The first CICC-type Bi-2212 insert coil for high-field applications up to 20 T

As the need for high-magnetic field magnets, this article made the first cable-in-conduit conductor (CICC) -type Bi-2212 insert coil. The Bi-2212 conductor consists of 24 wires, an Ag tube, and a 316 LN jacket. With the optimized heat-treatment regime, the insert coil exhibited excellent current-carrying capacity under magnetic fields up to 20 T: the I_c of the coil was up to 5.4 kA under 20 T backfield. With the ‘Pre-OP before cabling’ process, the void fraction was precisely controlled. Besides, the insert coil exhibits excellent stability with the electromagnetic loads and quenching process: no obvious change in performance was detected even when the electromagnetic loads increased to 101 kN m⁻¹; after the quench event where the voltage on the insert coil was up to ∼4000 times criterion, no degradation was detected. The excellent performance of the Bi-2212 insert coil gives a solid foundation for the development of full-size Bi-2212 CICC for high-field applications.