Investigation of the Noise Effect on Tomographic Reconstructions for a Tangentially Viewing Vacuum Ultraviolet Imaging Diagnostic

Abstract

Tomographic reconstruction for a tangentially viewing two-dimensional (2D) imaging system is studied. A method to calculate the geometry matrix in 2D tomography is introduced. An algorithm based on a PhillipsTikhonov (P-T) type regularization method is investigated, and numerical tests using the P-T method are conducted with both tokamak and Heliotron configurations. The numerical tests show that the P-T method is not sensitive to the added noise levels and the emission profiles with higher mode numbers can be reconstructed with adequate resolution. The results indicate that this method is suitable for 2D tomographic reconstruction for a tangentially viewing vacuum ultraviolet telescope system.

Estimate of the Deposition Profile of Carbon Pellets Using a High-Speed VUV Imaging System in the LHD

“…Each line element in the sightline is connected to one corresponding line element in the curved line with the magnetic field lines, as described in Refs. [7,8]. The magnetic field is estimated by the equilibrium calculated by the HINT2 code [9,10] .…”

High speed vacuum ultraviolet telescope system for edge fluctuation measurement in the large helical device

“…The tomographic reconstruction of the lineintegrated image based on this relation was examined by using a Tikonov-type renormalization. 9 A reconstructed image can be obtained when the quality of the line-integrated image is Fig. 2(a)) are shown.…”

“…From the numerical simulation, mode structures having a poloidal mode number of m = 10 were found to be resolved with this arrangement. 9 Even in the case where the solution of the reconstruction is not well converged, comparison of the synthetic image based on the modeled emission profile with the experimental image is quite useful, as is shown in Sec. III.…”