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Title: On a dual wavelength optical sensor system for measuring strain and temperature simultaneously in tokamak port plug
Author: Crolla, Paul
ISNI:       0000 0004 5362 6963
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2014
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A large variety of sources will provide energy, including nuclear fusion energy from tokamak type reactors; still at a research stage of development to produce 500 MW of energy. The reactor's structure will be affected by temperature changes and ionising radiation (neutrons produced by the burning plasma); it is therefore necessary to instrument the structure with long lasting, accurate, temperature and strain monitoring devices. This thesis demonstrates that using electrical sensors in the supporting structures of a fusion reactor for measuring strain and temperature will be strongly affected by the ionising radiation and the electromagnetic fields. This is because it was found that errors of over 100% can be present on the measurements due to combined electromagnetic and radiation effects. An optical fibre sensor was constructed to a strain resolution of ±10uε and temperature resolution of ±5°C. The fibre sensor is an off the shelf solution dual-wavelength fibre Bragg grating. The thesis proposes a method of coating the fibre in layers of silver and copper to protect this sensor. A new method of embedding the fibre in a stainless steel piece is described using a silver solder to couple the fibre with the steel increasing its temperature and strain sensitivity by approximately three times, with the solder melted using an induction heater. To measure the temperature and strain response from the fibre Bragg grating a broadband optical filter was used as a real-time interrogation system. Data capture and analysis software solution was created running at 30Hz and ~1pm resolution; temperature and strain requirements were met. This work describes a method of performing measurements of strain and temperature not subject to electromagnetic interference, with good electrical isolation possible and capable of operating in a near vacuum. The sensor package provides a robust, weldable solution for connecting the sensor to the port plug structure and/or plasma instrumentation equipment that will provide regular repeatable measurements of strain and temperature.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available