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Bi-2223/Ag multifilament superconducting tape has high critical temperature, high critical current, and low loss, which has great application potential in superconducting power devices. However, it is a multifilament structure, and it takes a long time to use the finite element method (FEM) to simulate its electromagnetic and thermal properties. A method called “homogenization” is applied to quickly evaluate the electromagnetic characteristics of multifilament tape under normal alternating current. However, further research is needed to determine the applicability of the homogenization model under fault currents. In this paper, we use the electromagnetic-thermal coupling model to compare and analyze the loss and temperature change of the original model and the homogenization model tape under normal alternating current and fault current. Under normal alternating current, the temperature rise of the tape can be ignored, so the influence of temperature on the loss of the tape can be ignored. At this time, the homogenization model can quickly and effectively evaluate the AC loss of multifilament tape. Under the fault current, when the fault degree is small (Ip/Ic0 is less than 1), the tape temperature rise is not obvious, and the difference between the two models is small. At this time, the homogenization model can still quickly and effectively evaluate the loss of multifilament tape. When the fault degree is large (Ip/Ic0 is greater than 2), the temperature rise of the tape obtained by the two models is significantly different, so the tape loss obtained by the two models is somewhat different. At this time, the homogenization model should be carefully selected to describe the loss of multifilament tape.

Cables made by HTS tapes usually have anisotropic dependence by magnetic field owing to the inherit anisotropic characteristics in HTS materials. By increasing number of tapes, the perpendicular magnetic field components weaken the critical current of the whole conductor, and also lead to larger AC loss during AC operation. To reduce the AC loss from stacked HTS conductors, this article studies gap optimization schemes between non-twisted stacked HTS tapes. Finite element modeling with performance comparisons for a stacked HTS conductor (10 tapes) using non-uniform schemes is demonstrated. The results indicate that gap optimizations have better impacts in AC loss reduction rather than those direct stacked conductors. Designs using non-twisted configurations would be simpler, cheaper, and more robust. Therefore, the gap optimization method can be used to explore high current design for large-scale HTS applications.

High-temperature superconductor (HTS) cables have great potential in power transmission. This study presents a comprehensive environmental and economic analysis of high-current stacked HTS cables. The analysis considers the impact of gap variation on both the environmental footprint and economic viability of the HTS cables. By optimizing the gaps between the HTS tapes, the cable losses and carbon emissions can be reduced. The techno-economic and environmental analysis on an electrical power transmission system indicated using the cables based on the stacked HTS conductors by non-uniform gap optimization could reduce annual operating cost by 183.73 k$, and annual CO2 emission by 1291.2 t. Overall, the results demonstrate the significance of gap optimization in enhancing the environmental and economic performance of high-current stacked HTS cables.

In light of the cumulative impact of the stochastic track irregularity, ensuring optimal performance of the electromagnetic levitation system requires not only achieving robust operating performances but also sustaining high reliability over extended service periods. This paper conducts comprehensive research of the structural safety of the levitation unit within a Maglev train's levitation system and established an efficient first-passage analysis of the levitation unit by employing the probability density evolution method. This study explores the probability density evolution of the air gap subject to track irregularity excitation, providing insights into the impact of track irregularities on the first-passage time of the levitation unit.

This study presents an experimental investigation into the resistance of superconducting joints in high temperature superconducting (HTS) linear plasma magnets. The focus is on examining the factors that influence joint resistance and how they can affect the overall performance and reliability of the magnet system. Through a series of rigorous experiments, key parameters such as air gaps, welding angles, and overlap lengths are analyzed to explore their impacts on joint resistance. The obtained results provide valuable insights into the design and optimization of superconducting joints for large-scale magnet applications, paving the way for improved performance and reliability in future superconducting technologies.

Large-scale high temperature superconducting (HTS) magnets usually have tens of double/single pancake coil units. The structural optimization and manufacture of the magnet assembly result in varying axial gaps between adjacent pancakes. This brings additional difficulties for inserting the superconducting joints and dealing with the welding factors such as the gap, welding angle and overlapped length. This article presents the simulation modeling and general joint design guideline of a spiral joint scheme for large-scale HTS magnets and other similar applications. An easy-to-implement model has been built to characterize the physical behaviors of joint resistance. This article explores feasible joint design guidance and performance evaluation solutions for large-scale applications of HTS magnets having a series of HTS-HTS joints among pancake coils.

Due to the anisotropy of high-temperature superconducting (HTS) materials, the stacked HTS conductors in a magnetic field are significantly affected, leading to a substantial reduction of critical current. In order to improve the performance of stacked conductors, we optimized the gap between these stacked tapes. First, we conducted experimental tests with four stacked tapes, and the results indicated that the critical current increased by about 5%. In order to explore the effect of the gap optimization scheme on the current distribution, we set up a model with 10 stacked conductors. Through modeling, it was found that the optimized gap scheme could improve the current distribution and increase the overall current carrying capability. This study provides a feasible optimization scheme for the design of high-current stacked HTS conductors, which can potentially enhance their performance in practical engineering.

Morden railway transportation usually requires high-quality power supplies to guarantee fast and safe operation. Renewable energy such as solar power and wind power, will be highly utilized in future transportation systems. However, renewable energy technologies have issues of instability and intermittence. An energy compensation scheme with superconducting magnetic energy storage (SMES) is introduced for solving these energy issues of railway transportation. A system model consisting of the 1.5 kV/1 kA traction power supply system and the 200 kJ SMES compensation circuit were established using MATLAB/Simulink. The case study showed that if a 50 ms voltage fluctuating fault was from 1.2 kV to 1.8 kV in a traction system, the SMES could rapidly response within 5 ms and stabilize the voltage at 1.5 kV. Overall, the proposed new SMES scheme can potentially achieve the voltage stabilization and energy compensation for urban railway transportation.

The swift evolution of contemporary electronics products, such as flexible screens and wearable electronic devices, highlights the significance of flexible protective coatings, which combine superior mechanical and optical properties. Even though the recently developed polymer protective coatings can satisfy requirements for flexibility and transparency, their intrinsic nature often results in a hardness below 1 GPa, rendering them susceptible to scratches. On the other hand, traditional inorganic coatings, known for their high hardness and transparency, fall short of meeting flexibility requirements. In the present study, a SiNx/BN periodical nanolayered coatings (PNCs) structure has been tailored to achieve high mechanical durability, transparency, and flexibility. In SiNx/BN PNCs, the optical and mechanical properties of the single-layer SiNxfilm are crucial to the overall performance of the PNCs. Therefore, pulse direct current (DC) magnetron sputtering was optimized first to enhance the ionization efficiency of Si and N, thereby promoting their reaction and diminishing the presence of elemental silicon in SiNx. The effects of the pulse frequency and duty cycle on SiNxwere evaluated. Additionally, the influence of the thickness ratio and modulation periods on the overall performance of the SiNx/BN PNCs was investigated. As a result, a SiNx/BN coating with sapphire-grade hardness, almost no optical absorption in the visible–near-infrared (vis–NIR) range, high wear resistance, and exceptional flexibility was demonstrated.

Magnetic resonance imaging (MRI) scanner consists of five major components: The main magnet, a gradient system, an RF coil system, a receiver, and a computer system for data acquisition. Gradient coils are an integral part of an MRI system, used for spatially encoding the MRI signal via modulations on the main magnetic field. In this article, we discuss the in-house design and production method of a particular gradient coil aimed as a part of a portable MRI instrument with a 1 T high-temperature superconducting (HTS) main magnet. We aim to reveal a clear path for those who want to follow.