New diagnostic methods for laser plasma- and microwave-enhanced combustion

Area of Science:

• Plasma physics
• Combustion science
• Laser diagnostics

Background:

• Studying laser and microwave plasma interactions in combustion requires rapid diagnostic methods.
• Understanding these interactions is crucial for determining combustion mechanisms.

Purpose of the Study:

• To present new rapid diagnostic methods for analyzing plasma interactions in combusting gases.
• To extend the capabilities of existing techniques like Rayleigh scattering, Thomson scattering, and resonance-enhanced multi-photon ionization (REMPI).
• To introduce femtosecond laser-induced velocity and temperature profile imaging.

Main Methods:

• Spectrally filtered Rayleigh scattering for planar temperature field imaging and line imaging of velocity, temperature, and density profiles.
• Depolarization of Rayleigh scattering to measure dissociation fraction.
• Multi-wavelength line imaging to separate Thomson and Rayleigh scattering.
• Radar REMPI for stand-off detection of species in combusting environments at atmospheric pressure.
• Femtosecond Laser Electronic Excitation Tagging (FLEET) for generating excited species and dissociation, yielding temperature and velocity profiles.

Main Results:

• Demonstrated spectrally filtered Rayleigh scattering for detailed profile imaging.
• Showcased Radar REMPI as a stand-off detection method for atmospheric pressure environments.
• Introduced FLEET for simultaneous temperature and velocity profile measurements.

Conclusions:

• The presented rapid diagnostic methods significantly enhance the capability to study laser- and microwave-induced plasma interactions in combustion.
• These techniques provide crucial data for understanding complex combustion mechanisms.
• The developed methods offer versatile applications in combustion research and diagnostics.