cited:14

Onset temperature of intrinsic pinning in a REBCO coated conductor from critical current anisotropy

Article Number:Article 100025 Corresponding Author: Nicholas M. Strickland Author:Nicholas M. Strickland, Arya Ambadiyil Soman, Martin W. Rupich, Stuart C. Wimbush Article preview
Abstract
The field-angle dependence of the critical current in a REBa2Cu3O7 coated conductor has been measured over a fine range of temperatures from 15 K to 80 K. The particular sample is demonstrated to have a very low fraction of extrinsic planar defects by its near-isotropic critical current at 77 K. At a representative magnetic field of 3 T we are able to track the emergence of the ab-plane peak usually associated with intrinsic pinning and quantify its evolution with temperature by fitting to a maximum-entropy function. We are also able to observe the evolution of dip and peak features in the angle dependence of the power-law index n with decreasing temperature and show that a dip appearing at 65 K is supplanted by a sharper positive peak from 50 K. The combination of critical current and power-law index temperature dependences shows the onset of intrinsic pinning at 50 K.
Review
cited:4

Preparation of Bi-2212/YBCO heterostructure and their interfacial characters

Article Number:Article 100030 Corresponding Author: Li Lei, Gaoyang Zhao Author:Minghu Shen, Li Lei, Gaoyang Zhao, Pengrong Ren, Mengmeng Ren, Man Wu, Bo Deng Article preview
Abstract
YBa2Cu3O7-x (YBCO) thin films were prepared on LaAlO3 (LAO) substrates by a sol–gel method, and the epitaxial growth of Bi-2212 thin films on YBCO thin films was investigated. Both YBCO and Bi2Sr2Ca1Cu2O8 (Bi-2212) bilayer films exhibit good biaxial texture and superconducting properties. Afterward, a cross-shaped Bi-2212/YBCO heterostructure was fabricated, and its interfacial atomic arrangement and I-V characteristics were analyzed. Atomic-resolution STEM images obtained from a spherical-aberration-corrected transmission electron microscope show that two superconducting films exhibit a layered structure and the atoms inside the films are artfully arranged. Moreover, the order of the seven atomic layers between Bi-2212 and YBCO layers with a thickness of about 1.32 nm is misarranged. Among them, the Y-O layer of YBCO and the Sr-O layer of Bi-2212 share a CuO2 layer. The I-V curves of Bi-2212/YBCO bilayer films show that the seven misarranged atomic layers at Bi-2212/YBCO interface acts as a barrier layer, which means that a Josephson junction can be fabricated using this interface characters.
Review
cited:11

Mechanical strain triggering flux jumps of multi-filamentary Nb3Sn wires

Article Number:Article 100031 Corresponding Author: Cun Xue, You-He Zhou Author:Qing-Yu Wang, Cun Xue, You-He Zhou Article preview
Abstract
The composite multi-filamentary Nb3Sn wire with a high critical current density is a preferred option for fabricating the superconducting magnet beyond the limit of NbTi wire (9–16 T). However, one crucial issue stems from the fact that electromagnetic force in superconducting coils is very strong, and the critical physical properties of Nb3Sn, such as Jc, are more sensitive to mechanical strain than those of other possible low-temperature superconductors. We theoretically investigated the impact of mechanical strain on the thermomagnetic instabilities such as the flux jump (FJ) and quenching of Nb3Sn wire exposed to a static magnetic field and transport current. The good agreements with H formulation or H-φ formulation implemented on COMSOL software confirm the validity of our numerical simulations using home-made codes. It is discovered that mechanical strain can trigger flux jumps even in a static magnetic field. Furthermore, the threshold value of mechanical strain to trigger the first flux jump is a monotonic function of the static magnetic field in the case of high transport currents, while it is a non-monotonic function in the case of low transport currents. It is attributed to the fact that flux can be released by the mechanical strain, causing smooth flux penetration before triggering the flux jump. We also present the stable/unstable regions by applying mechanical strain by varying transport current, magnetic field, and working temperature, which helps in avoiding thermomagnetic instabilities while designing the superconducting magnet.
Review
cited:5

Characterization of a Raman-based distributed fiber optical temperature sensor in liquid nitrogen

Article Number:Article 100028 Corresponding Author: Li Ren Author:Yi Yue, Guilun Chen, Jiajie Long, Li Ren, Kao Zhou, Xianhao Li, Ying Xu, Yuejin Tang Article preview
Abstract
Distributed Temperature Sensor (DTS) based on Raman scattering have a promising application in temperature monitoring and quench detection of high-temperature superconducting (HTS) fiber optic cable. In this paper, a series of mechanical property tests were carried out on fiber optical cables with different encapsulation materials to select the best material for the engineering environment. This was followed by loss testing of fiber optic cables with different outer diameters under liquid nitrogen (LN2) and the optimal outer diameter to meet measurement accuracy and engineering practicability was determined. Finally, the temperature measurement of fiber optic cables laid on HTS fiber optic cables were calibrated using thermocouple as a reference. The results of this research results provide a suitable fiber optic cable for engineering applications. At the same time, it provides a reference for the selection of optical cable structure parameters in HTS optical cable projects.
Review
cited:10

Development of superconducting microcalorimeters for the HUBS mission

Article Number:Article 100027 Corresponding Author: Wei Cui Author:Sifan Wang, Guole Wang, Naihui Chen, Yanling Chen, Wei Cui, Jiao Ding, Fajun Li, Yajie Liang, Qian Wang, Yeru Wang Article preview
Abstract
Hot Universe Baryon Surveyor (HUBS) is a proposed space-borne observatory for X-ray astronomy. The primary scientific objectives of the mission are to fill a void in probing the ecosystem of galaxies and thus to advance our understanding of galaxy formation and evolution, which is of fundamental importance in cosmology. More specifically, HUBS aims at directly detecting soft X-ray emission from diffuse gas of temperature exceeding 106 K, which is theoretically postulated to permeate the large structures in the cosmic web and also fill the extended halo of galaxies. However, although some indirect evidence exists, the presence of such hot gas has yet to be well established observationally, due to the lack of effective tools to probe it. In this paper, we describe the design of HUBS, focusing on its scientific payload, which employs superconducting technologies in the detector system, and particularly on progress in the development of superconducting microcalorimeters.
Review
cited:6

Flux penetration of an HTS coated-conductor tape by an approaching permanent magnet

Article Number:Article 100026 Corresponding Author: R.W. Taylor Author:R.W. Taylor, T. Booth, M.D. Ainslie, H.W. Weijers, R.A. Badcock, C.W. Bumby Article preview
Abstract

Interactions between inhomogeneous magnetic fields and a superconductor lie at the heart of several high-temperature superconducting (HTS) devices. An example is the situation where the magnetic field from a small permanent magnet (PM) is applied to a coated-conductor HTS tape, such that flux penetrates the superconductor. The PM field is highly spatially inhomogeneous, such that there is significant variation in the applied field magnitude and direction across the tape. This leads to a varying local critical current density, Jc(B,θ), across the tape, and consequently different ‘shielding’ (magnetic flux penetration) behaviour than is the case for a uniform applied field. Here, we report results from measurements and numerical simulations of the penetrating magnetic field within an HTS coated-conductor tape which occur as a PM dipole approaches from a distance. Electromagnetic simulations were performed using a finite-element model based on the H-formulation, and which incorporated experimentally-measured anisotropic Jc(B,θ) properties from a coated-conductor tape. This showed good agreement with experimental measurements. The effects of varying key modelling assumptions and parameters were then studied, including changing the widths of the PM and HTS tape and the magnitude of Jc(B,θ).

The inhomogeneity of the PM field leads to a characteristic gull-wing distribution of magnetic flux across the superconductor at elevated applied fields. Close approach of the PM to the tape suppresses Jc in the centre of the tape, and this results in the observation of a characteristic maxima for the total shielding currents circulating in the tape. A figure of merit is introduced which uses this effect to provide a threshold definition for ‘full flux penetration’ of an HTS tape by an inhomogeneous dipole field.

Review
Current page1, Total Pages6, Total Record31 First Prev 12345... Next Last Goto
Superconductivity One-Stop Service Platform
TOP