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At least 433 records · Page 24

Round superconductor wires

A round superconductor wire and method for fabricating same are disclosed. Embodiments are directed to a round superconductor wire including at least two superconductor tapes wound on a wire former. Each superconductor tape includes: bottom stabilizer and silver layers; substrate disposed above the bottom silver layer; buffer film stack disposed above the substrate; superconductor film disposed above the buffer film stack; top silver layer disposed above the superconductor film; and top stabilizer layer disposed above the top silver layer. At least one of the bottom stabilizer layer, bottom silver layer, substrate, buffer film stack, superconductor film, top silver layer, or top stabilizer layer is of a different width, thickness, or material composition in one of the superconductor tapes than in another of the superconductor tapes. These and other embodiments achieve a round superconductor wire having improved current density in high magnetic field applications when made in small diameters.

Majkic, Goran↗

Wire-based metallization and stringing for solar cells

Wire-based metallization and stringing techniques for solar cells, and the resulting solar cells, modules, and equipment, are described. In an example, a string of solar cells includes a plurality of back-contact solar cells, wherein each of the plurality of back-contact solar cells includes P-type and N-type doped diffusion regions. A plurality of conductive wires is disposed over a back surface of each of the plurality of solar cells, wherein each of the plurality of conductive wires is substantially parallel to the P-type and N-type doped diffusion regions of each of the plurality of solar cells. One or more of the plurality of conductive wires adjoins a pair of adjacent solar cells of the plurality of solar cells and has a relief feature between the pair of adjacent solar cells.

Sewell, Richard Hamilton↗

Wire-based metallization for solar cells

Approaches for fabricating wire-based metallization for solar cells, and the resulting solar cells, are described. In an example, a solar cell includes a substrate having a back surface and an opposing light-receiving surface. A plurality of alternating N-type and P-type semiconductor regions is disposed in or above the back surface of the substrate. A conductive contact structure is disposed on the plurality of alternating N-type and P-type semiconductor regions. The conductive contact structure includes a plurality of metal wires. Each metal wire of the plurality of metal wires is parallel along a first direction to form a one-dimensional layout of a metallization layer for the solar cell.

Sewell, Richard Hamilton↗

Controlling Cu–Sn mixing so as to enable higher critical current densities in RRP ® Nb 3 Sn wires

Dipole magnets for the proposed Future Circular Collider (FCC) demand specifications significantly beyond the limits of all existing Nb 3 Sn wires, in particular a critical current density (J c ) of more than 1500 A mm -2 at 16 T and 4.2 K with an effective filament diameter (D eff ) of less than 20 μm. The restacked-rod-process (RRP ® ) is the technology closest to meeting these demands, with a J c (16 T) of up to 1400 A mm -2 , residual resistivity ratio > 100, for a sub-element size D s of 58 μm (which in RRP ® wires is essentially the same as D eff ). An important present limitation of RRP ® is that reducing the sub-element size degrades J c to as low as 900 A mm -2 at 16 T for D s = 35 μm. To gain an understanding of the sources of this J c degradation, we have made a detailed study of the phase evolution during the Cu–Sn 'mixing' stages of the wire heat treatment that occur prior to Nb 3 Sn formation. Using extensive microstructural quantification, we have identified in this paper the critical role that the Sn–Nb–Cu ternary phase (Nausite) can play. The Nausite forms as a well-defined ring between the Sn source and the Cu/Nb filament pack, and acts as an osmotic membrane in the 300 °C–400 °C range—greatly inhibiting Sn diffusion into the Cu/Nb filament pack while supporting a strong Cu counter-diffusion from the filament pack into the Sn core. This converts the Sn core into a mixture of the low melting point (408 °C) η phase (Cu 6 Sn 5 ) and the more desirable ε phase (Cu 3 Sn), which decomposes at 676 °C. After the mixing stages, when heated above 408 °C towards the Nb 3 Sn reaction, any residual η liquefies to form additional irregular Nausite on the inside of the membrane. All Nausite decomposes into NbSn 2 on further heating, and ultimately transforms into coarse-grain (and often disconnected) Nb 3 Sn which has little contribution to current transport. Understanding this critical Nausite reaction pathway has allowed us to simplify the mixing heat treatment to only one stage at 350 °C for 400 h which minimizes Nausite formation while encouraging the formation of the higher melting point ε phase through better Cu–Sn mixing. Finally, at a D s of 41 μm, the Nausite control heat treatment increases the J c at 16 T by 36%, reaching 1300 A mm -2 (i.e. 2980 A mm -2 at 12 T), and moving RRP ® closer to the FCC targets.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Enhanced Second Generation (2G) High Temperature Superconducting (HTS) wire for Electric Motor Applications

This project focused on the development of a revolutionary Second Generation (2G) high temperature superconducting (HTS) wire engineered specifically to meet the requirements for a new generation of high temperature superconducting electric machines. This novel design combined a roll-to-roll irradiation process to enhance the performance of the HTS wire in the presence of strong magnetic fields (improved flux pinning) with an innovative process to incorporate multiple HTS layers within a single 2G wire.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Radiofrequency Wire Recanalization of Chronically Thrombosed TIPS

Radiofrequency (RF) guide wires have been applied to cardiac interventions, recanalization of central venous thromboses, and to cross biliary occlusions. Herein, the use of a RF wire technique to revise chronically occluded transjugular intrahepatic portosystemic shunts (TIPS) is described. In both cases, conventional TIPS revision techniques failed to revise the chronically thrombosed TIPS. RF wire recanalization was successfully performed through each of the chronically thrombosed TIPS, demonstrating initial safety and feasibility in this application.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

MRI-guided Wire Localization Surgical Biopsy in an Adolescent Patient with a Difficult to Diagnose Case of Lymphoma

A 17-year-old previously healthy female presented with a progressive soft tissue infiltrative process involving the neck and thorax. Extensive diagnostic evaluation including multiple imaging, laboratory, and biopsy studies was nondiagnostic. Due to an urgent need to establish a diagnosis and several previous nondiagnostic biopsies, she was referred to interventional radiology for MRI-guided wire localization immediately prior to open surgical biopsy. Under general anesthesia, wires were placed in the areas of increased T2 signal within the bilateral splenius capitis muscles using intermittent MRI-guidance followed by immediate surgical biopsy down to the wires. Pathology confirmed the diagnosis of diffuse large B-cell lymphoma.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Radiofrequency Wire Recanalization of Chronically Occluded Venous Stents: A Retrospective, Single-Center Experience in 15 Patients

Introduction: Chronically occluded venous stents may be difficult to salvage, necessitating multiple approaches and adjunctive techniques. Radiofrequency wires have been used to cross chronic obstructions in a variety of settings. Herein, radiofrequency wire recanalization (RFWR) of chronically occluded venous stents is presented. Materials and Methods: Fifteen patients (8 males; 7 females) aged 23–74 years (median 42 years) underwent prior venous stenting in the setting of venous occlusions. Seven had an underlying coagulopathy, three had May–Thurner syndrome, three had provoked deep venous thrombosis, one had a dialysis fistula, and one had pacer leads in situ. All indwelling venous stents were chronically occluded and symptomatic. Out of 15 patients, 13 (87%) had iliocaval venous stents, while two (13%) had superior vena cava and/or upper extremity venous stents. After failing conventional and blunt recanalization techniques, RFWR was performed to traverse the chronic occlusions. Technical success and complications were recorded. Results: Fifteen patients underwent 19 procedures. Twelve patients underwent one procedure, two patients had two procedures, and one patient had three procedures. RFWR alone was used in 12/19 (63%) procedures, while 7/19 (37%) required adjunctive sharp recanalization techniques. Technical success or crossing of the occlusion with flow restoration through the occluded segments was achieved in 17/19 (89%). One major and one minor complication occurred. Conclusion: Radiofrequency wire recanalization is an effective adjunct to revise chronically occluded venous stents, potentially increasing procedural success in challenging cases.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Structural-Phase States of Fe–Cu and Fe–Ag Bimetallic Particles Produced by Electric Explosion of Two Wires

X-ray phase analysis, transmission electron microscopy, and X-ray microanalysis were used to examine the structural-phase states of Fe–Cu and Fe–Ag bimetallic nanoparticles. The nanoparticles were obtained by the electric explosion of two twisted metal wires in argon atmosphere. It was demonstrated that the nanoparticles have the structure of Janus particles. Presence of the Janus particle structure in the samples indicates formation of binary melt under conditions of combined electric explosion of two wires. Phases based on supersaturated solid solutions were not found in the examined samples. The data obtained allow arguing that it is possible to achieve uniform mixing of the two-wire explosion products under the described experiment conditions.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

Fabrication of Copper-Rich Cu-Al Alloy Using the Wire-Arc Additive Manufacturing Process

An innovative wire-arc additive manufacturing (WAAM) process is used to fabricate Cu-9 at. pct Al on pure copper plates in situ, through separate feeding of pure Cu and Al wires into a molten pool, which is generated by the gas tungsten arc welding (GTAW) process. After overcoming several processing problems, such as opening the deposition molten pool on the extremely high-thermal conductive copper plate and conducting the Al wire into the molten pool with low feed speed, the copper-rich Cu-Al alloy was successfully produced with constant predesigned Al content above the dilution-affected area. Also, in order to homogenize the as-fabricated material and improve the mechanical properties, two further homogenization heat treatments at 1073 K (800 °C) and 1173 K (900 °C) were applied. The material and mechanical properties of as-fabricated and heat-treated samples were compared and analyzed in detail. With increased annealing temperatures, the content of precipitate phases decreased and the samples showed gradual improvements in both strength and ductility with little variation in microstructures. The present research opened a gate for in-situ fabrication of Cu-Al alloy with target chemical composition and full density using the additive manufacturing process.

36 MATERIALS SCIENCE↗

Advanced Process Possibilities in Friction Crush Welding of Aluminum, Steel, and Copper by Using an Additional Wire

Joining sheet metal can be problematic using traditional friction welding techniques. Friction crush welding (FCW) offers a high speed process which requires a simple edge preparation and can be applied to out-of-plane geometries. In this work, an implementation of FCW was employed using an additional wire to weld sheets of EN AW5754 H22, DC01, and Cu-DHP. The joint is formed by bringing together two sheet metal parts, introducing a wire into the weld zone and employing a rotating disk which is subject to an external force. The requirements of the welding preparation and the fundamental process variables are shown. Thermal measurements were taken which give evidence about the maximum temperature in the welding center and the temperature in the periphery of the sheet metals being joined. The high welding speed along with a relatively low heat input results in a minimal distortion of the sheet metal and marginal metallurgical changes in the parent material. In the steel specimens, this FCW implementation produces a fine grain microstructure, enhancing mechanical properties in the region of the weld. Aluminum and copper produced mean bond strengths of 77 and 69 pct to that of the parent material, respectively, whilst the steel demonstrated a strength of 98 pct. Using a wire offers the opportunity to use a higher-alloyed additional material and to precisely adjust the additional material volume appropriate for a given material alignment and thickness.

36 MATERIALS SCIENCE↗

Use of wire grid polarizers with liquid crystal display for large-volume stereolithography

Spatial light modulators that use liquid crystal devices (LCDs) to pattern ultraviolet light for vat polymerization suffer from a few limitations: limited range of wavelengths that can be patterned, low damage threshold for incoming light, and low efficiency of light transmission. A monochrome LCD can more efficiently transmit useful wavelengths of light for stereolithography (365–405 nm) than a color LCD, but it still contains two absorptive film polarizers that suffer from the aforementioned limitations. Wire grid polarizers reflect rather than absorb the blocked polarizations of light, resulting in a higher intensity damage threshold. They can also polarize lower wavelength light that is limited only by the wire pitch. In this work, this research investigates the effects of replacing an LCD’s film polarizers with wire grid polarizers to enable polarization and patterning of high intensity UV light, resulting in shorter curing times and the ability to print a wider range of stereolithography feedstocks.

42 ENGINEERING↗

DSP methods for correcting dispersion and pulse width effects during pulsed wire measurements

Measuring a magnetic field by applying electric current to a wire in a magnetic field for a short duration and recording the resulting travelling wave is referred to as the pulsed wire method. This technique is beneficial when other methods for acquiring magnetic field data are not feasible, e.g. small aperture limit of a Hall probe to measure an insertion device, or it can be used as a complement to other techniques. Data collected during pulsed wire measurements require corrections due to dispersion of the travelling wave and averaging effects of the current pulse duration. As a result, a flexible method for correcting dispersion has been developed using all pass digital filtering techniques and deconvolution is used to correct for pulse width averaging. Implementing the correction method is described along with the results of measuring a reference magnet and a 2.4-meter long undulator.

47 OTHER INSTRUMENTATION↗

Size effect in stainless steel thin wires under tension

Miniaturization of modern devices drives the exploration into how materials behave in small dimensions. However, the mechanical behaviors of micro-scale specimens under varied loading conditions are still challenging to characterize and predict. In this work, specimen size-dependent weakening effect was experimentally revealed in 316L stainless steel thin wires under tension with wire diameter decreasing from 200 μm down to 61 μm. The underlying mechanisms were primarily associated with surface grain softening and strain localization, which were largely dependent on the number of grains across wire diameter. Through an analog composite model with surface and interior grains that follows the Hall-Petch relation, the extent of surface grain softening was found to coincide with the flow stress reduction due to lack of boundary strengthening. Further using elasto-plastic self-consistent polycrystal modeling, the stress-strain behaviors of interior and surface grains were well described in analogy to those of bulk materials with similar-size grains and extremely large grains, respectively. Subsequently, the analog composite model well simulated the specimen size-dependent weakening effect under tension. This article provided more insights into the size effect exploration and proposed a practical model for describing size-dependent mechanical behaviors of small-scale materials to be applied to miniaturized devices.

316L stainless steel↗

Mechanical characterization of Cu-Zn wire electrode base used in EDM and study of influence of the process of machining on its properties

This work is part of a Research National project (PNR) carried out by the group of research of the engineering and material sciences laboratory of the polytechnic national school at Algiers in collaboration with company BCR, which relates to “the characterization of the wire intended for the EDM of matrices metal. The goal of this work is to bring metallographic explanations on the wire electrode used by the machine ROBOFIL 290P, mechanically characterized this wire as of knowing of advantage about the process of its manufacturing (wiredrawing, .) The methods of studies used are it micro Vickers pyramid hardness, the tensile test, optical microscopy and scan electronic microscopy SEM.

36 MATERIALS SCIENCE↗

Control of wire heating with resistively guided fast electrons through an inverse conical taper

The heating of a solid wire embedded in a solid substrate (of lower Z material) with relativistic electrons generated by ultra-intense laser irradiation is considered. Previously, it has been noted that the initial angular distribution of the fast electrons is a highly important factor in the efficacy of the heating [Robinson et al., Phys. Plasmas 20, 122701 (2013)]. We show that, using 3D numerical simulations, the addition of an inverse conical taper at the front of wire can considerably improve the heating of the wire due to the reduction of angular spread of the fast electrons which is caused by transport through the inverse conical taper [Robinson et al., “Guiding of laser-generated fast electrons by exploiting the resistivity-gradients around a conical guide element,” Plasma Phys. Controlled Fusion (to be published)].

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Ab-initio study of encapsulated and functionalized silicon nanotube with a monoatomically thin Cu wire

First principle calculations based on DFT have been performed to study the interaction of monoatomically thin Cu wire with silicon nanotube in armchair configuration having chirality (6, 6) both by placing it inside (encapsulation) and outside (functionalisation) the tube. The lowest energy for positioning monoatomically thin Cu wire inside and outside surfaces of SiNT were found to possess cohesive energies of 4.03 eV and 4.02 eV respectively and hence the stability of both SiNTs is found to be almost same. However, From the electronic band structures study, the conductance in case of SiNT for the encapsulated and functionalized positioning of the Cu wire have been found to be 2G{sub 0} and 4G{sub 0} respectively showing enhanced conductance for the functionalized SiNT.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Spectroscopy of a plasma formed in the vicinity of implosion of the shock wave generated by underwater electrical explosion of spherical wire array

The results of visible spectroscopy of the plasma formed inside a copper capillary placed at the equatorial plane of an underwater electrically exploded spherical wire array (30 mm in diameter; 40 wires, each of 100 μm in diameter) are reported. In the experiments, a pulsed power generator with current amplitude of ∼300 kA and rise time of ∼1.1 μs was used to produce wire array explosion accompanied by the formation of a converging strong shock wave. The data obtained support the assumption of uniformity of the shock wave along the main path of its convergence. The spectroscopic measurements show that this rather simple method of formation of a converging strong shock wave can be used successfully for studying the shock wave's interaction with matter and the evaporation processes of atoms from a target.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗