Bibliografie tematiche / Superconducting bulks

Letteratura scientifica selezionata sul tema "Superconducting bulks"

Autore: Grafiati

Pubblicato: 8 giugno 2024

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Articoli di riviste sul tema "Superconducting bulks":

Zhang, Sheng Nan, Xiao Bo Ma, Ji Xing Liu, Jian Qing Feng, Cheng Shan Li e Ping Xiang Zhang. "Effects of High-Energy Ball Milling Time on the Sintering Process of FeSe Superconductors". Materials Science Forum 848 (marzo 2016): 657–63. http://dx.doi.org/10.4028/www.scientific.net/msf.848.657.

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FeSe superconducting bulks were prepared with high energy ball milling (HEBM) aided sintering process, within which process, tetragonal β-FeSe superconducting phase could be formed directly with one step sintering process, and the formation of hexagonal δ-FeSe non-superconducting phase was effectively avoided. The influences of HEBM time on the sintering process of FeSe bulks were systematically investigated. With different HEBM time, the phase composition and morphology of precursor powders changed correspondingly, which thus influenced the final phase composition and superconducting properties of FeSe superconducting bulks. Due to the formation of FeSe bulks with larger tetragonal phase content and higher superconducting transition temperature, HEBM time of 6.0 h was recognized as the optimal parameter. Shorter HEBM time could lead to the insufficient decrease of particle size and low density. While longer HEBM time caused the formation of amorphous hexagonal δ-FeSe, which crystallized during sintering process. Thus no more tetragonal FeSe could be obtained. The FeSe superconducting bulk with the critical temperature Tc(onset) of 8.0 K was obtained with the HEBM time of 6 h, and sintering temperature of 700 oC for 12 h.

Zhang, Yufeng, Chunyan Li, Ziwei Lou, Penghe Zhang, Yan Zhang, Shuangyuan Shen, Guanjie Ruan e Jiaying Zhang. "The Performance of the Two-Seeded GdBCO Superconductor Bulk with the Buffer by the Modified TSMG Method". Micromachines 14, n. 5 (30 aprile 2023): 987. http://dx.doi.org/10.3390/mi14050987.

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The multiseeding technique is a method to grow large-sized REBa2Cu3O7−δ (REBCO, where RE is a rare earth element) high temperature superconducting bulks. However, due to the existence of grain boundaries between seed crystals, the superconducting properties of bulks are not always better than those of single grain bulks. In order to improve the superconducting properties caused by grain boundaries, we introduced buffer layers with a diameter of 6 mm in the growth of GdBCO bulks. Using the modified top-seeded melt texture growth method (TSMG), that is, YBa2Cu3O7−δ (Y123) as the liquid phase source, two GdBCO superconducting bulks with buffer layers with a diameter of 25 mm and a thickness of 12 mm were successfully prepared. The seed crystal arrangement of two GdBCO bulks with a distance of 12 mm were (100/100) and (110/110), respectively. The trapped field of the GdBCO superconductor bulks exhibited two peaks. The maximum peaks of superconductor bulk SA (100/100) were 0.30 T and 0.23 T, and the maximum peaks of superconductor bulk SB (110/110) were 0.35 T and 0.29 T. The critical transition temperature remained between 94 K and 96 K, with superior superconducting properties. The maximum JC, self-field of SA appeared in specimen b5, which was 4.5 × 104 A/cm2. Compared with SA, the JC value of SB had obvious advantages in a low magnetic field, medium magnetic field and high magnetic field. The maximum JC, self-field value appeared in specimen b2, which was 4.65 × 104 A/cm2. At the same time, it showed an obvious second peak effect, which was attributed to Gd/Ba substitution. Liquid phase source Y123 increased the concentration of the Gd solute dissolved from Gd211 particles, reduced the size of Gd211 particles and optimized JC. For SA and SB under the joint action of the buffer and the Y123 liquid source, except for the contribution of Gd211 particles to be the magnetic flux pinning center with the improvement of JC, the pores also played a positive role in improving the local JC. More residual melts and impurity phases were observed in SA than in SB, which had a negative impact on the superconducting properties. Thus, SB exhibited a better trapped field and JC.

FUJISHIRO, Hiroyuki. "Magnetization of Superconducting Bulks". TEION KOGAKU (Journal of the Cryogenic Society of Japan) 46, n. 3 (2011): 81–88. http://dx.doi.org/10.2221/jcsj.46.81.

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Cheng, Yanxing, Jun Zheng, Huan Huang e Zigang Deng. "A reconstructed three-dimensional HTS bulk electromagnetic model considering J _c spatial inhomogeneity and its implementation in a bulks’ combination system". Superconductor Science and Technology 34, n. 12 (12 novembre 2021): 125017. http://dx.doi.org/10.1088/1361-6668/ac336b.

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Abstract High-temperature superconducting (HTS) bulks in HTS Maglev systems are always arrayed in a combination to make full use of the applied magnetic field of the permanent magnet guideway (PMG). An excellent combination scheme improves the overall levitation and guidance performance significantly. In this paper, a three-dimensional (3D) electromagnetic model of the real HTS-PMG maglev system with an HTS bulk array was established. This model comprehensively expresses the influence of various factors on the E – J relationship and the 3D spatial distribution of J c, including internal factors such as the inhomogeneity and anisotropy of electromagnetic characteristics, as well as external factors such as applied magnetic field and working temperature. A ternary function was proposed to describe the uneven distribution of J c caused by the bulk’s growth process, which is an interesting phenomenological modeling attempt. In the simulations of the bulks’ combinations, perfect magnetic conductor boundary conditions were applied on the contact surface to simulate two bulks touching each other. Besides, the research target includes reproducing the shapes, the orientations, and the combination scheme of HTS bulks in the real PMG magnetic field. The calculation results of levitation force of the cylindrical bulk under different spatial orientations above the PMG were compared with the experimental results, through which the accuracy of the model was verified. On this basis, the influence of the magnetic field generated by the superconducting current on the nearby bulk was further explored. It was found that this magnetic field has a small contribution to the total levitation force and a relatively obvious influence on the guidance force. When the lateral displacement is large, such as 5 mm, the magnetic field generated by the superconducting current slightly increases the total guidance force stiffness. According to more simulated conditions, some optimization strategies on bulk combinations were proposed. This work provides not only a 3D descriptive model for fitting the real multi-bulk-combination maglev scenarios but also some optimization strategies for the HTS maglev transportation applications.

Imao, Hiroya, Kousuke Matsumoto e Satoru Kishida. "Preparation of Partial-Melted Sm-Ba-Cu-O Bulk Superconductor". Advances in Science and Technology 47 (ottobre 2006): 165–69. http://dx.doi.org/10.4028/www.scientific.net/ast.47.165.

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We prepared SmBa2Cu3Oy (SmBCO) superconducting bulks by partial melting growth with a top seed. From the results, we found that the SmBCO bulks prepared by melting process showed good superconductivity, where the critical temperature Tc and the temperature transition width ΔT of the bulk were 94K and about 1K, respectively. The as-prepared bulks required annealing at 500°C for 24h to improve the superconductivity. However, the characteristics of the bulks may be improved by more detailed study, for example optimum preparation and annealing conditions.

Douine, Bruno, Kevin Berger e Nickolay Ivanov. "Characterization of High-Temperature Superconductor Bulks for Electrical Machine Application". Materials 14, n. 7 (26 marzo 2021): 1636. http://dx.doi.org/10.3390/ma14071636.

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High-temperature superconducting (HTS) bulks can be used in electrical applications. Experimental characterization of large-size HTS bulks is a tricky issue. The relevant parameters for their application were directly measured in this study. This paper has three main aims. Firstly, features of YBaCuO bulks are presented. Secondly, an electrical motor application is developed using magnetic field shielding and trapping. Thirdly, the HTS bulks are characterized. Several classical methods were used, which are mainly magnetic methods only available for small samples. The complete penetration magnetic field and the critical current density were found to be the main parameters relevant for applications. An innovative entire HTS bulk characterization method is presented. This characterization method is useful for end users and engineers to better implement HTS bulks.

Li, Lei, Hong Zhang, Yong Zhao e Yong Zhang. "MgB2 superconductor prepared by Mg diffusion method with the addition of reduced graphene oxide". International Journal of Modern Physics B 32, n. 24 (13 settembre 2018): 1850268. http://dx.doi.org/10.1142/s0217979218502685.

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The effects of 0–5 wt.% reduced graphene oxide (rGO) addition on the superconducting properties of MgB2 bulks were investigated. We found that the dense and uniform MgB2 bulks were obtained by Mg diffusion method with rGO addition. The superconducting properties of MgB2 improved by the addition of rGO content of less than 2 wt.%. With more than 2 wt.% (including 2 wt.%) of rGO addition, nonsuperconducting phase MgB2C2 appeared and MgO content increased, which resulted in a decline in superconducting properties.

Zhang, Yufeng, Ziwei Lou, Penghe Zhang, Chunyan Li, Jiaying Zhang e Xiaojuan Zhang. "Flux Pinning Properties of Single-Grain Bulk GdBCO Superconductors Processed by Different Thicknesses of Y123 Liquid Source". Micromachines 13, n. 5 (29 aprile 2022): 701. http://dx.doi.org/10.3390/mi13050701.

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The performance of critical current density of GdBa2Cu3O7−δ (GdBCO or Gd123) superconductor bulk has an important influence on its practical applications. In this work, four single-domain GdBCO superconductor bulks were successfully processed by the modified top-seeded melt-texture growth method. The addition of a YBa2Cu3O7−δ (Y123) liquid source with different thicknesses, 0 mm (S0), 3 mm(S3), 5 mm (S5), 7 mm (S7), was introduced to study the influence on the superconducting properties. GdBCO bulk with the addition of the Y123 liquid source with a 3-mm thickness shows the best superconducting properties. The addition of the Y123 liquid source results in a decrease in the Gd3+ ion concentration required for Gd123 growth; thus, Gd2BaCuO5 (Gd211) particles in the liquid source need a larger self-decomposition to diffuse Gd3+ ions to Gd123 growth front, which refines the size and leads to a homogenous distribution of the Gd211 particles in the bulks. Thus, the more pinning centers of fined Gd211 particles improve the superconducting properties of GdBCO bulk. With increases in the thickness of Y123 liquid source to 5 mm and 7 mm, high RE3+ (Gd3+ and Y3+) concentration can coarsen Gd211 particles and fuse with Gd211 liquid source. The superconducting properties apparently drop. Therefore, the addition of a Y123 liquid source with a suitable thickness is a positive modification to obtain high-performance GdBCO bulk.

Fujimoto, H., H. Shimada e S. Yoshizawa. "Mechanical properties of DyBaCuO superconducting bulks". Physica C: Superconductivity and its Applications 463-465 (ottobre 2007): 374–78. http://dx.doi.org/10.1016/j.physc.2007.04.235.

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Mamalis, A. G., I. N. Vottea, D. E. Manolakos, A. Szalay e A. Kladas. "Numerical Simulation of Explosive Consolidation of Superconducting Bulk Components". International Journal of Modern Physics B 17, n. 18n20 (10 agosto 2003): 3563–67. http://dx.doi.org/10.1142/s0217979203021411.

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The explosive compaction technique has been used for manufacturing bulk superconducting components, e.g. three dimensional plates and axisymmetric billets, rods, discs and tubes, with high density and good electrical and magnetic characteristics. The high pressures and temperatures developed in a very short time result in sintering and in fracturing of the original grains, inducing primarily line defects that would provide flux pinning centers in Type II superconductors. Densified superconducting ceramic YBCO bulk components of various geometries were produced by this dynamic technique and the whole process was simulated by the explicit finite element code LS-DYNA3D. In this paper, experimental and numerical results of the fabricated superconducting bulks are reported and discussed. Applications are also briefly outlined.

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Tesi sul tema "Superconducting bulks":

Bozzo, Closas Bernat. "Superconducting joining of melt textured YBCO bulks". Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/369047.

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La obtenció de ceràmiques superconductores de YBa2Cu3O7 porta implícita una limitació en les dimensions i forma de les peces. Per tal de superar aquesta limitació, s’ha proposat un mètode de soldadura basat en l’ús d’una làmina de plata com a decapant. Aquest treball de Tesi està enfocat en: • El perfeccionament de la tècnica de soldadura de YBCO per tal de resoldre una sèrie de problemàtiques presents en el moment de començar aquest treball. • Caracterització de la microestructura de les mostres soldades. • El desenvolupament d’eines d’anàlisi quantitatiu per avaluar la qualitat de la soldadura des del punt de vista de les propietats magnètiques i elèctriques. • La expansió del mètode de soldadura per incloure soldadures on existeix una desorientació cristal·logràfica entre les dues peces unides i estudi de la influència d’aquesta desorientació en les propietats magnètiques i elèctriques. El primer pas seguit fou la construcció d’un forn equipat amb un sistema d’observació òptica in-situ. Aquest sistema va permetre obtenir gravacions de l’evolució de la mostra durant el tractament tèrmic. Aquests vídeos van permetre detectar la presència de dos tipus de líquids que eren arrossegats fora de la zona de soldadura. L’estudi de la microestructura de la soldadura van indicar que aquesta pèrdua de líquid afavoria l’aparició de defectes microestructurals. Una modificació del porta-mostres emprat solucionà el problema. Es van realitzar estudis de la microestructura més detallats per tal de poder entendre millor els mecanismes que en fan possible la seva formació amb la idea de postular-ne un possible model. Un estudi adequat de les propietats magnètiques també fou necessari, ja que l’objectiu final del mètode de soldadura és el d’unir diverses peces de YBCO, tot mantenint les propietats superconductores a la zona soldada. Per aquest motiu, es van realitzar mesures d’imatge magnètica, basades en una Sonda d’Efecte Hall. A partir dels mapes de magnetització local de les mostres, es va obtenir la distribució de densitats de corrent crítica, emprant un programari especialitzat. Per tal d’entendre millor aquests mapes de densitat de corrent i, també, per extreure’n informació útil, es va desenvolupar un programari de simulació i els coneixements adquirits, es van poder obtenir les densitats de corrent intergranular i intragranular (JcGB i JcG). Es va estudiar la dependència del quocient entre JcGB i JcG amb l’angle de desorientació cristal·lina. En principi s’esperava una dependència semblant a la que es troba en el cas de les cintes superconductores. No obstant, la dependència que es va trobar era més fluixa que la del cas model considerat. Aquesta dependència es va comprar, llavors, amb la d’altres estudis similars, fets amb fronteres de gra artificials en mostres superconductores volumètriques, revelant un comportament semblant entre elles, indicant que el valor del quocient JcGB/JcG era potencialment intrínsec al grau de desorientació. Aquesta hipòtesi es va confirmar quan es van comparar mostres de YBCO amb qualitats diferents, però amb el mateix angle de desorientació. Es van realitzar mesures dels mapes de magnetització en funció del camp magnètic per tal de determinar els règims d’ancoratge de vòrtexs presents en les mostres i es van comparar amb el cas de les cintes superconductores. Tot i que els règims d’ancoratge en la zona de soldadura són similars als de les fronteres de gra per una cinta superconductora, els règims en zones fora de la soldadura difereixen entre els dos casos. Finalment, es van realitzar mesures de nanoindentació per tal de correlacionar les propietats mecàniques amb les elèctriques. Concretament, es va avaluar la duresa del material en la zona de soldadura i fora d’aquesta zona. El quocient entre les dues dureses mostraven una gran correlació amb el valor del quocient JcGB/JcG.
The obtention of bulk YBa2Cu3O7 tiles by the Top Seeded Melt Growth method carries and implicit limitation on the shape and size of the pieces. In order to overcome this limitation a joining method based on the use of an Ag foil as a welding agent has been proposed. This thesis work was focused in the following aspects: • The refinement of the welding methodology for YBCO pellets in order to solve the issues present. • Characterization of the microstructure of welded pellets. • The development of suitable quantitative analysis tool for evaluating the weld quality in terms of its superconducting behavior. • The expansion of the methodology to include welds with crystallographic misorientation and study the influence of such a crystallographic misorientation on the electric and magnetic properties The first step was to develop a furnace bundled with an in-situ observation video setup that allowed visually record the evolution of the sample during the thermal process. Those videos revealed the existence of two types of liquids that were dragged out from the weld position. The microstructural study carried out on the welded samples indicated that this loss of liquid was the source of microstructural malformations at the weld position. A modification on the sample holder was required and solved the issue. All the studied samples were analyzed under the scope of their micro-structural characteristics and their magnetic properties. For the case of the micro-structural characterization, a basic study was carried out in order to determine the successfulness of the weld formation and it was used as a feedback parameter for fine-tuning the thermal process. The weld microstructure was further investigated in order to obtain more information about its characteristics and in order to obtain a better understanding about the mechanisms that make the weld formation possible. A proper study of the magnetic and electric properties was also required, since the final objective of the superconducting welding technology is to join several YBCO tiles while maintaining the superconducting properties at the weld position. For that purpose, magnetic imaging Hall Effect based measurements were performed on the specimens under study. From the local magnetization maps, current density distribution maps were obtained by using specialized software. In order to understand and obtain useful information from those current density maps, a simulation software piece was developed and the knowledge acquired from those simulations allowed obtaining the inter- and intra-granular critical current density values (JcGB and JcG) from each sample. The ratio between JcGB and JcG was studied as a function of the misorientation angle. In principle, a behavior similar to coated conductors was expected. However, the dependence found was weaker than the considered model case. That determined dependence was compared with similar studies on grain boundaries in bulk YBCO, revealing a similar behavior and indicating that the JcGB/JcG ratio value was potentially intrinsic to the misorientation angle. This hypothesis was confirmed when several samples with different YBCO grain characteristics but with the sample misorientation were compared. Field dependence measurements of the magnetization maps were also performed in order to determine the vortex pinning regimes present at the samples and to compare them with the thin film case. Despite the weld pinning regimes were similar, the behavior at the grain was slightly different. Finally, the superconducting properties were correlated with the mechanical properties. The hardness of the material was evaluated by using nano-indentation techniques at different positions. The ratio between the hardness at the weld and away from the weld exhibited a high correlation with the JcGB/JcG ratio.

Patel, Anup. "Pulsed field magnetization of composite superconducting bulks for magnetic bearing applications". Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/256579.

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Permanent magnets are essential components for many devices such as motors, which currently account for 45 % of global electricity consumption, generators and also superconducting magnetic bearings used for applications such as flywheel energy storage. But even the most powerful rare-earth magnets are limited to a remanent field of 1.4 T, whereas superconducting materials such as YBCO in their bulk form have the extraordinary ability to trap magnetic fields an order of magnitude higher, whilst being very compact. This gives them the potential to increase efficiency and allow significant volume and weight reductions for rotating machines despite the need for cooling. A new design of superconducting magnetic bearing has been developed which uses magnetized bulks as the field source, eliminating permanent magnets. Finite element modelling shows that the bulk – bulk design can achieve much higher force densities than existing permanent magnet – bulk designs, giving it potential to be used as a compact magnetic bearing. A system was created to magnetize bulks using a pulsed magnetic field down to 10 K and then measure levitation force. In proving the concept of the proposed design, the highest levitation forces ever reported between two superconducting bulks were measured, including a levitation force of 500 N between a 1.7 T magnetized YBCO bulk and a coaxial $MgB_{2}$ bulk tube. The biggest factor limiting the use of magnetized bulks in applications is magnetizing them in the first place. Using a pulsed magnetic field is most practical but generates excessive heat dissipation leading to a loss of flux in conventional bulk superconductors, which are 100% superconductor. Although multi-pulse techniques help maximise the trapped field, the poor thermal properties of bulk (RE)BCO are a limiting factor. New composite superconducting structures are reported which can overcome these problems by using high thermal conductivity materials, the motivation for which came from finite element modelling of the critical state coupled with heat transfer. In particular, composite structures created by cutting and stacking 12 mm wide (RE)BCO superconducting tape are shown experimentally to have exceptional field trapping ability due to superior thermal and mechanical properties compared to existing bulks. Up to 2 T was trapped in a stack of commercially available tape produced by SuperPower Inc. in the first reported pulsed magnetization of such a stack. Over 7 T was trapped between two stacks using field cooling at 4.2 K, the highest field yet trapped in such a sample.

Yan, Yu. "Thermally actuated magnetisation flux pump system for high temperature superconducting bulks". Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609510.

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Huang, Zhen. "A fully high temperature superconducting synchronous motor using pulsed field magnetization, bulks, and 2G HTS coils". Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709396.

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Susner, Michael A. "Influences of Crystalline Anisotropy, Doping, Porosity, and Connectivity on the Critical Current Densities of Superconducting Magnesium Diboride Bulks, Wires, and Thin Films". The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1344984007.

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Dorget, Rémi. "Étude et conception d'une machine supraconductrice à modulation de flux pour application aéronautique". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0018.

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Dans le cadre de la lutte contre le changement climatique, l'industrie aéronautique s'est fixé pour objectif la neutralité carbone totale en 2050. Pour cela, l'emploi de technologies de rupture est nécéssaire pour réduire les émissions de ce secteur en forte croissance. Parmi ces technologies, on retrouve l'électrification mais dont le déploiement nécessite de disposer de machines électriques à forte puissance spécifique. Dans ce contexte la supraconductivité peut être une voie d'amélioration pour les machines électriques grâce aux fortes densités de courant ainsi qu'aux champs magnétiques intenses qu'il est possible de générer avec les matériaux supraconducteurs. L'inconvénient principal de cette technologie est la nécessité de fonctionner à des températures cryogéniques. Cependant, la perspective de l'emploi par les avions de l'hydrogène liquide comme carburant, transporté à -253 °C, présente une synergie avec la supraconductivité. C'est dans ce cadre que se placent les travaux de cette thèse qui a pour but d'étudier l'utilisation des matériaux supraconducteurs à haute température critique pour le développement d'un moteur supraconducteur à haute puissance spécifique employant une topologie originale appelée « machine à modulation de flux ». Cette structure de machine est étudiée depuis plusieurs années à l'Université de Lorraine au sein du Groupe de Recherche en Énergie Électrique de Nancy (GREEN), laboratoire dans lequel cette thèse s'est déroulée. Les travaux relatés dans ce manuscrit interviennent dans le cadre d'une convention CIFRE avec l'entreprise SAFRAN. Afin de permettre l'étude de cette machine, ce mémoire comporte deux chapitres dédiés à la modélisation électromagnétique semi-analytique d'une machine à modulation de flux axiale. L'objectif de ce modèle est de permettre un calcul rapide et précis du couple et des pertes d'une machine. L'utilisation de ce modèle dans le chapitre suivant permet d'aboutir au dimensionnement électromagnétique d'un démonstrateur de 260 kW. Ce dimensionnement tient en outre compte des différentes contraintes techniques et logistiques rencontrées. Un cinquième chapitre détaille la construction en cours du démonstrateur et sa structure mécanique et cryogénique. Enfin le dernier chapitre de ce manuscrit porte sur l'extrapolation des résultats expérimentaux dans le but d'évaluer les performances potentielles des machines à modulation de flux à plus forte puissance
As part of the fight against climate change, the aeronautics industry has set itself the goal of becoming totally carbon neutral by 2050. To achieve this, the use of disruptive technologies is necessary to reduce the emissions of this fast-growing sector. Among these technologies, we find electrification, but its deployment requires high specific power electrical machines. In this context, superconductivity can be a way of improving electrical machines thanks to the high current densities and intense magnetic fields that can be generated with superconducting materials. The main drawback of this technology is the need to operate at cryogenic temperatures. However, the prospect of aircraft using liquid hydrogen as a fuel, transported at -253°C, presents a synergy with superconductivity. It is in this context that the work of this thesis is placed, which aims to study the use of high critical temperature superconducting materials for the development of a high specific power superconducting engine employing an original topology called "flux modulation machine". This machine structure has been studied for several years at the University of Lorraine within the Groupe de Recherche en Énergie Électrique de Nancy (GREEN), the laboratory in which this thesis was carried out. The work reported in this manuscript is part of a CIFRE agreement with the company SAFRAN. In order to allow the study of this machine, this thesis includes two chapters dedicated to the semi-analytical electromagnetic modelling of an axial flux modulation machine. The objective of this model is to allow a fast and accurate calculation of the torque and losses of a machine. The use of this model in the following chapter leads to the electromagnetic dimensioning of a 260 kW demonstrator. This design also takes into account the various technical and logistical constraints encountered. A fifth chapter details the ongoing construction of the demonstrator and its mechanical and cryogenic structure. Finally, the last chapter of this manuscript deals with the extrapolation of the experimental results in order to evaluate the potential performances of flux modulation machines at higher power

Grira, Sarra. "Microstructure, texture and superconductive properties of High Temperature Superconducting "HTS" oxides : yBCO thin films and bulk NBCO and YBCO". Thesis, Metz, 2009. http://www.theses.fr/2009METZ005S/document.

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Ce travail concerne l'étude de la texture et de la microstructure en relation avec les propriétés supraconductrices Tc et Jc de supraconducteurs haute température critique SHTc : YBCO et NBCO. Les techniques de caractérisation utilisées pour la microstructure sont la diffraction de RX et la diffraction d'électrons (Electron Back-Scatter Diffraction) "EBSD". Tc et Jc ont été déduits des mesures d'aimantation et de susceptibilité magnétique au SQUID (Superconducting Quantum Interference Device) et PPMS (Physical Properties Measument System). La première partie de l'étude traite de la caractérisation de la texture de couches minces SHTc d'YBCO, et de la possibilité de déterminer les relations d'épitaxie par EBSD entre le film déposé et la couche tampon. Ce type d'échantillon est constitué d'un substrat de saphir sur lequel 3 couches successives ont été déposées dont 300 nm de YBCO, destinées aux applications électrotechniques comme limiteurs de courant. La deuxième partie concerne l'étude de matériaux massifs supraconducteurs YBCO et NBCO fabriqués par différentes techniques. L'effet du dopage d'YBCO avec de l'argent a été étudié sur des échantillons fabriqués par la technique dite de "texturation par croissance orientée" soit MTG (Melt Textured Growth) et sous une faible pression partielle d'oxygène. Le dopage jusqu'à un certain pourcentage d'argent améliore la microstructure ainsi que la densité de courant critique. Une comparaison des caractéristiques physiques et structurales d'échantillons NBCO oxygénés ex-situ et YBCO in-situ, élaborés par MTG sous champ magnétique intense a été effectuée. De même des échantillons NBCO texturés par la technique de fusion de zone (Zone Melting) oxygénés respectivement in-situ et ex-situ ont été étudiés. Ils présentent des textures similaires avec présence de macles pour NBCO oxygéné ex-situ
The aim of this work is the study of crystallographic texture and microstructure in connection with the superconducting properties (Tc and Jc) of High Temperature Superconducting (HTS) materials: YBCO and NBCO. Microstructure is studied by X-Ray Diffraction (XRD) and Electron backscatter Diffraction (EBSD). The Determination of critical temperature (Tc) and critical current density (Jc) are made with Superconducting Quantum Interference Device (SQUID) magnetometer or Physical Properties Measurement System (PPMS). The first part of this work investigates the crystallographic textures of the YBCO film by using EBSD in order to deduce the epitaxial relationship between the superconducting layer and the buffer layer. This thin film is made up of three successive deposits (among which 300 nm of YBCO), used in fault current limiters for electrical engineering applications. The second part presents the study of NdBa2Cu3O7-d (NBCO) and YBCO bulks prepared by various techniques. The effect of silver doping of YBCO has been studied on samples prepared by the Melt Textured Growth (MTG) technique under low oxygen partial pressure. The doping up to a given amount of silver enhances the microstructure and the critical current density. A comparison of the physical and structural characteristics between NBCO oxygenated exsitu and YBCO oxygenated in-situ, prepared by MTG under high magnetic field has been made. Zone-melted NBCO samples textured by zone melting method oxygenated respectively in-situ and ex-situ have been studied. These samples exhibit the same texture with the occurrence of twins for the NBCO oxygenated ex-situ

Kurupakorn, C., N. Hayakawa, N. Kashima, S. Nagaya, M. Noe, K. P. Juengst e H. Okubo. "Development of high temperature superconducting fault current limiting transformer (HT/sub c/-SFCLT) with Bi2212 bulk coil". IEEE, 2004. http://hdl.handle.net/2237/6750.

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Manton, Stephen John. "Fabrication and characterisation of high temperature superconducting bulk YBCO". Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396128.

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Shimizu, H., K. Kato, Y. Yokomizu, T. Matsumura e N. Murayama. "Resistance rise in Bi2223 superconducting bulk after normal transition due to overcurrent". IEEE, 2001. http://hdl.handle.net/2237/6782.

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Più fonti

Libri sul tema "Superconducting bulks":

Koblischka, M. R. Growth and Characterization of HTSc Nanowires and Nanoribbons. A cura di A. V. Narlikar. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780198738169.013.11.

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This article describes the fabrication of high-temperature superconducting nanowires and their characterization by magnetic and electric transport measurements. In the literature, nanowires of high-temperature superconductors (HTSc) are obtained by means of lithography, using thin film material as a base. However, there are two main problems with this approach: first, the substrate often influences the HTSc nanowire, and second, only electric transport measurements can be performed. This article explains how nanowires and nanobelts of high-temperature superconducting cuprates can be prepared by the template method and by electrospinning. It also considers the possibilities for employing substrate-free HTSc nanowires as building blocks to realize new, nanoporous bulk superconducting materials for a variety of applications.

Inamuddin, a cura di. Superconductors. Materials Research Forum LLC, 2022. http://dx.doi.org/10.21741/978164490210.

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The book presents the current status of superconductor science and technology. It focuses on the design, properties and applications of superconductor materials. The superconductor categories covered include type-I, type-II, bulk, hard, soft, oxide, fermions, organic, iron, Lanthanide-based superconductors, high temperature superconductors and superconducting metamaterials.

Li, Y. Y., e J. F. Jia. Topological Superconductors and Majorana Fermions. A cura di A. V. Narlikar. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780198738169.013.6.

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This article discusses recent developments relating to the so-called topological superconductors (TSCs), which have a full pairing gap in the bulk and gapless surface states consisting of Majorana fermions (MFs). It first provides a background on topological superconductivity as a novel quantum state of matter before turning to topological insulators (TIs) and superconducting heterostructures, with particular emphasis on the vortices of such materials and the Majorana mode within a vortex. It also considers proposals for realizing TSCs by proximity effects through TI/SC heterostructures as well as experimental efforts to fabricate artificial TSCs using nanowires, superconducting junctions, and ferromagnetic atomic chains on superconductors.

Capitoli di libri sul tema "Superconducting bulks":

Honjo, Tetsuji, Seiichi Miyake e Takayo Hasegawa. "Mechanical and Superconducting Properties in Bi-2223 Bulks for Current Lead". In Advances in Superconductivity IX, 939–42. Tokyo: Springer Japan, 1997. http://dx.doi.org/10.1007/978-4-431-68473-2_70.

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Colle, Alexandre, Thierry Lubin, Sabrina Ayat e Jean Leveque. "Superconducting Motor Using HTS Bulk". In High-Tc Superconducting Technology, 477–527. New York: Jenny Stanford Publishing, 2021. http://dx.doi.org/10.1201/9781003164685-14.

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Murakami, Akira. "Mechanical Properties and Fracture Behaviors of Superconducting Bulk Materials". In High-Tc Superconducting Technology, 557–76. New York: Jenny Stanford Publishing, 2021. http://dx.doi.org/10.1201/9781003164685-16.

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Srikanth, Arvapalli Sai. "Ultrasonication: A Cost-Effective Way to Synthesize High-Jc Bulk MgB2". In High-Tc Superconducting Technology, 265–82. New York: Jenny Stanford Publishing, 2021. http://dx.doi.org/10.1201/9781003164685-8.

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Diko, P., K. Zmorayova, L. Vojtkova, V. Antal, V. Kucharova, R. Pagacova, V. Kavečanský et al. "Growth, Microstructure, and Superconducting Properties of Ce Alloyed YBCO Bulk Single-Grain Superconductors". In High-Tc Superconducting Technology, 75–149. New York: Jenny Stanford Publishing, 2021. http://dx.doi.org/10.1201/9781003164685-3.

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Nagashima, K., T. Miyamoto, S. I. Yoo, M. Murakami, Y. Iwasa, K. Sawa e H. Fujimoto. "Superconducting Bulk Levitation Using an Electromagnet". In Advances in Superconductivity XI, 1011–16. Tokyo: Springer Japan, 1999. http://dx.doi.org/10.1007/978-4-431-66874-9_237.

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Namburi, Devendra K., e David A. Cardwell. "Dense and Robust (RE)BCO Bulk Superconductors for Sustainable Applications: Current Status and Future Perspectives". In High-Tc Superconducting Technology, 17–74. New York: Jenny Stanford Publishing, 2021. http://dx.doi.org/10.1201/9781003164685-2.

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Guilmeau, E., Daniel Chateigner, J. Noudem e B. Ouladdiaf. "Combined Analysis of Bi2223 Superconducting Bulk Materials". In Solid State Phenomena, 385–90. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/3-908451-09-4.385.

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Oswald, B., M. Krone, M. Söll, T. Straßer, J. Oswald e K. J. Best. "Optimisation of Superconducting Motors with YBCO Bulk Material". In Advances in Cryogenic Engineering, 1653–57. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/978-1-4615-4215-5_89.

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Habisreuther, T., D. Litzkendorf R. Müller, M. Zeisberger, S. Kracunovska, O. Surzhenko, J. Bierlich, W. Gawalek e T. A. Prikhna. "Bulk Superconducting Function Elements for Electric Motors and Levitation". In Ceramic Transactions Series, 337–50. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118405932.ch30.

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Atti di convegni sul tema "Superconducting bulks":

Ohsaki, H., M. Sekino, T. Suzuki e Y. Terao. "Design study of wind turbine generators using superconducting coils and bulks". In 2009 International Conference on Clean Electrical Power (ICCEP). IEEE, 2009. http://dx.doi.org/10.1109/iccep.2009.5212007.

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Terao, Y., M. Sekino e H. Ohsaki. "Design study of linear synchronous motors using superconducting coils and bulks". In 2010 International Power Electronics Conference (IPEC - Sapporo). IEEE, 2010. http://dx.doi.org/10.1109/ipec.2010.5543127.

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Lojka, Michal, Jan Sklenka, Tomáš Hlásek, Filip Antončík, Anna-Marie Lauermannová e Ondřej Jankovský. "Comparison of superconducting properties of YBCO and EuBCO single-domain bulks". In 27TH INTERNATIONAL MEETING OF THERMOPHYSICS 2022. AIP Publishing, 2023. http://dx.doi.org/10.1063/5.0163788.

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Liu, L., e J. Li. "Levitation Force Transition of High-Tc Superconducting Bulks above a Spinning Permanent Magnetic Guideway". In 2016 Joint International Information Technology, Mechanical and Electronic Engineering Conference. Paris, France: Atlantis Press, 2016. http://dx.doi.org/10.2991/jimec-16.2016.55.

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Salem, M. K. Ben, E. Hannachi, Y. Slimani, A. Hamrita, L. Bessais, F. Ben Azzouz e M. Ben Salem. "Effect of nanowires SiO[sub 2] on superconducting properties of YBa[sub 2]Cu[sub 3]O[sub 7−d] bulks". In 3RD INTERNATIONAL ADVANCES IN APPLIED PHYSICS AND MATERIALS SCIENCE CONGRESS. AIP, 2013. http://dx.doi.org/10.1063/1.4849231.

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Lo, W. "Melt processing bulk magnets - what can be achieved". In IEE Colloquium on High Tc Superconducting Materials as `Magnets'. IEE, 1995. http://dx.doi.org/10.1049/ic:19951521.

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Gassot, H. "Analytical Predictions of Thermal Stress in Plasma Spray Coating and in Substrate at Low Temperature Compared with Strains Measurements". In ITSC 2000, a cura di Christopher C. Berndt. ASM International, 2000. http://dx.doi.org/10.31399/asm.cp.itsc2000p0371.

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Abstract An analytical thermal stress calculation and an in situ thermal stress measurement are developed at low temperatures (from room temperature to liquid helium temperature) on a cylindrical specimen made from an inner bulk niobium wall and a copper alloy VPS coating. This kind of structure is proposed for superconducting cavities in order to reduce the cavity frequency shift due to Lorentz forces. Since the superconducting cavity works at liquid helium temperature (below 4 K) and the niobium thermal expansion ratio is very different from the thermal expansion ratio of copper, thermal stress evaluations during the cool down are necessaries. The experimental approach consists in two series of measurements, the first series of measurements is performed at bulk niobium, bulk copper and thermal sprayed copper since the use of strain gage at liquid helium temperature is unknown from the manufacturer and the behaviour of the strain gage on the copper alloy coating is also unknown, the thermal compensation of strain gage from helium temperature to room temperature is imperative. Then the strain measurements are realized at inner surface (bulk niobium substrate) and outside (copper alloy VPS coating) of the cylindrical specimen. The analytical calculation takes into account non linear thermal expansivities of the materials, the calculated prediction of thermal stress is verified by measurement, a first observation on the copper alloy coating thermal expansion behaviour at low temperatures is established. Key words: thermal spray coating, thermal stress calculation and measurement, liquid helium temperature, superconducting radiofrequency cavities stiffening

Kumar, D., S. Yarmolenko, C. Waters e J. Sankar. "Synthesis and Characterization of MgB2 Bulk Superconductors With Enhanced Properties by Means of Silver Doping". In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-43375.

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Ag-doped MgB2 bulk superconductors have been prepared using a standard solid state processing. The addition of Ag to MgB2 powders during the sintering process has been found to result in an important advantage, namely, the prevention/reduction of loss of Mg, a problem most commonly observed in the sintering of MgB2 bulk samples at elevated temperature and ambient pressures. The Ag-doped MgB2 sample has a distinct superconducting transition temperature around 39 K, while the undoped MgB2 undergoes only a very feeble transition to a diamagnetic superconducting state at around 39 K. The normal conducting silver regions in the MgB2 matrix acts as pinning centers resulting in the realization of high critical currents in the presence of magnetic fields.

Zheng, Luhai, e Jianxun Jin. "Characteristics of high temprature superconducting bulk magnet". In 2009 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD). IEEE, 2009. http://dx.doi.org/10.1109/asemd.2009.5306706.

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ALFORD, MARK. "BULK VISCOSITY OF COLOR-SUPERCONDUCTING QUARK MATTER". In Proceedings of the International Symposium EXOCT07. WORLD SCIENTIFIC, 2008. http://dx.doi.org/10.1142/9789812797049_0037.

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Rapporti di organizzazioni sul tema "Superconducting bulks":

Netel, Harrie. Low temperature y-ray spectrometers based on bulk superconducting and dielectric absorber crystals. Office of Scientific and Technical Information (OSTI), novembre 1999. http://dx.doi.org/10.2172/15013114.

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