Superconducting magnetic energy storage (SMES) is an attractive technology for large-scale energy storage. SMES systems are particularly suitable for applications that require high power density. Energy conversion systems are critical components of SMES systems. SMES can be an efficient energy source for pulsed power applications. For bidirectional energy transfer between SMES and the pulsed load, a Power Conversion System (PCS) is essential. Two different power electronic conversion schemes are reported: a reduced IGBT count of H-bridges and a novel bidirectional DC/DC converter without any H-bridges. The new scheme has an additional voltage source converter capacitor stage to maintain the pulse shape required by the pulsed load, which removes the requirement of the H-bridge type PCS. Details of the two topologies and a comparison of the operation and converter loss studies using simulations of the new control scheme are discussed. © 2024 IEEE.

Continuous carbon nanotube (CNT) yarns are used to fabricate scalable composite laminates with high strength and stiffness for scaled-up manufacturing and potential engineering applications. CNT yarns are shown with specific tensile strengths of 1.77 N/tex due to a high degree of nanotube alignment. These properties are transferred to scalable unidirectional CNT yarn reinforced composite laminates fabricated using filament winding and aerospace resin matrices. Gamma ray treatments of 200 kGy, 700 kGy, and 1200 kGy are used to further improve the mechanical and interface properties of the constituent CNT yarns. The optimal dose is 700 kGy, yielding a specific tensile strength of 1.89 GPa/(g cm-3) and specific modulus of 258 GPa/(g cm-3), which represents a 37% and 44% improvement over the properties of the control laminate. The specific modulus exceeds current state-of-the-art unidirectional carbon fiber composite laminates. The results demonstrate an effective approach transferring high-strength CNT yarns into composites that retain the tensile performance of CNT materials at the flight article scale. © 2023 by DEStech Publications, Inc. and American Society for Composites. All rights reserved.

We report the superconductivity of the topological nodal-line semimetal candidate Sn x NbSe2-δ with a noncentrosymmetric crystal structure. The superconducting transition temperature T c of Sn x NbSe2-δ drastically varies with the Sn concentration x and the Se deficiency δ, and reaches 12 K, relatively higher than those of known topological superconductors. The upper critical field of this compound shows unusual temperature dependence, inconsistent with the WHH theory for conventional type-II superconductors. In a low-Tc sample, the zero-temperature limit of the upper critical field parallel to the ab plane exceeds the Pauli paramagnetic limit estimated from the simple BCS weak coupling model by a factor of ∼2, suggestive of unusual superconductivity stabilized in Sn x NbSe2-δ . Together with the robust superconductivity against disorder, these observations indicate that Sn x NbSe2-δ is a promising candidate to explore topological superconductivity. © Published under licence by IOP Publishing Ltd.

Nuclear magnetic resonance spectroscopy (NMR) probes using thin-film high temperature superconducting (HTS) resonators provide exceptional mass sensitivity in small-sample NMR experiments for natural products chemistry and metabolomics. We report improvements in sensitivity to our 1.5 mm 13C-optimized NMR probe based on HTS resonators. The probe has a sample volume of 35 microliters and operates in a 14.1 T magnet. The probe also features HTS resonators for 1H transmission and detection and the 2H lock. The probe utilizes a 13C resonator design that provides greater efficiency than our previous design. The quality factor of the new resonator in the 14.1 T background field was measured to be 4,300, which is over 3x the value of the previous design. To effectively implement the improved quality factor, we demonstrate the effect of adding a shorted transmission line stub to increase the bandwidth and reduce the rise/fall time of 13C irradiation pulses. Initial NMR measurements verify 13C NMR sensitivity is significantly improved while preserving detection bandwidth. The probe will be used for applications in metabolomics. © Published under licence by IOP Publishing Ltd.

Facing rapidly growing volumes of research datasets, scientists and research funding agencies are putting forward new principles of data management, such as data Findability, Accessibility, Interoperability, and Reusability (FAIR). To this end, data science experts are developing FAIR data policies, methods, protocols, and repositories, while actual research practices are lagging behind because FAIR compliance remains a burden for many researchers. Here we present a prototype data management infrastructure deployed at the National High Magnetic Field Laboratory (NHMFL/MagLab) aimed at helping scientists efficiently annotate and manage experimental data produced by their MagLab projects and making FAIR practices accessible and attractive. The infrastructure incorporates the Open Science Framework (OSF) data repository platform. We will describe infrastructure elements such as the data formats, the metadata schema, the repository integration, the naming conventions, the templates to organize the data, and the automated data pipeline from measurement stations to the FAIR repository objects.

Band structure, strain, and polarization engineering of nitride heterostructures open unparalleled opportunities for quantum sensing in the infrared. Intersubband absorption and photoluminescence are employed to correlate structure with optical properties of nonpolar strain-balanced InGaN/AlGaN nanostructures grown by molecular-beam epitaxy. Mid-infrared intersubband transitions in m-plane (In)AlxGa1-xN/In0.16Ga0.84N (0.19 <= x <= 0.3) multi-quantum wells were observed for the first time in the range of 3.4-5.1 mu m (244-360 meV). Direct and attenuated total-reflection infrared absorption measurements are interpreted using structural information revealed by high-resolution x-ray diffraction and transmission electron microanalysis. The experimental intersubband energies are better reproduced by calculations using the local-density approximation than the Hartree-Fock approximation for the exchange-correlation correction. The effect of charge density, quantum well width, and barrier alloy composition on the intersubband transition energy was examined to evaluate the potential of this material for practical infrared applications.Temperature-dependent continuous-wave and time-resolved photoluminescence (TRPL) measurements are also investigated to probe carrier localization and recombination in m-plane InGaN/AlGaN quantum wells. Average localization depths of 21 meV and 40 meV were estimated for the undoped and doped structures, respectively. Using TRPL, dual localization centers were identified in undoped structures, while a single type of localization centers was found in doped structures. At 2 K, a fast decay time of approximately 0.3ns was measured for both undoped and doped structures, while a longer decay time of 2.2 ns was found only for the undoped sample. TRPL in magnetic field was explored to examine the effect of doping sheets on carrier dynamics.