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Abstract The fabrication of a Fe-based coated conductor (CC) becomes possible when Fe(Se,Te) is grown as an epitaxial film on a metallic oriented substrate. Thanks to the material’s low structural anisotropy, less strict requirements on the template microstructure allow for the design of a simplified CC architecture with respect to the REBCO multi-layered layout. This design, though, still requires a buffer layer to promote the oriented growth of the superconducting film and avoid diffusion from the metallic template. In this work, Fe(Se,Te) films are grown on chemically-deposited, CeO2-based buffer layers via pulsed laser deposition, and excellent properties are obtained when a Fe(Se,Te) seed layer is used. Among all the employed characterization techniques, transmission electron microscopy proved essential to determine the actual effect of the seed layer on the final film properties. Also, systematic investigation of the full current transport properties J(θ, H, T) is carried out: Fe(Se,Te) samples are obtained with sharp superconducting transitions around 16 K and critical current densities exceeding 1 MA cm−2 at 4.2 K in self-field. The in-field and angular behavior of the sample are in line with data from the literature. These results are the demonstration of the feasibility of a Fe-based CC, with all the relative advantages concerning process simplification and cost reduction.

An overview is presented of the progress since 2021 in the construction and scientific programme preparation of the Divertor Tokamak Test (DTT) facility. Licensing for building construction has been granted at the end of 2021. Licensing for Cat. A radiologic source has been also granted in 2022. The construction of the toroidal field magnet system is progressing. The prototype of the 170 GHz gyrotron has been produced and it is now under test on the FALCON facility. The design of the vacuum vessel, the poloidal field coils and the civil infrastructures has been completed. The shape of the first DTT divertor has been agreed with EUROfusion to test different plasma and exhaust scenarios: single null, double null, X-divertor and negative triangularity plasmas. A detailed research plan is being elaborated with the involvement of the EUROfusion laboratories.

This work presents a comparison of different commercial tapes belonging to the second-generation High-Temperature Superconductors (2G HTS) produced by SuNAM Co., Ltd., SuperOx, and Shanghai Superconductors Technology Co., Ltd. (SST) companies. The aim is to investigate pinning mechanisms responsible for best performances, looking at the anisotropy of the irreversibility field and of the flux pinning energy. The irreversibility line states the upper limit of current-carrying capacity, whereas the flux pinning energy explores the ability of material defects to act as weak collectively or strong single vortex pinning centers. All investigated samples have artificial pinning centers (APCs) included in the superconducting matrix: BHO-doped EuBCO for SST, Y2O3 in YBCO for SuperOx, and Gd2O3 particles trapped in GdBCO for SuNAM. Resistive transition curves were measured in high magnetic fields up to 16 T for magnetic field orientations parallel and perpendicular to the tape surface. We found that the anistropy of SST tape shows an overall independence both on temperature and magnetic field, while the other two samples show a more complex behavior. This leads to the conclusion that properly engineered APC optimization in coated conductors can further reduce anisotropy of superconducting properties.

This work presents a comparison of different commercial tapes belonging to the second-generation High-Temperature Superconductors (2G HTS) produced by SuNAM Co., Ltd., SuperOx, and Shanghai Superconductors Technology Co., Ltd. (SST) companies. The aim is to investigate pinning mechanisms responsible for best performances, looking at the anisotropy of the irreversibility field and of the flux pinning energy. The irreversibility line states the upper limit of current-carrying capacity, whereas the flux pinning energy explores the ability of material defects to act as weak collectively or strong single vortex pinning centers. All investigated samples have artificial pinning centers (APCs) included in the superconducting matrix: BHO-doped EuBCO for SST, Y 2 O 3 in YBCO for SuperOx, and Gd 2 O 3 particles trapped in GdBCO for SuNAM. Resistive transition curves were measured in high magnetic fields up to 16 T for magnetic field orientations parallel and perpendicular to the tape surface. We found that the anistropy of SST tape shows an overall independence both on temperature and magnetic field, while the other two samples show a more complex behavior. This leads to the conclusion that properly engineered APC optimization in coated conductors can further reduce anisotropy of superconducting properties. [ABSTRACT FROM AUTHOR]

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The fabrication of a Fe-based coated conductor (CC) becomes possible when Fe(Se,Te) is grown as an epitaxial film on a metallic oriented substrate. Thanks to the material's low structural anisotropy, less strict requirements on the template microstructure allow for the design of a simplified CC architecture with respect to the REBCO multi-layered layout. This design, though, still requires a buffer layer to promote the oriented growth of the superconducting film and avoid diffusion from the metallic template. In this work, Fe(Se,Te) films are grown on chemically-deposited, CeO2-based buffer layers via pulsed laser deposition, and excellent properties are obtained when a Fe(Se,Te) seed layer is used. Among all the employed characterization techniques, transmission electron microscopy proved essential to determine the actual effect of the seed layer on the final film properties. Also, systematic investigation of the full current transport properties J(θ, H, T) is carried out: Fe(Se,Te) samples are obtained with sharp superconducting transitions around 16 K and critical current densities exceeding 1 MA cm−2 at 4.2 K in self-field. The in-field and angular behavior of the sample are in line with data from the literature. These results are the demonstration of the feasibility of a Fe-based CC, with all the relative advantages concerning process simplification and cost reduction. [ABSTRACT FROM AUTHOR]

The article delves into the essence of dialogue and camaraderie, tracing the author's journey through the literary landscape of the 1960s and 1970s in Puglia, Italy. It reflects on the significance of genuine interaction and communal engagement during a period marked by societal upheaval and the struggle against hierarchy. It intertwines personal reflections with broader social observations, highlighting the role of literature in navigating existential dilemmas and cultural alienation.

Among other Fe-based superconductors, Fe(Se,Te) is particularly interesting because of the low structural anisotropy, large upper critical fields, low field dependence of the critical current density and low toxicity. It can also be grown as an epitaxial film on a metallic oriented substrate, making the fabrication of a Fe-based coated conductor (CC) possible. Less strict requirements on the template microstructure allow for the design of a simplified design compared to REBCO CCs. This design requires a buffer layer to promote the oriented growth of the superconducting film and avoid diffusion from the metallic template. In this work, CeO2 based buffer layers are prepared on single crystals via two chemical deposition techniques, metal organic decomposition (MOD) and polymer assisted deposition (PAD). With the design of a suitable thermal treatment, it is possible to obtain oriented buffers with large flat grains and low values of surface roughness. Fe(Se,Te) films are deposited on these templates via laser deposition, and excellent samples are obtained when a Fe(Se,Te) seed layer is used to favour chemical matching with the buffer: sharp superconducting transitions around 16 K and critical current densities exceeding 1 MA cm−2 at 4.2 K in self-field are observed. These results are the demonstration of the feasibility of a Fe-based CC architecture, with all the relative advantages concerning process simplification and cost reduction. [ABSTRACT FROM AUTHOR]