SBIR Phase II: High-Frequency Shearing Interferometer Emission Velocimeter (SIEVE) for High-Temperature Gas Diagnostics

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Rostler 9529856 This Small Business Innovation Research Phase II project will develop a powerful optical diagnostic for high temperature gases that is fundamentally different from any technique currently in use. This diagnostic is spatially localized but completely nonperturbing. For hot luminous gases it utilizes the optical emission from the gas itself. For less luminous gases, the new method can also be used by monitoring refractive effects on laser beams passed through the flow. In either realization, the light emerging from the gas is separated into two components whose intensity difference is due only to fluctuations of selected scale size in a spatially localized region within the extended volume of the flow. For low-frequency (10 MHz) phenomena, the method has already been demonstrated and is currently being developed under other programs. The purpose of this Phase II program is to extend the technique to much higher frequencies, which will allow study of smaller-scale phenomena and faster flows, as well as fast waves in plasmas. In Phase I a high-frequency detector head was designed and a new ultrahigh-frequency instrument was invented. Prototypes of both instruments will be fabricated and tested in Phase II. A high-frequency localized optical velocimeter would be a valuable diagnostic for very hot gases such as are found in arcs, combustion furnaces and industrial plasma processing chambers. It would also be useful for detailed studies of small-scale phenomena in flowing gases, such as boundary layers and turbulent wakes in wind tunnels. In the future, it is envisioned that this new instrument could also be used in process control applications. Groups conducting research on gases and plasmas would be the initial customers for such an instrument.