Application of the Tikhonov tomography method for the gas electron multiplier (GEM) system on experimental advanced superconducting tokamak

A novel GEM (Gas Electron Multiplier) system has been installed on experimental advanced superconducting tokamak (EAST) which is used for collecting the line integral of the soft X-ray radiation (SXR) through a pinhole-collimated Beryllium window. The sightline of the 2-D GEM system is tangential to the toroidal field. To obtain the local SXR emission, the Tikhonov algorithm is applied for the imaging of the poloidal cross section emission in the vacuum vessel. In the meanwhile, the L-curve method is used to find an optimized solution of the regularizationparameters. The tomography reliability has been tested with a known emission function where the error is also discussed. The tomography method has been coded as a graphic user interface for the fast analysis of GEM experimental data. The typical tomography results have been shown for the EAST shot (#79282) in this paper.