SUPERSONIC RADIATIVE HEAT WAVES IN LOW-DENSITY HIGH-Z MATERIAL

The propagation of a radiation heat wave through lead-doped foam with a density of 80 mg/cm3 was experimentally investigated. The wave is driven by 100150 eV Hohlraum radiation generated in 13 mm diam gold cavities heated by a 2.5 kJ, 0.8 ns laser pulse (wavelength 0.35 m). The propagation velocity was obtained from the delayed onset of intense thermal emission from the rear side of the foam sample. The results agree with theoretical predictions for a nonablative heat wave and with numerical simulations, and indicate that the radiation heat wave propagates with a velocity that is larger than the sound velocity in the heated foam. © 1994 The American Physical Society.