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  Subjects -> ELECTRONICS (Total: 207 journals)
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Superconductor Science and Technology
Journal Prestige (SJR): 1.036
Citation Impact (citeScore): 3
Number of Followers: 3  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0953-2048 - ISSN (Online) 1361-6668
Published by IOP Homepage  [45 journals]
  • A proof-of-concept Bitter-like HTS electromagnet fabricated from a
           silver-infiltrated (RE)BCO ceramic bulk

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      Authors: R W Taylor; H W Weijers, M D Ainslie, J V J Congreve, J H Durrell, R A Badcock C W Bumby
      First page: 03LT01
      Abstract: A novel concept for a compact high-field magnet coil is introduced. This is based on stacking slit annular discs cut from bulk rare-earth barium cuprate ((RE)BCO) ceramic in a Bitter-like architecture. Finite-element modelling shows that a small 20 turn stack (with a total coil volume of 20 cm3) is capable of generating a central bore magnetic field of 2 T at 77 K and 20 T at 30 K. Unlike resistive Bitter magnets, the high-temperature superconducting (HTS) Bitter stack exhibits significant non-linear field behaviour during current ramping, caused by current filling proceeding from the inner radius outwards in each HTS layer. Practical proof-of-concept for this architecture was then demonstrated through fabricating an uninsulated four-turn prototype coil stack and operating this at 77 K. A maximum central field of 0.382 T was measured at 1.2 kA, with an accompanying 6.1 W of internal heat dissipation within the coil. Strong magnetic hysteresis behaviour was observed within the prototype coil, with ≈30% of the maximum central field still remaining trapped 45 min after the current had been removed. The coil was thermally stable during a 15 min hold at 1 kA, and survived thermal cycling to room temperature without noticeable deterioration in performance. A final test-to-destruction of the coil showed that the limiting weak point in the stack was growth-sector boundaries present in the original (RE)BCO bulk.
      Citation: Superconductor Science and Technology
      PubDate: 2024-02-13T00:00:00Z
      DOI: 10.1088/1361-6668/ad268b
      Issue No: Vol. 37, No. 3 (2024)
       
  • Review of materials for HTS magnet impregnation

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      Authors: Joshua Feldman; Wolfgang Stautner, Christopher Kovacs, Nenad Miljkovic Kiruba S Haran
      First page: 033001
      Abstract: Construction of high-temperature superconducting magnets typically involves impregnation of a coil in a liquid medium, such as epoxy, which is then solidified. This impregnation provides mechanical integrity to the magnet and facilitates heat transfer. The choice of material used for impregnation requires careful consideration of the material properties and the performance requirements in order to ensure optimal magnet operation. This paper offers a comprehensive educational resource on this topic, reviewing the literature available on materials for magnet impregnation. A detailed explanation of considerations for selecting an impregnation material are presented, along with a review of several types of materials and their characteristics as reported in the literature. The materials are compared, and their suitability to different applications is discussed. Topics for future research are suggested.
      Citation: Superconductor Science and Technology
      PubDate: 2024-02-05T00:00:00Z
      DOI: 10.1088/1361-6668/ad1aeb
      Issue No: Vol. 37, No. 3 (2024)
       
  • A 6-around-1 cable using high-temperature superconducting STAR ®
           wires for magnet applications

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      Authors: Nathaly Castaneda; Paolo Ferracin, Cyrus Funkhouser, Eduard Galstyan, Hugh C Higley, Sri Ram Korupolu, Goran Majkic, Hoang Nguyen, Soren O Prestemon, Venkat Selvamanickam, Huy Truong Xiaorong Wang
      First page: 035009
      Abstract: To generate a dipole field above 20 T, we need high-temperature superconductors, including REBa2Cu3O (RE = rare earth, rebco) coated conductors. However, the optimal architecture of a high-current flexible rebco cable is not yet settled for high-field magnet applications. Here we report a 6-around-1 cable concept based on the high-temperature superconducting star® wires. We made two cable samples. One had a single star® wire and the other had six star® wires. The cable with six star® wires was 1.5 m long. It had a diameter of 5.7 mm and a pitch length of 52 mm. The critical current of the cable before bending was 1448 A at 77 K, retaining at least 77% of the total critical current from individual star® wires. The cable had a low n value around 4.5. At a bend radius of 30 mm, the critical current and n value remained the same as before bending. The total resistance of electrical terminations was 61 nΩ at 77 K. The flexible and transposed 6-around-1 star® cable can provide another route toward practical rebco conductors for high-field accelerator and fusion magnet applications.
      Citation: Superconductor Science and Technology
      PubDate: 2024-02-02T00:00:00Z
      DOI: 10.1088/1361-6668/ad20fb
      Issue No: Vol. 37, No. 3 (2024)
       
  • Optimisation of the processing parameters for the fabrication of
           high-quality joints between Y–Ba–Cu–O single grain, bulk
           superconductors

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      Authors: J V J Congreve; Y Shi, H Druiff, A R Dennis, R W Taylor, C W Bumby, D A Cardwell J H Durrell
      First page: 035010
      Abstract: High-strength permanent magnets are essential for a wide range of technologies, including levitation devices, motors, generators and magnetic separators. Replacing permanent magnets with single grain, bulk superconductors will enable a step-change in the performance of these technologies by providing an order-of-magnitude increase in magnetic field. However, there remain many key challenges to the practical implementation of bulk superconductors, of which size and geometry are the most fundamental. The current limits to the size and geometry of (RE)-Ba–Cu–O single grain, bulk superconductors would be overcome substantially by the ability to fabricate high-quality joints between these technologically important materials. In this work we present new insights into the creation of superconducting joints between single grain bulk YBCO superconductors using a YBCO-Ag intermediate composition. We have investigated the effect of the joint fabrication temperature on the quality of the joint in order to begin to optimise the joint fabrication route for YBCO. We report on 35 joints produced at different joining temperatures as part of this study. The trapped field properties of the resulting joined samples were measured and the microstructure at each joint was examined. We show that this simple and rapid joining technique is robust to small changes in joint fabrication temperature and suggest routes to further optimise this potentially transformative technique.
      Citation: Superconductor Science and Technology
      PubDate: 2024-02-05T00:00:00Z
      DOI: 10.1088/1361-6668/ad221c
      Issue No: Vol. 37, No. 3 (2024)
       
  • Monolithic integration of superconducting-nanowire single-photon detectors
           with Josephson junctions for scalable single-photon sensing

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      Authors: Saeed Khan; Bryce A Primavera, Richard P Mirin, Sae Woo Nam Jeffrey M Shainline
      First page: 035011
      Abstract: We demonstrate superconducting single-photon detectors (SPDs) that integrate signals locally at each pixel. This capability is realized by the monolithic integration of superconducting-nanowire SPDs with Josephson electronics. The motivation is to realize superconducting sensor elements with integrating capabilities similar to their CMOS-sensor counterparts. The pixels can operate in several modes. First, we demonstrate that photons can be counted individually, with each detection event adding an identical amount of supercurrent to an integrating element. Second, we demonstrate an active gain control option, in which the signal added per detection event can be dynamically adjusted to account for variable light conditions. Additionally, the pixels can either retain signal indefinitely to record all counts incurred over an integration period, or the pixels can record a fading signal of detection events within a decay time constant. We describe additional semiconductor readout circuitry that will be used in future work to realize scalable, large-format sensor arrays of superconducting SPDs compatible with CMOS array readout architectures.
      Citation: Superconductor Science and Technology
      PubDate: 2024-02-06T00:00:00Z
      DOI: 10.1088/1361-6668/ad1a44
      Issue No: Vol. 37, No. 3 (2024)
       
  • Thermal runaway criterion as a basis for the protection of
           high-temperature superconductor magnets

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      Authors: M Marchevsky; S Prestemon
      First page: 035012
      Abstract: High-temperature superconductor (HTS) based high-field magnet systems are essential for particle accelerators and fusion energy applications. Quench protection of such magnets is difficult owing to a slow quench propagation velocity in HTS. While in conventional NbTi and Nb3Sn-based magnets, a normal zone expands typically quickly, and the stored energy is dissipated across a large volume of the windings, a normal zone in an HTS magnet propagates slowly and, thus, can heat up quickly to high temperatures destroying the conductor. At the same time, growing experimental evidence suggests that HTS conductors can operate in a stable dissipative flux flow regime for a substantial range of operational currents before entering an irreversible thermal runaway. Therefore, a new protection paradigm for HTS magnets has emerged, aiming to prevent quenching, using advanced diagnostics to detect the dissipative regime onset. In the present paper, we propose a simple criterion for the thermal runaway in HTS conductors and calculate allowable temperature margins within which an HTS magnet can be operated safely. Outside of those temperature margins, a common quench integral approach may be used to estimate the upper boundary of the time margin for activating the protection system. We verify the applicability of our approach by comparing the calculated runaway conditions for a Bi-2223 conductor with the experimentally measured values. The thermal and time margins can define the quench protection system’s requirements for implementing the quench-avoiding protection paradigm.
      Citation: Superconductor Science and Technology
      PubDate: 2024-02-07T00:00:00Z
      DOI: 10.1088/1361-6668/ad20fe
      Issue No: Vol. 37, No. 3 (2024)
       
  • Low-loss millimeter-wave resonators with an improved coupling structure

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      Authors: A Anferov; S P Harvey, F Wan, K H Lee, J Simon D I Schuster
      First page: 035013
      Abstract: Millimeter-wave superconducting resonators are a useful tool for studying quantum device coherence in a new frequency domain. However, improving resonators is difficult without a robust and reliable method for coupling millimeter-wave signals to 2D structures. We develop and characterize a tapered transition structure coupling a rectangular waveguide to a planar slotline waveguide with better than 0.5 dB efficiency over 14 GHz, and use it to measure ground-shielded resonators in the W band (75–110 GHz). Having decoupled the resonators from radiative losses, we consistently achieve single-photon quality factors above 105, with a two-level-system loss limit above 106, and verify the effectiveness of oxide removal treatments to reduce loss. These values are 4–5 times higher than those previously reported in the W band, and much closer to typical planar microwave resonators. The improved losses demonstrated by these on-chip millimeter-wave devices shed new light on quantum decoherence in a different frequency regime, offer increased selectivity for high-frequency detectors, and enables new possibilities for hybrid quantum experiments integrating millimeter-wave frequencies.
      Citation: Superconductor Science and Technology
      PubDate: 2024-02-08T00:00:00Z
      DOI: 10.1088/1361-6668/ad22ff
      Issue No: Vol. 37, No. 3 (2024)
       
  • Numerical study on the electromagnetic characteristics of multi-layer CORC
           cables

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      Authors: Chao Li; Wenchao Yang, Bin Li, Ying Xin Jiabin Yang
      First page: 035014
      Abstract: Due to the high isotropy and low AC losses, the multi-layer conductor on round core (CORC) cable is a good candidate for high field magnets, such as central solenoid magnets in fusion. Considering the difficulty in experimental measurement, numerical model is an effective way to illustrate the electromagnetic characteristics of the multi-layer CORC cable and provide further insights into its working performance. In this work, a 3D finite element model based on H formulation is proposed to simulate a CORC cable with as many as 18 layers considering electromagnetic coupling. The validity of the model has been verified by experimental results. Based on the proposed model, the DC transport current distribution characteristics and charge-discharge loss characteristics of multi-layer CORC cables wound in the same and opposite winding directions are investigated respectively. This work can provide an important reference for the design of multi-layer CORC cables for high-current or high-field application.
      Citation: Superconductor Science and Technology
      PubDate: 2024-02-13T00:00:00Z
      DOI: 10.1088/1361-6668/ad221d
      Issue No: Vol. 37, No. 3 (2024)
       
  • High critical current density in low-cost iron-based superconducting round
           wires annealed at ambient pressure

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      Authors: Caida Fu; Chiheng Dong, Chang Tu, Meng Han, He Huang, Dongliang Wang, Xianping Zhang Yanwei Ma
      First page: 035015
      Abstract: Superconducting round wires with isotropic architecture are preferred in fabrications of cables and magnets. To diminish the obstacles to supercurrent, e.g., voids, cracks and bubbles, over-pressure heat treatment or hot isostatic pressing is indispensable in the final annealing process. Here, we fabricated a stainless steel/Cu/Ag sheathed Ba0.6K0.4Fe2As2 superconducting round wire without the aid of high-pressure sintering. It was found that high-strength outer sheaths and groove rolling synergistically enhance the core density to ∼100%. Combined with the fiber and concentric texture of the superconducting core, the Jc reaches 4.45 × 104 A cm−2 at 4.2 K and 10 T. Furthermore, the specially designed conductor architecture not only reduces material costs by lowering the proportion of Ag to ∼3.1%, but also provides high mechanical and thermal stability. This straightforward and cost-effective process can be scaled up for the massive production of long wires for high-field applications.
      Citation: Superconductor Science and Technology
      PubDate: 2024-02-13T00:00:00Z
      DOI: 10.1088/1361-6668/ad20ff
      Issue No: Vol. 37, No. 3 (2024)
       
  • Fast and accurate electromagnetic modeling of non-insulated and
           metal-insulated REBCO magnets

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      Authors: Enric Pardo; Philippe Fazilleau
      First page: 035016
      Abstract: REBCO high-temperature superconductors are promising for all-superconducting high-field magnets, including ultra-high field magnets. Non-insulated (NI) and metal-insulated (MI) windings are a good solution for protection against electro-thermal quench. Design and optimization requires numerical modelling of REBCO inserts for high-field magnets. Here, we detail a fast and accurate two-dimensional cross-sectional model for the electromagnetic response of NI and MI coils, which is based on the minimum electro magnetic entropy production. Benchmarking with an A − V formulation method on a double pancake coil shows good agreement. We also analyse a fully superconducting 32 T magnet with a REBCO insert and a low-temperature superconducing outsert. In particular, we analyse the current density, the screening current induced field (SCIF), and the AC loss. We have shown that metal-insulated coils enable transfer of angular current in the radial direction, and hence magnet protection, while keeping the same screening currents and AC loss of insulated coils, even at relatively high ramp rates of 1 A s−1. Surprisingly, soldered coils with low resistance between turns present relatively low AC loss for over-current configuration, which might enable higher generated magnetic fields. The numerical method presented here can be applied to optimize high-field magnets regarding SCIF in MI or NI magnets. It also serves as the basis for future electro-thermal modelling and multi-physics modelling that also includes mechanical properties.
      Citation: Superconductor Science and Technology
      PubDate: 2024-02-13T00:00:00Z
      DOI: 10.1088/1361-6668/ad1c6f
      Issue No: Vol. 37, No. 3 (2024)
       
 
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  Subjects -> ELECTRONICS (Total: 207 journals)
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