The University of Southampton
University of Southampton Institutional Repository

Liquid Neon system and characterization of ac loss and quench propagation for MgB2 conductors

Bianchetti, Marco (2007) Liquid Neon system and characterization of ac loss and quench propagation for MgB2 conductors University of Southampton, School of Engineering Sciences, Doctoral Thesis , 124pp.

Record type: Thesis (Doctoral)

Abstract

Magnesium diboride (MgB2) was found to have superconducting characteristics in January 2001 below 39K. The abundance and low cost of its components and the possibility to manufacture long length of wires and tapes using the powder in tube technique makes this material a good candidate for cheaper alternative to many low temperature superconductor application.
A closed system Neon liquefier and dedicated hybrid current leads have been designed to investigate properties of MgB2 based conductors in liquid Neon in the temperature range from 24.5K to 31K. The system is capable of liquefying 3 litres of Ne and recover all the boil off. The temperature of the liquid Ne can be adjusted by controlling the temperature of copper surface extending in the Ne vessel. 900A hybrid current lead was designed and built using BSCCO superconducting tapes at the lower end while the top end was constructed as a liquid nitrogen cooled copper lead.
In the Ne cryostat transport AC loss measurements of a non magnetic NiCr sheathed and a magnetic Ni sheathed Cu stabilized MgB2 tape have been conducted. Despite the NiCr alloy is non-magnetic, the high temperature treatment of the superconductor results in the formation of a magnetic layer at the interface with the superconducting core. For both samples the losses are found to be dominated by the hysteresis losses of the magnetic layer and sheath. The results are presented and analyzed.
The minimum propagation zone and the quench energy of a MgB2 superconducting wire has been measured in Ne vapour environment. Our results show a good agreement with published literature where the minimum propagation zone of MgB2 has been found to increase with the transport current.
AC losses in external applied magnetic field have been measured on MgB2 samples using a purposely built rig and sample holder employing sapphire fingers to effectively thermally link the sample to a cold source, consequently eliminating the eddy current losses in the sample holder. The losses of the MgB2 samples below Tc are dominated by the losses of the magnetic sheath and are higher than the losses above Tc. Our measurements suggest that the losses in the superconducting state are the result of an interaction between the ferromagnetic sheath and the diamagnetic superconductor, where as the sample is cooled below Tc the field in the outer magnetic sheath is increased.

PDF Thesis.pdf - Other
Restricted to Repository staff only
Download (8MB)

More information

Published date: February 2007
Organisations: University of Southampton, Astronautics Group

Identifiers

Local EPrints ID: 65715
URI: http://eprints.soton.ac.uk/id/eprint/65715
PURE UUID: 8cfa8b20-da78-49f1-af76-04905ff7ddeb

Catalogue record

Date deposited: 17 Mar 2009
Last modified: 19 Jul 2017 00:31

Export record

Contributors

Author: Marco Bianchetti
Thesis advisor: Carlo Beduz

University divisions

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

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×