Introduction of CORC^®wires: highly flexible, round high-temperature superconducting wires for magnet and power transmission applications

Abstract

Conductor on Round Core (CORC®) technology has achieved a long sought-after benchmark by enabling the production of round, multifilament, (RE)Ba 2 Ca 3 O 7-x coated conductors with practical current densities for use in magnets and power applications. Recent progress, including the demonstration of engineering current density beyond 300 Amm-2 at 4.2 K and 20 T, indicates that CORC® cables are a viable conductor for next generation high field magnets. Tapes with 30 µm substrate thickness and tape widths down to 2 mm have improved the capabilities of CORC® technology by allowing the production of CORC® wires as thin as 3 mm in diameter with the potential to enhance the engineering current density further. An important benefit of the thin CORC® wires is their improved flexibility compared to thicker (7 to 8 mm diameter) CORC® cables. Critical current measurements were carried out on tapes extracted from CORC® wires made using 2 and 3 mm wide tape after bending the wires to various diameters from 10 cm to 3.5 cm. These thin wires are highly flexible and retain close to 90 % of their original critical current even after bending to a diameter of 3.5 cm. A small 5-turn solenoid was constructed and measured as a function of applied magnetic field, exhibiting an engineering current density of 233 Amm-2 at 4.2 K and 10 T. CORC® wires thus form an attractive solution for applications between 4.2 K and 77 K, including high-field magnets that require high current densities with small bending diameters, benefiting from a ready-to-use form (similar to NbTi and contrary to Nb 3 Sn wires) that does not require additional processing following coil construction.

J e (4.2 K, 31.2 T) beyond 1 kA/mm2 of a ~3.2 μm thick, 20 mol% Zr-added MOCVD REBCO coated conductor

“…However, from the perspective for magnet applications, multifilamentary round wire is strongly preferred for easy handling, isotropic performance and reduced ac loss. Several cabling techniques have been developed for REBCO coated conductors to produce suitable conductors for magnet builders with varying levels of success 41, 42 . The cabling unavoidably compromises the J e advantage of REBCO coated conductors because of the need for mechanical support.…”

Strain Distribution in REBCO-Coated Conductors Bent With the Constant-Perimeter Geometry

“…For a conductor layout shown in Fig. 2, a thinner substrate places the REBCO layer closer to the neutral plane and reduces the minimum bending diameter for round REBCO wires [28,29].…”

“…The configuration of a helical tape is used for CORC R [17,26,28,29] and other round cables [30,31]. The base curve for this configuration is a circular helix X = (r cos t, r sin t, p t), (6) where the radius r is the sum of the former radius and half of the tape thickness; t is the parameter in radian and 2πp is the pitch length.…”

Quench Detection for High-Temperature Superconductor Conductors Using Acoustic Thermometry

“…We adapted our technique to detect quenching in the prototype two-layer dipole assembly wound with HTS CORC ® [30] cable. The coil assembly layers are wound in "Canted Cosine Theta" [31] pattern around the 3D-printed "blue stone" mandrels using CORC ® conductor comprising 29 REBCO tapes (2 mm wide and 30 m-thick substrate) distributed around a copper core wire of 2.56 mm diameter.…”