Ion density measurements using coherence imaging spectroscopy on MAST

Lead Research Organisation: Durham University
Department Name: Physics


This project will involve developing a new calibration system for the Coherence Imaging spectrometer at MAST, and proposing and implementing design changes to improve the long-term stability. Measurements will be taken in several configurations including the new Super-X divertor at MAST-U. Theoretical aspects of the work will involve developing advanced tomographic inversion methods to compare the measurements with predictions from fluid code simulations such as UEDGE and SOLPS.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509140/1 01/10/2015 30/09/2020
1641825 Studentship EP/N509140/1 01/10/2015 30/09/2019 Joseph Allcock
Description We have developed a new technique for calibrating the coherence imaging (CI) plasma diagnostic for measurements of plasma flows. Previously, a bespoke tunable laser was required for the calibration, our work demonstrates that the calibration can be achieved using standard, off-the-shelf calibration lamps -- this reduces the cost of the procedure by an order of magnitude.

In the process, we have also developed analysis tools for modelling and fitting to coherence imaging data that have wider applications.

We have also developed new CI techniques that use novel sensor technology (pixellated polariser arrays) to optimise the spatial resolution of the measurement and reduce artefacts in the data. These new techniques have been demonstrated experimentally on the Magnum-PSI linear plasma experiment.
Exploitation Route The new calibration technique can be used by other plasma experiments, particularly smaller groups for whom expensive calibration hardware is not feasible.

The new imaging techniques which use novel sensor technology will likely find use at many fusion labs across the world.
Sectors Energy

Description University College Durham Travel Scholarship
Amount £300 (GBP)
Organisation Durham University 
Sector Academic/University
Country United Kingdom
Start 03/2017 
End 05/2017
Description DIFFER collaboration: testing new coherence imaging techniques for measuring electron density on Magnum-PSI 
Organisation Dutch Institute for Fundamental Energy Research
Country Netherlands 
Sector Public 
PI Contribution I designed and installed a novel coherence imaging plasma diagnostic capable of measuring electron density of plasma in conditions that match the edge plasma of fusion reactor experiments. I also analysed the data and am currently writing up a paper on the results.
Collaborator Contribution DIFFER hosted me for 3 weeks and gave me 2 weeks of experimental time on the Magnum-PSI linear plasma experiment. They also provided an optical lab for tests and help on interfacing with and controlling the Magnum-PSI experiment.
Impact A paper covering the results of the investigation is currently in preparation for submission to Review of Scientific Instruments.
Start Year 2019
Description LLNL DIII-D Coherence Imaging Calibration Collaboration 
Organisation Lawrence Livermore National Laboratory
Country United States 
Sector Public 
PI Contribution The LLNL Magnetic Fusion Experimental Research Group at DIII-D and our own group at Culham Centre for Fusion Energy (CCFE) both work on the novel Flow Coherence Imaging Spectroscopy (CIS) plasma diagnostic technique. Since communication between the two research groups has been limited in the past, the work has developed largely in isolation. The regular communication and secondment brought about by this collaboration has resulted in the transfer of expertise and information from our group to theirs.
Collaborator Contribution The LLNL group have developed hardware for the testing and calibration of flow CIS plasma diagnostics. A major contribution from the LLNL group to this partnership was to allow our MAST-U Flow CIS instrument to be tested and calibrated using their hardware. This involved myself and the equipment travelling to DIII-D, San Diego, for six weeks to work closely with the group to take measurements of the system. Significant knowledge exchange from LLNL / DIII-D to our group also occurred, significantly in techniques for measurement demodulation techniques and instrument stability.
Impact The results of the calibration testing of the MAST-U flow CIS diagnostic are currently being prepared to be presented on a poster at the upcoming 2018 High Temperature Plasma Diagnostics conference and also in a publication.
Start Year 2017
Description SWIP HL-2A Coherence Imaging Collaboration 
Organisation Center for Fusion Science of Southwestern Institute of Physics
Country China 
Sector Academic/University 
PI Contribution Our group imparted our expertise in Flow Coherence Imaging Spectroscopy (CIS) to help the group at SWIP develop their own CIS instrument and to perform impurity ion flow measurements on their tokamak fusion plasma experiment -- HL-2A.
Collaborator Contribution The group at SWIP provided us with a running tokamak experiment on which to test CIS design ideas and make impurity ion flow measurements.
Impact This collaboration is not multi-disciplinary.
Start Year 2015
Description New Scientist Live 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact New Scientist Live is an annual science festival at the ExCeL, London. I helped exhibit on behalf of United Kingdom Atomic Energy Authority (UKAEA), talking to attendees about the work of UKAEA, and the wider topic of fusion energy.
Year(s) Of Engagement Activity 2018
Description Primary School visits with the CCFE Sundome 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Culham Centre for Fusion Energy (CCFE) have a 'Sundome' event that tours primary schools in and around Oxfordshire area teaching children about the Sun and nuclear fusion. I have helped to run two of these days, reaching roughly 90 children on each. I lead the section explaining the work done at CCFE, and took questions from the children about what they had learnt.
Year(s) Of Engagement Activity 2017,2018