Plasma tomographic reconstruction from tangentially viewing camera with background subtraction

Area of Science:

• Plasma physics
• Optical diagnostics
• Fusion energy research

Background:

• Plasma emissivity reconstruction is crucial for understanding fusion devices.
• Specular reflections from metallic tokamak components introduce significant errors in optical measurements.
• Accurate plasma boundary determination is essential for operational control and data interpretation.

Purpose of the Study:

• To develop and validate an algorithm for accurate plasma boundary reconstruction in tokamaks.
• To mitigate systematic errors caused by light reflections from specular surfaces.
• To provide an independent method for estimating plasma boundary shape.

Main Methods:

• Utilized data from a fast visible light camera on the COMPASS tokamak.
• Performed tomographic reconstruction of plasma emissivity.
• Implemented a background reflection subtraction technique.
• Analyzed data from a D-shaped tokamak with a metallic vessel, including H-mode plasma conditions.

Main Results:

• Demonstrated the feasibility of obtaining realistic plasma boundary reconstructions despite highly specular tokamak walls.
• The developed algorithm proved robust against systematic errors in optical measurements and calibration.
• Successfully subtracted background reflections to improve reconstruction accuracy.

Conclusions:

• The developed algorithm provides a reliable method for plasma boundary reconstruction in tokamaks with metallic components.
• Accurate optical measurements are achievable even in the presence of challenging reflective environments.
• This technique offers an independent estimate of plasma boundary shape, aiding fusion research.