Optimized tomography methods for plasma emissivity reconstruction at the ASDEX Upgrade tokamak.

Area of Science:

• Plasma physics
• Fusion energy research
• Tomography

Background:

• Soft X-ray (SXR) emission is crucial for understanding high-temperature plasmas.
• Tomographic inversion of SXR data is essential for deriving local emissivity profiles.
• The ill-conditioned nature of inversion and algorithm choice pose significant challenges.

Purpose of the Study:

• To describe novel tomography algorithms for SXR emissivity profile reconstruction.
• To investigate the combination of Tikhonov regularization with minimum Fisher information.
• To explore statistical methods for optimal regularization parameter selection.

Main Methods:

• Development of tomography algorithms with linear computational complexity.
• Integration of Tikhonov regularization and minimum Fisher information.
• Application of statistical methods for regularization parameter optimization.
• Reconstruction of experimental SXR profiles from ASDEX Upgrade tokamak data.

Main Results:

• Demonstrated feasibility of combining Tikhonov and minimum Fisher information regularization.
• Investigated reliability and robustness of statistical methods for parameter selection.
• Successfully reconstructed experimental SXR profiles, including asymmetric impurity distributions.

Conclusions:

• The presented tomography algorithms offer accurate and robust methods for SXR emissivity profile reconstruction.
• The developed techniques are capable of handling complex plasma phenomena like poloidal asymmetries.
• This work advances plasma diagnostics in fusion devices.