Modified Phillips-Tikhonov regularization for plasma tomography

Abstract

The tomography has been used as a powerful diagnostic method for visualizing cross-sectional images in plasma research. Without any biasing data, the Phillips-Tikhonov (P-T) regularization method was attempted in this work to reconstruct cross-sectional phantom images of the plasma by minimizing the gradient between adjacent pixel data. A comparison of the tomographic reconstructions of the cross-sectional images similar to the tokamak plasmas by the P-T method and the maximum entropy (ME) method showed that the P-T method produced more accurate results. In addition, the P-T method was modified by adding an iteration procedure with a second-order correction to improve the accuracy of the reconstruction for noisy line-integrated data. Tomographic reconstructions in the presence of Gaussian-distributed random noise demonstrated that the modified P-T method with only several iterations significantly reduced the mean reconstruction error by (30-50)% of the original root-mean-square error caused by the random noise. (C) 2009 Elsevier B. V. All rights reserved.