Infrared imaging systems for wall protection in the W7-X stellarator (invited)

Area of Science:

• Fusion energy research
• Plasma physics
• Materials science

Background:

• Wendelstein 7-X (W7-X) stellarator aims for quasi-steady state operation with high heating power (10 MW for 30 min).
• Power exhaust management is critical, relying on actively water-cooled carbon-fiber-reinforced carbon (CFC) divertor units designed for 10 MW/m² steady-state loads.
• Exceeding these load limits risks CFC delamination and divertor module failure.

Purpose of the Study:

• To detail the development of monitoring and protection systems for Wendelstein 7-X divertors.
• To address challenges posed by long pulse operation on diagnostic systems.
• To evaluate new components for enhanced divertor protection.

Main Methods:

• Preparation of infrared endoscopes for monitoring plasma-facing components.
• Development of near real-time software for excessive temperature detection and alarm triggering.
• Testing of different camera systems and thermal decoupling of optics.

Main Results:

• Infrared endoscopes and real-time monitoring software are being prepared for W7-X.
• Diagnostic design constraints for long pulse operation, such as thermal decoupling, are being addressed.
• A graphite scraper element will be tested for divertor protection in the upcoming campaign.

Conclusions:

• Advanced monitoring and protection strategies are essential for W7-X's high-power, long-pulse operation.
• The developed systems aim to ensure the integrity of CFC divertor modules under demanding conditions.
• Protective elements like the graphite scraper are crucial for managing transient events and ensuring operational reliability.