Absorption experiments on X-ray-heated magnesium and germanium constrained samples

Absorption spectra of magnesium and germanium plasma were measured in the 8-11 Å range. The experiments used the Phébus laser (CEA-Centre d'Etudes de Limeil-Valenton) to irradiate a gold hohlraum, within which a CH-tamped Mg or Ge sample was radiatively heated. A 200-ps duration Pr backlight probed the sample at different delayed times to produce spectral absorption features. Temperature was monitored using Mg K-shell absorption measurement that was cross-checked with radiative-hydrodynamic calculations. The experimental technique was used to measure Ge L-shell absorption data. The interpretation of Ge spectral opacity data shows that the orbital relaxation treatment has a strong impact on theoretical results. This is confirmed by detailed-line accounting calculations.