/pdf/a-review-of-commercial-high-temperature-superconducting-2o02lszkmx.pdf

A review of commercial high temperature superconducting materials for large magnets: from wires and tapes to cables and conductors

https://iopscience.iop.org/article/10.1088/1741-4326/aad835/pdf

High temperature superconductors for fusion magnets

A Conductor on Round Core (CORC®) cable wound with a high temperature superconductor is an important cable concept for high current density applications. The design of a CORC cable makes understanding its electromagnetic performance—for example its AC losses—challenging. This paper presents a thorough study of CORC cables by combining experimental and numerical methods. In particular, it focuses on understanding how the cable structure influences the magnetization losses and on how these can be reduced. A novelty of this paper lies in the use of a new T-A formulation, which, for the first time, is employed for three-dimensional modelling of a CORC cable with real geometry. The use of the new T-A formulation in finite element software enables the study of how the winding direction and multiple-layer structure affect the magnetization losses of CORC cables. Moreover, influence of striation in CORC cables is studied as an effective way to reduce their losses. A CORC cable with striated tapes shows a significant magnetization loss reduction at high magnetic fields, in comparison to its counterpart without striated tapes. At low magnetic fields, tape striation leads to an increase in loss when the number of filaments is low, then the loss drops with a further increase in the number of filaments, but this loss reduction is much weaker than that at high fields. This paper provides an efficient tool for investigating the electromagnetic behaviour of CORC cables, which can provide valuable guidance in designing CORC cables with minimized losses for high energy physics and energy conversion applications.

/pdf/study-of-the-magnetization-loss-of-corc-cables-using-a-3d-t-1vivl5fee8.pdf

Study of the magnetization loss of CORC® cables using a 3D T-A formulation

We report on remarkably high in-field performance at 4.2 K achieved in >4 μm thick rare earth barium copper oxide (REBCO) samples with Zr addition. Two different samples have been measured independently at Lawrence Berkeley National Laboratory and the National High Magnetic Field Laboratory, achieving critical current densities (J c ) of 12.21 MA cm−2 and 12.32 MA cm−2 at 4.2 K, 14 T (), respectively, which corresponds to equivalent critical current (I c ) values of 2247 and 2119 A/4 mm. These I c values are about two times higher than the best reported performance of REBCO tapes to date and more than five times higher than the commercial HTS tapes reported in a recent study. The measured J c values, with a pinning force of ~1.7 T N m−3 are almost identical to the highest value reported for thin (~1 μm thick) REBCO at the field and temperature, but extended to very thick (>4 μm) films. This results in an engineering current density (J e ) above 5 kA mm−2 at 4.2 K, 14 T, which is more than five times higher than Nb3Sn and nearly four times higher than the highest reported value of all superconductors other than REBCO at this field and temperature. The reported results have been achieved by utilizing an advanced metal organic chemical vapor deposition system. This study demonstrates the remarkable level of in-field performance achievable with REBCO conductors at 4.2 K and strong potential for high-field magnet applications.

/pdf/engineering-current-density-over-5-ka-mm-2-at-4-2-k-14-t-in-4qfbgst9bc.pdf

Engineering current density over 5 kA mm-2 at 4.2 K, 14 T in thick film REBCO tapes

A comprehensive overview of inductive pad in electric vehicles stationary charging

Using ultrathin RE-Ba-Cu-O (REBCO, RE = rare earth) superconductor tapes, we have fabricated of a multilayer round wire with an outer diameter of 1.6 mm on a flexible copper former of 0.8 mm diameter with a critical current of 283 A at 77 K, self-field. A single-layer round wire's angular dependence of critical current in a magnetic field shows near isotropic characteristics. The critical current of a single-layer round wire has been measured over a temperature range of 30-77 K in magnetic fields up to 9 T.

Fabrication and Electromagnetic Characterization of Ultrasmall Diameter REBCO Wires

Round REBCO (RE = rare earth) wires of 1.6–1.85 mm diameter have been fabricated using ultrathin REBCO tapes where the superconductor film is positioned near the geometric center. Such symmetric tape round (STAR) wires exhibit excellent tolerance to bend strain with a critical current retention of more than 97% when bent to a radius of 15 mm. A 1.6 mm diameter REBCO STAR wire made with six 2.5 mm wide symmetric tapes reached an engineering current density (J e) of 454 A mm−2 at 4.2 K in a background field of 15 T at a bend radius of 15 mm. Such superior performance at a small bend radius can enable fabrication of future accelerator magnets, operating at magnetic fields above 20 T.

Symmetric tape round REBCO wire with J e (4.2 K, 15 T) beyond 450 A mm−2 at 15 mm bend radius: a viable candidate for future compact accelerator magnet applications

Erratum: Symmetric tape round REBCO wire with J e (4.2 K, 15 T) beyond 450 A mm−2 at 15 mm bend radius: a viable candidate for future compact accelerator magnet applications (2018 Supercond. Sci. Technol. 31 04LT01)

A 12-filament laser striated coated conductor is studied using Scanning Hall Probe Microscopy (SHPM). Remanent field is measured and critical current density distribution is calculated according to the measured field map. The results show that the SHPM technique is very sensitive to defects. A point-like defect can be readily discerned in the magnetic field map, even when the drop in critical current density is small. We also found that the choice of a proper filter is important for obtaining accurate critical current density values, especially for the multifilament superconducting tapes.

Scanning Hall Probe Microscopy on Laser Striated Multifilament Coated Conductor

The bending properties of RE-Ba-Cu-O (REBCO, RE = rare earth) coated conductors are a stringent constraint for coil and cable applications. While the use of thinner substrates reduces the stresses/strains in the REBCO layer, it is also possible to enhance the mechanical properties of these tapes by optimizing the stabilizer thickness in order to reduce the distance between the neutral axis and the REBCO layer. In this paper, we present both experimental and analytical results showing a significant improvement in the critical current (I
 c
) retention at small bend diameters (less than 2 mm) for tapes with various substrate thicknesses by using an optimized copper thickness on the REBCO side only. The presented analytical method accounts for the neutral axis shift caused by the progressive plastic deformation in the various layers (Hastelloy, silver, and copper). The Ic dependence of different substrate tapes on the thickness of single-sided electroplated copper stabilizer was measured at bending diameters ranging from 0.81 to 12.5 mm by means of a single-turn helical winding on a cylindrical former. The strains were then calculated and an optimized copper thickness is determined for the various configurations. Based on these results, an optimal design for ultra-small diameter REBCO wires is also presented.

Anis Ben Yahia

Papers

Fabrication and Electromagnetic Characterization of Ultrasmall Diameter REBCO Wires

Symmetric tape round REBCO wire with J e (4.2 K, 15 T) beyond 450 A mm−2 at 15 mm bend radius: a viable candidate for future compact accelerator magnet applications

Erratum: Symmetric tape round REBCO wire with J e (4.2 K, 15 T) beyond 450 A mm−2 at 15 mm bend radius: a viable candidate for future compact accelerator magnet applications (2018 Supercond. Sci. Technol. 31 04LT01)

Scanning Hall Probe Microscopy on Laser Striated Multifilament Coated Conductor

Modeling-Driven Optimization of Mechanically Robust REBCO Tapes and Wires