Stark broadening analysis of Mg lines to obtain sample density for Opacity-on-NIF

The Opacity-on-NIF campaign works to provide opacity data for Fe and other elements for comparison to theory.¹ This complements the Opacity-on-Z effort, to address the discrepancy that exists between theory and the Z experiments for temperatures between 170-200eV.² On NIF, the plasma density is currently obtained by measuring the expansion of the sample with time through an aperture in the side wall of the hohlraum^3,4,5. However, on Z the plasma density was obtained from a Stark broadening analysis of Mg lines, most reliant on the Mg He-g.⁵ The Stark method can also be used on Mg lines measured on the NIF, and will be valuable when higher density plasmas are studied. This work presents the initial Stark broadening analysis of NIF sample densities, with comparison to densities obtained through sample expansion measurements.

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