The multi-spectral line-polarization MSE system on Alcator C-Mod

Area of Science:

• Plasma Physics
• Fusion Energy Research
• Optical Diagnostics

Background:

• Tokamak devices require precise plasma diagnostics for fusion energy development.
• Motional Stark Effect (MSE) diagnostics measure plasma properties using polarized light.
• Existing MSE systems face challenges with polarized background subtraction.

Purpose of the Study:

• To develop and qualify a novel multi-spectral line-polarization motional Stark effect (MSE-MSLP) diagnostic.
• To enhance polarized background subtraction capabilities for tokamak plasma measurements.
• To create a versatile and cost-effective diagnostic system.

Main Methods:

• Simultaneous measurement of Stokes vector in multiple wavelength bands on a single sightline.
• Design and implementation of a ten-sightline, four-wavelength MSE-MSLP detector system.
• Utilization of high-throughput polychromators with narrow bandpass interference filters and avalanche photodiode detectors.
• Automated temperature tuning of filter wavelengths using custom ovens.

Main Results:

• Successful design, construction, and qualification of the MSE-MSLP system.
• Demonstrated capability for precise spectral filtering and large étendue.
• Development of a system with remote controllability and ease of retrofitting.

Conclusions:

• The developed MSE-MSLP diagnostic offers significant improvements for tokamak plasma analysis.
• The system provides enhanced polarized background subtraction, crucial for accurate measurements.
• This technology is adaptable and can be integrated into existing MSE setups.