Spatially resolved X-ray line emission allows a detailed study of axial-energy-transport processes in layered Al-SiO2 targets irradiated with 1.06-μm, 80-ps FWHM laser pulses and flux levels in the 1014–1016W·cm−2 range. By means of a double-laser-pulse technique, a comparison between simulations and experiments enables a thermal-flux inhibition factor and the fast-electron pre-heating characteristics to be determined.