Femtosecond Laser Electronic Excitation Tagging (FLEET)for imaging flow structure in unseeded hot or cold air or nitrogen
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A one millijoule, 150 femtosecond laser focused into either air or nitrogen dissociates nitrogen molecules along a line through the focal region, and the atomic nitrogen fragments emit light as they recombine. This emission lasts for tens of microseconds and allows the displaced line to be imaged with a time gated camera. Displacement and resolution can be measured to tens of microns. The images provide quantitative measurement of instantaneous velocity profiles and turbulent structure. Very little energy is deposited, so there is negligible flow perturbation, and the laser can be refocused through the volume to write multiple lines or patterns. Measurements in air range from several Torr to several atmospheres and from 100K to 2000K. 2013 by Princeton University.
51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013
author list (cited authors)
Miles, R. B., Edwards, M. R., Michael, J. B., Calvert, N. D., & Dogariu, A.