Temporal dynamics of femtosecond-TALIF of atomic hydrogen and oxygen in a nanosecond repetitively pulsed discharge-assisted methane–air flame. (23rd April 2021)

• Record Type: Journal Article
• Authors: Ding, Pengji; Ruchkina, Maria; Del Cont-Bernard, Davide; Ehn, Andreas; Lacoste, Deanna A; Bood, Joakim
• Is Part Of: Journal of physics. Volume 54:Number 27(2021)
• Publication Date: 2021-04-23
• Subjects: fs-TALIF -- plasma assisted combustion -- NRP -- atomic hydrogen -- atomic oxygen; Physics -- Periodicals; 530
• DOI: 10.1088/1361-6463/abf61f
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: The temporal dynamics of the spatial distribution of atomic hydrogen and oxygen in a lean methane–air flame, forced by a nanosecond repetitively pulsed discharge-induced plasma, are investigated via femtosecond two-photon absorption laser-induced fluorescence technique. Plasma luminescence that interferes with the fluorescence from H and O atoms was observed to decay completely within 15 ns, which is the minimum delay required for imaging measurements with respect to the discharge occurrence. During discharge, H atoms in the excited state rather than the ground state, produced by electron-impact dissociation processes, are detected at the flame front. It was found that the temporal evolution of H and O fluorescence intensity during a cycle of 100 µ s between two discharge pulses remains constant. Finally, the decay time of O-atoms produced by the discharge in the fresh methane–air mixture was about 2 µ s, which suggests a faster reaction between O-atoms and methane than in air.