This study presents experimental measurements of the magnetization of ReBCO CORC cables in magnetic fields up to 30 T at 4.2 K. Such data are relevant for accelerator, fusion, and other potential applications. The cable was comprised of 29 ReBCO tapes, with a cable OD of 3.63 mm and cable pitch of 7.16 mm. The tapes were 2 mm wide, had a substrate thickness of 30 mu m, and a Cu plating thickness of 5 mu m. The cable had an I(c )of 1675 A at 77 K and self-field. The CORC cable was received from Lawrence Berkeley National Laboratory (LBNL) with ID 170131-Berkeley. We used a susceptibility technique, with the NHMFL's Bitter (resistive) magnet acting as the primary coil. We constructed a sample holder with a pick-up coil (secondary) as well as a compensation coil. The CORC cables were measured first as a single and then a three-stack CORC, placed with the field perpendicular to the conductor length. Magnetization (M) versus applied magnetic field (mu H-0) was measured for field sweeps with amplitudes up to +/- 30 T. Additionally, "accelerator-like" magnetic cycles were performed. Here, the field, initially at some low (1 T) "injection" field was increased to the maximum ("collision") field, ramped back to some hold field near zero (B-h), and then increased to the nominal injection field again, mimicking operational conditions relevant to particle accelerators. The magnetization at injection (taken here as 1 T) was observed to be congruent to 1100 kA/m. Furthermore, the penetration field (B-p), which defines the point at which flux reaches the center of the conductor, was found to increase from 1.2 to 2 T when we moved from a single-stack to a three-stack of cables. These measurements are important for understanding the CORC cable's implementation in high-field applications such as particle accelerators.

Compared to Nb 3 Sn- and NbTi-wound superconducting undulators (SCUs), MgB 2 -wound SCUs are of interest for future electron synchrotron beam light sources owing to their higher temperature operating margin and associated stability. In this study, a three-period undulator consisting of twelve racetrack coils wound with 2nd generation (2 G) multifilamentary advanced-internal-magnesium-infiltration MgB 2 strands were fabricated and tested in liquid and gaseous helium (He) over a temperature range of 4.2 K–20 K. The coil winding cross sections (in each coil) were 5 mm wide and 4.8 mm thick. At 4.2 K, a critical current ( I c ) of 325.7 Amps produced a maximum undulator bore field of 1.19 T. It should be noted that the short, 3-period nature of the coil led to an asymmetry in the field profile (the maximum positive field was 1.19 T, the maximum negative was −0.25 T), suggesting a peak field of 0.72 T in the absence of end effects. Finite element modeling (FEM) results of simulations for a one meter long undulator of otherwise identical design gave 0.85 T (larger because of higher currents enabled by the lower field). But in any case, the I c value coil reached is 94% of that of the short sample (dictated by the 1.19 T positive field for the coil as tested). FEM was performed to study the magnetic field profile, which was validated experimentally. The magnetic field was measured using a Hall probe which was translated along the beam axis during measurement to explore the spatial field variation along the beam travel direction. The spatially alternating field was asymmetric, and the maximum field was more prominent in the positive direction than in the negative direction, the difference being due to broken symmetry, that is, short coil end effects. In this work, we show useful fields are possible for MgB 2 undulators; the use of such conductors can allow a larger thermal margin and enable conduction-cooled operation.

It is commonly acknowledged that polymer composites in service are often subjected to not only intricate mechanical loads but also harsh environmental conditions. The mechanical and thermal properties of five particular composites are explored here. The composites are composed of laminates of glass cloth type “E” sheet infilled with a duroplastic matrix. This is a thermoset polymer—epoxy resin with different molecular weights. The composites were fabricated by IZOERG company, which is based in Poland. The final articles were 1.5 mm thick by 60 cm long and 30 cm wide, with the glass layers arranged parallel to the thickness. Young’s modulus and tensile strength were measured at room temperature. Using the thermal analysis of dynamic mechanical properties (DMTA), the values of the storage modulus and the loss modulus were determined, and the damping factor was used to determine the glass transition temperature (Tg). It was revealed that the nature of changes in the storage modulus, loss modulus, and damping factor of composite materials depends on the type of epoxy resin used. Thermal expansion is a crucial parameter when choosing a material for application in cryogenic conditions. Thanks to the TMA method, thermal expansion coefficients for composite materials were determined. The results show that the highest value of the coefficient of thermal expansion leads the laminate EP_4_2 based on brominated epoxy resin cured with novolac P. Duroplastic composites were characterized at cryogenic temperatures, and the results are interesting for developing cryogenic applications, including electric motors, generators, magnets, and other devices.

Rare earth barium copper oxide (REBCO) coated conductor tapes and cables are promising material candidates for constructing high field magnets. In both the magnet constructing stage and operation stage, transverse pressure is exerted on the tapes/cables. Therefore, understanding the mechanical behavior of tapes/cable under transverse pressure and figuring out certain properties, such as modulus and stress limits, will be helpful for magnet design and magnet simulation study. We accomplished these goals by performing compression tests on several commonly used tapes/cables in high field magnets. We found that the mechanical behavior of tape stacks can be characterized in three distinct regimes. In the first regime (<20 MPa), tape stacks underwent flattening and self-relocation. Then in the second regime (20–60 MPa), the REBCO tape stack showed a modulus of 3.1 $ \pm $ 7% GPa, and the Ni-plated REBCO tape stack showed a modulus of 1.7 $ \pm $ 6% GPa. In the third regime (>60 MPa), the REBCO tape stack and its Ni-plated derivative had a modulus of 10 $ \pm $ 11% GPa and 4.6 $ \pm $ 9% GPa respectively. Roebel cable had similar mechanical behavior to the tape stack with three regimes, and the second and third regimes showed a modulus of 3.1 $ \pm $ 5% GPa and 9.1 $ \pm $ 11% GPa respectively. The conductor on round core (CORC) cable was more vulnerable to stress, and its fracture stress was around 27 MPa.

Current sharing is an important self-protection mechanism in rare earth barium copper oxide (REBCO) coated conductor (CC) tapes and cables that are intended for the construction of high field magnets. Because of the slower quench propagation rate of such cables, we expect that cooling is also required to facilitate the current sharing. We explored this idea by constructing FEM models that include liquid helium cooling and inter-strand contact properties. The results showed that given metallic inter-strand contact, a three-layer tape stack with a defective central tape could carry at least 3.05 Ic (where Ic is defined for an individual tape). When the inter-strand electrical contact efficiency, η ( η = inter-strand contact resistance ∗ contact area), was adjusted to be 5400 µΩ*cm 2 and the inter-strand thermal insulance, ω ( ω = inter-strand thermal resistance ∗ contact area), was 5.54 K*m 2 /W, the maximum current that could flow through the defective tape was 0.6 Ic with negligible current sharing to neighboring tapes. After reducing η to 10 µΩ*cm 2 and ω to 0.01 K*m 2 /W respectively, current sharing to neighboring tapes increased by 800 times, and the hot spot temperature was reduced. However, if the inter-strand thermal contact was insulating, regardless of the value of η, the same tape stack exhibited thermal runaway. Hence, current sharing in REBCO coated conductors is determined by both the inter-strand contact resistance (ICR) and the inter-strand thermal resistance (ITR).

Gallium oxide (Ga2O3) has emerged as a fourth-generation semiconductor for futuristic device requirements. Integration of Ga2O3 with industry-viable gallium nitride (GaN) can provide a pathway to design efficient device technology. In this paper, we design Ga2O3/GaN heterointerface by using a simple thermal annealing method under an oxygen-rich environment. Thermal annealing at 850 °C for 5 h results in a good yield of Ga2O3 from surficial GaN which was grown on sapphire and Si substrates. Surface morphology revealed a nanorod structure-based Ga2O3 on the GaN surface grown on industrial compatible Si substrate. XPS measurements provide a quantitative understanding of the heterostructure, where 84.62% and 70.92% of surficial GaN is converted into Ga2O3. Besides, the valence band maximum is shifted to a higher energy side in comparison to bare GaN samples. This helps in understanding the device physics of the grown heterostructures. Current-Voltage (I–V) characteristics revealed Schottky behaviour where the Schottky barrier height is increased after thermal annealing of the GaN films. Temperature correlated I–V characteristics suggest that the thermally annealed GaN films are stable up to 300 °C. These material structures can potentially be used in the high-temperature applications for power devices, optoelectronics, and sensing applications.

In recent years, solar-induced interfacial heating of water has proven to be an efficient technique to produce steam while harnessing solar energy. Herein, we report diesel soot coated on cotton as a novel photothermal membrane for highly efficient solar steam generation. A facile fabrication procedure was successfully followed to synthesize the photothermal membrane with hazardous diesel soot particles obtained from vehicular exhaust, and cotton cloth. In this photothermal membrane, the diesel soot particles embedded in the cotton cloth substrate help in the absorption of incident solar illumination, and the excellent hydrophilicity of cotton cloth assists in the rapid supply of water at the air-water interface to produce constant steam. As a result, the evaporation rate of water using the photothermal membrane was 3 times the bare water system with an excellent photothermal efficiency of 91.75% under 1 sun illumination. The photothermal membrane was also successful in water desalination using a simple laboratory setup. The results of this work should motivate further research of diesel soot and other waste products for high efficiency water evaporation and its applications.

Gallium Nitride (GaN) and Zinc Oxide (ZnO) are well established semiconductors with their heterostructures opening avenues for the future of next generation sensing and opto-electronics technologies due to their low lattice mismatch and high exciton energy. ZnO/GaN heterostructure based ultraviolet photodetectors with complimentary material properties are expected to yield optimum efficiency, though their performance has remained low due to challenges related to interfacial properties. Inadequate analysis of ZnO/GaN interfacial properties/states viz. electronic structure, band offsets, localized charge density and defect states associated with overlayer (i.e. ZnO) thickness, and their influence on device performance has remained as an underestimated issue. Interestingly, literature reports a huge anomaly in the valence band offset (VBO) at ZnO/GaN interfaces, which being an effective measure of charge transport assist in the optimization of photodetector efficiency. Therefore, in the present report, we have fabricated ZnO/GaN heterostructure (with variable ZnO thickness) based Schottky barrier photodectors and investigated the dependence of photosensitivity & other device parameters on interfacial states/properties. We have witnessed a peak responsivity & detectivity of 225 mA/W-1 & 4.83 (x10(13)) Jones and a high speed photoswitching associated with the band offset, barrier height & defect states at the ZnO/GaN heterojunction. The underlying scientific phenomenon (e.g. interfacial dipole strength, charge accumulation etc.) leading to perturbations & discontinuities in interfacial/electronic states were also correlated and discussed in detail.