REBCO Industrialization
REBCO coated conductors are now in mass production as unique practical wires available for emerging high field or liquid helium free applications. Although various manufacturing methods have been proposed, the IBAD/PLD method, which has been studied since the inception of coated conductors, is currently the most widely used for those high field applications such as high-end NMR systems and "compact" nuclear fusion, etc., which could not be achieved by LTS wires such as Nb3Sn [1].
Pulsed laser deposition (PLD) is a non-equilibrium vapour process characterised by a high growth rate under largely supersaturated conditions, though it also has excellent controllability of varied deposition conditions for complex multi-element oxide films even at sufficiently high oxygen pressure. It allows the production of stable conductors with high in-field performance, with densely dispersed pinning centres in sharply textured REBCO films growing at extremely high rates, also with high yield due to its high reproducibility, resulting in sufficient mass production throughput.
In order to improve the longitudinal uniformity and lot-to-lot variation of these optimised process conditions, we had designed and developed "hot-wall" reel-to-reel PLD equipment, which achieved quite robust and reproducible temperature uniformity by means of a furnace-like heating system [2]. We have succeeded in commercialising long length and uniform REBCO wires including BaHfO3 nanorods and have developed the productivity of these wires towards cost reduction without compromising quality control and uniformity for long piece length. It has also allowed us to expand the variety of wire widths to ensure sufficient single length conductors. We currently offer lineups of BaHfO3 doped EuBaCuO wires and undoped GdBaCuO wires in widths from 2mm to 12mm. Additional improvements are undergoing to explore further productivity, piece length, and quality of transporting and mechanical strength.
We are now expanding production capacity with Hot-Wall PLD. Although scale-up costs associated with UV pulsed lasers are unavoidable, they are decreasing and now acceptable enough to achieve mass production of affordable REBCO wires with reliable enough quality and throughput.
[1] P. Wikus, et.al., "Commercial gigahertz-class NMR magnets", Supercond. Sci. Technol. vol. 35, Art. no. 033001, (2022)
[2] Y. Iijima, et.al., "BMO-Doped REBCO-Coated Conductors for Uniform In-Field Ic by Hot-Wall PLD Process Using IBAD Template", IEEE Trans. Appl. Supercond.,vol. 27, no. 4, Art. no. 6602804, (2017)
A part of this work is based on results obtained at the High Field Laboratory for Superconducting Materials, IMR, Tohoku University.
Keywords: REBCO coated conductors, IBAD, Hot-Wall PLD, BaHfO3 BMO doped REBCO
With the beneficial characteristics of high irreversible field, high superconducting transition temperature and high critical current density, REBCO material has reached the stage of mass commercial production. Meanwhile a large number of superconducting power transmission projects and superconducting magnets have been developed using REBCO tapes. Recently, due to the significant demand for REBCO tapes by compact fusion industry, Shanghai Superconductor Technology Co., Ltd. (SST) has kicked off a new round of production expansion. Through independent design and manufacturing, SST has swiftly built a large number of vacuum coating equipment and post-processing equipment, including MS, IBAD, PLD, slitting, copper-plating, lamination and so on. This production expansion targets to further reduce the fabrication cost and improve the performance of REBCO tapes, providing a consistent supply of high performance tapes for downstream applications. By the end of 2023, the SST’s annual REBCO supply has reached 2000 km/12 mm, and will be further expanded to 4000 km/12 mm in 2025. Along with the production expansion, SST also carries out researches extensively on tape customization and problem solving for specific application scenarios, covering laser slitting, stainless steel lamination, insulation coating, low resistance joints, continuous online thickness measurement techniques, and superconducting coil winding technologies, to help customers meet their technical requirements and achieve a successful project using SST's REBCO products. This paper will focus on the industrialization and R&D progress that SST has recently achieved.
Keywords: REBCO tapes , mass prodution, practical research, compact nuclear fusion
For the development of compact fusion reactors and other applications, there is a growing demand for REBCO HTS tapes with high critical current (Ic) at low temperature and high magnetic field. While focusing on expanding our manufacturing capabilities, SuperPower is continuously working not only to enhance its in-filed Ic but also to improve length-wise in-field Ic uniformity, the uniformity of its geometric dimensions uniformity, and the reduction of variability between lots. In this presentation, overview of our recent progress will be presented.
In the past decades, REBa2Cu3O7-δ (REBCO; RE = Y, rare earth element) second-generation high-temperature superconducting coated conductors have been considered one of the most promising superconducting materials. Thickening the REBCO superconducting layer is always one of the most challenge research directions due to the thickness effect. Thus, we innovatively developed a TFA-MOD-derived semi-grown technology to solved the problem of thickness effect below 4 μm thickness and achieve high performance. The corresponding Ic(77K, self-field) achieved 1100 A/12 mm-width. Furthermore, to improve the in-field flux pinning of REBCO films, the BaMO3(M=Zr, Hf) nanocrystal addition strategy was extended to up-scaling thick REBCO coated conductors as long as hundreds of meters. The introduced monodispersed BaMO3(M=Zr, Hf) nanocrystals with controllable sizes act as effective pinning centers to improve the in-field performance, which is identical to both the thin and thick films. It is revealed that the in-field Ic enhances to 290 A at 4.2 K@20 T and to 1450 A at 30 K@3 T for 4 mm-width tapes. Besides, more than 3 μm thick MOD-derived REBCO tapes were stably fabricated to hundreds of meters with high self-field and in-field performances with BaMO3nanocrystal addition by the continuous MOD preparation line from Shanghai Creative Superconductor Technologies Co., Ltd.
The work is supported by the National Natural Science Foundation of China (52172271), the National Key R&D Program of China (2022YFE03150200), Shanghai Science and Technology Innovation Program (22511100200).
Keywords: High-temperature superconductor, REBa2Cu3O7-δ, artificial flux pinning, nanocrystal addition
In its ongoing pursuit of advancing superconducting wire technology, SuNAM has been at the forefront of developing innovative production techniques for coated conductors (CCs). By employing both the Reactive Co-evaporation-Deposition and Reaction (RCE-DR) and Pulsed Laser Deposition (PLD) techniques, we have successfully addressed a range of applications, including grid infrastructure and high-field devices. It is through the application of the RCE-DR method that the first commercial superconducting cables were produced in Korea, while it is the PLD system, too, which has proved pivotal in enhancing pinning properties for applications requiring higher magnetic fields.
Our research is focused on optimizing the PLD process to achieve superior performance in 2G high-temperature superconducting (HTS) wires, with a particular emphasis on parameters such as temperature control and layer uniformity. The objective of this optimization is to enhance the electromechanical characteristics and microstructural integrity of the wires, thereby improving their suitability for use in magnets and motors.
Additionally, SuNAM is developing a machine learning-based vision system to facilitate the automation of production processes, with the aim of reducing costs and increasing throughput without the necessity of expanding production lines. By increasing the width of the wires, new benchmarks are being set for the mass production of low-cost superconducting wires.