Doppler effects on 3-D non-LTE radiation transport and emission spectra

• Published in: High energy density physics 2011-12, Vol.7 (4), p.303-311
• Main Authors: Hansen, S.B., Jones, B., Giuliani, J.L., Apruzese, J.P., Thornhill, J.W., Scott, H.A., Ampleford, D.J., Jennings, C.A., Coverdale, C.A., Cuneo, M.E., Rochau, G.A., Bailey, J.E., Dasgupta, A., Clark, R.W., Davis, J.
• Format: Article
• Language: English
• Subjects: Collisional-radiative; Non-LTE; Radiative transfer; Spectroscopic
• ISSN: 1574-1818; 1878-0563
• DOI: 10.1016/j.hedp.2011.06.002

Spatially and temporally resolved X-ray emission lines contain information about temperatures, densities, velocities, and the gradients in a plasma. Extracting this information from optically thick lines emitted from complex ions in dynamic, three-dimensional, non-LTE plasmas requires self-consistent accounting for both non-LTE atomic physics and non-local radiative transfer. We present a brief description of a hybrid-structure spectroscopic atomic model coupled to an iterative tabular on-the-spot treatment of radiative transfer that can be applied to plasmas of arbitrary material composition, conditions, and geometries. The effects of Doppler line shifts on the self-consistent radiative transfer within the plasma and the emergent emission and absorption spectra are included in the model. Sample calculations for a two-level atom in a uniform cylindrical plasma are given, showing reasonable agreement with more sophisticated transport models and illustrating the potential complexity – or richness – of radially resolved emission lines from an imploding cylindrical plasma. Also presented is a comparison of modeled L- and K-shell spectra to temporally and radially resolved emission data from a Cu:Ni plasma. Finally, some shortcomings of the model and possible paths for improvement are discussed.