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A protection system for the JET ITER-like wall based on imaging diagnostics.
1Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon, United Kingdom.
The Review of Scientific Instruments
|November 8, 2012
Summary
A new camera system protects the fragile ITER-like wall in fusion reactors by detecting hot spots and safely stopping plasma. This system ensures operational safety for beryllium and tungsten components.
Area of Science:
- Nuclear Fusion Engineering
- Plasma Physics
- Materials Science
Background:
- The new JET ITER-like wall, composed of beryllium and tungsten, is susceptible to heat loads, necessitating active protection systems.
- Previous carbon fiber composite walls were more robust, but the current wall material requires advanced monitoring for plasma-facing components (PFCs).
Purpose of the Study:
- To detail the development and implementation of an active protection system for the JET ITER-like wall.
- To demonstrate the efficacy of analog CCD cameras for real-time surface temperature measurement and plasma control.
- To present findings on the system's performance, limitations, and operational constraints.
Main Methods:
- Utilized analog CCD cameras operating in the near-infrared spectrum to monitor PFC surface temperatures.
- Implemented real-time region of interest (ROI) analysis to identify maximum temperatures.
- Cross-validated temperature measurements using thermal IR cameras and bi-color pyrometers for calibration.
Main Results:
- The protection system, operational since October 2011, has successfully prevented damage by safely landing plasma when hot spots were detected.
- Demonstrated the viability of CCD camera-based protection, with examples of hot spot detection leading to plasma pulse termination.
- Identified challenges in divertor protection due to dust deposits causing false hot spot indications.
Conclusions:
- A CCD camera-based system provides effective real-time monitoring and active protection for the fragile ITER-like wall.
- The system enhances operational safety by enabling controlled plasma termination during overheating events.
- Further development is needed to address limitations, particularly concerning false positives in challenging environments like the divertor.
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