Laser-Initiated Ignition of Solid Rocket Propellants

Investigating the ignition of solid rocket propellants is essential for their characterization and application. Ignition is defined as self-sustained regression after initiation cessation and depends on propellant composition, as well as ambient conditions such as pressure and temperature. These conditions influence the characteristics of combustion initiation. Central parameters are the minimum ignition energy and the ignition delay, the energy and delay threshold for initiated combustion of the examined composite propellants. The determination of the initiation characteristics demands a reliable and repeatable ignition which is provided by laser irradiation. Laser initiation is precisely controllable and chemical-free, thus eliminating the need of primers and pyrotechnic igniters. With this ignition method, the probability for accidental initiation is decreased and contamination, handling and aging risks are reduced. The objective of this study is the characterization of ignition by altering the energy and power of the initiating laser excitation. Experiments are monitored by high-speed imaging. Results show a shortening in ignition delay for increased laser power.
The study delineates pressure-dependent ignition-energy maps and yields a power dependence of the ignition delay time following an exponential decay.