Feasibility study for a high-k temperature fluctuation diagnostic based on soft x-ray imaging

A new pseudolocal tomography algorithm is developed for soft X-ray(SXR) imaging measurements of the turbulent electron temperature fluctuations (delta T-e) in tokamaks and stellarators. The algorithm overcomes the constraints of limited viewing ports on the vessel wall (viewing angle) and limited number of lines of sight (LOS). This is accomplished by increasing the number of LOS locally in a region of interest. Numerical modeling demonstrates that the wavenumber spectrum of the turbulence can be reliably reconstructed, with an acceptable number of viewing angles and LOS and suitable low SNR detectors. We conclude that a SXR imaging diagnostic for measurements of turbulent delta T-e using a pseudolocal reconstruction algorithm is feasible. Published under license by AIP Publishing.

Automated summary

A new pseudolocal tomography algorithm has been developed for soft X-ray imaging measurements of turbulent electron temperature fluctuations in tokamaks and stellarators, overcoming constraints of limited viewing ports and lines of sight. Numerical modeling shows that the turbulence wavenumber spectrum can be reliably reconstructed with an acceptable number of viewing angles and lines of sight, using suitable low SNR detectors. It is feasible to use a SXR imaging diagnostic with a pseudolocal reconstruction algorithm for measuring turbulent delta T-e.