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
cited:15

A statistical model for the design of rotary HTS flux pumps based on deep-learning neuron network

Article Number:Article 100017 Corresponding Author: Hongye Zhang, Markus Mueller Author:Zezhao Wen, Hongye Zhang, Mengyuan Tian, Francesco Grilli, Markus Mueller Article preview
Abstract
Rotory high temperature superconducting (HTS) flux pumps can consistently generate a DC voltage by rotating magnets over superconducting tapes, and thus energize the circuit if a closed loop is formed. The voltage output is a crucial factor to reflect the performance of such an HTS flux pump, which is determined by a set of design specifications, and some of them have been investigated extensively in the current literature. However, no work has been done yet to study the HTS dynamo output voltage by efficiently integrating all the design parameters together. In this paper, a well-trained deep-learning neuron network (DNN) with back-propagation algorithms has been put forward and validated. The proposed DNN is capable of quantifying the output voltage of an HTS dynamo instantly with an overall accuracy of approximately 98% with respect to the simulated values with all design parameters explicitly specified. The model possesses a powerful ability to characterize the output behavior of HTS dynamos by considering multiple design parameters, e.g., airgap, superconductor tape width, operating frequency, remanent flux density, rotor radius, and permanent magnet width, which have covered all the typical design considerations. The output characteristics of an HTS dynamo against each of the design parameters have been successfully demonstrated using this model. Compared to conventional time-consuming finite element method (FEM) based numerical models, the proposed DNN model has the advantages of automatic learning, fast computation, as well as strong programmability. Therefore the DNN model can greatly facilitate the design and optimization process for HTS dynamos. An executable application has been developed accordingly based on the DNN model, which is believed to provide a useful tool for learners and designers of HTS dynamos.
Review
cited:64

A review of superconducting fault current limiters compared with other proven technologies

Article Number:Article 100018 Corresponding Author: Marcio Zamboti Fortes Author:Guilherme Gonçalves Sotelo, Gabriel dos Santos, Felipe Sass, Bruno Wanderley França, Daniel Henrique Nogueira Dias, Marcio Zamboti Fortes, Alexander Polasek, Rubens de Andrade Jr. Article preview
Abstract
Several substations in operation were commissioned decades ago. These substations are overstressed, then their protection equipment cannot provide an effective safety condition to the system. In the worst cases, short-circuits can cause permanent damage to the system if the overcurrent is higher than the capacity of the installed equipment. There are some possible solutions for those cases: replace all the equipment in the overstressed substation, build a new one in parallel or install a fault current limiter (FCL) device. From an economic point of view, introducing FCLs in the power system is the best way to solve the described problem. The commercial solutions available are the pyrotechnic FCL, air coil reactor, neutral earthing resistor, and high impedance transformer. However, these devices are limited and present several drawbacks. Since the ’70s, there has been a search for reliable FCL devices that do not interfere in the regular operation of substations and could limit the fault currents to the protection system rated level. There were so many FCL technologies proposed in the last decades. These proposed new devices may use superconducting technologies, power electronics, or both. This paper reviews proven FCL technologies, focusing on full-scale devices demonstrated in field and lab tests. The goal is to introduce the main FCL technologies in development and discuss didactically their operation principle, the built prototypes, the commercial units, whether they exist, and the main drawbacks for each technology presented. A final analysis of the level of maturity for each FCL technology is discussed using the TRL (Technology readiness level) scale in order to find technologies with more potential for mass production. The three technologies closer to the full commercial application are: the Resistive Superconducting FCL, the Saturated Iron Core FCL, and the Series Reactor FCL.
Review
cited:28

Development of a Roebel structure transposed cable with in-plane bending of REBCO tapes

Article Number:Article 100019 Corresponding Author: Qingjin Xu Author:Juan Wang, Rui Kang, Xin Chen, Chao Yang, Yingzhe Wang, Chengtao Wang, Qingjin Xu Article preview
Abstract
A compact High Temperature Superconductor (HTS) cable that can carry large current is crucial for developing high field superconducting accelerator magnets. Herein, we are reporting a high current and low AC loss REBCO cable that adopts the Roebel structure, but it is implemented by in-plane bending stacked REBCO tapes directly to realize the transposition, instead of by punching REBCO tapes to the desired shape. The cable maximizes the utilization of the original REBCO tapes, so that the material cost is significantly reduced comparing with the present “Roebel” REBCO cable. Recently, a prototype cable has been successfully fabricated. The critical current of each REBCO tape after cabling shows no degradation, and the cable’s measured critical current is 1939.8 A at 77 K and self-field, which is very close to the predicted critical current by simulation. Calculations also show that the AC loss of the cable is lower compared with that of a simple REBCO stack with the same cross-section and current-carrying capacity. In this paper, we first introduce the fabrication process of the cable. What follows is the measurement of the in-plane bending performance of REBCO tapes. Then, we present the design and fabrication of the prototype cable together with current-carrying performance tests. Finally, the AC loss calculation and analysis of the cable are reported.
Review
cited:10

Impact of Perlator on the cooling liquid flow and hottest point temperature of superconducting windings in HTS transformer

Article Number:Article 100021 Corresponding Author: Mohammad Yazdani-Asrami Author:Mahdi Mahamed, Mohammad Yazdani-Asrami, Vahid Behjat, Akbar Yazdani, Mojtaba Sharifzadeh Article preview
Abstract
The generated heat by the superconducting windings and the other parts such as current leads in transformer increases the hottest point temperature (HPT) and causes the high temperature superconducting (HTS) windings to quench. Due to the properties of superconducting windings, reducing the HPT is of critical importance for the stable operation of the HTS transformer. The cooling system of HTS transformers, not only provides the cryogenic temperature for the proper operation of the superconductors but also is responsible for dissipating the generated heat by the windings. In this paper, the effect of the angle of inlet pipes in cooling system was investigated. This was a simple and effective solution which increases the heat transfer in liquid nitrogen. It was shown that inlet angle has a significant effect on the flow turbulence and the windings temperature. The Perlator is used as a lattice sheet which is installed inside the inlet valve and increases the turbulence of inlet flow of liquid nitrogen to increase heat transfer and reduce HPT. The thermal analysis is obtained by finite element method using ANSYS Fluent software. The influence of changing the inlet pipe angle and different structure of Perlator on heat transfer was investigated.
Review
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