Superconductor Science and Technology最新文献

{"title":"Investigation of high-speed superconducting electric machines through time-space extrusion numerical modelling","authors":"Hongye Zhang","doi":"10.1088/1361-6668/ad7173","DOIUrl":"https://doi.org/10.1088/1361-6668/ad7173","url":null,"abstract":"Featured by high power density and efficiency, high temperature superconducting (HTS) electric machines provide a promising solution to heavy-duty electric transport, e.g. electric aircraft. However, designing HTS machines, particularly high-speed HTS motors, presents significant challenges: (1) modelling is highly time-consuming due to the non-linear resistivity of superconductors and complex machine topology; (2) accurately estimating the AC loss of HTS windings remains an open aspiration due to the complicated AC environment. To reduce computational complexity, the thin film approximation (only considering the approximated 1-D HTS film) for HTS coated conductors (CCs) has been widely adopted in simulations, such as the <bold>T</bold>-formulation models; however, the thin film approximation becomes inadequate for HTS CCs under high-frequency magnetic fields, as encountered in high-speed motors for aerospace. To efficiently and accurately model the AC loss of HTS windings in high-speed superconducting machines, taking a 1 MW superconducting synchronous motor with HTS armature windings as an example, this paper has adopted a time-space extrusion (TSE) method, which demonstrates a &gt;25-fold decrease in modelling time while maintaining comparable accuracy to two benchmark <bold>H-A</bold> models. The power dissipation in both normal-conducting and superconducting layers of HTS windings has been studied, the AC losses in different turns of the armature winding have been explored, and the slot leakage field harmonics have been illustrated. Results have shown that the losses in Cu and Ag layers for high-speed HTS machines operating at cryo-temperatures (e.g. liquid hydrogen temperature) are not neglectable, especially with a high residual resistance ratio and in the presence of harmonics. The HTS armature winding should be positioned away from the iron tooth and slot opening to minimise exposure to slot leakage fields. The adopted TSE modelling strategy and drawn conclusions have provided valuable insights for the efficient design of high-speed superconducting machines.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"58 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208405","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":"Pressure tuning of the Se-substituted BiS2-based superconductor LaO0.5F0.5Bi(S 1−xSex )2","authors":"Naoki Kase, Katsuo Kondo, Shigefumi Watanabe, Nobuaki Miyakawa","doi":"10.1088/1361-6668/ad6e23","DOIUrl":"https://doi.org/10.1088/1361-6668/ad6e23","url":null,"abstract":"We report the effect of hydrostatic pressure on LaO_0.5F_0.5Bi(S<inline-formula>\u0000<tex-math><?CDATA $ _{1-x}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mn>1</mml:mn><mml:msub><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:msub></mml:mrow></mml:math>\u0000<inline-graphic xlink:href=\"sustad6e23ieqn2.gif\"></inline-graphic></inline-formula>Se_{<italic toggle=\"yes\">x</italic>})₂ with chemical pressure applied to a conducting layer by means of electrical resistivity and ac-magnetic susceptibility measurements up to 2.5 GPa. We confirmed the bulk superconductive nature of the low superconducting (low-SC) and high superconducting (high-SC) phase using ac-magnetic susceptibility under hydrostatic pressure. The <inline-formula>\u0000<tex-math><?CDATA $T_mathrm{c}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>T</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"sustad6e23ieqn3.gif\"></inline-graphic></inline-formula> of the high-SC phase was observed to decrease with an increase in the Se substitution. The critical pressure <inline-formula>\u0000<tex-math><?CDATA $P_mathrm{c}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>P</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"sustad6e23ieqn4.gif\"></inline-graphic></inline-formula> shifted toward the higher <italic toggle=\"yes\">P</italic> and the <italic toggle=\"yes\">P</italic>-induced transition broadened with an increase in the Se content. The <inline-formula>\u0000<tex-math><?CDATA $T_mathrm{c}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>T</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"sustad6e23ieqn5.gif\"></inline-graphic></inline-formula> of the low-SC phase can be expressed by assuming an applied hydrostatic pressure of 0.75 GPa as the Se substitution of <italic toggle=\"yes\">x</italic> = 0.1. The broad <inline-formula>\u0000<tex-math><?CDATA $P_mathrm{c}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>P</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"sustad6e23ieqn6.gif\"></inline-graphic></inline-formula> transition is likely to be ascribed to the inhomogeneity of the Se substitution.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208399","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":"Characterization of high-speed writing and reading operations of the superconducting memory cell","authors":"Yue Wang, Xianghai Zhong, Junwen Zeng, Yinping Pan, Denghui Zhang, Shujie Yu, Ling Wu, Lu Zhang, Wei Peng, Jie Ren, Lei Chen, Zhen Wang","doi":"10.1088/1361-6668/ad70dc","DOIUrl":"https://doi.org/10.1088/1361-6668/ad70dc","url":null,"abstract":"Superconducting memory cells that use flux quanta as their storage medium can achieve ultra-fast access times with ultra-low power consumption. However, the data signal generated by a flux quantum memory (FQM) cell is usually too weak and too fast to be measured directly. Here, we present a method to characterize the real-time operation of an FQM cell. The storage loop of the FQM cell, configured with a Nb/NbN<italic toggle=\"yes\">_X</italic>/Nb Josephson junction, was proven the capability to store multiple flux quanta. The readout was demonstrated by a superconducting quantum interference device composed of underdamped Nb/Al-AlO<italic toggle=\"yes\">_X</italic>/Nb Josephson junctions. The writing and reading operations were achieved by a short pulse ranging from 0.1 ns to 2.5 ns, and a constant bit error rate of ∼2.46% was measured for the fabricated FQM cell. The method presented here can be used to study real-time operation of an FQM cell in a direct manner.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208400","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":"Noise scaling in SQUID arrays","authors":"O A Nieves, K-H Müller","doi":"10.1088/1361-6668/ad70dd","DOIUrl":"https://doi.org/10.1088/1361-6668/ad70dd","url":null,"abstract":"We numerically investigate the noise scaling in high-<italic toggle=\"yes\">T_c</italic> commensurate 1D and 2D SQUID arrays. We show that the voltage noise spectral density in 1D arrays violates the scaling rule of <inline-formula>\u0000<tex-math><?CDATA ${sim}1/N_p$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mrow><mml:mo>∼</mml:mo></mml:mrow><mml:mn>1</mml:mn><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:msub><mml:mi>N</mml:mi><mml:mi>p</mml:mi></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"sustad70ddieqn1.gif\"></inline-graphic></inline-formula> for the number <italic toggle=\"yes\">N_p</italic> of Josephson junctions in parallel. In contrast, in 2D arrays with <italic toggle=\"yes\">N_s</italic> 1D arrays in series, the voltage noise spectral density follows more closely the expected scaling behaviour of <inline-formula>\u0000<tex-math><?CDATA ${sim}N_s/N_p$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mrow><mml:mo>∼</mml:mo></mml:mrow><mml:msub><mml:mi>N</mml:mi><mml:mi>s</mml:mi></mml:msub><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:msub><mml:mi>N</mml:mi><mml:mi>p</mml:mi></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"sustad70ddieqn2.gif\"></inline-graphic></inline-formula>. Additionally, we reveal how the flux and magnetic field rms noise spectral densities deviate from their expected <inline-formula>\u0000<tex-math><?CDATA ${sim}(N_sN_p)^{-1/2}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mrow><mml:mo>∼</mml:mo></mml:mrow><mml:mo stretchy=\"false\">(</mml:mo><mml:msub><mml:mi>N</mml:mi><mml:mi>s</mml:mi></mml:msub><mml:msub><mml:mi>N</mml:mi><mml:mi>p</mml:mi></mml:msub><mml:msup><mml:mo stretchy=\"false\">)</mml:mo><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math><inline-graphic xlink:href=\"sustad70ddieqn3.gif\"></inline-graphic></inline-formula> scaling and discuss their implications for designing low noise magnetometers.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208401","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":"Mechanical behavior and critical current density variation of the twisted stacked-tape slotted-core cable-in-conduit conductor under bending and axial tensile load","authors":"Yang Liu, Yuanwen Gao","doi":"10.1088/1361-6668/ad68d2","DOIUrl":"https://doi.org/10.1088/1361-6668/ad68d2","url":null,"abstract":"The second generation (2G) high-temperature superconducting (HTS) REBCO tape and the HTS cable made by the REBCO company are considered to be alternative materials for future superconducting magnet design due to their exceptional performance. The twisted stacked-tape slotted-core (TSSC) cable-in-conduit-conductor cable, which is one of the crucial layout structures in HTS cables, has been extensively studied by numerous research groups over the years. In this paper, a 3D finite element model of the TSSC HTS cable under bending and axial tensile loads is established using the bilinear isotropic hardening model in COMSOL commercial finite element software. The mechanical behavior of the TSSC cable under bending and axial tensile loads, as well as the evolution process of overall cable performance and critical current of individual tapes inside slots, are revealed by conducting mechanical analysis and using an empirical fitting formula between the critical current density of the 2G HTS tapes and axial strain. Furthermore, optimization engineering suggestions for its structure are provided, such as reducing the twist pitch, decreasing the tape width, increasing the number of tapes, reducing the slot width while avoiding direct contact between tapes and slot walls, increasing the number of slots, increasing diameter of diversion trench and inner diameter of helical core under predominant bending loads. In the case of axial tensile loads, the aforementioned suggestions are also applicable except for the inner and outer diameters of the helical core. The critical current performance can be enhanced by augmenting the outer diameter of the helical core in this case. However, it is almost unaffected by the inner diameter of the helical core.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208402","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":"A novel low-resistance solder-free copper bonding joint using a warm pressure welding method for REBCO coated conductors","authors":"Yuwei Zhou, Zhen Huang","doi":"10.1088/1361-6668/ad6e24","DOIUrl":"https://doi.org/10.1088/1361-6668/ad6e24","url":null,"abstract":"Constrained by the fabrication of second-generation high-temperature superconducting (2G HTS) tapes, connecting multiple pieces of tapes through joints is often necessary in large-scale applications. In the application of HTS magnets, joint technology is key for achieving closed-loop operation and reducing thermal loads. However, most soldered joints still cannot achieve the expected results. Thus, there is an urgent need to find a method for easily fabricating low-resistance joints. In this study, a low-resistance solder-free copper bonding joint for 2G HTS copper-plated tapes is proposed. The formation mechanism of the joint is presented, and the effects of the bonding temperature and pressure on the electrical and mechanical properties of the copper bonding joint are investigated. The results show that the copper bonding joint can be manufactured by pretreating the tape for 5 min and bonding it in the air for 3 min at 333 MPa at temperatures higher than (or equal to) 150 °C or at pressures greater than (or equal to) 250 MPa and 180 °C. The characteristic resistance of this joint is approximately 16.8 nΩ cm², which is approximately one-third lower than that of soldered joints, and it has mechanical properties similar to those of soldered joints under axial tension. We believe that the application of this type of copper bonding joint can significantly aid in the design and manufacturing of large HTS magnets.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226525","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":"A novel and fast electromagnetic and electrothermal software for quench analysis of high field magnets","authors":"Anang Dadhich, Philippe Fazilleau, Enric Pardo","doi":"10.1088/1361-6668/ad68d3","DOIUrl":"https://doi.org/10.1088/1361-6668/ad68d3","url":null,"abstract":"High-field superconducting REBCO magnets contain several coils with many turns. For these magnets, electro-thermal quench is an issue that magnet designers need to take into account. Thus, there is a need for a fast and accurate software to numerically model the overall performance of full-scale magnets. High temperature superconductors can be modeled using different techniques for electro-magnetic and thermal (finite element method) analysis. However, it takes a lot of time to model the electro-magnetic and electro-thermal behavior of superconductors simultaneously, especially for non-insulated or metal-insulated coils. In addition, most of the available methods ignore screening currents, which are an important feature of REBCO magnets. We have developed a novel software programmed in C++, which performs coupled electro-magnetic and electro-thermal analysis using variational methods based on minimum electro-magnetic entropy production and finite difference, respectively. The developed software, which takes screening currents into account, is applied to axi-symmetric full scale magnets of more than 32 T field strength under the SuperEMFL project for thermal quench reliability during standard operation. We show that magnets incorporating non-insulated coils are more reliable against quench than metal insulated coils. Also, realistic cooling conditions at the boundaries are essential for such simulations. The model developed can be used for a quick and complete electro-magnetic and electro-thermal analysis of superconducting high field magnets.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208403","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":"Thermal degradation analysis and optimization of controlled heat treatment for stacked high temperature superconducting tapes","authors":"Shige Yang, Bohan Tang, Zhilai Yue, Hui Yu, Bowen Xie, Sicheng Li, Yanquan Chen, Rui Niu, Jun Zhao, Peng Zhou, Wenge Chen, Shili Jiang, Donghui Jiang, Guangli Kuang","doi":"10.1088/1361-6668/ad6ada","DOIUrl":"https://doi.org/10.1088/1361-6668/ad6ada","url":null,"abstract":"High temperature superconducting (HTS) tapes have crucial applications for generating high magnetic fields with minimal power input. Given a single tape has a limited current-carrying capacity, stacked tapes are common, fabricated through methods like solder soldering or epoxy impregnation requiring heat treatment. In this work, we have investigated the efficient region for vacuum heat treatment applicable of commercial HTS tapes, analysed the thermal degradation principles and accordingly proposed a controlled heat treatment process for stacked HTS tapes to achieve more precise regulation of the critical current (<inline-formula>\u0000<tex-math><?CDATA ${I_{text{c}}}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mrow><mml:msub><mml:mi>I</mml:mi><mml:mrow><mml:mtext>c</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:mrow></mml:math><inline-graphic xlink:href=\"sustad6adaieqn1.gif\"></inline-graphic></inline-formula>). This heat treatment process was explored using a specialized multi-temperature zone vacuum system. Critical parameters in this process include heat treatment temperature, duration and pressure on the tape. A series of experiments were conducted at 77 K in a self-field to investigate how these parameters affect the superconductivity performance of stacked HTS tapes. Based on the experimental results, an optimal heat treatment process has been proposed. Under the current process, with the heat treatment temperature set at 200 °C, duration at 20 min, and pressure on the tape at 12 MPa, the samples exhibit favourable properties characterized by a smooth and neat appearance without defects such as pinholes or false soldering, and the superconductivity performance can be consistently maintained at more than 97%. The obtained measurements were compared with simulated results, demonstrating an error margin within 0.5%. Moreover, precise control of <inline-formula>\u0000<tex-math><?CDATA ${I_{text{c}}}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mrow><mml:msub><mml:mi>I</mml:mi><mml:mrow><mml:mtext>c</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:mrow></mml:math><inline-graphic xlink:href=\"sustad6adaieqn2.gif\"></inline-graphic></inline-formula> is achieved, tailored to tape and stacking specifications, allowing manageable degradation as required. This heat treatment process for stacked HTS tapes holds significant importance, especially in the context of designing cable-in-conduit conductors fabricated with stacked HTS tapes. It serves as a valuable reference for further advancements in this field.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208404","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":"Fast current discharging using self-coupling energy absorption for insulated high temperature superconductor magnets","authors":"Jingyi Liu, Zhen Lu, Yawei Wang, Qingqing Yang, Yutong Fu, Yue Zhao, Zhijian Jin","doi":"10.1088/1361-6668/ad6e26","DOIUrl":"https://doi.org/10.1088/1361-6668/ad6e26","url":null,"abstract":"Quench protection has always been challenging for high-temperature superconductor (HTS) coils. Fast current discharge after quench detection is important for a successful coil protection. The copper plates initially intended for cooling can significantly accelerate the discharging process for HTS coils through electromagnetic coupling between coils and copper plates. However, the underlying physical mechanism of this technique has not been studied thoroughly. Here we present a detailed study on the electromagnetic and thermal characteristics of HTS coils coupled with copper plates through experiments and simulations. The results show that a considerable current rebound occurs after an accelerating current drop in the early stage of the fast-discharging process. This coil current rebound is induced by temperature rise as well as the resistivity of copper plates, which are heated by induced eddy current. The heat transfer from copper plates can uniformly heat the whole coil rapidly, which speeds up the discharging process, meanwhile it can also induce overcurrent quench risk. A 30 T@20 K HTS magnet with 36 single pancakes is analyzed. The coupling copper plates can make the coil current drop to 36.9% within the initial 8 ms. The temperature rise induced by copper plates shows a considerable nonuniform distribution among the multiple coil systems. The protection can be enhanced by optimizing the resistivity of copper plates and magnetic coupling strength between plates and coils. This technique has great potential for the protection of insulated HTS magnets.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208451","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":"Suppression of grain boundary weak link by Ca doping in YBa2Cu3O7 coated conductor","authors":"Kentaro Yamamoto, Yutaka Yoshida, Tomoya Horide","doi":"10.1088/1361-6668/ad68d7","DOIUrl":"https://doi.org/10.1088/1361-6668/ad68d7","url":null,"abstract":"YBa₂Cu₃O₇ coated conductors are a strategic material for superconducting applications such as high field magnets, fusion, and motors. Grain boundaries reduce the critical current density (<italic toggle=\"yes\">J</italic>_c) even at a tilt angle as low as 5°, but the successful development of the highly oriented substrates seemed to overcome the weak link problem at grain boundaries. However, it reappears when we visit the homogeneity of the coated conductors. To suppress the weak link in the coated conductors, the Ca doping was investigated. The Ca-doped YBa₂Cu₃O₇ films were fabricated on the moderately oriented substrates. While the grain boundaries in the moderately oriented substrates significantly degraded the <italic toggle=\"yes\">J</italic>_c without Ca doping, the Ca doping improved the <italic toggle=\"yes\">J</italic>_c especially at low temperature. This indicates that the tilt angle dependence of <italic toggle=\"yes\">J</italic>_c was varied by the Ca doping. While the <italic toggle=\"yes\">J</italic>_c for the moderately oriented substrate was 20 times smaller than that for the highly oriented substrate, the Ca doping restored 1/2 of the <italic toggle=\"yes\">J</italic>_c for the highly oriented substrate at 40 K and 9 T. The vortex structure changed from Abrikosov Josephson vortices to the Abrikosov vortices with increasing the Ca content. The combination of Ca doping and moderate substrate texture is another design of coated conductors. The Ca doping can patch the local degradation of the substrate texture to mass produce the practical coated conductors with improved homogeneity.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"73 2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208450","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}