Development of N2 laser-induced fluorescence (LIF) techniques is desirable for probing reacting and non-reacting air flows. However, the absence of N2 absorption spectra accessible to available lasers prevented, until now, the development of such techniques. We identified experimentally an efficient multi-photon, laser-induced N2 ionization process. The resulting ions can serve for temperature measurements or as tracers for velocity measurements in hostile environments or in-flight applications. The ionization path, ion concentration, quenching parameters, and application of a scheme for velocity and temperature measurements were evaluated.
© 1991 Optical Society of AmericaPDF Article