Project description
Improving the accuracy of temperature measurements in fusion devices
Fusion occurs when matter is heated to extremely high temperatures and highly energetic particles collide. Fusion devices support basic science experiments and could also produce huge amounts of emission-free energy. There are currently over 130 globally in stages from planning to operation. Ensuring high power and safe operation relies, in part, on infrared cameras to monitor and control the plasma-facing components, yet accurate temperature measurements are difficult to obtain. With the support of the Marie Skłodowska-Curie Actions programme, the MAGRITTE project will develop a digital twin of the machine and an optimisation algorithm, comparing real to predicted images to determine the real temperature when the images they produce match.
Objective
Infrared (IR) cameras are key diagnostics to monitor and control plasma-facing components (PFCs) in fusion devices. Nevertheless, the use of all-metallic PFCs with low and variable emissivity (ε ~ 0.1-0.5) makes it difficult to obtain a correct surface temperature measurement. The radiance collected by the IR camera includes both the thermal radiation emitted by the target and parasitic radiation coming from the target's surroundings. Furthermore, target emissivity changes with the surface temperature and roughness. This causes significant errors in the surface temperature measurement that we need to address for achieving high power and safe plasma operation. Inaccurate interpretation of IR temperature measurement could endanger machine safety (temperature underestimation) or on the contrary, lead to unnecessary pulse interruptions that reduce the overall performance of the machine (temperature overestimation). The current approach is to convert the radiance collected by each pixel in an apparent using a physical relationship between emitted radiance and temperature (Planck’s law). Because a portion of the collected radiance is due to reflection on the target, a systematic error is made. This method is unable to recover the portion of reflected radiance and to deduce the correct temperature of the target using only the emitted radiance. The proposed technique in this project is to use a digital twin of the machine and to make in it assumptions on the temperatures of the different elements of the machine in order to simulate the images that would be measured under these supposed conditions. By comparing to the real image measured by the camera and using optimization techniques, the assumptions on the parameters can be updated until the simulated and measured images are close enough. It is then deduced that the assumptions made on the parameters of the digital twin are correct and that they correspond to the real temperatures in the machine.
Fields of science
Programme(s)
- HORIZON.1.2 - Marie Skłodowska-Curie Actions (MSCA) Main Programme
Funding Scheme
HORIZON-TMA-MSCA-PF-EF - HORIZON TMA MSCA Postdoctoral Fellowships - European FellowshipsCoordinator
1000 Ljubljana
Slovenia