Development of a high-pressure quasi-isentropic plane wave generating capability

A new technique for generating quasi-isentropic compressive waves in condensed materials is described. The method makes use of a pillow impactor to cushion the impact that creates the wave. Uniaxial strain compression is produced for ease of data analysis, and the method can be used to generate waves over a very wide range of peak stresses, including multi-megabar waves. A number of facets of the technique are discussed, such as input wave risetimes, simultaneous shock-up concepts, pillow spall tendencies, and data analysis techniques. Using the new technique on aluminum has resulted in new experimental support for recent theories on localized shear heating during dynamic loading. Finally, the fabrication of the pillow impactors is described in some detail, and pillow quality control testing is discussed.