Spatially resolved extreme ultraviolet spectra were measured from the rear side of gold foils irradiated with 1.05-μm wavelength, 100-ps pulses at intensities of 3× ${10}^{14}$ W/${\mathrm{cm}}^2$. In the energy range of 0.1 to 1.0 keV the radiation intensity decayed exponentially with foil thickness up to 1 μm but remained almost constant over the range of 1 to 6 μm. These results indicate that radiation heat conduction plays an important role in high-$Z$ plasma energy transport. Ablation by the radiation heat flux is briefly discussed.

• Received 18 March 1981

DOI:https://doi.org/10.1103/PhysRevLett.47.1000