Thermal relaxation phenomena across the metal/window interface and its significance to shock temperature measurements of metals

Abstract

Difficulties in connection with the radiometry measurement of shock temperatures for metals, due to our insufficient knowledge of the high-pressure thermophysical properties of materials, are discussed in this paper. The thermal radiation histories from shocked iron film/sapphire interfaces are observed. It is found that after the passage of a shock wave, the thermal relaxation process at the metal/window interface is not always so rapid that the available pyrometric system is unable to respond. Shock temperature measurement experiments show that the spectral radiance history observed at this interface consists of an initial spike followed by a plateau, demonstrating distinctly the temperature relaxation behavior. This fact is contrary to the previous arguments in which the interface temperatures instantly approach their time-independent equilibrium value. Release temperatures are obtained directly from the observed amplitude of the irradiance spike, these values are comparable to those calculated theoretically from the plateau via the instantaneous equilibrium temperature model based on the well-known thermophysical properties of iron and sapphire at high pressure and high temperature. The observation of the thermal relaxation process shows that it is possible to obtain directly the release temperature of the metal samples even though their thermophysical properties at high pressures are not known. Therefore all the difficulties mentioned above can be avoided.

Temperature determination in shocked condensed materials using Raman scattering

“…1-10 Despite these refinements, questions remain about the use of pyrometry in particular situations. 8,9 Hence, the use of other experimental methods particularly at lower temperatures ͑below 2000 K͒ needs to be explored. In this communication, we describe the use of time-resolved, Raman scattering measurements to determine shock temperatures in condensed materials.…”