Diagnosis of core-shell mixing with absorption and emission spectra of a doped layer. Final technical report

Shell-core mixing which can occur during the deceleration phase of laser-driven implosion is believed to be the major limitation on target performance. The authors proposed a diagnostic method for detecting core-shell mixing based on the comparison of absorption and emission spectra due to a signature layer embedded in the target shell. Experimentally the method is simple as it does not require backlighting nor imaging. They have developed a mixing and radiation transport model used here to demonstrate the proposed diagnostic method. The proposal consists of target experiments on OMEGA as well as the interpretation and analysis of these experiments. They show that a signature layer of a high-Z dopant can be placed within the shell such that, in the absence of mixing, the emergent spectrum will only show absorption lines (of L-shell ionic species). Mixing causes the appearance of K-shell lines in emission. The more severe the mixing, the higher is the intensity of emission lines, as compared with that of the absorption lines. Modeling results are presented to demonstrate a numerical analysis of doped target experiments carried out on OMEGA