Sapphire fiber could enable cleaner energy and air-travel
Date:
April 21, 2022
Source:
University of Oxford
Summary:
Oxford University researchers have developed a sensor made of
sapphire fibre that can tolerate extreme temperatures, with the
potential to enable significant improvements in efficiency and
emission reduction in aerospace and power generation.
FULL STORY ========================================================================== Oxford University researchers have developed a sensor made of sapphire
fibre that can tolerate extreme temperatures, with the potential to
enable significant improvements in efficiency and emission reduction in aerospace and power generation.
==========================================================================
The work, published in the journal Optics Express, uses a sapphire
optical fibre -- a thread of industrially grown sapphire less than half a millimetre thick -- which can withstand temperatures over 2000DEGC. When
light is injected onto one end of the sapphire fibre, some is reflected
back from a point along the fibre which has been modified to be sensitive
to temperature (known as a Bragg grating). The wavelength (colour)
of this reflected light is a measure of the temperature at that point.
The research resolves a 20-year-old problem with existing sensors
that, whilst the sapphire fibre seems very thin, in comparison to the wavelength of light it is huge. This means that the light can take
many different paths along the sapphire fibre, which results in many
different wavelengths being reflected at once. The researchers overcame
this problem by writing a channel along the length of the fibre, such
that the light is contained within a tiny cross- section, one-hundredth
of a millimetre in diameter. With this approach, they were able to make
a sensor reflecting predominantly a single wavelength of light.
The initial demonstration was on a short length of sapphire fibre 1
cm long, but the researchers predict that lengths of up to several
metres will be possible, with a number of separate sensors along this
length. This would enable temperature measurements to be made throughout
a jet engine, for example. Using this data to adapt engine conditions
in-flight has the potential to significantly reduce nitrogen oxide
emissions and improve overall efficiency, reducing the environmental
impact. The sapphire's resistance to radiation also gives applications
in the space and fusion power industries.
Research team member Dr Mohan Wang, Department of Engineering Science, University of Oxford said: 'The sensors are fabricated using a high-power
laser with extremely short pulses and a significant hurdle was preventing
the sapphire from cracking during this process.'
==========================================================================
The work is part of a -L-1.2M EPSRC Fellowship Grant held by Dr Julian
Fells at the University of Oxford's Department of Engineering Science and
was carried out in partnership with Rolls-Royce, the UK Atomic Energy
Authority (Remote Applications in Challenging Environments -- RACE),
Cranfield University, Halliburton and MDA Space and Robotics.
Mark Jefferies, Chief of University Research Liaison at Rolls-Royce
plc said: 'This is exciting news and yet another important scientific achievement resulting from our long-standing partnership with Oxford University. This fundamental research could in time enable more efficient
and accurate multi- point temperature measurement in harsh environments, improving control, efficiency, and safety. We look forward to working
with the University of Oxford to explore its potential.' Rob Skilton,
Head of Research at RACE, UK Atomic Energy Authority said: 'These sapphire optical fibres will have many different potential applications within
the extreme environments of a fusion energy powerplant. This technology
has the potential to significantly increase the capabilities of future
sensor and robotic maintenance systems in this sector, helping UKAEA
in its mission to deliver safe, sustainable, low carbon fusion power
to the grid.' Dr Fells, who is leading the research, said: 'We are
very grateful to the UK Engineering and Physical Sciences Research
Council (EPSRC) for supporting this work and to the reviewers who saw
the potential for the challenging work we proposed. We are now working
with our partners to further develop the technology to the point where
it can be integrated into suitable infrastructure.'
========================================================================== Story Source: Materials provided by University_of_Oxford. Note: Content
may be edited for style and length.
========================================================================== Journal Reference:
1. Mohan Wang, Patrick S. Salter, Frank P. Payne, Adrian Shipley,
Stephen M.
Morris, Martin J. Booth, Julian A. J. Fells. Single-mode sapphire
fiber Bragg grating. Optics Express, 2022; 30 (9): 15482 DOI:
10.1364/OE.446664 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/04/220421100135.htm
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