Stress gage system for the megabar range

The report covers a one-year study of the feasibility of measuring stress wave profiles in the megabar range. The primary objective was accomplished with the successful manganin gage recording of a 1.2 megabar stress wave profile, including release to zero stress. The conductivities of various insulators were measured at shock stresses of 700-800 kbar. Lucalox (Al2O3 ceramic), fused silica, and a Cabal glass were excellent insulators in this stress range. The electrical resistivity of epoxy at high shock stresses was improved by adding Al2O3 powder. The mutual inductance particle velocity gage did not show promise of working at very high stresses in a nuclear test environment. Further developmental work is suggested.