Development of an ultrasonic acoustic interferometer for silicate liquids in an internally heated pressure vessel

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EAR-0447113Lange The goal of this project is the development of a high-pressure acoustic interferometer that can be used to measure the sound speed and density (and thus compressibility) of silicate liquids in an internally heated pressure vessel (IHPV). We plan to develop two different techniques at elevated pressure: (1) the frequency sweep method to measure liquid sound speed, and (2) the reflection coefficient method to measure liquid density. We will use an existing IHPV that is operable to 0.3 GPa and 1200 degrees celsius. Funds from this grant will be used for various equipment and machine shop costs and to partially support a full-time technician. Measurement of the density and compressibility of silicate liquids at high pressure is a major experimental imperative in the earth sciences, especially when applied to volatile-bearing melts. These data are needed for accurate thermodynamic calculations of crystal-melt and fluid-melt equilibrium at depth, which in turn are required for quantitative models of partial melting, melt transport, crystallization and degassing, and the mechanics of magma eruption. The graduate students involved in this project will obtain a strong background in thermodynamics, acoustics and signal processing, as well as petrology and geochemistry. It is anticipated that the techniques that we develop will become widely used throughout the ultrasonics and earth sciences community.