Opacity measurements of a radiatively heated boron sample

A preliminary measurement of the opacity of a thin boron foil radiatively heated at moderate temperatures (5-20 eV) in conditions near local-thermodynamic-equilibrium (LTE) are reported. The opacity of a 0.37 μm thick boron sample has been measured in the K-shell range (40-60 Å) using a 5000 1 mm^-1 transmission grating. The sample is heated by the X-rays emitted at the rear side of two laser-irradiated 0.1 μm thick gold foils. Ab-initio atomic structure calculations are used to fit the experimental spectrum and deduce the ionization charge distribution. Using a non-LTE kinetic code, the heated sample temperature and density ranges are determined. The plasma conditions are predicted with a radiative hydrodynamic code and compared with experimental data. This preliminary analysis shows that the numerical tools are ready for the analysis of future experiments which will be performed with cleaner experimental conditions.