Superconductivity最新文献

{"title":"Numerical simulation on AC loss in REBCO tapes carrying non-sinusoidal currents","authors":"Katsuya Uejima ,&nbsp;Yueming Sun ,&nbsp;Daisuke Miyagi ,&nbsp;Jakub Glowacki ,&nbsp;Nicholas J. Long ,&nbsp;Zhenan Jiang","doi":"10.1016/j.supcon.2023.100063","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100063","url":null,"abstract":"<div><p>AC loss is one of the greatest obstacles for high-temperature superconducting (HTS) applications. In some HTS applications, coated conductors carry non-sinusoidal currents. Thus, it is important to investigate the effect of various waveforms on AC loss in coated conductors. In this work, transport AC loss in a 4 mm - wide REBCO coated conductor carrying sinusoidal and non-sinusoidal currents, is numerically investigated. The current amplitudes, the frequency of the transport current, and <em>n</em>-value are varied. Non-sinusoidal transport current waveforms studied include square, five types of trapezoidal, and triangular waveforms. Simulated results show that, for a given current amplitude, AC loss for the square current waveform is the greatest, that for the triangular waveform is the smallest. The sequence of AC loss in the conductor for different current waveforms coincides with the penetration depth, which implies the penetration depth determines the AC loss of the coated conductor. Furthermore, the transport AC loss in the conductor was found to decrease with frequency as <span><math><mrow><msup><mrow><mi>f</mi></mrow><mrow><mo>-</mo><mn>2</mn><mo>/</mo><mi>n</mi></mrow></msup></mrow></math></span> for non-sinusoidal transport current.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"8 ","pages":"Article 100063"},"PeriodicalIF":0.0,"publicationDate":"2023-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49698985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oxidation in Ca/K-1144 iron-based superconductors polycrystalline compounds","authors":"Zuhawn Sung ,&nbsp;Anastasiya Duchenko ,&nbsp;Giuseppe Celentano ,&nbsp;Jaeyel Lee ,&nbsp;Xiaobing Hu ,&nbsp;Nicola Pompeo ,&nbsp;Francesca Varsano ,&nbsp;Andrea Masi","doi":"10.1016/j.supcon.2023.100062","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100062","url":null,"abstract":"<div><p>Iron-based superconductors (IBSCs) are a class of material under investigation for the development of superconducting wires in the low-temperature-high magnetic fields power application. Among the various families of IBSCs, the 1144 CaKFe₄As₄ compound is a promising material able to achieve outstanding superconducting properties with a cheap and simple chemical composition. Oxidation, in these compounds, is considered an obstacle for high intergranular critical current density, <em>J_c,GB</em>. A study devoted to the evaluation of oxidation phenomena and their effects on the superconducting properties is thus needed in order to fully understand the involved mechanisms. From the evaluation of polycrystalline samples obtained by a mechanochemically assisted synthesis route, a degradation of the critical temperature and critical currents has been observed concurrently with oxygen accumulation at grain boundaries in open porosities. However, the crystalline structure at an atomic level seems not affected, as well as intragranular superconducting properties assessed by means of calorimetric methods. These results suggest that loss of superconducting properties in Ca/K-1144 compounds following oxidation is significantly associated with the worsening of grain connectivity.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"8 ","pages":"Article 100062"},"PeriodicalIF":0.0,"publicationDate":"2023-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49698983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dominant effect of residual secondary phase of powders on Jc and microstructure of Bi-2212 superconducting wires","authors":"L.H. Jin,&nbsp;G.Q. Liu,&nbsp;J.Q. Feng,&nbsp;X.Y. Xu,&nbsp;G.F. Jiao,&nbsp;S.N. Zhang,&nbsp;Q.B. Hao,&nbsp;P.X. Zhang,&nbsp;C.S. Li","doi":"10.1016/j.supcon.2023.100060","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100060","url":null,"abstract":"<div><p>Bi₂Sr₂CaCu₂O_8+δ (Bi-2212) superconducting round wires exhibited great potential for use in high-field applications. The purity of the precursor powders is critical for the transport current of the wires. However, the role of the residual secondary phase in the precursor powders is not fully understood. Here, the origin of the secondary phase was investigated in precursor powders that were prepared using ultrasonic spray pyrolysis (USP) and calcination processing. The microstructure and phase evolution of the precursor powders during the crystallization process were analyzed. Moreover, the effects that the residual secondary phase has on melting behavior, morphology properties, and the supercurrent flow of Bi-2212 multi-filamentary wires are systematically discussed. The residual secondary phase in the filament caused further crystallization, and this led to the formation of more and larger Bi-2201 grains at the onset of the melting process. The poor microstructure and low critical current of the final Bi-2212 wires can be attributed to the presence of the residual copper-rich phase. Bi-2212 wires that were prepared with fully crystallized powders had a high critical current density (<em>J</em>_c) of 6773 A/mm² at 4.2 K, self-field. It was revealed that control of the secondary phases in precursor powders is greatly significant for achieving superior values of <em>J</em>_c.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"8 ","pages":"Article 100060"},"PeriodicalIF":0.0,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49698975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Gd addition on the superconducting properties of Ti-based V, Nb, Ta alloys","authors":"SK Ramjan ,&nbsp;L.S. Sharath Chandra ,&nbsp;Rashmi Singh ,&nbsp;M.K. Chattopadhyay","doi":"10.1016/j.supcon.2023.100048","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100048","url":null,"abstract":"<div><p>The critical current density (<span><math><mrow><msub><mrow><mi>J</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math></span>) of the body centered cubic (<em>bcc</em>) V_0.6Ti_0.4 alloy enhances significantly after the addition of rare earth Gd as the latter is immiscible in the matrix [S. Paul, et.al, IEEE Trans. Appl. Supercond. <strong>31</strong>, 5 (2021)]. Very low solubility of Gd in other <em>bcc</em> elements like Ta and Nb is also well known [Jr. KA Gschneidner in Prog Sci Technol Rare Earths, vol. 1, pp. 222–258, 1964 <span><math><mrow><mi>&amp;</mi></mrow></math></span> M Neuberger, et.al in Handbook of Electronic Materials, Vol 4, 1972]. We use these facts to find the effect of adding 1 at.% Gd into the Nb_0.6Ti_0.4 and Ta_0.4Ti_0.6 alloys on the superconducting properties e.g., the transition temperature (<span><math><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math></span>), <span><math><mrow><msub><mrow><mi>J</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math></span>, flux pinning force density (<span><math><mrow><msub><mrow><mi>F</mi></mrow><mrow><mi>p</mi></mrow></msub></mrow></math></span>) and the microstructure. In spite of Gd being ferromagnetic, the <span><math><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math></span> in these alloys change only marginally (increase by 0.3 K in Ta_0.4Ti_0.6 and decrease by 0.15 K in Nb_0.6Ti_0.4 after Gd addition. The <span><math><mrow><msub><mrow><mi>J</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math></span> (<span><math><mrow><mi>H</mi><mo>=</mo><mn>1</mn></mrow></math></span> T, <em>T</em> = 4 K) increases by 5 and 1.5 times respectively in the Gd containing Nb_0.6Ti_0.4 and Ta_0.4Ti_0.6 alloys, which is quite small as compared to the increase observed in the V_0.6Ti_0.4 (20 times) system. With Gd addition, the grain size reduces approximately by 65% and 10% respectively in Nb_0.6Ti_0.4 and Ta_0.4Ti_0.6. Our analysis indicates that grain boundaries are the major flux line pinning centres in these alloys and the role of Gd in increasing the <span><math><mrow><msub><mrow><mi>J</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math></span> depends on the effectiveness of Gd in reducing the grain size. The grain boundary density depends strongly on the distribution of Gd precipitates, which is quite different from each other for two alloy systems under study. Moreover, our results suggest that the addition of Gd to commercial Nb-Ti (Nb_0.37Ti_0.63) alloy is a new promising route for achieving higher <span><math><mrow><msub><mrow><mi>J</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math></span> values.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"6 ","pages":"Article 100048"},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49880874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Low-temperature superconductors: Nb3Sn, Nb3Al, and NbTi","authors":"Nobuya Banno","doi":"10.1016/j.supcon.2023.100047","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100047","url":null,"abstract":"<div><p>Low-temperature superconducting (LTS) wires are of significant importance in high-field magnet applications. Current developments of the LTS wires are attributed to many studies. Particularly, Nb₃Sn is an attractive superconductor with substantial potential for performance improvement in view of an ideal microstructure that maximizes flux pinning properties. To date, various reviews have been reported on the physical properties of low-temperature superconductors. Therefore, this review focuses on understanding the fundamental phase formations and microstructural controls of low-temperature superconductors from the perspectives of growth kinetics, nucleation theory, and chemical potentials to facilitate the syntheses of these superconductors and advancement of wire production. Taking Nb₃Sn as an example, the effect of Cu addition to Nb₃Sn on Nb/Sn reactive diffusion is briefly described. Then, representative Nb₃Sn formations are schematically summarized to broaden our understanding of the development behaviors of Nb₃Sn. These behaviors are qualitatively reviewed in terms of Sn chemical potential. After mentioning the potential for performance improvement of Nb₃Sn, the influences of element additions, specifically those of Zr and Hf additions, resulting in breakthrough microstructural refinements, on Nb/Sn diffusion are investigated. Subsequently, strengthening of the matrix via element additions is reviewed. Thereafter, taking Nb₃Al as an example, the features of Nb₃Al formation and basic development processes, including low-temperature processes, metastable phase transformations, and microstructural control, are described. Strain sensitivity, one of the most important properties of Nb₃Al, is also briefly reviewed. Then, taking Nb alloy as an example, <em>α</em>-Ti precipitation in a binary Nb–Ti system is concisely summarized. Subsequently, recently reported new artificial pin incorporation based on a powder method is introduced, followed by a unique study of the application of high-temperature-tolerable Nb superconducting alloys in superconducting joints. This review makes a novel contribution to the literature as it provides a comprehensive understanding of phase formation in low-temperature superconductors.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"6 ","pages":"Article 100047"},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49880875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of a finite impulse response filter for rapid single-flux-quantum signal processors based on stochastic computing","authors":"Ruidi Qiu,&nbsp;Peiyao Qu,&nbsp;Xiangyu Zheng,&nbsp;Guangming Tang","doi":"10.1016/j.supcon.2023.100045","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100045","url":null,"abstract":"<div><p>Rapid-Single-Flux-Quantum (RSFQ) circuit technology is well known for its low power consumption and latency, which enables digital signal processing up to tens of GHz. As a fundamental digital filter, the Finite Impulse Response (FIR) filter has wide applications in communication systems. A design of an FIR filter based on RSFQ circuit technology is proposed. However, the FIR filter consumes large amounts of adders and multipliers. Based on Stochastic Computing (SC) theory with which adder and multiplier are much simpler, the hardware cost of FIR filter is dramatically reduced. A novel stochastic number generator (SNG), a stochastic-to-binary converter (SBC), and the FIR filter were designed and verified via logic simulation with a target frequency of 10 GHz. The results indicated the FIR filter performs correct operations. The proposed FIR filter consists of 2255 Josephson junctions (JJs) without wiring cells (i.e., Josephson Transmission Lines (JTLs), Passive Transmission Lines (PTLs)), which is acceptable, making it possible to be used in RSFQ digital signal processors.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"6 ","pages":"Article 100045"},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49880862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"AC loss mitigation for high temperature superconducting coils in wireless power transfer","authors":"Hongyi Chen ,&nbsp;Hongye Zhang","doi":"10.1016/j.supcon.2023.100044","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100044","url":null,"abstract":"<div><p>With the rapid development of high temperature superconducting (HTS) technology, second generation (2G) HTS materials have become a promising alternative to traditional conductive materials in the power transmission industry. Recently, the topic of using HTS materials in wireless power transfer (WPT) systems for electric vehicles (EVs) has attracted widespread attention in the background of net zero transport. With virtually zero DC resistance and superior current-carrying capacity, HTS materials can achieve high quality factor and power density in the WPT resonant circuits compared to conventional metals, e.g., copper. However, the optimal working frequency for the conventional WPT system is relatively high in the order of kilohertz level. Superconducting coils working at high frequencies could generate high AC losses, reducing the overall power transfer efficiency (PTE) and increasing the cooling burden. In order to improve the PTE of HTS-WPT systems, the AC loss mitigation methods for different HTS coil topologies have been investigated in this paper by varying the inter-turn gap and tape width. Three HTS coil structures, namely the spiral coil, the solenoid coil and the double pancake (DP) coil, have been studied with a 2D axisymmetric multi-layer numerical model based on the <strong><em>H</em></strong> - formulation, and the simulation results have been validated by the published experimental data. The general loss characteristics, loss distributions in each turn, as well as magnetic flux densities have been analysed in detail for three types of HTS coils. Moreover, the impact of these two loss reduction methods on the WPT performance has also been evaluated. Findings have shown that increasing the inter-turn gap and tape width can effectively reduce the AC power losses and increase the PTE of the HTS-WPT system. The spiral coil demonstrates the highest AC power loss reduction effect and PTE while maintaining a stable level of magnetic fields. This paper is believed to deepen the understanding of superconducting WPT and provide a useful reference for more efficient wireless energisation applications.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"6 ","pages":"Article 100044"},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49880861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hope and challenge of ternary hydrogen-based superconductors under pressure","authors":"Guangtao Liu,&nbsp;Hanyu Liu","doi":"10.1016/j.supcon.2023.100046","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100046","url":null,"abstract":"","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"6 ","pages":"Article 100046"},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49880858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"J-A formulation: A finite element methodology for simulating superconducting devices","authors":"Gabriel dos Santos ,&nbsp;Bárbara Maria Oliveira Santos ,&nbsp;Felipe Sass ,&nbsp;Flávio Goulart dos Reis Martins ,&nbsp;Guilherme Gonçalves Sotelo ,&nbsp;Rubens de Andrade Junior","doi":"10.1016/j.supcon.2023.100049","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100049","url":null,"abstract":"<div><p>High-temperature superconductors are a powerful technological option to be applied in the current scenario of energy transition. Their applications include fault current limiters, power electrical cables, and electrical machines, for example. Due to the non-linearities of superconductors, it is computationally costly to run real models of superconducting equipment. Therefore, it is of paramount importance to have a reliable and fast formulation to model superconducting devices. This paper proposes a new hybrid J-A formulation to simulate superconducting devices. The new formulation is validated with 5 case studies, some of which are benchmarks. The J-A formulation agrees in all cases and has a smaller computation time when compared with the T-A formulation. Moreover, due to the simple implementation, the proposed formulation allows the possibility of running the J and A formulations in the same order and presents itself as a potential feature to speed up and help the design of the superconducting devices.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"6 ","pages":"Article 100049"},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49880860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Concept design of an HTS linear power generator for wave energy conversion","authors":"Petrus Kambo ,&nbsp;Yuhi Yamanouchi ,&nbsp;Antomne A. Caunes ,&nbsp;Kota Yamaguchi ,&nbsp;Mitsuru Izumi ,&nbsp;Tetsuya Ida","doi":"10.1016/j.supcon.2023.100043","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100043","url":null,"abstract":"<div><p>We show a conceptual structure for a wave energy converter, which features a direct-drive linear power generator with REBaCuO high-temperature superconducting (HTS) bulk field poles and driven by a heaving buoy. A dual translator power generation system of the proposed concept structure is a linear generator in which both the HTS bulks and armature copper coils move in opposite directions simultaneously. A performance analysis of our linear generator was conducted using a finite-element electromagnetic field analysis method. The results of the analysis were compared between the HTS dual translator linear power generator and the HTS single translator linear power generator. The maximum electromagnetic force and the average output power of the HTS dual translator are around 5 % and 11 % higher than that of the HTS single translator. We further present the results of the analysis regarding the influence of reducing the stroke length of the linear generator translator on the output power, where the output power for the HTS dual translator system increased up to a factor of two, in comparison to the HTS single translator counterpart, for the same reduction of stroke length.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"6 ","pages":"Article 100043"},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49880859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}