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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:21
Multiphysics multilayer modelling and simulation of HTS REBCO magnets carrying direct currents under AC magnetic fields
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Article Number:Article 100157
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Abstract
Corresponding email:jun.ma@bristol.ac.uk
High temperature superconducting homopolar inductor machine (HTS-HIM) is concerned and studied for electric aircraft because of its high power density, high efficiency, and high power-to-weight ratio. In an HTS-HIM, the high temperature superconducting magnets carrying DC currents under alternating background magnetic fields work as excitation magnets. Under extreme electromagnetic conditions, the voltage, loss, and temperature of the HTS magnets will increase because of the dynamic resistance effect. To predict the behaviors of the HTS magnet, it is necessary to analyze its electromagnetic-thermal characteristics by using a multiphysics model. This paper establishes a 2D axisymmetric multilayer multiphysics HTS magnet model based on the H-formulation. By using this multilayer multiphysics model, the electromagnetic-thermal characteristics of each turn can be analyzed. Meanwhile, this model can not only analyze the total loss and loss components of each layer under various operating conditions but also predict the temperature and quench behaviors of each part. The result shows that the loss components of the REBCO layer have distinct temperature dependence. When considering the thermal field effect, the magnetization loss of the REBCO layer reduces by 75% and the transport loss of the REBCO layer increases by 45% under high direct currents and high AC magnetic fields. Meanwhile, the temperature of the external turn is higher than the internal turn, and the external turn is at risk of quench in the operating process when the direct currents and AC magnetic fields are high. The multilayer multiphysics model is a powerful tool for designing, analyzing, and optimizing the HTS magnets in HTS-HIMs, and this multiphysics modelling technique can be utilized in modelling and simulating HTS REBCO magnets in various applications.
cited:2
Stress accommodation in nanoscale dolan bridges designed for superconducting qubits after critical failures
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Article Number:Article 100158
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Abstract
Corresponding email:ctharri@sandia.gov
Josephson junctions are the principal circuit element in numerous superconducting quantum information devices and can be readily integrated into large-scale electronics. However, device integration at the wafer scale necessarily depends on having a reliable, high-fidelity, and high-yield fabrication method for creating Josephson junctions. When creating Al/AlO based superconducting qubits, the standard Josephson junction fabrication method relies on a sub-micron suspended resist bridge, known as a Dolan bridge, which tends to be particularly fragile and can often times fracture during the resist development process, ultimately resulting in device failure. In this work, we demonstrate a unique Josephson junction lithography mask design that incorporates stress-relief channels. Our simulation results show that the addition of stress-relief channels reduces the lateral stress in the Dolan bridge by more than 70% for all the bridge geometries investigated. In practice, our novel mask design significantly increased the survivability of the bridge during device processing, resulting in 100% yield for over 100 Josephson junctions fabricated.
cited:13
Hysteresis loss scaling of round REBCO cable towards 20 T
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Article Number:Article 100165
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Abstract
Corresponding email:a.nijhuis@utwente.nl
High Temperature Superconductor (HTS) cables are considered for use in tokamaks such as DEMO (EU) and Chinese next generation fusion device (CN) or compact fusion machines. HTS cables offer the advantage of increased operating temperature and field strength of the magnet coils. In particular for Central Solenoid (CS) coils, the HTS high current cabled conductor windings are exposed to fast ramping AC magnetic fields inducing AC losses. The AC loss in HTS cables for fusion is mainly explored at low magnetic field amplitudes due to lack of testing facilities at higher fields. However, since the operating field in CS coils may be up to 20 T, it is essential to obtain quantitative knowledge on the AC losses for the entire applied field range with reasonable accuracy. This is important for thermohydraulic analysis of the operating temperature margin in coil designs. A method is used here to scale the hysteresis loss of a REBCO cable without transport current, measured up to only 1.4 T, to the entire field and temperature range up to 20 T and 50 K respectively. The field shielding and penetration effects of a multi-layer REBCO CORC®-like cable are quantified by measurements on stacked tape samples with a Vibrating Sample Magnetometer (VSM) up to fields significantly higher than the round cable’s full penetration field, found to be at 4.2 T. For higher fields, using measured critical current () data up to 19 T and an (B,T) scaling law for field (B) and temperature (T) serve to cover the required range of data within the window of coil operation parameters. Basic well-known theory on AC loss, particularly on the relation between hysteresis loss and critical current density against magnetic field, serves as a validation for this work.
Abstract
Corresponding email:yangwjbuaa@buaa.edu.cn; dz286@shu.edu.cn
Split pulsed magnets are widely employed in high temperature superconducting (HTS) motor armature winding as magnetizing coils to implement in-situ pulsed field magnetization (PFM) for HTS field pole magnets. We have designed and developed a compact and portable split pulsed magnet, that balances a peak central magnetic field of nearly 7 T and a rise time of 24 ms, making it particularly suitable for PFM of HTS materials at lower temperatures. Single and two-step PFM experiments of HTS GdBa 2Cu3O (GdBCO) bulk in different temperature ranges are conducted and the maximum trapped fields are observed to be T in the 40–50 K temperature range and nearly 4 T at 30 K in a 30 mm diameter GdBCO bulk. The trapped field results validate the excellent PFM ability of this designed split pulsed magnet and indicate a high trapped field (close to 4 T) can also be obtained in a coreless double armature. Moreover, multi-physical field responses of the split pulsed magnet during discharge are analyzed by a 3D field-circuit coupling model, which manifests that the split pulsed magnet is in a stable and safe operating state even under the highest charge voltage. Finally, this study may provide a novel clue for the development of coreless HTS bulk motors and suggest that HTS coreless motors can maintain a high air gap magnetic field while avoiding losses and thrust or torque fluctuations caused by iron core saturation under high magnetic fields.
cited:0
Single-gap two-band superconductivity well above the Pauli limit in non-centrosymmetric TaIr2B2
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Article Number:Article 100167
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Abstract
Corresponding email:tshiroka@phys.ethz.ch; tomasz.klimczuk@pg.edu.pl
Non-centrosymmetric superconducting materials represent an exciting class of novel superconductors featuring a variety of unconventional properties, including mixed-parity pairing and very high upper critical fields. Here, we present a comprehensive study of TaIrB (with K), using a set of complementary experimental methods, including bulk- and surface-sensitive techniques. We provide evidence that this system is a two-band, yet it behaves as a single-gap superconductor with a strong coupling. The upper critical field of TaIrB significantly exceeds the Pauli limit and exhibits a nearly linear temperature dependence down to the lowest temperatures. This behavior, rarely seen in superconductors, is discussed in terms of anti-symmetric spin–orbit interaction, two-band-, and strong-coupling effects, as well as disorder.
cited:5
Finite element approach for calculating stress distribution in non-circular high-temperature superconducting coils
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Article Number:Article 100168
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Abstract
Corresponding email:wei.wu@sjtu.edu.cn
Complex stress distribution arises in high-temperature superconducting (HTS) coil based on REBCO coated conductors, which is affected by the applied winding tension, thermal stress during cooling down, and electromagnetic forces when energizing the coil. The material and structure of bobbin and overband also play an important role.
In this study, a finite element (FE) method model was proposed for analyzing the stress of HTS coils with non-circular geometries, especially the stresses arise from winding tension and overband. Compared to traditional analytical methods, this approach is not only applicable to circular coils but also to coils of other shapes, such as racetrack and D-shape coils that could hardly be calculated analytically. Comparison between the traditional analytical model and the proposed FE method model was obtained, which validated the latter one according to the simulation results on the radial and hoop stresses of two circular coils. Next, the proposed approach was used to analyze the stress distribution of a racetrack coil and a D-shaped coil. Furthermore, a comprehensive analysis of the stress distributions in the epoxy impregnated racetrack coil and the D-shaped coil was conducted, considering winding stress, thermal stress, electromagnetic stress, and the influence of overband. Finally, we calculated the winding stress in the racetrack coil considering nonlinear compressive behaviors. The results show that the stress distributions are quite different from the case that not considering compressibility.
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