Probability distribution of laser-induced breakdown and ignition of ammonia

Laser-induced breakdown and ignition of atmospheric pressure ammonia and ammonia/oxygen mixtures were studied using a nominal 7-ns pulsed Nd : YAG laser source. The probability distribution functions (pdf) for the breakdown and ignition events were determined. For the pdf measurements, the NH-radical ground electronic state was observed using resonant laser-induced fluorescence (LIF), and comparison of the LIF and spontaneous emission of the NH A-state emission is shown. The NH X-state concentration is shown to give a reliable indicator of ignition at 5 mu s following breakdown. (C) 2000 Elsevier Science Ltd. All rights reserved.