Spectroscopic signature of strong dielectronic recombination in highly ionized xenon produced by irradiating a gas puff with laser

Highly stripped xenon is produced by irradiating a gas-puff target with a laser pulse of 1-ns duration at an intensity of ${10}^{13}{\mathrm{W}/\mathrm{c}\mathrm{m}}^2.$ The spectrum in the 16.5–19.5-Å wavelength range is measured using a grazing incidence diffractive spectrograph. Spectral lines of Fe-, Co-, Ni-, and Cu-like xenon arising from $3d-4p$ radiative transitions are identified. A collisional-radiative model that includes dielectronic capture processes and radiation trapping is used to achieve the line identification and to describe the relative line intensities. The results of the model clearly show that the relatively strong intensities of the ${3d}^9{4l-3d}^{8}4p4l$ Ni-like quasicontinuum emission between 17.8 and 18.4 Å arise from dielectronic recombination processes, which probably take place during the cooling phase of the plasma. The resonant nature of the dielectronic recombination processes enables us to diagnose the average electron temperature of the plasma during the recombination phase, and it is found to be about 150 eV.