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Abstract Pulsed dielectric barrier discharges (DBD) in He–H 2 O and He–H 2 O–O 2 mixtures are studied in near atmospheric conditions using temporally and spatially resolved quantitative 2D imaging of the hydroxyl radical (OH) and hydrogen peroxide (H 2 O 2 ). The primary goal was to detect and quantify the production of these strongly oxidative species in water-laden helium discharges in a DBD jet configuration, which is of interest for biomedical applications such as disinfection of surfaces and treatment of biological samples. Hydroxyl profiles are obtained by laser-induced fluorescence (LIF) measurements using 282 nm laser excitation. Hydrogen peroxide profiles are measured by photo-fragmentation LIF (PF-LIF), which involves photo-dissociating H 2 O 2 into OH with a 212.8 nm laser sheet and detecting the OH fragments by LIF. The H 2 O 2 profiles are calibrated by measuring PF-LIF profiles in a reference mixture of He seeded with a known amount of H 2 O 2 . OH profiles are calibrated by measuring OH-radical decay times and comparing these with predictions from a chemical kinetics model. Two different burst discharge modes with five and ten pulses per burst are studied, both with a burst repetition rate of 50 Hz. In both cases, dynamics of OH and H 2 O 2 distributions in the afterglow of the discharge are investigated. Gas temperatures determined from the OH-LIF spectra indicate that gas heating due to the plasma is insignificant. The addition of 5% O 2 in the He admixture decreases the OH densities and increases the H 2 O 2 densities. The increased coupled energy in the ten-pulse discharge increases OH and H 2 O 2 mole fractions, except for the H 2 O 2 in the He–H 2 O–O 2 mixture which is relatively insensitive to the additional pulses.
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This content will become publicly available on April 21, 2026
Mid-wave infrared laser absorption tomography of nitrogen oxides for spatially resolved quantitative thermochemistry in H 2 -N 2 O flames
A tomographic laser absorption spectroscopy technique, using mid-wave infrared light sources, is presented as a quantitative method to spatially resolve the mole fraction and temperature in small-diameter reacting flows relevant to the combustion of nitrogen-based fuels and propellants, with particular applicability to the study of green propulsion concepts. Tunable quantum and interband cascade lasers are used to spectrally resolve multiple rovibrational transitions near 4.42 and 5.18 µm to measure N2O, NO, and H2O mole fractions, as well as gas temperature in an axially symmetric H2-N2O premixed jet flame. Signal processing methods for direct N2O thermometry utilizing a Boltzmann regression are detailed for the experiment, including considerations for the tomographic reconstruction of axial and radial profiles of thermochemical structure for the flame. The tomographic absorption spectroscopy technique is demonstrated to recover radially resolved N2O, NO, and H2O mole fractions for multiple planes at different heights above the jet exit, revealing distinct reaction zones in the jet flame associated with the production of each H2O and NO surrounding the relatively cool reactant core containing N2O.
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- PAR ID:
- 10584310
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Applied Optics
- Volume:
- 64
- Issue:
- 16
- ISSN:
- 1559-128X; APOPAI
- Format(s):
- Medium: X Size: Article No. D103
- Size(s):
- Article No. D103
- Sponsoring Org:
- National Science Foundation
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