Two-dimensional ion temperature measurement by application of tomographic reconstruction to Doppler spectroscopy

A novel 2D ion temperature measurement for toroidal plasmas has been developed by use of cost-effective discrete tomography reconstruction of 2D ion Doppler spectroscopy composed of a polychromator with an ICCD camera and optical fibres. The 2D projection of the line spectrum collected by 35 (7 x 5) optical fibres is transformed into the r-z profile of the local spectrum by means of the Abel inversion at each wavelength and finally into the 2D (r-z) profile of the ion temperature. Numerical tests of its algorithm indicate that the reconstruction error for a peaked temperature profile is smaller than 15% if the chord-integrated signals have noise smaller than 5%. This system successfully measured the peaked ion temperature profile of a torus plasma on the r-z plane under the condition of negligibly small plasma flow.