We continue to develop a wide range of diagnostics that employ tunable diode laser absorption spectroscopy for sensing temperature, pressure, veloctiy, and a variety of chemical species. These diagnostics can be used to monitor and control combustion emissions, plasma semiconductor processing flowfields, fuel leaks, and bioreactor exhaust.

We use tunable pulsed lasers to investigate interactions between molecules and laser light. From this information we gain insight into the physical chemistry of these processes, which allows us to design imaging diagnostics based on planar laser-induced fluorescence (PLIF).

We use shock tubes to generate controlled temperatures and pressures and apply laser photolysis and laser frequency modulation spectroscopy to generate and monitor important chemical species. Reaction rates measured are used to model combustion and atmospheric chemistry to minimize pollutant production and optimize performance of combustion and propulsion systems.

We use laboratory-scale pulse detonation engines, shock tunnels, and expansion tubes to explore novel propulsion systems, including pulse-detonation engines, scramjets, and ram-accelerators. Diode-laser diagnostics, Schlieren imaging, and PLIF imaging diagnostics are applied to these systems to monitor performance and elucidate flow structure.

We have greatly extended the range of fuels and fuel loadings that we can study with a specially designed shock tube in which the fuel is injected as an aerosol. The aerosol injection technique allows us to study the chemical kinetics of fuels with very low vapor pressures. The technique can easily be extended to real fuels, which typically have multiple components or even more exotic fuels consisting of solid nano-particles.

We have developed a methodology for introducing micron sized biological spores into the aerosol shock tube. Along with a system that was developed to sample the spores after being exposed to a shock wave, the technique allows us to study the effect that shock waves have on the viability of bio-aerosols. Important shock wave characteristics such as the aerosol carrier gas composition, the shock strength and the duration of high temperatures and pressures can be independently varied to note their effect on spore mortality.