Superconductivity最新文献

{"title":"Influence of Sr/Ca on the phase evolution mechanism, phase purity and critical current density of Bi-2212 wires","authors":"Zhenbao Li,&nbsp;Guoqing Liu,&nbsp;Gaofeng Jiao,&nbsp;Xiaoyan Xu,&nbsp;Qingbin Hao,&nbsp;Kai Yao,&nbsp;Jianfeng Li","doi":"10.1016/j.supcon.2024.100136","DOIUrl":"10.1016/j.supcon.2024.100136","url":null,"abstract":"<div><div>Two batches of Bi-2212 precursor powder with Sr/Ca = 2.24, 2.33 were prepared by the spray pyrolysis technology. Then two Bi-2212 superconducting wires marked as Line4 and Line8-2 were prepared by the above powders. Line4 with Sr/Ca = 2.24 showed much higher phase purity, higher texture and its critical current density(<em>J_c</em>) was 1.5 times that of Line8-2 with Sr/Ca = 2.33. Their micro-structure evolution was scrutinized by quenching each wire at 7 instantaneous moments during the partial melting process(PMP). Bi-2212 was found to decompose into (Sr,Ca)₁₄Cu₂₄O_x(14:24AEC), Bi₉Sr₁₁Ca₅O_x(9:16CF), Bi-rich liquid Bi-2212 and Bi-rich solid Bi-2212 at the initial stage of PMP. When Bi-2212 began to solidify, the above four phases reacted to generate Bi-2212. By analyzing the particle size, the content and the composition variation for 14:24AEC, 9:16CF as well as the composition variation for Bi-2212 matrix in above 7 moments of PMP, the phase evolution’s difference between two wires was finally confirmed. The formation energy of 14:24AEC was smaller compared with 9:16CF, while 9:16CF was faster on dynamics. 14:24AEC determined the whole synthetic reaction’s rate of Bi-2212, and Sr/Ca as well as its value fluctuation in Bi-2212 precursor powder can decide both the timeline and the driving force of PMP. A larger Sr/Ca in Line8-2 made it melt earlier compared with Line4, which led to its earlier timeline during the melting stage of PMP. While the more consistent phase evolution’s pace between 14:24AEC and 9:16CF in Line4 finally contributed a larger Sr/Ca after solidification. Both the larger Sr/Ca and its larger fluctuation in Line4 finally contributed to its faster phase evolution’s pace, higher phase purity, better texture and higher <em>J_c</em>. The deep logic driving the phase evolution mechanism in Bi-2212 wires was disclosed for the first time, which will be very helpful to the future improvement of <em>J_c</em> for Bi-2212 wires.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"12 ","pages":"Article 100136"},"PeriodicalIF":5.6,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a novel joint-less double aperture REBCO magnet with an innovative excitation circuit for stable magnetic field generation","authors":"Hao Dong ,&nbsp;Daxing Huang ,&nbsp;Hao Yu ,&nbsp;Hongwei Gu ,&nbsp;Fazhu Ding","doi":"10.1016/j.supcon.2024.100139","DOIUrl":"10.1016/j.supcon.2024.100139","url":null,"abstract":"<div><div>Second-generation high-temperature superconducting (2G-HTS) magnets operating in persistent current mode (PCM) effectively address the challenge of magnetic field stability. This paper introduces a novel joint-less double aperture (JDA) REBa₂Cu₃O_7−δ (REBCO, RE: rare earth) magnet, designed to overcome the limitations posed by joint resistance in traditional 2G-HTS magnets. A single slit REBCO tape is innovatively wound into double-pancake (DP) coils on both sides and placed in spaced apertures within the magnet. This closed-loop design generates two stable magnetic fields while effectively preventing tape twisting between the DP coils. Furthermore, a new portable excitation circuit is proposed for the JDA REBCO magnet, utilizing pulsed magnetic fields generated by the copper coil, which eliminates the need for current leads, electrodes, and persistent current switches (PCSs), significantly reducing system complexity. Initially, a traditional PCS was used to charge the JDA REBCO magnet to 40 A at 77 K, generating a magnetic field of 60.6 mT at the center of one of the DP coil apertures. The magnet was then successfully excited using a pulse circuit after about 200 cycles. A comparative analysis with the PCS results showed that the current induced by the pulse circuit was approximately 40 A. The stability of the magnetic field within one DP coil of the JDA REBCO magnet was monitored for 107 h, with a magnetic field drift rate of approximately 0.86 ppm/h. The closed-loop advantage of the JDA REBCO magnet, combined with the portable pulsed excitation circuit, demonstrates the promising potential for applications in double aperture magnetic resonance imaging (MRI) equipment, particle accelerators, and other advanced technologies.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"12 ","pages":"Article 100139"},"PeriodicalIF":5.6,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Topological versus conventional superconductivity in a Weyl semimetal: A microscopic approach","authors":"Enrique Muñoz ,&nbsp;Juan Esparza ,&nbsp;José Braun ,&nbsp;Rodrigo Soto-Garrido","doi":"10.1016/j.supcon.2024.100132","DOIUrl":"10.1016/j.supcon.2024.100132","url":null,"abstract":"<div><div>Starting from a microscopic model for the particle–particle interactions in a Weyl semimetal, we analyzed the possibility for conventional as well as monopole Cooper pairing between quasiparticle excitations at the same (intra-nodal) or opposite (inter-nodal) Weyl nodes. We derived a coupled system of self-consistent BCS-like equations, where the angular dependence of the pairings is directly determined from the microscopic interaction symmetries. We studied the competition between conventional and monopole superconducting phases, thus obtaining explicitly the phase diagrams from the microscopic interaction model parameters. We determined the critical temperatures for both phases, and the low temperature critical behavior, including the specific heat, that we suggest as possible experimental probe for topological quantum criticality in Weyl semimetals.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"12 ","pages":"Article 100132"},"PeriodicalIF":5.6,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recent progress in high-temperature superconducting undulators","authors":"Zhuangwei Chen ,&nbsp;Marco Calvi ,&nbsp;John Durrell ,&nbsp;Cristian Boffo ,&nbsp;Dabin Wei ,&nbsp;Kai Zhang ,&nbsp;Zhentang Zhao","doi":"10.1016/j.supcon.2024.100134","DOIUrl":"10.1016/j.supcon.2024.100134","url":null,"abstract":"<div><div>Considerable effort has been devoted to the development of superconducting undulators (SCUs) intended for particle accelerator-based light sources, including synchrotrons and free electron laser (FEL) facilities. Recently, a high-temperature superconducting (HTS) undulator prototype, consisting of staggered-array Re-Ba-Cu–O bulks, achieved an on-axis sinusoidal magnetic field profile with a peak amplitude <em>B</em>₀ of 2.1 T and a period length of 10 mm, resulting in a deflection parameter <em>K</em> = 1.96. Such a short period HTS undulator not only enables the generation of higher-energy photons, but also supports the construction of economically feasible and compact FELs with shorter linear accelerators (LINACs). This article provides a comprehensive review of recent advances in the staggered-array bulk HTS undulator as well as other types of HTS undulators. Furthermore, it offers insights into the development of engineering HTS undulator prototypes designed for deployment in synchrotron and free electron laser (FEL) facilities. We conclude by discussing opportunities for and the challenges facing the use of HTS undulators in practical applications.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"12 ","pages":"Article 100134"},"PeriodicalIF":5.6,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142758927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Meter-length REBCO ultralow resistance joint for the gigahertz NMR magnet","authors":"Xiaoru Tian ,&nbsp;Hongli Suo ,&nbsp;Zili Zhang ,&nbsp;Maolai Ye ,&nbsp;Lei Wang ,&nbsp;Jianhua Liu ,&nbsp;Qiuliang Wang","doi":"10.1016/j.supcon.2024.100138","DOIUrl":"10.1016/j.supcon.2024.100138","url":null,"abstract":"<div><div>In this paper, we present a meter-length REBCO joint using the most conventional soldering method. The joint resistance can attain 7.21 × 10^-11 Ω at 4.2 K with a joint length of 2 m. It essentially displays a linear relationship with the joint length. The microstructures of the joints were investigated systematically using scanning electron microscopy (SEM) and micro-computed tomography (micro-CT). Multiple voids were identified in all the joints. More importantly, the voids were not distributed homogeneously. The internal voids near the innermost and outermost rings were larger than those in the middle ring. Two types of gigahertz magnetic resonance spectroscopy (NMR) magnets were designed: 15 T low temperature superconductor (LTS) + 15 high temperature superconductor (HTS) and whole HTS. The current 10^-11 Ω-level joint can satisfy the magnetic field decay criterion of 1 ×10^-8/h. However, a pure HTS gigahertz NMR magnet requires a joint length of over 20 m, which is not feasible. The current resistance resource of the meter-length joint was also discussed by an equivalent circuit analysis. This paper presents a reliable engineering REBCO joint fabrication method for gigahertz NMR magnets without heat treatment.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"12 ","pages":"Article 100138"},"PeriodicalIF":5.6,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Chinese magneto-biased superconducting current limiter has achieved long-term grid-connected demonstration, withstanding transmission line fault","authors":"Jiahui Zhu ,&nbsp;Zhengyu Li ,&nbsp;Jianfeng Sun ,&nbsp;Defu Wei ,&nbsp;Kaizhong Ding","doi":"10.1016/j.supcon.2024.100131","DOIUrl":"10.1016/j.supcon.2024.100131","url":null,"abstract":"","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"12 ","pages":"Article 100131"},"PeriodicalIF":5.6,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142707271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical study of the effect of anisotropy and field dependence of critical current on AC loss in REBCO coated conductors and stacks","authors":"Wenhao Li ,&nbsp;Zhenan Jiang ,&nbsp;Difan Zhou ,&nbsp;Chuanbing Cai","doi":"10.1016/j.supcon.2024.100130","DOIUrl":"10.1016/j.supcon.2024.100130","url":null,"abstract":"<div><div>High-temperature superconducting (HTS) AC electrical devices generally carry AC transport currents and are exposed to AC external magnetic fields with arbitrary orientations. Realistic HTS coated conductors (CCs) show diverse critical current anisotropy and field dependence (<em>I</em>_c(<strong><em>B</em></strong>,<span><math><mrow><mi>θ</mi></mrow></math></span>)), which directly affect the superconducting behavior. However, under complex electromagnetic (EM) conditions, the discrepancies in AC loss characteristics caused by different <em>I</em>_c(<strong><em>B</em></strong>,<span><math><mrow><mi>θ</mi></mrow></math></span>) features are still unclear. Moreover, the selection of CCs with desirable <em>I</em>_c(<strong><em>B</em></strong>,<span><math><mrow><mi>θ</mi></mrow></math></span>) features to further reduce AC loss under various EM conditions remains overlooked. In this work, the transport AC loss (<em>Q</em>_t) (without field), magnetization loss (<em>Q</em>_m), and total AC loss (<em>Q</em>_tot) of the nearly isotropic Shanghai Creative (SCST) CC and the strongly anisotropic Fujikura (FYSC) CC, along with their stacks, are investigated in the range of 90° and 90° (parallel to the CC wide surface) field angles based on the <strong><em>H</em></strong>-formulation. The results show that, due to the opposite angular dependence of <em>I</em>_c, the effective penetration fields of these two CCs or stacks exhibit distinct trends with the field angle, and the <em>Q</em>_m in the nearly isotropic CC is less dominated by the perpendicular field component compared to that in the strongly anisotropic CC. Furthermore, due to the different field dependence of <em>I</em>_c at various field angles, the two CCs or stacks exhibit opposite flux flow loss behaviors with the field angle. Overall, the SCST CC and its stack show lower <em>Q</em>_tot within the angle range around 0°, and this range expands as the external field increases, while the FYSC CC and its stack show lower <em>Q</em>_tot at the remaining angles. This is further explained by analyzing the field distribution and <em>Q</em>_tot of each tape in the stacks. This paper clarifies the discrepancies in AC loss caused by different <em>I</em>_c(<strong><em>B</em></strong>,<span><math><mrow><mi>θ</mi></mrow></math></span>) and identifies the applicable EM conditions for different REBCO materials to reduce AC loss, providing valuable references for material selection to minimize loss in HTS AC devices across different scenarios.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"12 ","pages":"Article 100130"},"PeriodicalIF":5.6,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental and numerical study of radial and axial HTS magnetic couplers","authors":"Maxim Osipov,&nbsp;Irina Martirosian,&nbsp;Aleksandr Starikovskii,&nbsp;Dmitrii Aleksandrov,&nbsp;Sergei Pokrovskii","doi":"10.1016/j.supcon.2024.100128","DOIUrl":"10.1016/j.supcon.2024.100128","url":null,"abstract":"<div><div>The paper presents the results of an experimental study and numerical calculations of torques in magnetic couplers of various configurations. A comparison was made for model couplers based on permanent magnets (PMG) and couplers based on high-temperature superconducting (HTS) tapes cooled with liquid nitrogen. In PMG-couplers, both coupler halves are made of permanent magnets, while in HTS-couplers, one coupler half is made of HTS-tapes stacks, and the second of permanent magnets. Both types of couplers are considered in both axial and radial configurations, with different clearances between the coupler halves. The results of experimental studies showed that in the configurations we considered, radial HTS-couplers are superior to their axial analogues in terms of the maximum torque between the coupler halves. In addition, in the considered configurations, PMG couplers exceeded their HTS analogues in torque by 10 times. Numerical finite element calculations using a combined A-T-H formulation were used to optimize the design of the HTS-coupler. The model was verified using the obtained experimental data for moments in model couplers. The model was used to calculate an optimized coupler with added HTS-windings, lower HTS temperature and stronger permanent magnets. The calculation results showed that HTS-couplers can be comparable with their PMG analogues, at the same time they are significantly superior to them in damping external disturbances. Due to the fact that the best characteristics were shown by model radial couplers with minimal gaps between the coupler halves, radial couplers were manufactured based on windings of 10 and 20 layers of HTS-tapes and the torques in them were measured in the FC and ZFC modes. It has been shown that in most operating conditions, 10-layer couplers outperform 20-layer couplers.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"12 ","pages":"Article 100128"},"PeriodicalIF":5.6,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142527654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Critical current density and AC magnetic susceptibility of high-quality FeTe0.5Se0.5 superconducting tapes","authors":"Xin Zhou ,&nbsp;Wenjie Li ,&nbsp;Qiang Hou ,&nbsp;Wei Wei ,&nbsp;Wenhui Liu ,&nbsp;Ke Wang ,&nbsp;Xiangzhuo Xing ,&nbsp;Linfei Liu ,&nbsp;Jun-Yi Ge ,&nbsp;Yanpeng Qi ,&nbsp;Huajun Liu ,&nbsp;Li Ren ,&nbsp;Tsuyoshi Tamegai ,&nbsp;Yue Sun ,&nbsp;Zhixiang Shi","doi":"10.1016/j.supcon.2024.100127","DOIUrl":"10.1016/j.supcon.2024.100127","url":null,"abstract":"<div><div>Iron telluride-selenium superconducting materials, known for their non-toxicity, ease of preparation, simple structure, and high upper critical fields, have attracted much research interest in practical application. In this work, we conducted electrical transport measurements, magneto-optical imaging, and AC magnetic susceptibility measurements on FeTe_0.5Se_0.5 superconducting long tapes fabricated via reel-to-reel pulsed laser deposition. Our transport measurements revealed a high critical current density that remains relatively stable even with increasing external magnetic fields, reaching over 1 × 10⁵ A/cm² at 8 K and 9 T. The calculated pinning force density indicates that normal point pinning is the primary mechanism in these tapes. The magneto-optical images demonstrated that the tapes show homogeneous superconductivity and uniform distribution of critical current density. The AC magnetic susceptibility measurements also confirmed their strong flux pinning nature of withstanding high magnetic field. Based on these characteristics, FeTe_0.5Se_0.5 superconducting tapes show promising prospects for applications under high magnetic field.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"12 ","pages":"Article 100127"},"PeriodicalIF":5.6,"publicationDate":"2024-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142527653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High performance rapid single-flux-quantum bit-slice arithmetic logic unit","authors":"Jing Ren ,&nbsp;Pei-Yao Qu ,&nbsp;Jia-Hong Yang ,&nbsp;Xiang-Yu Zheng ,&nbsp;Hui Zhang ,&nbsp;Jie Ren ,&nbsp;Guang-Ming Tang","doi":"10.1016/j.supcon.2024.100116","DOIUrl":"10.1016/j.supcon.2024.100116","url":null,"abstract":"<div><p>Two optimization technologies, namely, bypass and carry-control optimization, were demonstrated for enhancing the performance of a bit-slice Arithmetic Logic Unit (ALU) in 2^<em>n</em>-bit Rapid Single-Flux-Quantum (RSFQ) microprocessors. These technologies can not only shorten the calculation time but also solve data hazards. Among them, the proposed bypass technology is applicable to any 2^<em>n</em>-bit ALU, whether it is bit-serial, bit-slice or bit-parallel. The high performance bit-slice ALU was implemented using the 6 <em>k</em>A/cm² Nb/AlO_<em>x</em>/Nb junction fabrication process from Superconducting Electronics Facility of Shanghai Institute of Microsystem and Information Technology. It consists of 1693 Josephson junctions with an area of 2.46 <span><math><mrow><mo>×</mo></mrow></math></span> 0.81 mm². All ALU operations of the MIPS32 instruction set are implemented, including two extended instructions, i.e., addition with carry (ADDC) and subtraction with borrow (SUBB). All the ALU operations were successfully obtained in SFQ testing based on OCTOPUX and the measured DC bias current margin can reach 86<span><math><mrow><mo>%</mo></mrow></math></span> - 104<span><math><mrow><mo>%</mo></mrow></math></span>. The ALU achieves a 100<span><math><mrow><mo>%</mo></mrow></math></span> utilization rate, regardless of carry/borrow read-after-write correlations between instructions.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"11 ","pages":"Article 100116"},"PeriodicalIF":5.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772830724000334/pdfft?md5=96f792fb9935383fe687678b7f003e24&pid=1-s2.0-S2772830724000334-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142172154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}