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In the process of manufacturing products from high-temperature superconductors (HTS), quality control must be carried out. Traditionally, for HTS coils, electrical tests are carried out to determine critical current. In the case of an unacceptable result, it is necessary to determine the cause. Therefore, it is necessary to develop nondestructive testing methods. This article proposes a technology for manufacturing quality evaluation. It is based on determining the actual location of the tape and the gaps between the turns and rows of the coil and analyzing these values. For this purpose, samples were scanned using computed tomography (CT) with a Nordson Dage XD7600NT X-ray inspection system with a μCT module. The obtained data were analyzed using VolumeGraphics VGStudio 2.2 software. Furthermore, the proposed technology can be used as part of a predictive analysis of the state of HTS coils in the windings of electrical machines.

Ultrafast lasers are an increasingly important tool to control and stabilize emergent phases in quantum materials. Among a variety of possible excitation protocols, a particularly intriguing route is the direct light engineering of microscopic electronic parameters, such as the electron hopping and the local Coulomb repulsion (HubbardU). In this work, we use time-resolved x-ray absorption spectroscopy to demonstrate the light-induced renormalization of the HubbardUin a cuprate superconductor,La1.905Ba0.095CuO4. We show that intense femtosecond laser pulses induce a substantial redshift of the upper Hubbard band while leaving the Zhang-Rice singlet energy unaffected. By comparing the experimental data to time-dependent spectra of single- and three-band Hubbard models, we assign this effect to an approximately 140-meV reduction of the on-site Coulomb repulsion on the copper sites. Our demonstration of a dynamical HubbardUrenormalization in a copper oxide paves the way to a novel strategy for the manipulation of superconductivity and magnetism as well as to the realization of other long-range-ordered phases in light-driven quantum materials.

High-temperature superconductors (HTS) are being increasingly used for magnet applications. One of the known challenges of practical conductors made with high-temperature superconductor materials is a slow normal zone propagation velocity resulting from a large superconducting temperature margin in combination with a higher heat capacity compared to conventional low-temperature superconductors (LTS). As a result, traditional voltage-based quench detection schemes may be ineffective for detecting normal zone formation in superconducting accelerator magnet windings. A developing hot spot may reach high temperatures and destroy the conductor before a practically measurable resistive voltage is detected. The present paper discusses various approaches to mitigating this problem, specifically focusing on recently developed non-voltage techniques for quench detection.

High-temperature superconductor (HTS) magnet systems, especially those designed for fusion reactors, require effective and reliable monitoring to avoid damaging anomalies. In tokamaks, some of the magnetic coils are time-dependent, which causes strain and large inductive voltages within the magnet, rendering detection of incipient quench challenging. Ionizing radiation can also create material defects and lead to non-uniform degradation of conductors. The resulting decrease in critical current uniformity across the magnet, along with manufacturing defects, such as failure of structural materials or cooling systems, can all potentially initiate a quench. HTS magnets have a lower normal zone propagation velocity than low-temperature superconductors, and this causes normal zones to be localized, increasing the risk of permanent damage. Fiber optic sensors have several qualities that are essential in fusion systems. Unlike traditional voltage-based sensors, fiber optic cables are immune to the large electromagnetic fields present. This study presents and validates a fiber optic interrogation technique for monitoring magnetic confinement fusion and other high-temperature superconducting magnet systems. Coherent-phase optical time domain reflectometry (OTDR) allows for the high sampling rates (tens of kHz) necessary to quickly detect and mitigate quench events over the long distances required to monitor fusion magnet systems. This technique was demonstrated to successfully detect localized thermal transients at cryogenic temperatures as low as 6 K. These outcomes were also demonstrated using fibers embedded in HTS magnet coils at 77 K, verifying the potential for this interrogation technique's use for failure detection in HTS coils.

In this letter, electromagnetically induced transparency (EIT) is implemented in the microwave region with an experimental system composed of two indirectly coupled high‐temperature superconducting resonators. The transition condition between EIT and Autler–Townes splitting is analyzed, giving a physical explanation of this transition based on the superposition of dressed modes in a three‐level system. Benefit from the ultra‐low loss of superconducting circuit, it is experimentally shown that either EIT or Autler–Townes splitting can be explicitly achieved through control of the detuning between the two resonators and a group delay as high as 5 μs is obtained for the EIT case. This work suggests that high temperature superconducting circuit is a concise and explicit platform for investigating indirectly coupled resonators with standing‐wave modes and the physical mechanism underneath coherence phenomena in the microwave region. In this study, electromagnetically induced transparency (EIT) is achieved in the microwave region using an experimental setup consisting of two indirectly coupled high‐temperature superconducting resonators. A physical explanation is provided for the transition between EIT and Autler–Townes splitting based on the superposition of dressed modes in a three‐level system. The experimental results matched the theoretical calculations, demonstrating the feasibility of explicitly controlling EIT and achieving a high group delay of up to 5 μs. This work offers a promising device for delaying and storing electromagnetic waves and shows potential for future applications in remote sensing due to the sensitivity of EIT to resonant frequencies.

The development of superconducting technology has seen continuously increasing interest, especially in the area of clean power systems and electrification of transport with low CO2 emission. Electric machines, as the major producer and consumer of the global electrical energy, have played a critical role in achieving zero carbon emission. The superior current carrying capacity of superconductors with zero DC loss opens the way to the next-generation electric machines characterized by much higher efficiency and power density compared to conventional machines. The persistent current mode is the optimal working condition for a superconducting magnet, and thus the energization of superconducting field windings has become a crucial challenge to be tackled, to which high temperature superconducting (HTS) flux pumps have been proposed as a promising solution. An HTS flux pump enables current injection into a closed superconducting coil wirelessly and provides continuous compensation to offset current decay, avoiding excessive cryogenic losses and sophisticated power electronics facilities. Despite many publications regarding the design and analyses of various types of HTS flux pumps, the practical application of HTS flux pumps in a high-performance superconducting machine has been rarely reported. Therefore, it is of significance to specify the main challenges for building and implementing a reliable HTS flux pump. In addition, the physical mechanisms of distinct HTS flux pumps have caused some confusion, which should be clarified. Above all, a systematic review of the recent development and progress of HTS flux pumps remains lacking. Given the above-mentioned issues, this paper summarized the most up-to-date advances of this emerging technology, clarified the working mechanisms and commonly adopted modeling approaches, presented objective analyses of the applicability of various HTS flux pumps, specified the primary challenges for implementing HTS flux pumps, and proposed useful suggestions to improve this wireless excitation technology. The overall aim of this work is to bring a deep insight into the understanding of HTS flux pumps and provide comprehensive guidance for their future research and applications.

AbstractElectromagnetic systems (EMS) of the largest and ambitious modern fusion scientific facilities, such as ITER—the most eminent international project under construction—rely upon a well-developed industry of low-temperature superconductor (LTS) wires. At the same time, a number of state and private research companies demonstrate increasing interest towards high-temperature superconductors (HTS) as a basic material for more compact EMS operating at a higher magnetic field. Two reasons underlie this interest. The first one is a huge progress in the development of HTS conductors confirmed by construction and tests of several magnets made with commercially available HTS wires, which demonstrate stable operation at a magnetic field beyond 30 T. The second reason is economical assessments of funds and time expenses needed for the construction of “thermonuclear power plants” in the future. The assessments have shown that optimal EMSs for such facilities should be compact (small-size), operate at a magnetic field at a level of at least 18–22 T and temperature of 10–25 K with a design current density of 70–100 A/mm2. Only high-temperature superconductors can show such performance. The construction of HTS systems requires attaining new solutions for traditional design problems and revising design criteria for major EMS elements such as winding conductors, joints, cryogenic, diagnostic, and protection systems, and insulation. Reflecting some technical solutions presented in open sources for such projects as SPARС and ST-HTS [1, 2] and taking into account the first results of theoretical and experimental programs performed in support of the conceptual design of a tokamak with reactor technologies (TRT) [3], the authors suggest discussion on the basic principal and design criteria of modern HTS EMS for fusion.

In this paper, a single-layer terahertz tri-band bandpass filter without a dielectric substrate is designed using high-temperature superconductor YBa2Cu3O7−δ (YBCO) metamaterial. The proposed single-layer terahertz tri-band bandpass filter achieves its three passband resonances through the weak coupling and superposition of three sub-resonators: a cross-shaped slot resonator (CSSR), a split square ring slot resonator (SSRSR), and a split circular ring slot resonator (SCRSR). In comparison to single-layer filters designed with metallic Au metamaterial, the YBCO-based single-layer filter offers superior frequency selectivity, when the superconducting metamaterial YBCO is at a temperature of 20 K, which is below the transition temperature (Tc). Within the frequency range of 2–5 THz, the corresponding resonant frequencies for the three passbands are 2.861 THz, 3.332 THz, and 3.956 THz, all achieving transmittance exceeding 97% and remaining polarization-insensitive under vertically incident terahertz waves. The proposed single-layer superconducting metamaterial terahertz tri-band bandpass filter holds immense promise for applications in terahertz sensing technology, terahertz biomedical frequency detection, and low-cost, low-insertion-loss terahertz communication filtering devices within the terahertz spectrum.

Hydrogen production from renewable energy sources is a crucial pathway to achieving the carbon peak target and realizing the vision of carbon neutrality. The hydrogen production from offshore superconducting wind power (HPOSWP) integrated systems, as an innovative technology in the renewable energy hydrogen production field, holds significant market potential and promising development prospects. This integrated technology, based on research into high-temperature superconducting generator (HTSG) characteristics and electrolytic water hydrogen production (EWHP) technology, converts offshore wind energy (OWE) into hydrogen energy locally through electrolysis, with hydrogen storage being shipped and controlled liquid hydrogen (LH2) circulation ensuring a stable low-temperature environment for the HTSGs’ refrigeration system. However, due to the significant instability and intermittency of offshore wind power (OWP), this HPOSWP system can greatly affect the dynamic adaptability of the EWHP system, resulting in impure hydrogen production and compromising the safety of the LH2 cooling system, and reduce the fitness of the integrated system for wind electricity–hydrogen heat multi-field coupling. This paper provides a comprehensive overview of the fundamental structure and characteristics of this integrated technology and further identifies the key challenges in its application, including the dynamic adaptability of electrolytic water hydrogen production technology, as well as the need for large-capacity, long-duration storage solutions. Additionally, this paper explores the future technological direction of this integrated system, highlighting the need to overcome the limitations of electrical energy adaptation within the system, improve product purity, and achieve large-scale applications.