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ISSN: 2772-8307
Copyright © 2026 Shanghai Jiaotong University. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
cited:60
Review of high temperature superconducting flux pumps
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Article Number:Article 100022
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Abstract
Corresponding email:weiwangca283@gmail.com
High temperature superconducting (HTS) magnets conduct DC currents ranging from hundreds to tens of thousands of amperes. To achieve such DC output amplitudes, conventional power supplies are unsuitable, owing to their extreme cost, energy consumption, and bulkiness. The indispensable current leads of conventional power supplies carrying large DC current cause an extra heat leakage into the cryogenic system, thus increasing the number of required cryocoolers. A potential solution to tackle this problem, however, is to use HTS flux pumps that inject a large amount of DC current into the HTS magnet in a wireless fashion, thereby eliminating the need for current leads, and allow the magnets to work in the quasi-persistent current mode. Compared with the conventional power supplies, the flux pumps offer the advantages of low cost, low energy consumption, and compact size, etc., which essentially have broad application prospects in nuclear magnetic resonance (NMR/MRI), fusion, particle accelerators, superconducting electric machine, maglev train, etc. Over the last decade, a variety of HTS flux pumps have been invented with improved DC outputs, reaching over kilo-amperes. Moreover, those flux pumps have different working principles, structures and operation strategies. In this paper, we provide an in-depth review on the HTS flux pumps developed in the last decade. In particular, for the HTS travelling wave flux pumps and HTS transformer-rectifier flux pumps, the discussions are focused on their working principles and technical advances. In the end, we discuss the present applications of HTS flux pumps, along with their potential future applications.
cited:35
Performance of highly flexible sub-cable for REBCO Cable-In-Conduit conductor at 5.8 T applied field
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Article Number:Article 100023
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Abstract
Corresponding email:jinhuan@ipp.ac.cn
Due to the high current capability and excellent flexibility, High Flexible REBCO Cables (HFRC) have emerged as an important candidate for composite high-temperature superconducting conductors. The REBCO six around one Cable-In-Conduit Conductor (CICC) concept has been designed for application in the Central Solenoid (CS) coil of the China Fusion Engineering Test Reactor. In the application of fusion devices, the performance of CICC under electromagnetic (EM) loading and thermal stress is very important for reliable and economic operation. Therefore, a 1.22 m long sub-cable with HFRC design for CICC was manufactured and tested at 4.2 K in a background magnetic field up to 5.8 T. The aim is to investigate the stability of the current-carrying properties of the HFRC cable under electromagnetic and thermal cyclic loading. The test results show that the critical current (Ic) of the HFRC cable reached 17.3 kA in a background magnetic field of 5.8 T at 4.2 K. Furthermore, no performance degradation was observed after 24 cycles of 80 kN/m peak load with a background field of 5.8 T and 8 warm-up-cool-down cycles between 77 K and room temperature. The test results provide a good basis for the development of full-size conductors in future magnet applications.
Abstract
Corresponding email:gaopf@lzu.edu.cn
High-temperature superconducting (HTS) rare-earth barium copper oxide (REBCO)-coated conductors (CCs) are widely used in large-scale applications owing to their high critical performance and excellent mechanical stability. However, defects can significantly degrade their performance by distorting current distributions. Conventional nondestructive evaluation techniques typically involve stepwise inversion from magnetic field measurements to current distributions, and then to defect morphology. However, these approaches suffer from intrinsic ill-posedness and limited ability to identify complex or multiple defects. To address these challenges, we propose an integrated inverse-forward framework that combines deep learning with physical modeling to directly map surface magnetic field measurements to internal defect morphology and current density distributions. The core of this method is a specially designed conditional generative adversarial network (cGAN) as the primary learner. It undergoes adversarial training on a dataset containing complex multi-defect configurations and their corresponding magnetic field distributions, enabling robust inverse prediction of defect morphology. The reconstructed defect geometry is then incorporated as a boundary constraint into the forward solution of Maxwell's equations coupled with superconducting nonlinear constitutive relations, enabling high-fidelity reconstruction of the current density distribution. Validation was performed using finite element simulations of REBCO-CCs with various defect types under current-carrying conditions. The adversarial training was performed using the generated finite element dataset. The trained model accurately identified multiple complex defect morphologies across different operating conditions and demonstrated strong generalization capability. Furthermore, the reconstructed current density accurately reproduced the original magnetic field distribution, confirming the reliability of the proposed method. This work integrates data-driven inference with physics-based modeling to establish a unified “magnetic field–defect morphology–current density” inversion paradigm, providing an efficient and reliable approach for nondestructive evaluation and performance assessment of REBCO-CCs.
cited:0
A novel Pre-HIP two-step annealing process for enhancing the critical current of Ba1-xKxFe2As2 superconducting tapes
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Article Number:Article 100221
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Abstract
Corresponding email:liuhj@ipp.ac.cn; fangliu@ipp.ac.cn
Iron-based superconductors (IBSs) are compelling candidates for high-field magnet applications due to their excellent intrinsic properties. The hot isostatic pressing (HIP) effectively enhances their critical current density by increasing core density. However, IBS tapes are highly stress-sensitive after heat treatment. This necessitates fabricating magnets prior to the HIP process. Consequently, the requirement for large-volume HIP furnaces for full-scale magnets presents significant technological and cost barriers. To circumvent this manufacturing bottleneck, this paper introduces a novel “pre-HIP” two-step annealing process. The principle involves an initial, low-temperature HIP (pre-HIP) heat treatment on IBS tapes to achieve densification. Subsequently, the tapes are wound into the desired magnet or conductor geometry, followed by a final heat treatment at atmospheric pressure (AP). This strategy allows large-scale magnets to be treated in conventional, cost-effective furnaces. We systematically evaluated the effect of the pre-HIP temperature (370-450 °C at 50 MPa) on the transport properties and bend performance of 7-filamentary Ba1-xKxFe2As2 (Ba-122) tapes. Results show that pre-HIP significantly enhances the critical current. However, a critical trade-off was identified: higher pre-HIP temperatures yield superior critical performance but induce local grain growth, causing severe degradation during bending. Samples pre-HIP at 370 °C retained 78 % of their initial performance after bending to 10 mm diameter, whereas the 450 °C samples degraded significantly. This study confirms that pre-HIP is a cost-effective method to improve IBS magnet performance when the optimal temperature is selected.
cited:0
Fracture behavior of high-temperature superconducting filmswith an edge slit produced by flux avalanches
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Article Number:Article 100222
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Abstract
Corresponding email:lujiang@upc.edu.cn；liujianlin@upc.edu.cn
In type-II superconducting films, the metastable state can be disrupted by flux avalanches, leading to severe degradation of the electromagnetic properties and irreversible damage to the material in even relatively lower fields. In this study, an electrical-magnetic-thermal-mechanical coupling model is developed to investigate the electromagnetic and mechanical responses of YBa2Cu3O (YBCO) superconducting films with an edge slit during the flux avalanche, taking into account the effects of the edge slit on the triggering of the first flux avalanche. The distribution of magnetic field, temperature, and stress within the superconducting film, as well as the initiation and propagation of crack is numerically simulated by combining the Fast Fourier Transform (FFT) method and the Extended Finite Element Method (XFEM), allowing for an in-depth analysis of the fracture mechanism. The results indicate that thermal stress induced by magnetic flux avalanches is the dominant driving force behind the initiation and propagation of cracks, which has also previously been observed at the trunk of the dendritic flux avalanche in the YBCO superconducting film. Detailed analyzes are performed to discuss the influence of the working temperature, magnetic field ramp rate, and edge slit geometry on crack behavior. It is found that higher working temperatures lead to larger-scale avalanches and more pronounced non-uniform temperature rises, thereby significantly increasing fracture risk. Moreover, the applied magnetic field with lower ramp rates is more likely to induce fracture during the first flux avalanche. As for edge slit geometry, smaller edge slit widths or lengths intensify local heating and thermal stress concentration, further promoting crack propagation.
cited:5
Opportunities and challenges of offshore direct drive high-temperature superconducting wind turbine generators
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Article Number:Article 100230
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Abstract
Corresponding email:zhen.huang@sjtu.edu.cn
Offshore direct drive high-temperature superconducting (HTS) wind turbine generators, a key application of superconductors in the energy sector, are entering a phase of commercial opportunity. In the wind power industry, one clear trend is the increasing power rating of units: current models exceed 15 MW, with over 20 MW generators emerging. For such high-power units, the high power density of superconducting generators minimizes mass and material usage, thereby achieving a higher power-to-weight ratio. Beyond power scaling, another trend is the deployment of wind turbines in deep waters to tap into more abundant wind resources and reduce the need for onshore land; however, operating expenditure (OpEx) in deep waters drives increased demand for reliability. HTS generators operate without a gearbox, offering a reliability advantage—especially critical in deep waters subject to multiple excitations and strong dynamic loads. As a result, modular direct drive HTS generators are increasingly becoming the preferred choice for this scenario. Modularization—dividing the generator's rotor and stator into symmetrical sectors and assembling them at the end of the production chain—facilitates manufacturing, transportation, installation, and replacement. Notably, the price of HTS tape has been declining lately, a trend driven by the surge in compact magnetic confinement fusion reactors. This reduction lowers the capital expenditure (CapEx) of superconducting generators, enhances market competitiveness, and underpins research into high-magnetomotive force (MMF) machine designs. Nevertheless, HTS generator design and manufacturing are system-level endeavors, involving trade-offs across electromagnetic, thermal, and mechanical aspects that demand targeted optimization and rigorous reliability testing.
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