Superconductivity最新文献

{"title":"Characterizations of the electrothermal parameters of a transition edge sensor microcalorimeter and its energy resolution","authors":"Yue Zhao,&nbsp;Hubing Wang,&nbsp;Bo Gao,&nbsp;Zhen Wang","doi":"10.1016/j.supcon.2023.100051","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100051","url":null,"abstract":"<div><p>We developed a transition-edge sensor microcalorimeter (μ-calorimeter) using Mo/Au/Au thin films. We report the detector fabrication, the measurements of the electrothermal parameters and the noise characterizations of the transition-edge sensor μ-calorimeters. We estimated the energy resolution of the μ-calorimeter using the measured noise spectrum and the calculated power-to-current responsivity. Using a ⁵⁵Fe radioactive X-ray source, we characterized the detector responses to incident photons at various working points. The best instrumental energy resolution achieved was 4.13 eV @ 5.9 keV, which agrees qualitatively with the resolution of 4.01 eV estimated from the noise spectrum.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"7 ","pages":"Article 100051"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49698988","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":"Estimation of critical current density of bulk superconductor with artificial neural network","authors":"Gangling Wu,&nbsp;Huadong Yong","doi":"10.1016/j.supcon.2023.100055","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100055","url":null,"abstract":"<div><p>In the applications of superconducting materials, the critical current density <span><math><mrow><msub><mi>J</mi><mi>c</mi></msub><mrow><mfenced><mrow><mi>B</mi></mrow></mfenced></mrow></mrow></math></span> is a crucial performance parameter. The conventional method of measuring <span><math><mrow><msub><mi>J</mi><mi>c</mi></msub><mrow><mfenced><mrow><mi>B</mi></mrow></mfenced></mrow></mrow></math></span> of bulk superconductor is magnetization method. However, there are errors in the estimation of <span><math><mrow><msub><mi>J</mi><mi>c</mi></msub><mrow><mfenced><mrow><mi>B</mi></mrow></mfenced></mrow></mrow></math></span> in the lower field, and the estimation is not applicable in the region where the magnetic field reverses. In this paper, <span><math><mrow><msub><mi>J</mi><mi>c</mi></msub><mrow><mfenced><mrow><mi>B</mi></mrow></mfenced></mrow></mrow></math></span> of the bulk superconductor is determined by the hysteresis and magnetostriction loops with artificial neural network (ANN), respectively. Compared with double-output ANN, the critical current density obtained by single-output ANN is more accurate. Finally, the prediction results given by the hysteresis and magnetostriction loops are discussed.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"7 ","pages":"Article 100055"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49699009","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":"The event and skepticism for the electrical conductor LK-99 at ambient temperature and pressure","authors":"Zili Zhang","doi":"10.1016/j.supcon.2023.100059","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100059","url":null,"abstract":"","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"7 ","pages":"Article 100059"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49698720","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 full-wave HTS flux pump using a feedback control system","authors":"James H.P. Rice ,&nbsp;Ben P.P. Mallett ,&nbsp;Dominic A. Moseley ,&nbsp;Alexander Petrov ,&nbsp;Heng Zhang ,&nbsp;Steven Wray ,&nbsp;Rodney A. Badcock","doi":"10.1016/j.supcon.2023.100064","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100064","url":null,"abstract":"<div><p>Transformer-rectifier flux pumps are DC superconducting power supplies capable of charging superconducting magnets to high currents and stored magnetic energies. Here, we demonstrate a full-wave superconducting flux pump assembled from high-temperature superconducting (HTS) wire that utilizes superconducting switches controlled by applied magnetic field. A negative DC offset occurs in the superconducting secondary of the circuit during operation which is related to the output load current. A feedback control system is proposed and demonstrated to account for the negative DC offset. Increasing the primary current proportional to the load current during operation allowed for the maximum output of the flux pump to be increased from 35 A to more than 275 A. These results are reproduced using a coupled electrical- and magnetic–circuit model formulated in the MATLAB Simulink® package.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"8 ","pages":"Article 100064"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49698993","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":"Electrical, magnetic and thermal circuit modelling of a superconducting half-wave transformer rectifier flux pump using Simulink","authors":"A.C. Francis ,&nbsp;S. Venuturumilli ,&nbsp;D.A. Moseley ,&nbsp;S. Claridge ,&nbsp;B. Leuw ,&nbsp;R.A. Badcock ,&nbsp;C.W. Bumby","doi":"10.1016/j.supcon.2023.100053","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100053","url":null,"abstract":"<div><p>Superconducting flux pumps (FP) are capable of supplying superconducting circuits with high currents by additively supplying current over a number of cycles without introducing large amounts of heat into the cryogenic environment. Superconducting FPs can be broadly classified into two types: dynamo and transformer rectifier. Modelling the behaviour of these systems is an emerging field. In this work a model of a half wave magnetically switched transformer rectifier FP created in MATLAB/Simulink/Simscape is presented. Unlike existing models, the characteristics of all circuit elements are fully integrated allowing all superconducting elements to be accurately incorporated. The presented method uses pre-calculated look-up tables, populated with experimentally derived material qualities to simulate these superconducting elements. The thermal evolution of the switches, calculated simultaneously to the magnetic field switching interaction has also been included. This model is compared to the performance of a real world FP during the pumping of a load coil and is found to be accurate. Furthermore, the presented model illustrates how small amounts of heating at a magnetic switch can profoundly affect a FPs performance over many cycles.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"7 ","pages":"Article 100053"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49698995","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":"Charging process simulation of a coil by a self-regulating high-Tc superconducting flux pump","authors":"Pengbo Zhou ,&nbsp;Yanyu Zhou ,&nbsp;Mark Ainslie ,&nbsp;Asef Ghabeli ,&nbsp;Francesco Grilli ,&nbsp;Guangtong Ma","doi":"10.1016/j.supcon.2023.100061","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100061","url":null,"abstract":"<div><p>Self-regulating high-temperature superconducting (HTS) flux pumps enable direct current injection into a closed-loop superconducting coil without any electrical contact. In this work, the process of charging a coil by a self-regulating HTS flux pump is examined in detail by numerical modeling. The proposed model combines an <span><math><mrow><mi>H</mi></mrow></math></span>-formulation finite element method (FEM) model with an electrical circuit, enabling a comprehensive evaluation of the overall performance of self-regulating HTS flux pumps while accurately capturing local effects. The results indicate that the proposed model can capture all the critical features of a self-regulating HTS flux pump, including superconducting properties and the impact of the secondary resistance. When the numerical results are compared to the experimental data, the presented model is found to be acceptable both qualitatively and quantitatively. Based on this model, we have demonstrated how the addition of a milliohm range, normal-conducting secondary resistance in series with the charging loop can improve the charging process. In addition, its impact on the charging performance is revealed, including the maximum achievable current, charging speed, and the generated losses. The modeling approach employed in this study can be generalized to the optimization and design of various types of flux pumps, potentially expediting their practical application.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"7 ","pages":"Article 100061"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49698793","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":"Field and current driven versions of Brandt method for calculating transport ac loss of superconducting cylinder and strip","authors":"Xiao-Fen Li ,&nbsp;Shuo Li ,&nbsp;Du-Xing Chen","doi":"10.1016/j.supcon.2023.100052","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100052","url":null,"abstract":"<div><p>As an elegant and fast numerical tool for solving time-dependent electromagnetic field problems in hard superconductors, Brandt’s method has played an important role in understading the magnetic behavior of superconducting strips, discs, bars and cylinders in various aspect ratios. However, the application of this convenient method was mainly in magnetization processes. Traditionally, the solution of current transport problem needs to introduce a driving electric field <span><math><mrow><msub><mrow><mi>E</mi></mrow><mrow><mi>a</mi></mrow></msub></mrow></math></span>, which requires a low efficiency iterative process and <span><math><mrow><msub><mrow><mi>E</mi></mrow><mrow><mi>a</mi></mrow></msub></mrow></math></span> itself was not clearly explained. In this work, three integral algorithms based on the Brandt’s method are developed to deal with current transport problems, which directly adopt the applied current as a boundary condition. Namely the current (<em>I</em>)-driven version and two current-field-driven versions A and B. Moreover, the arbitrary applied magnetic field can also be included in the <em>I</em>-driven version. The derivation with all necessary formulas for the methods are given in this work. As an example, the new methods, as well as the traditional method are used for calculating transport ac loss <em>Q</em> of a superconducting cylinder or strip obeying a power-law relation of <span><math><mrow><mi>E</mi><mo>∝</mo><msup><mrow><mi>J</mi></mrow><mrow><mi>n</mi></mrow></msup></mrow></math></span> as a function of a given <span><math><mrow><mi>I</mi><mo>(</mo><mi>t</mi><mo>)</mo></mrow></math></span>. Derived from the Ampère law and the differential rather than the integral expression of the Faraday law, the current-driven version can be used for more accurate and much quicker computation. Being an intermediate quantity, <span><math><mrow><msub><mrow><mi>E</mi></mrow><mrow><mi>a</mi></mrow></msub><mo>(</mo><mi>t</mi><mo>)</mo></mrow></math></span> in the two current-field-driven versions is accurately calculated under the given <span><math><mrow><mi>I</mi><mo>(</mo><mi>t</mi><mo>)</mo></mrow></math></span>, but version B is much quicker than A. Problems relating to <span><math><mrow><msub><mrow><mi>E</mi></mrow><mrow><mi>a</mi></mrow></msub><mo>(</mo><mi>t</mi><mo>)</mo></mrow></math></span> and <em>Q</em> stabilization process are discussed.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"7 ","pages":"Article 100052"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49698989","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":"Numerical simulation on AC loss in REBCO tapes carrying non-sinusoidal currents","authors":"Katsuya Uejima ,&nbsp;Yueming Sun ,&nbsp;Daisuke Miyagi ,&nbsp;Jakub Glowacki ,&nbsp;Nicholas J. Long ,&nbsp;Zhenan Jiang","doi":"10.1016/j.supcon.2023.100063","DOIUrl":"https://doi.org/10.1016/j.supcon.2023.100063","url":null,"abstract":"<div><p>AC loss is one of the greatest obstacles for high-temperature superconducting (HTS) applications. In some HTS applications, coated conductors carry non-sinusoidal currents. Thus, it is important to investigate the effect of various waveforms on AC loss in coated conductors. In this work, transport AC loss in a 4 mm - wide REBCO coated conductor carrying sinusoidal and non-sinusoidal currents, is numerically investigated. The current amplitudes, the frequency of the transport current, and <em>n</em>-value are varied. Non-sinusoidal transport current waveforms studied include square, five types of trapezoidal, and triangular waveforms. Simulated results show that, for a given current amplitude, AC loss for the square current waveform is the greatest, that for the triangular waveform is the smallest. The sequence of AC loss in the conductor for different current waveforms coincides with the penetration depth, which implies the penetration depth determines the AC loss of the coated conductor. Furthermore, the transport AC loss in the conductor was found to decrease with frequency as <span><math><mrow><msup><mrow><mi>f</mi></mrow><mrow><mo>-</mo><mn>2</mn><mo>/</mo><mi>n</mi></mrow></msup></mrow></math></span> for non-sinusoidal transport current.</p></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"8 ","pages":"Article 100063"},"PeriodicalIF":0.0,"publicationDate":"2023-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49698985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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

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