High definition imaging in the Mega Amp Spherical Tokamak

Area of Science:

• Plasma Physics
• Fusion Energy
• Diagnostic Instrumentation

Background:

• The MAST spherical tokamak requires advanced diagnostics for plasma characterization.
• Accurate imaging is crucial for understanding plasma behavior and improving fusion reactor designs.

Purpose of the Study:

• To deploy and validate an absolutely calibrated, visible imaging diagnostic system on the MAST spherical tokamak.
• To enable unambiguous 2D measurements of plasma cross-sections.

Main Methods:

• Utilized stacked multi-cavity interference filters, color-glass filters, and a color-pixel sensor for three-color channel definition.
• Implemented a compact system with a single viewing pupil and telecentric optical control.
• Employed a sensor with 12-bit dynamic range, variable integration times (50 μs to 10 ms), and 640 × 480 resolution.

Main Results:

• Successfully deployed an absolutely calibrated visible imaging diagnostic.
• The system captures a complete plasma cross-section, including edge and interior emissions.
• Observed neutral beam emissions, impurity charge-exchange emissions, and bremsstrahlung radiation.

Conclusions:

• The developed diagnostic provides reliable, high-resolution 2D imaging of tokamak plasmas.
• This tool enhances the capability for detailed plasma analysis in fusion research.
• The system's design facilitates accurate comparisons of measurements across the plasma cross-section.