 ]. Throughout the years, new IBS “families” came into play, sharing some common intriguing features [ 4 ], such as their multiband nature [ 5 ], unconventional pairing [ 6 , 7 ], and nontrivial pairing symmetries [ 8 ], and for these reasons they are currently the object of an intense study effort by research groups throughout the world.…”