Pub Date : 2024-07-04DOI: 10.1088/1361-6668/ad5f58
Xuechun Wang, Xiongfang Liu, Dabin Wei, Ya Shi, C. Cai, Yi Bing Zhang, Kai Zhang, Difan Zhou
High-temperature superconducting (HTS) undulator exploiting the high trapped field of HTS bulk superconductors enables the design of extremely short-period insertion devices for synchrotron light sources and free electron lasers. In such a promising application the trapped field performance and the uniformity of the HTS bulk superconductors are essential. In this study, the half-moon shaped YBa2Cu3O7−δ (YBCO) single-grain superconductors have been directly grown by the top-seeded melted-growth (TSMG) method. Half-moon shaped samples directly grown from preforms with four different type of seed crystal arrangements were compared with that cut from larger cylindrical bulk superconductors in regarding to the trapped magnetic fields and correspondingly the distribution. We found that the arrangement of seed crystals greatly affects the melt-growth process and hence the homogeneity of the samples. The one-step grown half-moon shaped samples show higher trapped field (Btrap), 0.542 T for a 24 mm and 0.785 T for a 32 mm diameter sample, and better uniformity of trapped field distribution compared to that obtained from machining with Btrap of 0.427 T and 0.528 T. It was found that the growth sectors would be restricted when the seed crystal was placed at the edge of a preform, and the angle of the seed crystal, parallel or 45° to the long edge would influence the melt growth as well.
利用高温超导（HTS）块状超导体的高陷波场，高温超导（HTS）起动装置可以为同步辐射光源和自由电子激光器设计极短周期的插入装置。在这种前景广阔的应用中，HTS 体超导体的陷波场性能和均匀性至关重要。在这项研究中，我们采用顶部播种熔融生长（TSMG）方法直接生长出了半月形的 YBa2Cu3O7-δ （YBCO）单晶粒超导体。我们比较了从具有四种不同籽晶排列方式的预型件中直接生长出的半月形样品与从较大的圆柱形块状超导体中切割出的半月形样品在捕获磁场和相应分布方面的差异。我们发现，籽晶的排列会极大地影响熔融生长过程，从而影响样品的均匀性。一步法生长的半月形样品显示出更高的陷波磁场（Btrap），直径为 24 毫米的样品为 0.542 T，直径为 32 毫米的样品为 0.785 T，与加工获得的 0.427 T 和 0.528 T 的陷波磁场相比，陷波磁场分布的均匀性更好。
{"title":"High performance one-step grown half-moon shaped YBCO bulk superconductors","authors":"Xuechun Wang, Xiongfang Liu, Dabin Wei, Ya Shi, C. Cai, Yi Bing Zhang, Kai Zhang, Difan Zhou","doi":"10.1088/1361-6668/ad5f58","DOIUrl":"https://doi.org/10.1088/1361-6668/ad5f58","url":null,"abstract":"\u0000 High-temperature superconducting (HTS) undulator exploiting the high trapped field of HTS bulk superconductors enables the design of extremely short-period insertion devices for synchrotron light sources and free electron lasers. In such a promising application the trapped field performance and the uniformity of the HTS bulk superconductors are essential. In this study, the half-moon shaped YBa2Cu3O7−δ (YBCO) single-grain superconductors have been directly grown by the top-seeded melted-growth (TSMG) method. Half-moon shaped samples directly grown from preforms with four different type of seed crystal arrangements were compared with that cut from larger cylindrical bulk superconductors in regarding to the trapped magnetic fields and correspondingly the distribution. We found that the arrangement of seed crystals greatly affects the melt-growth process and hence the homogeneity of the samples. The one-step grown half-moon shaped samples show higher trapped field (Btrap), 0.542 T for a 24 mm and 0.785 T for a 32 mm diameter sample, and better uniformity of trapped field distribution compared to that obtained from machining with Btrap of 0.427 T and 0.528 T. It was found that the growth sectors would be restricted when the seed crystal was placed at the edge of a preform, and the angle of the seed crystal, parallel or 45° to the long edge would influence the melt growth as well.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141679612","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}
Pub Date : 2024-07-03DOI: 10.1088/1361-6668/ad5b23
Zulei Xu, Xiaoni Wang, Xiaoyu Liu, Ming Yang, Yixin Liu, Wei Peng, Gang Mu and Zhi-Rong Lin
Reducing the negative impact of magnetic vortex motion is a long-term challenge for superconducting applications. Here, we conduct an in-depth investigation on the response of NbN nanowires on applied magnetic fields with the transverse size down to 10 nm. It is found that the vortex-free state can sustain under field up to 9 T in the sample of this dimension, demonstrating a unique approach to reduce the negative effects of flux motion in applications. Such a conclusion is further confirmed by the vanished flux-low instability velocity. Moreover, the upper critical field of the NbN nanowires reveals clear anisotropic features, which can be interpreted based on the framework of the Ginzburg–Landau model. Our results provide important information for understanding the behavior of nanoscale superconducting materials under magnetic fields, which is significant for the application of superconducting micro/nano devices.
减少磁涡旋运动的负面影响是超导应用面临的一项长期挑战。在这里，我们深入研究了横向尺寸小至 10 纳米的氮化铌纳米线对外加磁场的响应。研究发现，在这一尺寸的样品中，无涡旋状态可在高达 9 T 的磁场中维持，这展示了一种在应用中减少磁通运动负面影响的独特方法。通量-低不稳定速度的消失进一步证实了这一结论。此外，氮化铌纳米线的上临界场显示出明显的各向异性特征，这可以根据金兹堡-朗道模型框架进行解释。我们的研究结果为理解纳米级超导材料在磁场下的行为提供了重要信息，对超导微/纳米器件的应用具有重要意义。
{"title":"Size effect on the response of superconductivity in NbN nanowires to external magnetic field","authors":"Zulei Xu, Xiaoni Wang, Xiaoyu Liu, Ming Yang, Yixin Liu, Wei Peng, Gang Mu and Zhi-Rong Lin","doi":"10.1088/1361-6668/ad5b23","DOIUrl":"https://doi.org/10.1088/1361-6668/ad5b23","url":null,"abstract":"Reducing the negative impact of magnetic vortex motion is a long-term challenge for superconducting applications. Here, we conduct an in-depth investigation on the response of NbN nanowires on applied magnetic fields with the transverse size down to 10 nm. It is found that the vortex-free state can sustain under field up to 9 T in the sample of this dimension, demonstrating a unique approach to reduce the negative effects of flux motion in applications. Such a conclusion is further confirmed by the vanished flux-low instability velocity. Moreover, the upper critical field of the NbN nanowires reveals clear anisotropic features, which can be interpreted based on the framework of the Ginzburg–Landau model. Our results provide important information for understanding the behavior of nanoscale superconducting materials under magnetic fields, which is significant for the application of superconducting micro/nano devices.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141548762","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}
NdFeAs(O,H) microstrips with line widths of about 1–5 µm were fabricated by photolithography and Ar-ion dry etching. The microstrips were fabricated under two different etching conditions: 25 min etching at a power of 20 W (long duration, low power) and 3 min etching at 100 W (short duration, high power). For both conditions, the narrowest microstrips, which were 0.9 µm in width, retained high critical temperatures of about 85% of those before microfabrication. Further, the 0.9 µm microstrip fabricated under the high-power, short-duration condition exhibited a high critical current density (Jc) of more than 4 MA cm−2 at 4 K. However, Jc of the microstrip fabricated under the low-power, long-duration condition was somewhat lower. Our analysis suggests that the edges of the microstrips were damaged more than twice as wide as those of the microstrips fabricated under the high-power, short-duration condition. This indicates that a short duration is more effective to reduce the damage than using a lower etching power.
{"title":"Fabrication of microstrips of iron-based superconductor NdFeAs(O,H)","authors":"Atsuro Yoshikawa, Takafumi Hatano, Hiroto Hibino, Hiroya Imanaka and Hiroshi Ikuta","doi":"10.1088/1361-6668/ad5b24","DOIUrl":"https://doi.org/10.1088/1361-6668/ad5b24","url":null,"abstract":"NdFeAs(O,H) microstrips with line widths of about 1–5 µm were fabricated by photolithography and Ar-ion dry etching. The microstrips were fabricated under two different etching conditions: 25 min etching at a power of 20 W (long duration, low power) and 3 min etching at 100 W (short duration, high power). For both conditions, the narrowest microstrips, which were 0.9 µm in width, retained high critical temperatures of about 85% of those before microfabrication. Further, the 0.9 µm microstrip fabricated under the high-power, short-duration condition exhibited a high critical current density (Jc) of more than 4 MA cm−2 at 4 K. However, Jc of the microstrip fabricated under the low-power, long-duration condition was somewhat lower. Our analysis suggests that the edges of the microstrips were damaged more than twice as wide as those of the microstrips fabricated under the high-power, short-duration condition. This indicates that a short duration is more effective to reduce the damage than using a lower etching power.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141548764","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}
Pub Date : 2024-07-02DOI: 10.1088/1361-6668/ad5a44
I Aviles Santillana, S Sgobba, M D Crouvizier, A Devred, G Arnau Izquierdo, B Bulat, A Moros, S Izquierdo Bermudez, A Milanese, F Savary and E Todesco
The future of particle accelerators is strongly linked to the development of high—field magnets. The European Organization for Nuclear Research (CERN) is currently developing Nb3Sn-based magnets for the high-luminosity upgrade of the large hadron collider (HL-LHC), to fully exploit its potential and surpass the intrinsic performance limitations of Nb–Ti-based magnets. The fabrication of Nb3Sn magnets is a challenging process as it requires managing the brittle and strain sensitive conductor after the reaction heat treatment to generate the superconducting phase. Accelerator magnet coils are usually manufactured following the wind-react-and-impregnate fabrication process. This reduces the difficulty of working with brittle compounds but adds uncertainties associated with volume change during phase transition and thermal expansion/contraction differentials during the temperature ramps of the heat treatment and cooldown to cryogenic temperatures. To investigate the root causes of performance limitation or degradation observed on HL-LHC magnet prototypes, several Nb3Sn-based coils have been examined. The present paper illustrates an innovative methodology of investigations of the root causes at several fabrication stages and after cooldown and powering. The approach is based on a sequence of mesoscale observations of whole coil sections by an innovative high—energy linac x-ray computed tomography, followed by materialographic assessment of internal events, geometrical distortions and potential flaws using light microscopy. Additionally, scanning electron microscopy and focused ion beam were used to analyze damage at localized positions. This comprehensive approach provides an in-depth view of the examined coils by characterizing atypical features and imperfections in both the strands and the glass fiber/resin of the insulation system, univocally associating the limiting quenches experienced by the coils to identified physical events.
{"title":"Advanced examination of Nb3Sn coils and conductors for the LHC luminosity upgrade: a methodology based on computed tomography and materialographic analyses","authors":"I Aviles Santillana, S Sgobba, M D Crouvizier, A Devred, G Arnau Izquierdo, B Bulat, A Moros, S Izquierdo Bermudez, A Milanese, F Savary and E Todesco","doi":"10.1088/1361-6668/ad5a44","DOIUrl":"https://doi.org/10.1088/1361-6668/ad5a44","url":null,"abstract":"The future of particle accelerators is strongly linked to the development of high—field magnets. The European Organization for Nuclear Research (CERN) is currently developing Nb3Sn-based magnets for the high-luminosity upgrade of the large hadron collider (HL-LHC), to fully exploit its potential and surpass the intrinsic performance limitations of Nb–Ti-based magnets. The fabrication of Nb3Sn magnets is a challenging process as it requires managing the brittle and strain sensitive conductor after the reaction heat treatment to generate the superconducting phase. Accelerator magnet coils are usually manufactured following the wind-react-and-impregnate fabrication process. This reduces the difficulty of working with brittle compounds but adds uncertainties associated with volume change during phase transition and thermal expansion/contraction differentials during the temperature ramps of the heat treatment and cooldown to cryogenic temperatures. To investigate the root causes of performance limitation or degradation observed on HL-LHC magnet prototypes, several Nb3Sn-based coils have been examined. The present paper illustrates an innovative methodology of investigations of the root causes at several fabrication stages and after cooldown and powering. The approach is based on a sequence of mesoscale observations of whole coil sections by an innovative high—energy linac x-ray computed tomography, followed by materialographic assessment of internal events, geometrical distortions and potential flaws using light microscopy. Additionally, scanning electron microscopy and focused ion beam were used to analyze damage at localized positions. This comprehensive approach provides an in-depth view of the examined coils by characterizing atypical features and imperfections in both the strands and the glass fiber/resin of the insulation system, univocally associating the limiting quenches experienced by the coils to identified physical events.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141524317","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}
Pub Date : 2024-07-01DOI: 10.1088/1361-6668/ad54f3
Md Asaduzzaman, Ryan M L McFadden, Edward Thoeng, Robert E Laxdal and Tobias Junginger
We report measurements of the first-flux-penetration field in surface-treated and coated Nb samples using . Using thin Ag foils as energy moderators for the implanted muon spin-probes, we ‘profile’ the vortex penetration field at sub-surface depths on the order of m to m. In a coated sample [Nb3Sn( )/Nb], we find that is depth-independent with a value of 234.5(35) mT, consistent with Nb’s metastable superheating field and suggestive of surface energy barrier for flux penetration. Conversely, in a surface-treated sample [Nb baked in vacuum at 120 ∘ for ], vortex penetration onsets close to pure Nb’s lower critical field , but increases with increasing implantation depth, consistent with flux-pinning localized at the surface. The implication of these results for technical applications of superconducting Nb, such as superconducting radio frequency cavities, is discussed.
我们报告了在经过表面处理和涂层的铌样品中使用.NET技术测量的第一流穿透场。在镀膜样品[Nb3Sn( )/Nb]中，我们发现涡流穿透场与深度无关，其值为234.5(35) mT，与铌的瞬态过热场一致，并表明通量穿透存在表面能障。相反，在经过表面处理的样品[在真空中以 120 ∘ for 的温度焙烧铌]中，涡流穿透开始时接近纯铌的较低临界磁场，但随着植入深度的增加而增加，这与表面局部的磁通引化相一致。本文讨论了这些结果对超导铌技术应用（如超导射频空腔）的影响。
{"title":"Measurements of the first-flux-penetration field in surface-treated and coated Nb: distinguishing between near-surface pinning and an interface energy barrier","authors":"Md Asaduzzaman, Ryan M L McFadden, Edward Thoeng, Robert E Laxdal and Tobias Junginger","doi":"10.1088/1361-6668/ad54f3","DOIUrl":"https://doi.org/10.1088/1361-6668/ad54f3","url":null,"abstract":"We report measurements of the first-flux-penetration field in surface-treated and coated Nb samples using . Using thin Ag foils as energy moderators for the implanted muon spin-probes, we ‘profile’ the vortex penetration field at sub-surface depths on the order of m to m. In a coated sample [Nb3Sn( )/Nb], we find that is depth-independent with a value of 234.5(35) mT, consistent with Nb’s metastable superheating field and suggestive of surface energy barrier for flux penetration. Conversely, in a surface-treated sample [Nb baked in vacuum at 120 ∘ for ], vortex penetration onsets close to pure Nb’s lower critical field , but increases with increasing implantation depth, consistent with flux-pinning localized at the surface. The implication of these results for technical applications of superconducting Nb, such as superconducting radio frequency cavities, is discussed.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141501713","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}
Pub Date : 2024-06-26DOI: 10.1088/1361-6668/ad59ce
Antonio Bianchi, Marco Bonura, Carlota P A Carlos, Stewart Leith, Guillaume Rosaz, Carmine Senatore and Walter Venturini Delsolaro
Niobium-coated copper radio-frequency cavities are cost-effective alternatives to bulk niobium cavities, given the lower material costs of copper substrates and their operation in liquid helium at around 4.2 K. However, these cavities historically exhibited a gradual degradation in performance with the accelerating field. This phenomenon, not yet fully understood, limits the application of niobium thin film cavities in accelerators where the real-estate gradient needs to be maximized. Recent studies on niobium films deposited on copper using high power impulse magnetron sputtering (HiPIMS) technique show promising results in mitigating the performance degradation of niobium thin film radio-frequency cavities. This paper examines the effect of film thickness on the superconducting properties of niobium films deposited on copper using HiPIMS. The study provides insights into how the critical temperature, transition width, lower and upper critical fields, and critical current density vary with the film thickness. Increasing the thickness of niobium films deposited through HiPIMS is found to enhance superconducting properties and reduce densities of defects and structural irregularities in the crystalline lattice. This shows potential for enhancing overall performance and potentially mitigating the observed performance degradation in niobium thin film radio-frequency cavities. Additionally, the Ivry’s scaling relation among critical temperature, thickness, and sheet resistance at the normal state appears applicable to niobium films up to approximately 4 µm. This extends the previously confirmed validity for niobium films, which was limited to around 300 nm thickness.
{"title":"Thickness effect on superconducting properties of niobium films for radio-frequency cavity applications","authors":"Antonio Bianchi, Marco Bonura, Carlota P A Carlos, Stewart Leith, Guillaume Rosaz, Carmine Senatore and Walter Venturini Delsolaro","doi":"10.1088/1361-6668/ad59ce","DOIUrl":"https://doi.org/10.1088/1361-6668/ad59ce","url":null,"abstract":"Niobium-coated copper radio-frequency cavities are cost-effective alternatives to bulk niobium cavities, given the lower material costs of copper substrates and their operation in liquid helium at around 4.2 K. However, these cavities historically exhibited a gradual degradation in performance with the accelerating field. This phenomenon, not yet fully understood, limits the application of niobium thin film cavities in accelerators where the real-estate gradient needs to be maximized. Recent studies on niobium films deposited on copper using high power impulse magnetron sputtering (HiPIMS) technique show promising results in mitigating the performance degradation of niobium thin film radio-frequency cavities. This paper examines the effect of film thickness on the superconducting properties of niobium films deposited on copper using HiPIMS. The study provides insights into how the critical temperature, transition width, lower and upper critical fields, and critical current density vary with the film thickness. Increasing the thickness of niobium films deposited through HiPIMS is found to enhance superconducting properties and reduce densities of defects and structural irregularities in the crystalline lattice. This shows potential for enhancing overall performance and potentially mitigating the observed performance degradation in niobium thin film radio-frequency cavities. Additionally, the Ivry’s scaling relation among critical temperature, thickness, and sheet resistance at the normal state appears applicable to niobium films up to approximately 4 µm. This extends the previously confirmed validity for niobium films, which was limited to around 300 nm thickness.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141501714","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}
Pub Date : 2024-06-17DOI: 10.1088/1361-6668/ad54f8
Jingnan Cai, Robin Cantor, Johanne Hizanidis, Nikos Lazarides and Steven M Anlage
We consider, for the first time, the effects of strong capacitive and inductive coupling between radio frequency superconducting quantum interference devices (rf SQUIDs) in an overlapping metamaterial geometry when driven by rf flux at and near their self-resonant frequencies. The equations of motion for the gauge-invariant phases on the Josephson junctions in each SQUID are set up and solved. Our model accounts for the high-frequency displacement currents through capacitive overlap between the wiring of SQUID loops. We begin by modeling two overlapping SQUIDs and studying the response in both the linear and nonlinear high-frequency driving limits. By exploring a sequence of more and more complicated arrays, the formalism is eventually extended to the overlapping metamaterial array, where we develop an understanding of the many ( ) resulting resonant modes in terms of three classes of resonances. The capacitive coupling gives rise to qualitatively new self-resonant responses of rf SQUID metamaterials, and is demonstrated through analytical theory, numerical modeling, and experiment in the 10–30 GHz range on capacitively and inductively coupled rf SQUID metamaterials.
{"title":"Effects of strong capacitive coupling between meta-atoms in rf SQUID metamaterials","authors":"Jingnan Cai, Robin Cantor, Johanne Hizanidis, Nikos Lazarides and Steven M Anlage","doi":"10.1088/1361-6668/ad54f8","DOIUrl":"https://doi.org/10.1088/1361-6668/ad54f8","url":null,"abstract":"We consider, for the first time, the effects of strong capacitive and inductive coupling between radio frequency superconducting quantum interference devices (rf SQUIDs) in an overlapping metamaterial geometry when driven by rf flux at and near their self-resonant frequencies. The equations of motion for the gauge-invariant phases on the Josephson junctions in each SQUID are set up and solved. Our model accounts for the high-frequency displacement currents through capacitive overlap between the wiring of SQUID loops. We begin by modeling two overlapping SQUIDs and studying the response in both the linear and nonlinear high-frequency driving limits. By exploring a sequence of more and more complicated arrays, the formalism is eventually extended to the overlapping metamaterial array, where we develop an understanding of the many ( ) resulting resonant modes in terms of three classes of resonances. The capacitive coupling gives rise to qualitatively new self-resonant responses of rf SQUID metamaterials, and is demonstrated through analytical theory, numerical modeling, and experiment in the 10–30 GHz range on capacitively and inductively coupled rf SQUID metamaterials.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141531949","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}
Pub Date : 2024-06-16DOI: 10.1088/1361-6668/ad52f6
Eva Cuninková, Lubomír Frolek, Ján Šouc, Filip Ferenčík, Lucia Bónová, Zoltán Száraz, Michal Skarba, Simona Hulačová, Marcela Pekarčíková and Štefan Šimon
REBCO (rare-earth barium copper oxide) high-temperature superconducting tapes, have a high potential for winding of large magnet coils. Tapes on round tube (TORT) cables represent a promising option for achieving a conductor suitable for the winding of magnet coils. However, certain applications, such as accelerator magnets, require the use of superconducting cables with low magnetization alternative current (AC) losses. There are several methods to reduce AC losses in TORT cables. Our first approach was to get rid of eddy currents by replacing the copper former with dielectric materials based on polymers and composites, i.e. polyethylene terephthalate glycol-modified reinforced with carbon fibers. Additional reduction of hysteretic loss was achieved by striating of copper coated REBCO tapes. We employed chemo-mechanical striating, for these objectives. However, the superconductor is exposed during the striating process, which may lead to later moisture-related degradation. Hence multilayers based on Ti/AlN were deposited using magnetron sputtering in order to protect the superconductor immediately after the striating process from water and atmospheric moisture corrosion. Subsequently, striated tapes as well as the non-striated tapes were then wound onto formers with diameters of 10 mm, 7 mm and 5.5 mm, and then on the short TORT cables bending tests were performed. After each technological step, direct current measurements were performed on the samples and finally the AC losses were measured.
{"title":"Characterization of a novel TORT cable wound of stabilized striated REBCO tapes for reduced magnetization AC losses","authors":"Eva Cuninková, Lubomír Frolek, Ján Šouc, Filip Ferenčík, Lucia Bónová, Zoltán Száraz, Michal Skarba, Simona Hulačová, Marcela Pekarčíková and Štefan Šimon","doi":"10.1088/1361-6668/ad52f6","DOIUrl":"https://doi.org/10.1088/1361-6668/ad52f6","url":null,"abstract":"REBCO (rare-earth barium copper oxide) high-temperature superconducting tapes, have a high potential for winding of large magnet coils. Tapes on round tube (TORT) cables represent a promising option for achieving a conductor suitable for the winding of magnet coils. However, certain applications, such as accelerator magnets, require the use of superconducting cables with low magnetization alternative current (AC) losses. There are several methods to reduce AC losses in TORT cables. Our first approach was to get rid of eddy currents by replacing the copper former with dielectric materials based on polymers and composites, i.e. polyethylene terephthalate glycol-modified reinforced with carbon fibers. Additional reduction of hysteretic loss was achieved by striating of copper coated REBCO tapes. We employed chemo-mechanical striating, for these objectives. However, the superconductor is exposed during the striating process, which may lead to later moisture-related degradation. Hence multilayers based on Ti/AlN were deposited using magnetron sputtering in order to protect the superconductor immediately after the striating process from water and atmospheric moisture corrosion. Subsequently, striated tapes as well as the non-striated tapes were then wound onto formers with diameters of 10 mm, 7 mm and 5.5 mm, and then on the short TORT cables bending tests were performed. After each technological step, direct current measurements were performed on the samples and finally the AC losses were measured.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141524318","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}
Pub Date : 2024-06-13DOI: 10.1088/1361-6668/ad5113
I Hušek, P Kováč, T Melišek, D Berek and L Kopera
The effects of the interface angle and applied deformation on the transport current and structure of scarf architecture joints between single- and multi-core MgB2 wires are studied in this paper. The transport currents of the joints were measured at 4.2 K, external magnetic fields of 2–8 T, and joint’s resistances between 27 and 42 K. Resistive transitions and critical currents of the prepared joints were compared with the transition and critical current of the unjointed MgB2 wires. The interface structure of joined in situ wires was analysed using optical microscopy. Increasing the interface area between the joined wires and optimizing deformation by pressing allows to enlarge the superconducting current path. In-field transport currents of up to 73% of wire’s Ic were measured for joined single-core MgB2/Fe wires. In the case of six-filament wires, the maximal transport current up to 53% of wire’s Ic was reached. The results show that the presented joint technique could potentially be used for superconducting MgB2 coils in a persistent mode.
本文研究了界面角度和外加变形对单芯和多芯 MgB2 金属丝之间的传输电流和疤痕结构接头结构的影响。在 4.2 K、2-8 T 的外部磁场以及 27 至 42 K 的接头电阻条件下测量了接头的传输电流。使用光学显微镜分析了原位接合导线的界面结构。增大接合导线之间的界面面积并通过加压优化变形可以扩大超导电流路径。在连接的单芯 MgB2/Fe 线材上测量到的场内传输电流高达线材 Ic 的 73%。在六芯线的情况下，最大传输电流可达线材 Ic 的 53%。结果表明，所介绍的连接技术有可能用于持续模式下的超导 MgB2 线圈。
{"title":"Effects of interface angle, added powder and applied deformation on the transport current and structure of scarf joints of single- and multi-core unreacted MgB2 wires","authors":"I Hušek, P Kováč, T Melišek, D Berek and L Kopera","doi":"10.1088/1361-6668/ad5113","DOIUrl":"https://doi.org/10.1088/1361-6668/ad5113","url":null,"abstract":"The effects of the interface angle and applied deformation on the transport current and structure of scarf architecture joints between single- and multi-core MgB2 wires are studied in this paper. The transport currents of the joints were measured at 4.2 K, external magnetic fields of 2–8 T, and joint’s resistances between 27 and 42 K. Resistive transitions and critical currents of the prepared joints were compared with the transition and critical current of the unjointed MgB2 wires. The interface structure of joined in situ wires was analysed using optical microscopy. Increasing the interface area between the joined wires and optimizing deformation by pressing allows to enlarge the superconducting current path. In-field transport currents of up to 73% of wire’s Ic were measured for joined single-core MgB2/Fe wires. In the case of six-filament wires, the maximal transport current up to 53% of wire’s Ic was reached. The results show that the presented joint technique could potentially be used for superconducting MgB2 coils in a persistent mode.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141524324","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}
Pub Date : 2024-06-13DOI: 10.1088/1361-6668/ad5114
I F Llovo, J Mosqueira, Ding Hu, Huiqian Luo and Shiliang Li
The critical current of single crystals of the iron pnictide superconductor BaFe2(As Px)2 has been studied through measurements of magnetic hysteresis cycles. We show that the introduction of micrometer-scale irregularities on the surface significantly increases , primarily near the irreversibility magnetic field . The observed increase can be attributed to a non-dissipative surface current that arises from the collective bending of the vortex lattice at the sample surface, enabled by the surface irregularities. This mechanism, which is not pinning in the proper sense, has previously been studied in clean, low- , metallic superconductors, but had not been investigated in Fe-based superconductors. The observed increase in is consistent with a theoretical estimate based on the Mathieu-Simon continuum theory of the vortex state.
{"title":"Enhancement of the critical current by surface irregularities in Fe-based superconductors","authors":"I F Llovo, J Mosqueira, Ding Hu, Huiqian Luo and Shiliang Li","doi":"10.1088/1361-6668/ad5114","DOIUrl":"https://doi.org/10.1088/1361-6668/ad5114","url":null,"abstract":"The critical current of single crystals of the iron pnictide superconductor BaFe2(As Px)2 has been studied through measurements of magnetic hysteresis cycles. We show that the introduction of micrometer-scale irregularities on the surface significantly increases , primarily near the irreversibility magnetic field . The observed increase can be attributed to a non-dissipative surface current that arises from the collective bending of the vortex lattice at the sample surface, enabled by the surface irregularities. This mechanism, which is not pinning in the proper sense, has previously been studied in clean, low- , metallic superconductors, but had not been investigated in Fe-based superconductors. The observed increase in is consistent with a theoretical estimate based on the Mathieu-Simon continuum theory of the vortex state.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141524325","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}
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