Designing ITER motional Stark effect line shift (MSE-LS) spectrometers

Area of Science:

• Plasma physics
• Fusion energy research
• Spectroscopy

Background:

• ITER requires advanced diagnostics for plasma characterization.
• Conventional Motional Stark Effect (MSE) polarimetry faces calibration challenges in the ITER environment.
• A spectral approach using Stark splitting offers a more robust alternative for ITER.

Purpose of the Study:

• To design and model a novel MSE diagnostic for ITER utilizing the line shift (LS) method.
• To quantify the Lorentz electric field magnitude by measuring Stark manifold splitting.
• To address the unique challenges posed by ITER's high magnetic fields and beam energies.

Main Methods:

• Development of a full system model and numerical simulations for MSE-LS sightlines.
• Photon noise analysis across various optical transmission fractions to determine statistical uncertainties.
• Conceptual design of a high-throughput spectrometer incorporating a volume phase transmission grating.

Main Results:

• Statistical uncertainties were determined through photon noise analysis, guiding spectrometer design parameters.
• The study provides crucial insights into spectrometer throughput, dispersion, and optical component selection.
• A conceptual design for a high-throughput spectrometer suitable for the MSE-LS diagnostic was presented.

Conclusions:

• The MSE-LS spectral approach is a promising diagnostic for ITER, despite stringent error tolerances.
• The developed system model and simulations are essential for optimizing the diagnostic design.
• This work provides guidance for critical design choices, ensuring the feasibility of the MSE-LS diagnostic on ITER.