 Subjects -> ELECTRONICS (Total: 207 journals)
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- Cuprate superconductors for nuclear fusion: shining light on imperfections
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Authors: Stefan Guénon
First page: 120501
Citation: Superconductor Science and Technology
PubDate: 2023-10-17T23:00:00Z
DOI: 10.1088/1361-6668/ad01ea
Issue No: Vol. 36, No. 12 (2023)
- Transient research on distribution networks incorporating superconducting
cables utilizing field–circuit coupling method-
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Authors: Xianhao Li; Yuejin Tang, Li Ren, Hongyi Huang, Jing Shi, Zhenzi Wang, Peng Yu, Zhonghang Li, Zhe Wang, Anlong Zhang Ying Xu
First page: 125001
Abstract: High temperature superconducting (HTS) cable represents a promising solution for fulfilling the power demands of cities with large loads and high density. However, due to their connection to the distribution network, HTS cables are vulnerable to fault currents exceeding ten times their rated current, which poses a serious threat to both the safety of the cable and the operation of the grid. Considering the highly nonlinear nature of superconducting conductivity, this study develops a field–circuit coupling model to investigate the transient characteristics of distribution networks incorporating superconducting cables (DNSC). Firstly, a finite element model based on the two-dimensional H formulation was built to calculate the electrical and thermal parameters of the HTS cable. Subsequently, an equivalent circuit model of the distribution network was employed to estimate the short-circuit currents. Communicating via a co-simulation server, the superconducting cable current and distribution network impedance were updated in each step. Further, based on an actual DNSC system in Shenzhen, China, the highest quenching temperature of the cable and the maximum fault current of busbars were assessed. Finally, by integrating current limiters into the system, the withstand capability of the cable and busbars was determined, which indicates that the improved protection configuration can effectively suppress fault currents and ensure safe operation. Successfully applied to an actual distribution network, the co-simulation model utilizing the field–circuit coupling method addresses the challenges of solving highly nonlinear and time-varying systems, enabling transient analysis and protection research for the integration of superconducting devices into the conventional grid.
Citation: Superconductor Science and Technology
PubDate: 2023-10-17T23:00:00Z
DOI: 10.1088/1361-6668/ad01eb
Issue No: Vol. 36, No. 12 (2023)
- Monodisperse BaZrO3 nanocrystals and flux pinning effect on upscaling
MOD-derived (Y,Dy)Ba2Cu3O7− δ superconducting tapes-
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Authors: Rongtie Huang; Jing Chen, Zhiyong Liu, Wenzhi Dou, Ning Zhang Chuanbing Cai
First page: 125002
Abstract: In the present work, monodisperse BaZrO3 (BZO) nanocrystals with controllable sizes are successfully introduced into trifluoroacetate metal–organic deposition derived (Y,Dy)Ba2Cu3O7−δ ((Y,Dy)BCO)-coated superconducting tapes to act as effective pinning centers. The BZO nanocrystal addition strategy is extended to upscaling coated conductors as long as hundreds of meters, and as thick as 3.4 μm, of (Y,Dy)BCO layers. The corresponding superconducting performances of BZO-added (Y,Dy)BCO-coated conductors are systematically investigated under various applied magnetic fields and temperatures. It is revealed that the Ic (77 K, self-field) of BZO-added tapes decreases linearly with BZO concentration, while the corresponding in-field lift-factors increase for all studied BZO additions. In-field Jc values under various fields at low temperatures show that the (Y,Dy)BCO tape with 5%-BZO addition exhibits a better performance than that of other concentrations. Besides, this benefit of BZO addition appears identical for both thin and thick samples, as well as for tapes that are hundreds of meters long. The angular dependence of in-field Ic also shows that significant improvement occurs in all the studied angular ranges after nanocrystal BZO additions, demonstrating that the nanocrystal addition strategy is of great value for upscaling commercial (Y,Dy)BCO tape for in-field applications.
Citation: Superconductor Science and Technology
PubDate: 2023-10-18T23:00:00Z
DOI: 10.1088/1361-6668/acff25
Issue No: Vol. 36, No. 12 (2023)
- The on-chip scanning probe with dual niobium nitride nanoscale
superconducting quantum interference devices for magnetic imaging at the
high temperature-
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Authors: Denghui Zhang; Yinping Pan, Guangting Wu, Shujie Yu, Xianghai Zhong, Yue Wang, Xiaoyu Liu, Ling Wu, Wei Peng, Lu Zhang, Lei Chen Zhen Wang
First page: 125003
Abstract: The scanning superconducting quantum interference device (SQUID) microscope is a powerful tool for investigating the microscale magnetic properties of quantum materials. However, the low operating temperature of SQUIDs limits the application of the microscope. In this work, we developed an on-chip probe with dual niobium nitride (NbN) nano-SQUIDs for scanning SQUID microscope. The working temperature of the NbN nano-SQUID on-chip probe was up to 8 K, and it enabled the magnetic imaging of samples at the temperature up to 128 K. We used a gradiometric readout scheme for dual nano-SQUIDs in one probe to reduce the influence of the background magnetic field. Furthermore, we demonstrated the capabilities of both topographic and current imaging by the on-chip probe with spatial resolutions of 1 μm and 2 μm, respectively. The advantage of the probe at the high temperature was also demonstrated by the investigation of the superconducting vortices distribution in the yttrium-barium-copper-oxide film.
Citation: Superconductor Science and Technology
PubDate: 2023-10-18T23:00:00Z
DOI: 10.1088/1361-6668/ad0182
Issue No: Vol. 36, No. 12 (2023)
- On the dilemma between percolation processes and fluctuating pairs as the
origin of the enhanced conductivity above the superconducting transition
in cuprates-
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Authors: I F Llovo; J Mosqueira F Vidal
First page: 125004
Abstract: The confrontation between percolation processes and superconducting fluctuations to account for the observed enhanced in-plane electrical conductivity above but near Tc in cuprates is revisited. This dilemma is currently an open and debated question, whose solution would contribute to the phenomenological understanding of the emergence of superconductivity in these compounds. The cuprates studied here, La1.85Sr0.15CuO4, Bi2Sr2CaCu2O_{8+\delta}, and Tl2Ba2Ca2Cu3O10, have a different number of superconducting CuO2 (ab)-layers per unit-cell length and different Josephson coupling between them, and are optimally-doped to minimize Tc-inhomogeneities. The excellent chemical and structural quality of these optimally-doped samples also contribute to minimize the effect of extrinsic T{c}-inhomogeneities, a crucial aspect when analyzing the possible presence of intrinsic percolative processes. Our analyses also cover the so-called high reduced-temperature region, up to the resistivity rounding onset ɛonset. By using the simplest form of the effective-medium theory, we show that possible emergent percolation processes alone cannot account for the measured enhanced conductivity. In contrast, these measurements can be quantitatively explained using the Gaussian–Ginzburg–Landau (GGL) approach for the effect of superconducting fluctuations in layered superconductors, extended to ɛonset by including a total energy cutoff, which takes into account the limits imposed by the Heisenberg uncertainty principle to the shrinkage of the superconducting wavefunction. Our present analysis confirms the adequacy of this cutoff, which was introduced heuristically, and that the effective periodicity length is controlled by the relative Josephson coupling between superconducting layers, two long standing debated aspects of the GGL approaches for multilayered superconductors. These conclusions are reinforced by analyzing, as an example, one of the recent works that allegedly discards the superconducting fluctuations scenario while supporting a percolative scenario for the enhanced conductivity above Tc in cuprates.
Citation: Superconductor Science and Technology
PubDate: 2023-10-18T23:00:00Z
DOI: 10.1088/1361-6668/acff8a
Issue No: Vol. 36, No. 12 (2023)
- A sulfurization method for creating the buffer-layers current flow
diverter architecture in REBa2Cu3O7 coated conductors-
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Authors: P Barusco; J Giguère, C Lacroix, F Sirois, X Granados, T Puig X Obradors
First page: 125005
Abstract: The current flow diverter (CFD) is a known concept that has proven to effectively reduce the probability of destructive hot spots in REBa2Cu3O7 (REBCO; RE = rare earth) coated conductors (CCs) by boosting the normal zone propagation velocity. However, the implementation of the CFD concept requires additional steps in a fabrication process that is already complex and has struggled to find a simple reel-to-reel fabrication method. This work reports on the details of a fabrication route for the buffer-layers-CFD (bCFD) architecture using a solid-vapor silver sulfurization technique to tune the geometry of the metal stabilizer in the high-temperature superconductor tape. The analysis of the microstructure and superconducting properties of the Ag2S/Ag/GdBCO trilayer processed under different conditions shows how we achieved a new customized functional CC with the bCFD architecture. In DC limitation experiments, this bCFD-sulfide architecture allowed to generate an electric potential much faster than the conventional architecture (60 V s−1 vs. 1.2 V s−1) thanks to the strong enhancement of the NPZV.
Citation: Superconductor Science and Technology
PubDate: 2023-10-18T23:00:00Z
DOI: 10.1088/1361-6668/ad01ec
Issue No: Vol. 36, No. 12 (2023)
- High temperature superconductors for commercial magnets
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Authors: Arno Godeke
First page: 113001
Abstract: The steadily increasing magnetic fields that can be generated with superconducting magnets are reaching the limits of what is achievable with low-temperature superconductors (LTS). At the same time, a reduction of fossil-fuel extraction will amplify the already limited availability of helium as a coolant for superconducting magnets in the near future. Hence, manufacturers of commercial applications that rely on superconducting magnets have become increasingly interested in exploring technologies that enable a move beyond the magnetic-field limitations posed by LTS conductors, and/or enable higher operating temperatures to allow for cryogen-free operation. High-temperature superconductors (HTS), such as \mathrm{[RE]Ba}_2\mathrm{Cu}_3\mathrm{O}_{7-\delta} (REBCO), \mathrm{Bi_2Sr_2CaCu_2O}_{8+x} (Bi-2212), and Bi_{2-x}PbxSr2Ca2Cu3O_{10-y} (Bi-2223) have all matured to a certain commercial extent, and have thereby become enablers for such technologies. The emergence of various new commercial magnet-systems that utilize HTS, suggests that we are at the dawn of a wider commercial implementation. A review of which HTS properties are critical for these magnets, what is currently available, and what is missing, is therefore considered timely and appropriate in this context.
Citation: Superconductor Science and Technology
PubDate: 2023-10-12T23:00:00Z
DOI: 10.1088/1361-6668/acf901
Issue No: Vol. 36, No. 11 (2023)
- Surface oxides, carbides, and impurities on RF superconducting Nb and
Nb3Sn: a comprehensive analysis-
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Authors: Zeming Sun; Zhaslan Baraissov, Catherine A Dukes, Darrah K Dare, Thomas Oseroff, Michael O Thompson, David A Muller Matthias U Liepe
First page: 115030
Abstract: Surface structures on radio-frequency (RF) superconductors are crucially important in determining their interaction with the RF field. Here we investigate the surface compositions, structural profiles, and valence distributions of oxides, carbides, and impurities on niobium (Nb) and niobium–tin (Nb3Sn) in situ under different processing conditions. We establish the underlying mechanisms of vacuum baking and nitrogen processing in Nb and demonstrate that carbide formation induced during high-temperature baking, regardless of gas environment, determines subsequent oxide formation upon air exposure or low-temperature baking, leading to modifications of the electron population profile. Our findings support the combined contribution of surface oxides and second-phase formation to the outcome of ultra-high vacuum baking (oxygen processing) and nitrogen processing. Also, we observe that vapor-diffused Nb3Sn contains thick metastable oxides, while electrochemically synthesized Nb3Sn only has a thin oxide layer. Our findings reveal fundamental mechanisms of baking and processing Nb and Nb3Sn surface structures for high-performance superconducting RF and quantum applications.
Citation: Superconductor Science and Technology
PubDate: 2023-10-10T23:00:00Z
DOI: 10.1088/1361-6668/acff23
Issue No: Vol. 36, No. 11 (2023)
- Non-uniform current distribution in parallel-wound no-insulation
high-temperature superconductor coil during ramping and fast discharging
operations-
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Authors: Yutong Fu; Yawei Wang, Weihang Peng, Yue Zhao, Guangtong Ma Zhijian Jin
First page: 115031
Abstract: A parallel-wound no-insulation (PWNI) high-temperature superconductor (HTS) coil is a kind of pancake-shaped no-insulation (NI) coil wound with parallel-stacked HTS tapes, which combines the characteristics of a NI coil and non-twisted stacked-tape cable. It shows a significant advantage in accelerating the ramping response compared with traditional NI HTS coils wound by a single tape, and is a promising alternative for large-scale high-field magnets. The stacked cable approach can lead to current redistribution between parallel tapes during ramping operations. It couples with the turn-to-turn current redistribution and leads to a much more complicated current redistribution inside the PWNI coil, the mechanism of which remains unclear so far. The aim of this work is to investigate electromagnetic behavior of a PWNI HTS coil in ramping and fast discharging process. A simulation model was developed by integrating an equivalent circuit network model and an improved T–A model. A three-tape PWNI coil and its insulated counterpart were wound and tested, and this model was validated by charging and discharging tests. Results show that there is a significant non-uniform current distribution on parallel tapes in the same turn during ramping operations and the maximum azimuthal current (transport current) can be 2.26 times the minimum one in the three-tape PWNI coil in this study. Meanwhile, the radial current shows a considerable accumulation in the tape near turn-to-turn contacts and the radial current through the turn-to-turn contacts can be 4.16 times of that the flow through tape-to-tape contacts (parallel tapes) in the same turn. During the fast discharging process, a significant coupling current is generated in the PWNI coil, leading to a large opposite transport current in local areas; the amplitude of variation of this can be 4.66 times the initial operating current. The radial current shows a similar distribution but opposite direction to that during ramping, and its amplitude is two orders of magnitude higher. These results provide practical guidelines for the design of large-scale high-field HTS magnets.
Citation: Superconductor Science and Technology
PubDate: 2023-10-11T23:00:00Z
DOI: 10.1088/1361-6668/acff26
Issue No: Vol. 36, No. 11 (2023)
- High temperature superconducting CORC cable with variable winding angles
for low AC loss and high current carrying SMES system-
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Authors: Jinxing Zheng; Yuan Cheng, Ming Li, Fei Liu, Xufeng Liu Haiyang Liu
First page: 115032
Abstract: Owing to the rising demand for enhanced high-current capacity within superconducting magnetic energy storage (SMES) system used in power grids, there is a growing focus on enhancing the current-carrying capability of SMES setups wound with conductor on round core (CORC) cables. However, it is crucial to note that the dissipation of AC losses in CORC cables during rapid charge and discharge cycles can substantially impact the safe operation of SMES. The CORC cable is crafted by spirally winding numerous ReBCO tapes around copper tubes. Even slight alterations in the winding angles of these tapes can result in shifts at current distribution across the ReBCO tapes, thus leading to differences in AC losses. Hence, the primary objective of this paper is to study the effect of varying winding angles of each ReBCO layer on AC loss. The adoption of variable angles results in the reduction of current flowing through the outermost tapes. And the AC losses in the outermost tapes happen to account for the majority of the total AC losses. Through simulations and experiments, it was observed that the AC loss in the CORC cable with variable angles (4 × 12, 25°–40°) was 25% lower than that in the case of fixed angles (3 × 11, 45°). These findings demonstrate a noteworthy downward trajectory in AC losses when variable angles are applied to the CORC cable. These insights hold significant value for the practical application of CORC cables within SMES systems.
Citation: Superconductor Science and Technology
PubDate: 2023-10-11T23:00:00Z
DOI: 10.1088/1361-6668/acff8b
Issue No: Vol. 36, No. 11 (2023)
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