About this publication
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:6
Design and experimental verification of the quench detection system for the CFETR central solenoid model coil
-
Article Number:Article 100212
Article preview
Abstract
Corresponding email:xiaoyz@ipp.ac.cn
To ensure the safe and stable operation of superconducting magnets in fusion devices under high current and complex operating conditions, a highly reliable quench detection system was developed for the Central Solenoid Model Coil (CSMC) of the Chinese Fusion Engineering Testing Reactor (CFETR). The system adopts voltage-based detection as the primary criterion and implements a primary induced voltage compensation architecture based on Co-Wound Wire (CWW) and Co-Wound Tape (CWT) techniques. In addition, a secondary compensation algorithm is introduced to effectively suppress the risk of misjudgment caused by electromagnetic coupling. In the system design, a multi-redundant compensation scheme was proposed with full consideration of the magnet structure and cabling constraints. During the engineering commissioning phase, both room-temperature continuity tests and low-current compensation coefficient calibration were conducted. Induced voltage suppression tests under different current variation rates demonstrated that CWT provides superior compensation performance compared to CWW, with induced voltage suppression rates exceeding 99.8 % for CWW and 99.95 % for CWT. Furthermore, reliability tests under three simulated fault scenarios confirmed that the diagnostic system could accurately identify system states without false triggers, showing strong anti-interference capability and engineering stability. Ultimately, the system was successfully deployed in a high-current energization test of the CSMC, operating at up to 48 kA. It maintained stable performance throughout the test without any false alarms or missed detections, verifying its feasibility and reliability under real engineering conditions. The quench detection compensation methods and system architecture proposed in this study provide a solid technical foundation and practical support for the future development and deployment of the CFETR Central Solenoid superconducting magnet quench detection system.
cited:3
Concurrent superconductivity and ultrahardness in pressure-induced BC19
-
Article Number:Article 100213
Article preview
Abstract
Corresponding email:zx777@jlu.edu.cn；hanyuliu@jlu.edu.cn
Conventional hard and superhard materials, such as diamond and cubic boron nitride, are attractive for both scientific and industrial applications, but their intrinsically poor electrical conductivity limits broader use. This motivates the exploration of novel materials that combine superior hardness with excellent superconductivity. Herein, we performed a comprehensive structure search of the B–C system under pressures ranging from 0 to 100 GPa using machine-learning-potential (attention-coupled neural network, ACNN) based crystal structure prediction (CALYPSO). A stable BC19 phase was identified at 50 GPa, featuring a diamond-like covalent framework with metallic character. Interestingly, BC19 shows anisotropic superconductivity with an estimated superconducting critical temperature (Tc) of 24 K at ambient pressure. Further analysis indicates that the high superconductivity of BC19 originates from the strong coupling between the σ electrons and stretching vibrations of the covalent B–C framework. Additionally, BC19 demonstrates superhard characteristics with a Vickers hardness of 76 GPa, exceeding that of cubic boron nitride. These results suggest that pressure-stabilized BC19 represents a promising theoretical candidate for concurrent superconductivity and ultrahard mechanical performance.
cited:3
Hybrid envelope-to-rectangle (HER) three-stage optimization method for ultra-high field MRI superconducting magnets
-
Article Number:Article 100214
Article preview
Abstract
Corresponding email:zhanzhang1986@gmail.com
This paper introduces a novel Hybrid Envelope-to-Rectangle (HER) optimization methodology addressing critical design challenges in ultra-high field magnetic resonance imaging (MRI) superconducting magnets. Traditional two-stage magnet design methods, which integrate linear programming (LP) with nonlinear programming (NLP), frequently produce irregular non-zero current clusters that necessitate manual intervention for coil regularization. This approach is computationally inefficient, particularly in ultra-high field systems where electromagnetic constraints are highly sensitive to geometric deviations. The HER methodology comprises three distinct phases: 1) initialization through linear programming with multi-layer current density constraints, 2) geometric conversion using elliptical envelope parameterization and dual-field matching, and 3) constrained nonlinear optimization incorporating harmonic suppression. The HER method systematically converts irregular current clusters into rectangular coils through dual geometric-field optimization, achieving a peak-to-peak homogeneity of 0.31 parts per million (ppm) within a 120 mm diameter spherical volume (DSV). This approach enhances computational efficiency while maintaining robustness, thereby advancing automation and precision in ultra-high field magnet engineering.
cited:6
Critical current distribution prediction in REBCO coated conductors via magnetization field and electromagnetic inversion
-
Article Number:Article 100215
Article preview
Abstract
Corresponding email:gaopf@lzu.edu.cn
Accurate prediction of the critical current (Ic) is essential for understanding the operating mechanisms and engineering applications of Rare-earth Barium Copper Oxide (REBCO) coated conductor (CC) tapes. Ic uniformity in these tapes is typically characterized using magnetic field measurements, performed either under an applied external field or after magnetization. The combined effect of the background magnetic field and the screening-current self-field reduces the current in the tape to a value below the self-field critical current (Ic0). Furthermore, magnetic relaxation following magnetization negatively affects the accuracy of Ic0 evaluation. Existing calibration models that relate magnetic field to Ic0 are predominantly empirical and rely on external methods such as the four-probe technique for parameterization. This study proposes a novel Ic0 prediction model that uses magnetic measurement data and electromagnetic inversion while fully accounting for magnetic field and relaxation effects. The method was validated through numerical simulations and experiments. Results show that it can accurately predict Ic0 values for both flawless and defective tapes during and after magnetization. Additionally, the method successfully identifies defects and reveals their influence on current distribution. This approach shows promise for application in reel-to-reel processes, enabling accurate Ic0 prediction in long-length REBCO tapes.
cited:8
Numerical study of dynamic resistance and total loss in insulated and non-insulated HTS REBCO double-pancake coils at 77 K
-
Article Number:Article 100216
Article preview
Abstract
Corresponding email:zhenan.jiang@vuw.ac.nz
No-insulation (NI) coils emerged as a viable alternative to traditional insulated (INS) high temperature superconducting (HTS) coils primarily due to their inherent ability to self-protect during quench and enhanced mechanical stability. When coils carrying direct current (DC) are exposed to an external alternating current (AC) magnetic field, total loss in the coil is the sum of magnetisation loss due to the AC field and dynamic loss arising from the interaction between the DC current and the AC field. In this work, we numerically study the total loss and its components in NI and INS double-pancake coils (DPCs) of identical dimensions, wound with 4 mm wide SuperPower Rare-earth barium copper oxide (ReBCO) coated conductor (CC) tapes at 77 K. The analysis is carried out for external AC magnetic fields up to 200 mT at 72.73 Hz, with the coil carrying DC current up to 90 % of the coil self-field critical current. The results show that under a perpendicular magnetic field, the total loss and its components in the INS-DPC are higher than in the NI-DPC, which is attributed to the presence of insulation which hinders the current bypass. The NI-DPC and INS-DPC coils show similar electromagnetic behaviour under the perpendicular field, and the evolution of dynamic resistance, which gives rise to dynamic loss, is also similar. Under parallel field the loss in the NI-DPC is higher than that for the perpendicular field, and the coil level shielding similar to bulk superconductor is also observed. Surprisingly, under parallel fields, a dynamic resistance higher than that under perpendicular fields is evident in the NI-DPC, arising from a finite average electric field over a cycle.
cited:13
Electromagnetic modeling, loss analysis, and stress evaluation of parallel-wound no-insulation high-temperature superconducting magnets
-
Article Number:Article 100217
Article preview
Abstract
Corresponding email:qiuliang@mail.iee.ac.cn；liujianhua@mail.iee.ac.cn
The parallel-wound technique is an effective method for reducing charging delay and enhancing electromagnetic margin of no-insulation high-temperature superconducting (NI HTS) coils, as demonstrated by both experiments and numerical simulations. From an engineering standpoint, the parallel-wound design also mitigates the constraint of individual conductor length, which is a significant limitation in large-scale coils requiring a single continuous conductor of the same specifications. However, traditional electromagnetic modeling of parallel-wound no-insulation (PWNI) HTS coils relies on equivalent circuit models, and a combined finite element model is required to capture the screening current characteristics of HTS coated conductors. The mutual invocation between circuit models and finite element models increases the technical demands on simulation engineers and complicates the analysis of electromagnetic interactions with other physical fields. To address these challenges, we first propose an axisymmetric distributed equivalent circuit model for PWNI HTS double pancake (DP) coils. The equivalent circuit model is then integrated directly into the finite element framework of T-A formulation, resulting in a streamlined electromagnetic finite element model. The validity of this model is confirmed through the charging and discharging experiments with a dual-wound NI HTS coil. Utilizing this model, we further investigate the effects of joint resistance and turn-to-turn contact resistivity on the electromagnetic characteristics of PWNI HTS coils. Additionally, the excitation loss and stress of multiple PWNI HTS DP coils in a 35 T all-superconducting high field magnet are also analyzed. The results indicate that both the lower turn-to-turn contact resistivity and joint resistance may lead to significant non-uniform currents within the coil. The joint resistance has a significant impact on the critical current of PWNI HTS coils, and the optimization of energization methodology increased the critical current of the experimental coil by 12 A. Enhancing the equivalent radial resistance between bundled turns proves more effective for reducing charging delay of PWNI coil than increasing that within bundled turns. Multiple PWNI coils in high field magnet exhibit elevated losses relative to single-tape equivalents due to coupling currents, particularly during the initial excitation. However, their peak strain accumulation is marginally lower than that of single-wound configuration.
Review