Sandia hypervelocity gun technology for validating EOS at extreme pressures and temperatures

Abstract

At very high impact velocities material properties will be dominated by phase-changes, such as melting or vaporization. These phase changes are not easily attainable at typical light-gas gun velocities of 8km/s. Development of well-controlled shock loading capabilities is the first step necessary to improve the understanding of material behavior at extreme pressures and temperatures not currently available using conventional two-stage light-gas gun techniques. In this paper, techniques that have been used to extend both the launch capabilities of a two-stage light gas gun to 16 km/s, and their use to determine the material properties at pressures and temperature states higher than those ever obtained using two-stage light-gas gun loading techniques are summarized. The newly developed hypervelocity launcher (HVL) can launch intact (macroscopic dimensions) plates to 16 km/s. Time-resolved interferometric techniques have been used to determine shock-loading/release characteristics of aluminum impacted by an aluminum flier, and shock-induced vaporization phenomena in fully vaporized zinc at impact velocities of 10 km/s. These experiments also define the maximum stress limit i.e., 200 GPa to which lithium-fluoride windows can be utilized as a laser velocity interferometer window.