Abstract

Alkali metals are prevalent in coal combustion, biomass thermal conversion to fuels, and energetic material combustion, and have applications as dopants for combustion diagnostics and plasma-based combustion control. Recently, the dynamic control of propellant burning rate and pyrotechnic luminosity have been demonstrated through combined microwave field radiation and incorporation of alkali dopants. Understanding of the alkali distribution within the flame is essential to predicting field–flame interaction. However, the multiphase propellant combustion environment exhibits significant particle scattering, broadband emission background, and high optical density, which complicate optical measurements. Here, multiple two-photon laser-induced fluorescence (LIF) schemes for atomic sodium were compared in gas-phase flames and sodium-doped solid propellant combustion. For the two-photon Na LIF scheme, a rate equation model incorporating fluorescence, amplified spontaneous emission, and ionization shows good agreement with experimental characterization in a gas-phase flame. The technique was then extended to sodium-doped solid propellant flames, a multiphase combustion environment characterized by strong particle scattering. The 3s–3d two-photon excitation LIF achieved a better signal-to-noise ratio of ${\sim}100$ in the propellant flame and allowed imaging of gradients in the gas-phase sodium distribution at the burning surface.

© 2020 Optical Society of America

Full Article  |  PDF Article
More Like This
Laser-induced fluorescence detection strategies for sodium atoms and compounds in high-pressure combustors

Karen J. Rensberger Weiland, Michael L. Wise, and Gregory P. Smith
Appl. Opt. 32(21) 4066-4073 (1993)

High-repetition-rate three-dimensional OH imaging using scanned planar laser-induced fluorescence system for multiphase combustion

Kevin Y. Cho, Aman Satija, Timothée L. Pourpoint, Steven F. Son, and Robert P. Lucht
Appl. Opt. 53(3) 316-326 (2014)

References

You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Figures (7)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Tables (2)

You do not have subscription access to this journal. Article tables are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Equations (13)

You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Metrics

You do not have subscription access to this journal. Article level metrics are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription