A viable dipole magnet concept with REBCO CORC^®wires and further development needs for high-field magnet applications

Abstract

REBCO coated conductors maintain high engineering current density above 16 T at 4.2 K. That fact will significantly impact markets of various magnet applications including high-field magnets for high-energy physics and fusion reactors. One of the main challenges for the high-field accelerator magnet is the use of multitape REBCO cables with high engineering current density in magnet development. Several approaches developing high-field accelerator magnets using REBCO cables are demonstrated. In this paper, we introduce an alternative concept based on the canted cos θ (CCT) magnet design using Conductor on Round Core (CORC R) wires that are wound from multiple REBCO tapes with a Cu core. We report the development and test of double-layer three-turn CCT dipole magnets using CORC R wires at 77 K and 4.2 K. The scalability of the CCT design allowed us to effectively develop and demonstrate important magnet technology features such as coil design, winding, joints and testing with minimum conductor lengths. The test results showed that the CCT dipole magnet using CORC R wires was a viable option in developing REBCO accelerator magnet. One of the critical development needs is to increase the engineering current density of the 3.7 mm diameter CORC R wire to 540 A mm −2 at 21 T, 4.2 K and to reduce the bending radius to 15 mm. This would enable a compact REBCO dipole insert magnet to generate a 5 T field in a background field of 16 T at 4.2 K.

Stable, predictable and training-free operation of superconducting Bi-2212 Rutherford cable racetrack coils at the wire current density of 1000 A/mm2

“…The feasible quench detection and possible quench-free operation for standalone Bi-2212 magnets enables magnet use of the unique characteristics so far only found in Bi-2212, a combination of high stability that comes with high-T c cuprate superconductors, isotropic behavior due to the round, multifilamentary wire architecture, and the ability to produce long wires and cables with high uniformity and current sharing. With these capabilities, Bi-2212 has taken a huge step towards practical applications such as user-friendly, [25][26][27][28][29][30] T class solenoid research magnets 42 , 20-T class, canted cosine theta geometry 43,44 , accelerator magnets useful for future high-energy colliders, including a high-energy LHC upgrade, and >1.3 GHz NMR magnets due to Bi-2212 being the only isotropic, multifilamentary HTS round wire that permits high magnetic field quality. holding steps during which coil inductive signals die away and noise is much reduced b.…”

Dipole Magnets above 20 Tesla: Research Needs for a Path via High-Temperature Superconducting REBCO Conductors

“…Minimum bending radius (R min ) as shown in Figure 4 with at least 80% of I c retention after bending. Although the CCT design drives this requirement to improve the efficiency of dipole field generation [215], a small bending radius can benefit other magnet designs.…”

“…Two double-layer magnets were developed to test winding and joints. One magnet (C0a) used a 16-tape CORC R wire and the other (C0b) used a 27-tape wire [215]. Both magnets were hand-wound without tension.…”

Quench Detection for High-Temperature Superconductor Conductors Using Acoustic Thermometry

“…Layers are spliced in series using Indium-filled and bolt-tightened copper block. Details of the CCT CORC ® coil development can be found in [32,33]. The coil is instrumented with voltage taps and custom-built acoustic transducers (Fig.…”