Superconductivity最新文献

{"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}

{"title":"Numerical simulation of dynamic loss and total loss in the REBCO tapes under perpendicular AC magnetic fields up to 8 T at 20 K and 50 K","authors":"Yuhui Zhang,&nbsp;Yueming Sun,&nbsp;Nicholas M Strickland,&nbsp;Zhenan Jiang","doi":"10.1016/j.supcon.2024.100117","DOIUrl":"10.1016/j.supcon.2024.100117","url":null,"abstract":"<div><p>REBCO tapes carry DC current under AC magnetic fields in proposed HTS fusion applications. AC loss will be generated in the process and it is important to understand the AC loss behaviour for safe operation of the fusion magnets. In this work, magnetisation loss (<em>Q</em>_m), dynamic resistance (<em>R</em>_dyn), and total loss (<em>Q</em>_total) in four different REBCO tapes are numerically studied, using the measured <span><math><mrow><msub><mi>J</mi><mi>c</mi></msub><mrow><mfenced><mrow><mi>B</mi><mo>,</mo><mi>θ</mi></mrow></mfenced></mrow></mrow></math></span> and <span><math><mrow><mi>n</mi><mrow><mfenced><mrow><mi>B</mi><mo>,</mo><mi>θ</mi></mrow></mfenced></mrow></mrow></math></span>, for the magnetic field amplitude applied perpendicularly up to 8 T at 20 K and 50 K, where <span><math><mrow><msub><mi>J</mi><mi>c</mi></msub><mrow><mfenced><mrow><mi>B</mi><mo>,</mo><mi>θ</mi></mrow></mfenced></mrow></mrow></math></span> represents the magnetic field and field angle (<span><math><mrow><mi>θ</mi></mrow></math></span>) dependent critical current density. The peak of Theva <span><math><mrow><msub><mi>J</mi><mi>c</mi></msub><mrow><mfenced><mrow><mi>B</mi><mo>,</mo><mi>θ</mi></mrow></mfenced></mrow></mrow></math></span> data is different from that of other tapes. We artificially shifted the <em>ab</em>-plane peak of Theva <span><math><mrow><msub><mi>J</mi><mi>c</mi></msub><mrow><mfenced><mrow><mi>B</mi><mo>,</mo><mi>θ</mi></mrow></mfenced></mrow></mrow></math></span> to the left by 25° to match the peak value. The newly shifted data is named as Theva-shift, which was also investigated to study the influence of the Theva peak shift on AC loss. The normalised DC transport current level (<em>i</em> = <em>I</em>_t/<em>I</em>_c0) ranges from 0.05 to 0.9, where the DC current amplitude and the self-critical current of the tape are represented by <em>I</em>_t and <em>I</em>_c0, respectively. The simulation results show that the AC losses deviate significantly from the Brandt-Indenbom (BI) equation at high magnetic fields. <em>J</em>_c and instantaneous loss curves for different tapes show correlation at high magnetic fields. The simulation results also show how different <span><math><mrow><msub><mi>J</mi><mi>c</mi></msub><mrow><mfenced><mrow><mi>B</mi><mo>,</mo><mi>θ</mi></mrow></mfenced></mrow></mrow></math></span> characteristics for different tapes influence AC losses. When AC loss values are scaled by the self-field critical current, <em>Q</em>_m without current and <em>Q</em>_total with current in the different tapes show a good agreement. It implies that the temperature dependence of the two types of loss can be calculated from a known loss at one temperature and the self-field critical current.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"11 ","pages":"Article 100117"},"PeriodicalIF":5.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772830724000346/pdfft?md5=88c2ad712a21095c2e0acbd832e9eeda&pid=1-s2.0-S2772830724000346-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142229056","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":"Optimisation of pulsed laser deposited Ba1-xKxBiO3 thin films with tunable superconducting properties by control of K doping level, x","authors":"A. Kursumovic ,&nbsp;J. Prestigiacomo ,&nbsp;M. de h-Óra ,&nbsp;W. Li ,&nbsp;J. Feighan ,&nbsp;V. Smolyaninova ,&nbsp;I. Smolyaninov ,&nbsp;M. Osofsky ,&nbsp;J.L. MacManus-Driscoll","doi":"10.1016/j.supcon.2024.100115","DOIUrl":"10.1016/j.supcon.2024.100115","url":null,"abstract":"<div><p>The mid-<em>T</em>_C superconductor Ba_1-XK_XBiO₃ (BKBO) exhibits different superconducting mechanisms depending on x, in the range ∼ 0.35–0.65. The optimal doping for the highest <em>T</em>_C is reported to be around x  = 0.4. To understand more about the dependence of the superconducting mechanism on x, high quality and reproducible epitaxial films with controlled x are needed. This has been challenging owing to the volatility of K and (to a lesser extent) Bi. In this work, we use pulsed laser deposition (PLD) with several novel process steps to achieve high-quality films in a reproducible way. These include a modified method for target preparation, a low NO₂ growth pressure, and precise positioning of substrates in the PLD plume. Optimum <em>T</em>_C films (32 K onset) were grown from an x  = 0.4 target, i.e. with no excess K, as is normally used. Stable, higher K content films (made from an x = 0.45 target), were also grown. These x = 0.45 films had a lower <em>T</em>_C (22.5 K onset), as expected for (K) overdoped films, with very high upper critical field, <em>H</em>_C2 (0 K), and irreversibility field, <em>H</em>_irr (0 K), values, from linear extrapolation, of ∼ 31.7 T and ∼ 28.8 T, respectively. The growth methodology demonstrated in this work is highly beneficial for fundamental mechanistic studies of this complex superconductor on which there is renewed interest, and where controlled compositions and crystalline quality are currently limited.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"11 ","pages":"Article 100115"},"PeriodicalIF":5.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772830724000322/pdfft?md5=6e44af9fc754192ef1aabc09fd102f6e&pid=1-s2.0-S2772830724000322-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142148837","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":"Advancements in dynamic characteristics analysis of superconducting electrodynamic suspension systems: Modeling, experiment, and optimization","authors":"Huan Huang ,&nbsp;Haitao Li ,&nbsp;Tim Coombs ,&nbsp;Hanlin Zhu ,&nbsp;Yougang Sun ,&nbsp;Guobin Lin ,&nbsp;Junqi Xu ,&nbsp;Jun Zheng","doi":"10.1016/j.supcon.2024.100114","DOIUrl":"10.1016/j.supcon.2024.100114","url":null,"abstract":"<div><p>Superconducting electrodynamic suspension (EDS) presents numerous advantages, including large suspension gaps, high lift-to-drag ratios, and lower requirements for track irregularities. Recent advancements in superconducting materials have further enhanced the feasibility of this technology, and hence multiple research institutions are actively developing and improving this high-speed rail technology. Superconducting EDS achieves passive suspension and guidance by the interaction between ground null-flux coils and onboard superconducting magnets, forming an electromechanical coupled system. Thus, electromechanical coupling modeling and equivalent experimental methods are essential in evaluating and optimizing this system. This article reviews the research on dynamic characteristics analysis of superconducting EDS, focusing on modeling and experimental methods. Firstly, it revisits the development history of superconducting EDS and the new opportunities brought by advancements in superconducting materials. Secondly, it discusses various modeling approaches for the suspension system, emphasizing their benefits and limitations. Thirdly, it describes equivalent experimental methods and their respective application scenarios. Then, it reviews important conclusions and possible optimization methods related to dynamic performance and electromechanical coupling research. Additionally, the sliding window method is introduced to improve computational efficiency in vehicle dynamics modeling. This article provides insights into the current state and future directions of superconducting EDS research, serving as a valuable reference for researchers and engineers.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"11 ","pages":"Article 100114"},"PeriodicalIF":5.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772830724000310/pdfft?md5=46adfaf16db0cf7aa63b9000768c6fbc&pid=1-s2.0-S2772830724000310-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142148836","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":"Superconducting materials − tools to combat with climate change","authors":"Muralidhar Miryala","doi":"10.1016/j.supcon.2024.100113","DOIUrl":"10.1016/j.supcon.2024.100113","url":null,"abstract":"","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"11 ","pages":"Article 100113"},"PeriodicalIF":5.6,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772830724000309/pdfft?md5=fc498a98f267c4d5329bcb672a91fd77&pid=1-s2.0-S2772830724000309-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142088097","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":"Enhancing in-field performance of GdBCO coated conductors by cooperative irradiation with Ti ions and protons","authors":"Daxing Huang ,&nbsp;Hao Dong ,&nbsp;Tongxin Wang ,&nbsp;Hao Yu ,&nbsp;Kaigui Zhu ,&nbsp;Hongwei Gu ,&nbsp;Fazhu Ding","doi":"10.1016/j.supcon.2024.100112","DOIUrl":"10.1016/j.supcon.2024.100112","url":null,"abstract":"<div><p>Irradiation can accurately manipulate defects and adjust pinning landscapes within REBa₂Cu₃O_7-<em>_δ</em> (REBCO, RE: rare earths) coated conductors (CCs). This study reports a productive method to dramatically boost the in-field critical current density (<em>J</em>_c) for GdBCO CCs using cooperative irradiation with Ti ions and protons. Remarkably, the in-field <em>J</em>_c of commercial CCs can be almost doubled at a wide range of temperatures and magnetic fields. Defects of various sizes induced by cooperative irradiation are more uniform distribution through the entire GdBCO film to improve the vortex pinning characteristics, thereby enhancing the in-field performance of the GdBCO CC. This method highlights how combining different particle irradiation types can tailor defect size and distribution, optimizing pinning landscapes for commercial REBCO CCs.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"11 ","pages":"Article 100112"},"PeriodicalIF":5.6,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772830724000292/pdfft?md5=1d8a1e8656a36c52fb889d3851377434&pid=1-s2.0-S2772830724000292-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141993434","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 simulations on the AC loss of REBCO stacks under rotating magnetic fields","authors":"Yuan Wang ,&nbsp;Jin Fang ,&nbsp;Timothy Haugan ,&nbsp;Rodney A. Badcock ,&nbsp;James G. Storey ,&nbsp;Zhenan Jiang","doi":"10.1016/j.supcon.2024.100111","DOIUrl":"10.1016/j.supcon.2024.100111","url":null,"abstract":"<div><p>AC loss presents a significant challenge for high-temperature superconducting (HTS) rotating machines. To date, the behaviour of total AC loss (<em>Q</em>_tol) (with current) and magnetization loss (<em>Q</em>_m) (without current) in a single HTS tape under rotating magnetic fields (RF) have been explored. However, a research gap remains in understanding how these findings translate to the more complex HTS windings of rotating machines. Further exploration is needed to understand the loss behaviour of more complex HTS structures, such as HTS stacks. In this work, <em>Q</em>_tol and <em>Q</em>_m, in the HTS stacks under RF and a perpendicular AC standing wave magnetic field are numerically investigated. Two different RF models are considered: one is the Uni-RF model, characterized by a uniform field with equal field amplitudes and phases at each position, and the other is a non-uniform field created by a rotating Halbach array, referred to as the Hal-RF model. The dependence of AC loss on parameters such as the number of tapes in the stacks, tape width (2a), and the inclination angle (<em>α</em>) of tapes, which refers to the angle between the normal direction of the stack and the vertical direction, have been explored. The number of tapes in the stacks ranges from 1 to 16, <em>α</em> ranges from 0° to 90°, and the tape width includes 4 mm and 40 mm. Additionally, different rotating field directions are also considered. Interestingly, the analytical values from Brandt and Indenbom equation for <em>Q</em>_m of a superconducting strip (BI-strip) are close to <em>Q</em>_m results of the stacks under the standing wave at high fields, while they are over twice as high as those in the Hal-RF model at 1 T. This suggests the BI-strip equation is not reliable for predicting <em>Q</em>_m under RF at high fields. We also show in the Hal-RF model that different rotation directions of the field lead to varying <em>Q</em>_m and <em>Q</em>_tol when asymmetric <em>J</em>_c (<em>B</em>, <em>θ</em>) data are applied. Moreover, it has been observed that the inclination angle has no impact on <em>Q</em>_m under uniform RF while significantly impacts both <em>Q</em>_m and <em>Q</em>_tol in the Hal-RF model.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"11 ","pages":"Article 100111"},"PeriodicalIF":5.6,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772830724000280/pdfft?md5=e488a162ac5d6460d16d0da22359d19b&pid=1-s2.0-S2772830724000280-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141963919","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}