Application of three-dimensional tomography to infrared imaging bolometer on HL-2A

An infrared imaging bolometer diagnostic has been developed recently for the HL-2A tokamak to measure the spatial and temporal distribution of plasma radiation. The three dimensional tomography, reduced to a two dimensional problem by the assumption of plasma radiation toroidal symmetry, has been performed. The solid angles viewed by the detector elements were taken into account in defining the chord brightness. And the local plasma emission is obtained by inverting the measured brightness with minimum fisher regularization (MFI) method. A typical HL-2A plasma radiation model was chosen to optimize a regularization parameter on the criterion of generalized cross validation. Finally this method was applied to an H-mode discharge in HL-2A, with increasing radiation from the plasma edge after the H-mode transition being observed. (authors)