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

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.