Laser Ignition of Various Pyrotechnic Mixtures - an Experimental Study

• Published in: Propellants, explosives, pyrotechnics explosives, pyrotechnics, 2015-10, Vol.40 (5), p.755-758
• Main Authors: Sivan, Jonathan, Haas, Yehuda
• Format: Article
• Language: English
• Subjects: Combustion chambers; Correlation; Delay; Emission spectroscopy; Fuels; Ignition; Laser ignition; Lasers; Oxidizers; Pyrotechnics; Thermal ignition theory
• ISSN: 0721-3115; 1521-4087
• DOI: 10.1002/prep.201500080

Ignition of several pyrotechnic mixtures by diode‐laser was studied experimentally using a novel combustion chamber. The ignition delay times dependence on laser intensity could be fit by the expression tign=aI−n for all compositions, with I being the laser intensity at target and n=1.4–2.1. This is roughly in accordance with thermal ignition theories assuming a semi‐inert solid. Differences in ignition delay times did not depend on fuel alone or oxidizer alone. The temperature of oxidizer decomposition does not correlate with ignition delay time. Furthermore, the steady state combustion temperature, deduced from emission spectra of the composition products are not correlated with ignition delay time. It is proposed that chemical reactions, taking place in the gas‐phase or in the solid‐phase, play a significant role, but are not solely responsible for ignition delay time. The seemingly uncorrelated ignition delay results between pyrotechnics containing either the same fuel or oxidizer hamper the construction of a “unified theory” for laser ignition of pyrotechnic mixtures.