Heuristic reconstruction of three-dimensional laser-imploded targets from x-ray pinhole images

Abstract

Implosion symmetry has long been an important issue in inertial confinement fusion (ICF) research. In order to evaluate the implosion symmetry of ICF, a computer tomography (CT) technique developed for medical diagnostics is traditionally employed. This attempt was made to reconstruct the three-dimensional (3D) compressed core from several x-ray pinhole images. Unfortunately the reconstructed result is often constrained by the number of available pinhole images and is affected by the noise in them. In this article, we propose a heuristic method for 3D image reconstruction from a limited number of pinhole images and in the presence of noise. We represent the 3D compressed core as a summation of 3D Gaussian functions. The 3D image can be reconstructed by estimating the width and height of each Gaussian function. One heuristic method, simulated annealing, is used. The technique has been successfully applied to real laser–plasma experiments for the reconstruction of 3D compressed core utilizing only three x-ray pinhole images.