Immersed-Foil Method for Measuring Shock Wave Profiles in Solids

A new technique is described for measuring, essentially directly, a complex shock front profile that is transmitted into a transparent liquid from a solid material. The image of a grid light source, reflected from a Mylar foil immersed within the liquid, is recorded with a streak camera.Index of refraction data for liquids in the high‐pressure shocked state (required for calculating particle velocities from image displacements) are reported for glycerol, ethanol, water, and hexane to 220, 135, 58, and 41 kbar, respectively. The increase of index of refraction with density for water agrees with that reported by Zel'dovich, Sinitsyn, and Kormer, but is considerably less (as are also the results for the other liquids) than that predicted by the Lorentz‐Lorenz formula. Hugoniot data obtained concurrently with the refractive index data agree closely with those of Rice and Walsh. Applications of the immersed‐foil method are discussed for: (a) determining the release adiabats from shock states produced by a double shock front in a solid; (b) the study of shock wave attenuation in solids; and (3) measurement of the adiabatic sound velocity of liquids in the high‐pressure shocked state