The expansion velocities of laser-produced plasmas determined from extreme ultraviolet spectral line profiles

Abstract
The expansion of laser‐produced plasma is determined from the shapes of spectral lines of highly ionized iron emitted in the extreme ultraviolet. The plasmas were produced by focusing the pulse from a Nd : glass laser onto solid planar targets, and spectra were recorded with a high‐resolution grazing incidence spectrograph. From the Doppler broadening of lines of Fe XX and Fe XXI, expansion velocities of ∼830 km s−1 were determined. The relative time‐averaged ion abundances of Fe XVIII, Fe XIX, Fe XX, and Fe XXI are estimated for three different spectra. The abundances do not differ by more than a factor of 4 for any of the spectra.