Investigation of a polychromatic tomography method for the extraction of the three-dimensional spatial structure of implosion core plasmas

Abstract

A spectroscopic method has been developed to extract the three-dimentional spatial structure (i.e., spatial distribution of electron temperature and density) of inertial confinement fusion implosion cores based on the analysis of space-resolved spectra from a tracer element recorded along three quasi-orthogonal lines of sight. We discuss a spectral model that computes space-resolved spectra for a given spatial structure. This model is then combined with a multi-objective search and optimization technique driven by a Pareto genetic algorithm to perform the inversion and to extract the spatial structure of the implosion core from a simultaneous and self-consistent analysis of a set of space-resolved spectra. This method is investigated with a series of synthetic data test cases to explore its reliability, requirements, and limitations. We have found a constraint parameter Pconst such that the method is robust and the extracted spatial structure is reliable when Pconst > 1. The idea of polychromatic tomography is general and has potential to extract the spatial structure of other laboratory high energy-density plasmas.