The prototype imaging motional Stark effect diagnostic for ASDEX upgrade.

Area of Science:

• Plasma physics
• Fusion energy research
• Diagnostic instrumentation

Background:

• The Motional Stark-Effect (MSE) diagnostic is crucial for measuring magnetic fields in fusion plasmas.
• Existing MSE diagnostics face challenges with complex spectra and component non-idealities.
• Accurate magnetic field measurements are vital for understanding and controlling fusion plasmas.

Purpose of the Study:

• To develop and test a prototype Imaging Motional Stark-Effect (IMSE) diagnostic for the ASDEX Upgrade tokamak.
• To establish analytical methods for evaluating complex MSE spectra with high accuracy.
• To assess and mitigate systematic errors in IMSE measurements.

Main Methods:

• Detailed description of the IMSE diagnostic's core hardware and theory of operation.
• Testing with a simulated MSE-polarized spectrum to evaluate modulation modes.
• Development of analytical methods for evaluating spectral accuracy.
• Investigation of non-ideal component effects, such as intrinsic contrast and ellipticity.

Main Results:

• The IMSE diagnostic prototype was successfully developed and tested for ASDEX Upgrade.
• Small systematic errors were identified in tested modulation modes due to non-ideal components.
• Intrinsic contrast from birefringent plates significantly impacts accuracy; mitigation methods were discussed.
• Polarization orientation accuracy within ±0.2° and ellipticity measurement accuracy within ±2.0° were demonstrated.
• The system exhibits robustness against background light, temperature variations, and spectral complexities.

Conclusions:

• The developed IMSE diagnostic is a viable tool for accurate plasma magnetic field measurements on ASDEX Upgrade.
• Careful calibration and correction for component non-idealities are essential for achieving high accuracy.
• The IMSE diagnostic offers high precision and robustness, crucial for fusion research.