Density depression in laser-created plasma unveiled with table-top soft x-ray laser interferometry.

Soft x-ray laser interferograms of laser-created plasmas generated at moderate irradiation intensities (1x10[SUP11] - 7x10[SUP12] W cm[SUP-2]) with λ = 1.06 µm light pulses of ∼3 ns FWHM 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 2-dimensional hydrodynamic behavior is essentially a universal phenomenon that is the result of plasma radiation induced mass ablation and cooling in the areas surrounding the focal spot. These measurements, which mapped plasma densities up to 0.9x10[SUP21] cm[SUP-3], demonstrate the use of a portable soft x-ray laser interferometer as a high resolution tool for the study of high density plasma phenomena and the validation of hydrodynamic codes. [ABSTRACT FROM AUTHOR]