Automated UFO detection via infrared diagnostics in fusion reactors: Application to the WEST tokamak.

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Bibliographic Details
Title: Automated UFO detection via infrared diagnostics in fusion reactors: Application to the WEST tokamak.
Authors: Grelier, Erwan1 (AUTHOR) erwan.grelier@cea.fr, Bonnail, Julie1 (AUTHOR), Courtois, Xavier1 (AUTHOR)
Source: Fusion Engineering & Design. Dec2025, Vol. 221, pN.PAG-N.PAG. 1p.
Subjects: Tokamaks, Deep learning, Fusion reactors, Convolutional neural networks, Detection algorithms, Infrared radiometry, Particle detectors
Abstract: We present UFOund, a deep-learning-based system for the automated detection and localization of moving particles (nicknamed UFOs) in infrared thermography data from the WEST tokamak. UFOs — small particles eroded from plasma-facing components (PFCs) — pose a significant disruption risk during experimental campaigns, accounting for approximately 35% of disruptions in WEST's March–April 2023 experiments. Our approach processes sequences of infrared frames from WEST's infrared thermography diagnostic using a spatiotemporal convolutional neural network. The model, trained on a manually annotated dataset of 295 infrared movies, achieves a balanced accuracy of 0.78 and an F1 score of 0.67 on an unseen test set with a detection threshold of 0.95, and gives very good qualitative results during operation at WEST. We further demonstrate a neural activation-based method to extract segmentation masks and approximate particle trajectories without additional manual annotations. Since November 2024, UFOund has been integrated into WEST's post-pulse analysis pipeline, delivering near-real-time detection across all infrared views and significantly accelerating between-pulse decision making by the PFC Protection Officers. • Deep learning model detects flying particles in WEST tokamak infrared sequences. • Weak supervision enables localization without cumbersome manual annotation. • Automated detection supports fast analysis and decisions during WEST operation. • Generic method applicable to other or future fusion devices such as ITER. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:We present UFOund, a deep-learning-based system for the automated detection and localization of moving particles (nicknamed UFOs) in infrared thermography data from the WEST tokamak. UFOs — small particles eroded from plasma-facing components (PFCs) — pose a significant disruption risk during experimental campaigns, accounting for approximately 35% of disruptions in WEST's March–April 2023 experiments. Our approach processes sequences of infrared frames from WEST's infrared thermography diagnostic using a spatiotemporal convolutional neural network. The model, trained on a manually annotated dataset of 295 infrared movies, achieves a balanced accuracy of 0.78 and an F1 score of 0.67 on an unseen test set with a detection threshold of 0.95, and gives very good qualitative results during operation at WEST. We further demonstrate a neural activation-based method to extract segmentation masks and approximate particle trajectories without additional manual annotations. Since November 2024, UFOund has been integrated into WEST's post-pulse analysis pipeline, delivering near-real-time detection across all infrared views and significantly accelerating between-pulse decision making by the PFC Protection Officers. • Deep learning model detects flying particles in WEST tokamak infrared sequences. • Weak supervision enables localization without cumbersome manual annotation. • Automated detection supports fast analysis and decisions during WEST operation. • Generic method applicable to other or future fusion devices such as ITER. [ABSTRACT FROM AUTHOR]
ISSN:09203796
DOI:10.1016/j.fusengdes.2025.115401