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???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.