Superconductor Science and Technology最新文献

{"title":"The dependence of operating frequency of NbN toggle flip-flop on parameters of NbN josephson junctions","authors":"Yingyi Shao, Huiwu Wang, Minghui Niu, Wei Peng, Jie Ren, Zhen Wang","doi":"10.1088/1361-6668/ad54f4","DOIUrl":"https://doi.org/10.1088/1361-6668/ad54f4","url":null,"abstract":"\u0000 We performed a comprehensive investigation of the relationship between the maximum operating frequency of the NbN superconducting frequency divider and the key parameters of the NbN Josephson junction. We designed a superconducting frequency divider that uses a single NbN Josephson junction as a pulse generator, several NbN Josephson transmission lines (JTLs), an NbN Toggle Flip-flop (TFF), and a load. By comparing the bias voltage Vin of the pulse generator with the output voltage Vout of the load, we determined if the circuit was working correctly and calculated the maximum operating frequency fmax. Additionally, we employed JSICsim software for simulations to analyze the impact of key parameters of the NbN Josephson junction, such as critical current density Jc, gap voltage Vg, characteristic voltage Vc, quality factor Q, and specific capacitance Cs, on fmax. The simulation results demonstrate that fmax increases with increasing Jc and Q. Specifically when Jc exceeds 300 kA/cm2 and Q surpasses 4, the superconducting frequency divider can achieve a fmax of 1 THz. Furthermore, we successfully fabricated a superconducting frequency divider using a 10 kA/cm2 process and tested a fmax of 260 GHz, with a deviation of approximately 6% from the simulation results.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"144 7‐8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141381283","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":"26.86-tesla direct-current magnetic field generated with an all-REBCO superconducting magnet","authors":"Xintao Zhang, Shuai Hu, Liang Guo, Wen Hong, Zhaoran Wang, Hong-jun Ma, Shuqing Zhang, J. Qin, Chao Zhou, Peng Gao, H. Jin, Liangjun Shao, Ti-Ming Qu, Zhiyong Hong, Fang Liu, Hua-jun Liu, Yuntao Song, Jiangang Li","doi":"10.1088/1361-6668/ad54f9","DOIUrl":"https://doi.org/10.1088/1361-6668/ad54f9","url":null,"abstract":"\u0000 This paper reports an all REBCO (REBa2Cu3Ox, where RE=Y, Gd) superconducting magnet that generated a direct-current magnetic field of 26.86 T at 4.2 K in self-field, which is the highest magnetic field achieved by the high temperature superconducting (HTS) magnet. The magnet consists of a stack of 10 double pancake (DP) coils wound with two different width REBCO tapes, and the no-insulation (NI) winding technology was applied to increase its engineering current density. The inner and outer winding diameters and overall height of the magnet are 30 mm, 103.98 mm, and 102.6 mm, respectively. In order to control the stress risk in HTS magnet, the over-banding made of high elastic modulus stainless steel tapes was employed to the magnet. In addition, no obvious degradation was found in the performance of the magnet after quench at 26.86 T of 295.5 A. These test results demonstrate the great potential of REBCO magnets in high field applications.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"73 s314","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141376577","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":"In-situ synchrotron x-ray photoelectron spectroscopy study of medium-temperature baking of niobium for SRF application","authors":"A Prudnikava, Y Tamashevich, A Makarova, D Smirnov, J Knobloch","doi":"10.1088/1361-6668/ad4825","DOIUrl":"https://doi.org/10.1088/1361-6668/ad4825","url":null,"abstract":"In order to determine optimal parameters of vacuum thermal processing of superconducting radiofrequency niobium cavities exhaustive information on the initial chemical state of niobium and its modification upon a vacuum heat treatment is required. In the present work the chemical composition of the niobium surface upon ultra-high vacuum baking at 200 ^∘C–400 ^∘C similar to ‘medium-temperature baking’ and ‘furnace baking’ of cavities is explored <italic toggle=\"yes\">in-situ</italic> by synchrotron x-ray photoelectron spectroscopy (XPS). Our findings imply that below the critical thickness of the <inline-formula>\u0000<tex-math><?CDATA $textrm{Nb}_2textrm{O}_5$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mtext>Nb</mml:mtext><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mtext>O</mml:mtext><mml:mn>5</mml:mn></mml:msub></mml:mrow></mml:math>\u0000<inline-graphic xlink:href=\"sustad4825ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> layer (<inline-formula>\u0000<tex-math><?CDATA ${approx}1textrm{nm}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:mrow><mml:mo>≈</mml:mo></mml:mrow><mml:mn>1</mml:mn><mml:mtext>nm</mml:mtext></mml:mrow></mml:math>\u0000<inline-graphic xlink:href=\"sustad4825ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>) niobium starts to interact actively with surface impurities, such as carbon and phosphorus. By studying the kinetics of the native oxide reduction, the activation energy and the rate-constant relation have been determined and used for the calculation of the oxygen-concentration depth profiles. It has been established that the controlled diffusion of oxygen is realized at temperatures 200 ^∘C–300 ^∘C, and the native-oxide layer represents an oxygen source, while at 400 ^∘C the pentoxide is completely reduced and the doping level is determined by an ambient oxygen partial pressure. Fluorine (F to Nb atomic ratio is 0.2) after the buffered chemical polishing was found to be incorporated into the surface layer probed by XPS (<inline-formula>\u0000<tex-math><?CDATA ${approx}4.6,textrm{nm}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:mrow><mml:mo>≈</mml:mo></mml:mrow><mml:mn>4.6</mml:mn><mml:mstyle scriptlevel=\"0\"></mml:mstyle><mml:mtext>nm</mml:mtext></mml:mrow></mml:math>\u0000<inline-graphic xlink:href=\"sustad4825ieqn3.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>), and its concentration increased during the low-temperature baking (F/Nb = 0.35 at 230 ^∘C) and depleted at higher temperatures (F/Nb = 0.11 at 400 ^∘C). Thus, the influence of fluorine on the performance of mid-T baked, nitrogen-doped and particularly mild-baked (120 ^∘C/48 h) cavities must be considered. The possible role of fluorine in the educed <inline-formula>\u0000<tex-math><?CDATA $textrm{Nb}^{+5} rightarrow textrm{Nb}^{+4}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:msup><mml:mtext>Nb</mml:mtext><mml:mrow><","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"65 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141524328","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":"Heat transfer in superconducting nanowire single-photon detectors: mechanism and modulation","authors":"Wenlei Yin, Hao Wang, Xiaohan Wang, Rui Yin, Qi Chen, X. Jia, Huabing Wang, La-bao Zhang, Peiheng Wu","doi":"10.1088/1361-6668/ad54f2","DOIUrl":"https://doi.org/10.1088/1361-6668/ad54f2","url":null,"abstract":"\u0000 Superconducting nanowire single-photon detectors (SNSPDs) have been widely applied in quantum information and deep-space exploration owing to their high detection efficiency, low dark count rate, and wide spectral response. In particular, the heat transfer in SNSPDs largely affects their performance parameters (e.g., quantum efficiency, count rates and recovery time), which can be modulated to optimize the performance and develop novel devices. Considering the potential of SNSPDs and the significance of heat transfer, the most recent progress toward understanding the mechanism and the modulation of heat transfer in SNSPDs is critically reviewed, with particular emphasis on the macroscopic correlation with device performance parameters and the microscopic analysis of existing theories, especially at interfaces. Furthermore, representative novel devices inspired by the need for heat transfer modulation in SNSPDs are discussed in detail. Finally, the development of heat transfer in SNSPDs is placed in perspective with the aim of highlighting future theoretical directions and practical applications.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"7 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141380576","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":"Quantitative analysis of ITER Poloidal Field joints through rigorous resistivity parameterization","authors":"Jianfeng Huang, Y. Ilyin, Y. Zhai, H. T. Ten Kate, A. Nijhuis","doi":"10.1088/1361-6668/ad54f6","DOIUrl":"https://doi.org/10.1088/1361-6668/ad54f6","url":null,"abstract":"\u0000 The lap-type twin-box joints are integral components in ITER fusion magnets, with profound implications for magnet stability based on their electro-magnetic, thermal, and mechanical properties. Throughout the extensive R&D process, rigorous qualification tests are conducted to meet stringent standards. However, existing tests often prioritize global performance, which lack of strand-level details due to inherent limitations in test setups. Furthermore, as the referencing test facility of SULTAN falls short in replicating relevant ITER operating conditions, numerical methods that offer both accuracy and the requisite level of detail for comprehensive magnet and component analysis and development are necessary. This paper introduces the utilization of the JackPot-AC/DC code, developed at the University of Twente, as a fundamental tool for achieving strand-level precision in handling CICCs and joints, which encompasses copper and solder components. The primary focus of this study is to obtain precise input parameters, emphasizing their role in conducting a quantitative analysis using JackPot-AC/DC. The investigation centers on an ITER PF5 joint (PFJEU6), where contact resistances and AC losses were measured under parallel magnetic fields. Given the constraints in the measured results, an enhanced parameterization is performed to derive precise resistivity and solder-related parameters. Additionally, sensitivity analyses of individual parameters and cable compact configurations are thoughtfully evaluated. With the optimal input parameters acquired, systematic simulations of the joint exposed to transverse magnetic fields, mimicking SULTAN and ITER operating conditions, are processed and validated against experimental results. This research establishes a comprehensive foundation for the analysis of lap-type twin-box joints, including DC, AC, and stability properties. The outcomes will significantly contribute to advancing the understanding of the intricate behavior of these joints in the context of fusion magnet applications.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141376952","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":"Flight verification of cooling self-sustaining high-temperature superconducting motor","authors":"Jinxing Zheng, Jinxin Sun, Fei Liu, Xufeng Liu, Junyi Peng, Jiong Zhang, Chi Zhang, Lei Zhu, Xiaoliang Zhu, Chen Huang, Yuan Cheng, Dongdong Su","doi":"10.1088/1361-6668/ad54f5","DOIUrl":"https://doi.org/10.1088/1361-6668/ad54f5","url":null,"abstract":"The global shift towards sustainable development and technological advancements has propelled the energy transition trend. Recognizing the substantial environmental impact of conventional commercial airplanes, there is a growing urgency to develop a sophisticated superconducting motor system for commercial aviation. The advent of high-temperature superconducting motors presents a transformative leap, offering significant advantages in power density and efficiency when compared to traditional motors. To validate the issues that future liquid-hydrogen superconducting electric airplanes may encounter, a kilowatt-class aerospace high-temperature superconducting motor is designed. Based on the requirements of airborne applications, critical parameters such as electromagnetic characteristics, operating characteristics, and AC losses have been analyzed. Furthermore, extensive research and testing have been conducted on the superconducting motor magnet, leading to the successful assembly of a prototype. The superconducting motor has a rated output power of 2.7 kW and a rated speed of 5000 rpm. Rigorous ground operation performance tests have also been conducted to ensure the feasibility and reliability of the motor in practical applications. Benefiting from the topological structure design, the superconducting motor has an excellent sealing performance at low temperatures. The superconducting motor can maintain low temperature and high vacuum for a long time, when the vacuum pump is removed and the liquid nitrogen inlet is closed after the motor is completely cooled. The culmination of these endeavors is the realization of a successful flight validation of an unmanned aerial vehicle equipped with a high-temperature superconducting motor, demonstrating a sustained flight of nearly one hour.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"140 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141376864","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":"Multiscale modelling on the multi-physical behaviors of high temperature superconducting magnets based on a combined global homogenization and local refinement scheme","authors":"Ya-Ning Wang, Ze Jing","doi":"10.1088/1361-6668/ad54f7","DOIUrl":"https://doi.org/10.1088/1361-6668/ad54f7","url":null,"abstract":"\u0000 The safe and stable operation is a crucial issue in the development of high-field high temperature superconducting (HTS) magnets. In this paper, we construct a multiscale model which couples the homogenized global (macroscopic) behavior and the refined local (mesoscopic) characteristics to simulate the coupled electromagnetic-mechanical-thermal behaviors of the HTS magnets. In the model, the numerical homogenization method is adopted to simulate the macroscopic behavior of the magnets and identify the “dangerous region” of the magnet which are prone to damage or quench. Then, a refined local sub-model which coupling with the macroscopic homogenization model is established by considering the microstructure and physical parameters of each components of the HTS tapes in the “dangerous region”. Thus, a combined global homogenization and local refinement scheme which balances the computational efficiency and numerical accuracy is developed to simulate the coupled multi-physical behaviors of the HTS magnets including the quench and its propagation. Our results show that the refined local sub-model can simulate the electromagnetic field and the stress-strain at the scale of the tape more accurately. Characteristics, such as the discontinuous stress distribution across the interfaces between different layers and the current shunt from the HTS layer to metallic layers during the quench process of HTS tapes, which are beyond the capability of the homogenization model, have also been well depicted by the refined sub-model.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"7 16","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141379747","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":"Modeling of contact resistivity and simplification of 3D homogenization strategy for the H formulation","authors":"Sijian Wang, H. Yong, Youhe Zhou","doi":"10.1088/1361-6668/ad541f","DOIUrl":"https://doi.org/10.1088/1361-6668/ad541f","url":null,"abstract":"\u0000 The finite element method (FEM) provides a powerful support for the calculations of superconducting electromagnetic responses. It enables the analysis of large-scale high-temperature superconducting (HTS) systems by the popular H formulation. Nonetheless, modeling of contact resistivity in three-dimensional (3D) FEM is still a matter of interest. The difficulty stems from the large aspect ratio of the contact layer in numerical modeling. Nowadays, an available solution is to model the contact layer with zero thickness but requires the discontinuity conditions of the magnetic field. In this paper, the energy variational method is utilized to incorporate the contribution of contact resistivity into the H formulation. From the perspective of energy transfer, the contact resistivity is related to the energy dissipation of the radial current flowing through the contact interface. In terms of applications, this method can be employed to calculate the charging delay of no-insulation (NI) coils and the current sharing behaviors of CORC cables. One advantage of this model is that the magnetic field is continuous and hence can be easily implemented in FEM. Additionally, it requires fewer degrees of freedom and hence presents advantages in computational efficiency. Moreover, this method can be employed to simplify the 3D H homogeneous model for insulated coils. The above discussions demonstrate that the proposed model is a promising tool for the modeling of contact resistivity.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"3 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141266199","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":"Winding angle optimization and testing of small-scale, non-planar, high-temperature superconducting stellarator coils","authors":"P. Huslage, David Kulla, J. Lobsien, Tristan Schuler, Eve V Stenson","doi":"10.1088/1361-6668/ad5382","DOIUrl":"https://doi.org/10.1088/1361-6668/ad5382","url":null,"abstract":"\u0000 We designed and constructed two non-planar coils with high-temperature superconductors (HTS) based on shapes from the Wendelstein 7-X stellarator. Tape track orientation of the HTS was optimized to reduce the coil size as much as possible while staying within the strain limits of the Gadolinium Barium Copper Oxide (GdBCO) superconductor. This resulted in average coil radii of 0.23 m and 0.48 m at strain limits of up 0.45 % to for the coil shapes that were chosen. The coils were produced by winding the GdBCO tapes onto 3D-printed plastic frames. We confirmed the integrity of the superconducting layer after winding by spatially resolved measurement of the critical current and by energizing the coils in liquid nitrogen. Coil 1 showed a resistance of 1.75 µΩ and did not have any critical current degradation, while coil 5 had a resistance of 195 µΩ and showed only one dropout, attributable to a handling error. We measured the magnetic field of the coil with a 3-axis Hall probe system and found good agreement with predictions. This work demonstrates the manufacturing of small-scale, non-planar magnetic coils from commercially available HTS.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"44 40","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141270200","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":"Enhancement of electron-phonon coupling due to increased magnetism and applied hydrostatic pressure in FeSe","authors":"Xiaofang Ouyang, Zeyi Song, Yuzhong Zhang","doi":"10.1088/1361-6668/ad5383","DOIUrl":"https://doi.org/10.1088/1361-6668/ad5383","url":null,"abstract":"\u0000 Inspired by the parabolic trend of the superconducting transition temperature(Tc) of bulk FeSe under hydrostatic pressure, we investigated the effect of magnetism and hydrostatic pressure on the electron-phonon coupling (EPC) in FeSe using density-functional perturbation theory. We found that both magnetism and hydrostatic pressure enhanced EPC. The enhancement of the EPC is mainly attributed to phonon softening and deformation potential induced by magnetism, rather than Fermi surface nesting. Furthermore, we investigated the effect of spin fluctuations on superconductivity by applying the random phase approximation method (RPA). A possible application of our results to the phase diagram of FeSe under hydrostatic pressure was discussed, and we demonstrated that when EPC and spin fluctuations are both considered, a parabolic superconducting Tc may be obtained, providing a plausible explanation for the phase of FeSe under hydrostatic pressure.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"19 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141270912","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}