Performance Evaluation Methodology for Materials Subjected to Explosively-Driven Highly Non-Radial Implosive Motion*

Non-radial implosive motion is experienced during the early stages of various important device formation processes, such a shaped charge jet. If the response of the material can be characterized during this initial stage of motion, then often the subsequent motion will be predictable. Diagnostics are either available or are under development, such as Modulation Based Ranging (MBR), to address this initial stage of motion. The use of velocimetry to evaluate material response when non-radial flow occurs is complicated by the non-colinearity of the velocity the surface normal, and non-colinearity with the laser beam. The result is that ordinary velocimetry results in an incomplete measurement, that of the component of velocty in the direction of the laser beam. We introduce a method, MBR, that measures the position that any object that intersects the laser line as a function of time, approximately closing the measurement system and enabling the application of the velocity-based evaluation methodologies. We describe our use of simultaneous Photon Doppler Velocimetry (PDV) and MBR along with radiography to characterize and compare the response two geometrically identical hemispherical shells that were manufactured differently.