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
cited:11

Design aspects of transmission voltage superconducting fault current limiters with YBCO tapes in China

Article Number:Article 100029 Corresponding Author: Tao Ma Author:Tao Ma, Shaotao Dai, Meng Song, Jiamin Zhu, Jing Zhang Article preview
Abstract
The design progress of superconducting fault current limiter (SFCL) for transmission voltage is presented, with a focus on the results of recent key experiments that have led to a state-of-the-art high-voltage high-capacity super-conducting current limiting techniques: the resistive alternating current (AC) SFCL, saturated iron cores AC SFCL, and resistive direct current (DC) SFCL. The main driving factors for designing SFCL in these projects are the preparation of high-performance superconducting materials, the development of large-scale superconducting current limiting winding, system testing, and operation technology. Based on the authors’ experience with both AC and DC SFCLs, this paper focuses on the main design aspects of resistive SFCL at transmission voltage. The relationship between the hot spot caused by the inhomogeneity of long superconducting tape and the overall parameter selection is presented. In addition, the thermal calculation based on the current limiting resistance and a real-time current curve is also proposed for the parameter design of the current limiting winding.
Review
cited:34

Review of synthesis of high volumetric density, low gravimetric density MgB2 bulk for potential magnetic field applications

Article Number:Article 100015 Corresponding Author: Qiuliang Wang, Judith Louise MacManus-Driscoll Author:Zili Zhang, Judith MacManus-Driscoll, Hongli Suo, Qiuliang Wang Article preview
Abstract
This review paper summarizes and analyses the current literature on the synthesis of dense MgB2 bulk with high density and by both the modified solid reaction method and the Mg infiltration method. MgB2 bulk shows Telsa-level magnetic field-trapping ability in small volumes (1–5 cm3) at 15–20 K, which is beneficial for multiple applications, particularly where light weighting is beneficial. The review also compares the properties of MgB2 to rare earth barium cuprate bulk magnets and NbTi solenoid magnets and discuess potential applications such as magnetic lenses, compact NMR, and magnetic shielding.
Review
cited:3

High-temperature solution growth of large size chalcogenide FeTxSe (T: Fe, Co) superconducting single crystals

Article Number:Article 100016 Corresponding Author: Anil K. Yadav Author:Veg Singh Bhatt, Anil K. Yadav, Dinesh Dixit, C.V. Tomy Article preview
Abstract
We report the growth of high quality Fe excess and Co doped, FeTxSe single crystals in nominal ratio via slow cooling method of high temperature solution growth technique and, their structural and physical properties through the X-ray diffraction, Raman spectroscopy, magnetic and transports measurements. Selective area electron diffraction (SAED) patterns and X-ray diffraction of cleavage piece confirm the growth of single crystals in (h0l) orientations. Observations of phonon vibration modes (A1g and B1g) in Raman spectroscopy measurements mark the qualitative analysis of these single crystals. Low temperature magnetic and electrical transport studies manifest the superconducting nature of both single crystals.
Review
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