Development of a high-speed small-angle infrared thermography system in EAST

Area of Science:

• Plasma Physics
• Fusion Energy Research
• Materials Science

Background:

• Edge Localized Modes (ELMs) are crucial phenomena in tokamak fusion devices, significantly impacting plasma confinement and material integrity.
• Accurate measurement of heat flux during ELMs is essential for understanding plasma-edge physics and designing robust fusion reactor components.
• Existing diagnostic systems often face limitations in spatial resolution and temporal response for capturing transient ELM events.

Purpose of the Study:

• To develop and implement a high-speed infrared small-angle infrared thermography system (SATS) for real-time surface temperature measurement of the divertor target on the EAST tokamak.
• To enable the calculation of high heat flux induced by Edge Localized Modes (ELMs) and facilitate the study of key parameters like power decay length (λq) and ELM characteristic times.
• To provide an advanced diagnostic tool for observing and analyzing plasma-edge physics phenomena in fusion devices.

Main Methods:

• Development and installation of a high-speed infrared small-angle infrared thermography system (SATS) on the Experimental Advanced Superconducting Tokamak (EAST).
• Utilization of an endoscopic optical system for clear imaging of the divertor plate, ensuring protection from impurities and tungsten ablation.
• Design of an endoscopic optical system with a specific field of view (13° horizontal, 9° vertical) to cover approximately 35° of the lower-outer divertor and a portion of the lower-inner divertor, achieving a spatial resolution of ~2 mm/pixel.

Main Results:

• The SATS system successfully captured high-speed infrared thermography data from the EAST tokamak divertor.
• Preliminary experimental results demonstrated the capability of SATS to measure surface temperature and calculate heat flux during ELM crashes.
• The radial distribution of heat flux induced by an ELM crash was successfully mapped and analyzed.

Conclusions:

• The newly developed SATS is a viable and effective diagnostic tool for measuring high heat flux on tokamak divertor targets during ELMs.
• SATS provides valuable data for fundamental research into ELM physics, including power decay length and characteristic times.
• This system enhances the observational capabilities for studying critical plasma-edge parameters in fusion devices like EAST.