Laboratory Plasma Experiments and Spectral Modeling for Neutron Star Merger Elements

Heavy elements believed to originate in neutron star mergers lack high quality diagnostic information on local plasma conditions and abundances for the nebular phase of the kilonova. Initial results are shown for spectral measurements taken of heavy elements in various plasma conditions in the Compact Toroidal Hybrid (CTH) plasma experiment at Auburn University. Comparisons are made to results from computational modeling for these elements. Synthetic spectra are created by collisional-radiative modeling using calculated atomic collision data to compare both wavelengths and spectral line intensities for observed emission from the elements in question. Additional modeling accounting for dielectronic recombination predicts diagnostically useful spectral lines other than those from collisionally excited levels. Results are also presented for time-dependent ionization-balance modeling of sputtered species near the CTH probe tip.