Research Of Reconstruction Of The Spatial Distribution Of Visible Radiation In The J-TEXT Tokamak

In this paper, the methods of spatial distribution reconstruction and Abel inversionhave been studied by using chord intergrated values, and applied to data analysis andprocessing in the J-TEXT tokamak. Because of the different characteristics of the visibleradiation diagnositcs and the chord-integrated signals in the J-TEXT tokamak, somepractical methods have been proposed. The codes of spatial distribution reconstruction andAbel inversion are verified by test functions and a better method has been chosen.Meanwhile, the preprocessing and calibration program was designed for visible radiationsignals in the J-TEXT tokamak. Finally, the results of spatial distribution reconstruction ofmeasurement data in the J-TEXT tokamak are given.In tokamaks, many diagnostics give the chord-integrated measurements. Abelinversion is generally used to obtain its radial or spatial profiles on the cross-section foronly a single array or parallel chords of measurements. Two-dimensional spatialdistribution reconstruction methods can be used for multi-array and multi-channelmeasurements. These methods are successfully applied to diagnostic signal processing inmany tokamaks, but specific methods of reconstructing visible radiation spatial distributionare rarely mentioned in the literatures. Therefore, we should analyse various existingmethods, and then try to find suitable methods that can be used and verified.All kinds of algorithms of spatial distribution reconstruction have been studied indetail with tokamak diagnostics’ signals. Because of the different characteristics of thevisible radiation diagnostics, we choose three practical methods after analyzing theadaptability and characteristics of these algorithms. The three methods’ codes of spatialdistribution reconstruction are verified by test functions, and then the bettermethod——Cubic spline function method has been chosen. There are non-negligible noises and baseline offset in measurement signals. Westudied the original signals, and designed software method to eliminate baseline offsetalong with wavelet denoising program. Because of different detection power of diagnostics’PDA probes, we have also designed calibration program for PDA probes.In the end, the reconstructed images of spatial distribution of visible radiation in theJ-TEXT tokamak are demonstrated. There are still some problems, but we should obtainideal results as the experimental conditions are improved, and then the methods will be putinto practical applications. We expect that research of reconstruction of the spatialdistribution of visible radiation in the J-TEXT tokamak and design of relevant signalprocessing can provide theoretical and practical experience for the subject of reconstructingvisible radiation spatial distribution.