The fabrication and characterisation of high temperature superconducting tapes and coils
The fabrication and characterisation of high temperature superconducting tapes and coils
The design and construction of High Temperature Superconducting (HTSC) devices requires long lengths of tape, high critical current densities (Jc) and good mechanical characteristics. This work focuses on two areas; firstly the influence of the processing parameters on Jc, and secondly the mechanical characteristics of HTSC tapes.
The addition of large (�80μm) silver particles into the precursor powders of the Ag alloy-sheathed (BiPb)2223 tapes resulted in a novel core configuration. These silver particles flattened upon rolling, produced multi-connected core filaments, yielding a high Jc (�20kA/cm2) for short sintering times. The silver particles accelerate the rate of the (BiPb)2223 phase formation, homogenise the phase distribution and produce a uniform Jc across the thickness of the core. This is in contrast with the large local variations in both Jc and percentage conversion seen in mono-core tapes without silver addition. The samples with silver addition show improved Jc-bending strain characteristics comparable to that of multifilamentary tapes, with the advantage of a single production step.
T1(2223) tapes have been fabricated using partially calcined powders, which are mainly composed of Tl(2212), CaO and CuO. The maximum measured Jc for these tapes was 4000A/cm2 for sintering times of less than one hour. Optical, XRD, and SEM investigations of the core microstructure are presented. The influence of sintering time, sintering temperature and intermediate rolling on the core microstructure and Jc are demonstrated and discussed. The results show that the tapes are poorly aligned, although a slight enhancement in the core texture can be observed in tapes that have undergone intermediate rolling.
The strain dependence of the critical current density of superconducting tapes with various geometrical configurations has also been investigated. The measured Jc-axial strain characteristics were used to predict the Jc-bending strain behaviour. These predictions were validated by comparison with experimental data obtained using a purpose built bending device. A 33 turn double layer pancake coil was constructed using commercially available (BiPb)2223 tape by the 'react and wind' method. The influence of the winding procedure, epoxy impregnation and thermal cycling on the Jc of the coil was assessed.
The I-V characteristics of 20m lengths of (BiPb)2223 multi-filamentary tapes were investigated. The results show that, for a given strain value, the I-V curves display three distinct regimes, which respond differently to the applied strain. A model which considers superconducting regions of different quality is proposed to explain the observed I-V characteristics. The effects of thermal processing on these regimes was also investigated.
University of Southampton
Al-Mosawi, Maitham Khazal
1998
Al-Mosawi, Maitham Khazal
Al-Mosawi, Maitham Khazal
(1998)
The fabrication and characterisation of high temperature superconducting tapes and coils.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The design and construction of High Temperature Superconducting (HTSC) devices requires long lengths of tape, high critical current densities (Jc) and good mechanical characteristics. This work focuses on two areas; firstly the influence of the processing parameters on Jc, and secondly the mechanical characteristics of HTSC tapes.
The addition of large (�80μm) silver particles into the precursor powders of the Ag alloy-sheathed (BiPb)2223 tapes resulted in a novel core configuration. These silver particles flattened upon rolling, produced multi-connected core filaments, yielding a high Jc (�20kA/cm2) for short sintering times. The silver particles accelerate the rate of the (BiPb)2223 phase formation, homogenise the phase distribution and produce a uniform Jc across the thickness of the core. This is in contrast with the large local variations in both Jc and percentage conversion seen in mono-core tapes without silver addition. The samples with silver addition show improved Jc-bending strain characteristics comparable to that of multifilamentary tapes, with the advantage of a single production step.
T1(2223) tapes have been fabricated using partially calcined powders, which are mainly composed of Tl(2212), CaO and CuO. The maximum measured Jc for these tapes was 4000A/cm2 for sintering times of less than one hour. Optical, XRD, and SEM investigations of the core microstructure are presented. The influence of sintering time, sintering temperature and intermediate rolling on the core microstructure and Jc are demonstrated and discussed. The results show that the tapes are poorly aligned, although a slight enhancement in the core texture can be observed in tapes that have undergone intermediate rolling.
The strain dependence of the critical current density of superconducting tapes with various geometrical configurations has also been investigated. The measured Jc-axial strain characteristics were used to predict the Jc-bending strain behaviour. These predictions were validated by comparison with experimental data obtained using a purpose built bending device. A 33 turn double layer pancake coil was constructed using commercially available (BiPb)2223 tape by the 'react and wind' method. The influence of the winding procedure, epoxy impregnation and thermal cycling on the Jc of the coil was assessed.
The I-V characteristics of 20m lengths of (BiPb)2223 multi-filamentary tapes were investigated. The results show that, for a given strain value, the I-V curves display three distinct regimes, which respond differently to the applied strain. A model which considers superconducting regions of different quality is proposed to explain the observed I-V characteristics. The effects of thermal processing on these regimes was also investigated.
This record has no associated files available for download.
More information
Published date: 1998
Identifiers
Local EPrints ID: 463698
URI: http://eprints.soton.ac.uk/id/eprint/463698
PURE UUID: b54d5f85-2666-44c2-b7db-7cf8a1440b36
Catalogue record
Date deposited: 04 Jul 2022 20:55
Last modified: 04 Jul 2022 20:55
Export record
Contributors
Author:
Maitham Khazal Al-Mosawi
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics