Suchergebnisse

This manuscript presents a new design for superconducting linear motor (SLM). This SLM uses stacks of second generation (2G) superconducting tapes, which are responsible for replacing YBCO bulks. The proposed SLM may operate as a synchronous motor or as a hysteresis motor, depending on the load force magnitude. A small scale linear machine prototype with 2G stacks was constructed and tested to investigate the proposed SLM topology. The stator traveling magnetic field wave was represented by several Nd-Fe-B permanent magnets. A relative movement was produced between the stator and the stack, and the force was measured along the displacement. This system was also simulated by finite element method, in order to calculate the induced currents in the stack and determine the electromagnetic force. The H-formulation was used to solve the problem and a power law relation was applied to take into account the intrinsically nonlinearity of the superconductor. The simulated and measured results were in accordance. Simulated results were extrapolated, proving to be an interesting tool to scale up the motor in future projects. The proposed motor presented an estimated force density of almost 500 N/kg, which is much higher than any linear motor. ; The authors would like to thank the Brazilian Agency CNPq for the grant "Science without Borders" and the financial supported given by the: European Union agencies for the FORTISSIMO project FP7-2013-ICT-609029, EUROTAPES project FP7-NMP-Large-2011-280432, Eurofusion project PPPT-WPMAG 2014, and EU COST ACTIONS MP1201 and MP1014; Spanish Government agencies for Severo Ochoa Programme Centres of Excellence in R&D (SEV-2015-0496), CONSOLIDER Excellence Network (MAT2015-68994-REDC) and project MAT2014-56063-C2-1-R; Catalan Government for 2014-SGR-753. ; Peer reviewed

Modulation of carrier concentration in strongly correlated oxides offers the unique opportunity to induce different phases in the same material, which dramatically change their physical properties, providing novel concepts in oxide electronic devices with engineered functionalities. This work reports on the electric manipulation of the superconducting to insulator phase transition in YBa2Cu3O7−δ thin films by electrochemical oxygen doping. Both normal state resistance and the superconducting critical temperature can be reversibly manipulated in confined active volumes of the film by gate-tunable oxygen diffusion. Vertical and lateral oxygen mobility may be finely modulated, at the micro- and nano-scale, by tuning the applied bias voltage and operating temperature thus providing the basis for the design of homogeneous and flexible transistor-like devices with loss-less superconducting drain–source channels. We analyze the experimental results in light of a theoretical model, which incorporates thermally activated and electrically driven volume oxygen diffusion. ; We acknowledge the financial support from Spanish Ministry of Economy and Competitiveness through the Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0496), CONSOLIDER Excellence Network (MAT2015-68994-REDC), COACHSUPENERGY project (MAT2014-51778-C2-1-R), co-financed by the European Regional Development Fund. We also thank the support from the European Union for NanoSC Cost Action (MP1201), NANOCOHYBRI (CA 16218) and ERC-2014-ADG-669504, and from the Catalan Government with 2014-SGR-753 and Xarmae. A.F.-R. and J.C.G.-R. thank Spanish Ministry of Economy for his FPI Spanish grants (BES-2016-077310, BES-2012-053814). ; Peer reviewed

5 pages, 6 figures. v2: minor updates after referee comments, matches published version in IEEE ; The axion is a hypothetical particle which is a candidate for cold dark matter. Haloscope experiments directly search for these particles in strong magnetic fields with RF cavities as detectors. The Relic Axion Detector Exploratory Setup (RADES) at CERN in particular is searching for axion dark matter in a mass range above 30 $\mu$eV. The figure of merit of our detector depends linearly on the quality factor of the cavity and therefore we are researching the possibility of coating our cavities with different superconducting materials to increase the quality factor. Since the experiment operates in strong magnetic fields of 11 T and more, superconductors with high critical magnetic fields are necessary. Suitable materials for this application are for example REBa$_2$Cu$_3$O$_{7-x}$, Nb$_3$Sn or NbN. We designed a microwave cavity which resonates at around 9~GHz, with a geometry optimized to facilitate superconducting coating and designed to fit in the bore of available high-field accelerator magnets at CERN. Several prototypes of this cavity were coated with different superconducting materials, employing different coating techniques. These prototypes were characterized in strong magnetic fields at 4.2 K. ; This project has received funding from the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871 (ARIES-TNA). BD and JG acknowledge funding through the European Research Council under grant ERC-2018-StG-802836 (AxScale). We also acknowledge funding via the Spanish Agencia Estatal de Investigacion (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) under project PID2019- 108122GB-C33, and the grant FPI BES-2017-079787 (under project FPA2016-76978-C3-2-P). Furthermore we acknowledge support from SuMaTe RTI2018-095853-B-C21 from MICINN co-financed by the European Regional Development Fund, Center of Excellence award Severo Ochoa CEX2019- 000917-S and CERN under Grant ...