Energy dependence of Xe ion lines produced by beam-foil interaction

Xenon ions are present in stellar atmospheres and in astrophysically interesting plasmas on the ground. Atomic spectra of xenon ions induced by the beam-foil interaction have been recorded in the far-ultraviolet region between 30 and 120 nm. From the relative intensities of Xe II to Xe IX lines that appear in our spectra, we have deduced the first experimental charge state distribution of xenon ions at the exit of a carbon foil target for energies ranging from 0.2 to 1.9 MeV. Our results differ from the predictions of different theoretical models and indicate that xenon is two times easier to ionize than what was predicted by existing models.