X-ray laser radiography of hydrodynamic perturbations due to laser imprint

Abstract

Extreme ultraviolet (XUV) laser radiography is a technique that allows the investigation of hydrodynamic perturbations with high spatial and temporal resolution. A Ne-like Ge XUV laser with wavelength lambda = 19.6 nm was used as a backlighter for 2 pm thick Al foils, and a Ni-like Sm XUV laser at lambda = 7.3 nm for 2 pm thick CH foils. The imprinted modulation and growth due to a low intensity (I = 5.0(12) to 1.5.10(13) W/cm(2)) 0.53 mu m drive beam incident on the thin foils has been determined. Smoothing techniques were used to minimise the optical perturbations, and the growth rates for the different smoothing schemes are compared. Moreover, single mode perturbation with I = 15, 30, 70 and 90 mu m wavelengths have been investigated to gain better insight into the physical processes of imprinting. XUV laser radiography is also suitable to determine the change in opacity for shock compressed materials. For the investigated conditions, the opacity of Al increases by a factor of 1.4 to 1.6, depending on the drive intensity