Applied Sciences (Dec 2021)

Real-Time Detection of Overloads on the Plasma-Facing Components of Wendelstein 7-X

  • Aleix Puig Sitjes,
  • Marcin Jakubowski,
  • Dirk Naujoks,
  • Yu Gao,
  • Peter Drewelow,
  • Holger Niemann,
  • Joris Fellinger,
  • Victor Moncada,
  • Fabio Pisano,
  • Chakib Belafdil,
  • Raphael Mitteau,
  • Marie-Hélène Aumeunier,
  • Barbara Cannas,
  • Josep Ramon Casas,
  • Philippe Salembier,
  • Rocco Clemente,
  • Simon Fischer,
  • Axel Winter,
  • Heike Laqua,
  • Torsten Bluhm,
  • Karsten Brandt,
  • The W7-X Team

DOI
https://doi.org/10.3390/app112411969
Journal volume & issue
Vol. 11, no. 24
p. 11969

Abstract

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Wendelstein 7-X (W7-X) is the leading experiment on the path of demonstrating that stellarators are a feasible concept for a future power plant. One of its major goals is to prove quasi-steady-state operation in a reactor-relevant parameter regime. The surveillance and protection of the water-cooled plasma-facing components (PFCs) against overheating is fundamental to guarantee a safe steady-state high-heat-flux operation. The system has to detect thermal events in real-time and timely interrupt operation if it detects a critical event. The fast reaction times required to prevent damage to the device make it imperative to automate fully the image analysis algorithms. During the past operational phases, W7-X was equipped with inertially cooled test divertor units and the system still required manual supervision. With the experience gained, we have designed a new real-time PFC protection system based on image processing techniques. It uses a precise registration of the entire field of view against the CAD model to determine the temperature limits and thermal properties of the different PFCs. Instead of reacting when the temperature limits are breached in certain regions of interest, the system predicts when an overload will occur based on a heat flux estimation, triggering the interlock system in advance to compensate for the system delay. To conclude, we present our research roadmap towards a feedback control system of thermal loads to prevent unnecessary plasma interruptions in long high-performance plasmas.

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