Soft-x-ray laser interferograms of laser-created plasmas generated at moderate irradiation intensities $(1\mathrm{}\times {10}^{11}–7\times {10}^{12}{\mathrm{W}\mathrm{}\mathrm{cm}}^{-2})$ with $\lambda =1.06\mathrm{}\mu \mathrm{m}$ light pulses of ∼13-ns-FWHM (full width at half maximum) duration and narrow focus (∼30 μm) reveal the unexpected formation of an inverted density profile with a density minimum on axis and distinct plasma sidelobes. Model simulations show that this strong two-dimensional hydrodynamic behavior is essentially a universal phenomena that is the result of plasma radiation induced mass ablation and cooling in the areas surrounding the focal spot.

• Received 13 June 2002

DOI:https://doi.org/10.1103/PhysRevE.67.056409