Analysis of burning rate phenomena and extinguished solid propellants from an interrupted closed bomb with plasma igniter [ETC launchers]

The morphological and chemical characterization of M30 propellants recovered after conventional and plasma ignition with polyethylene (PE) and polyethylene terephthalate (Mylar) in an interrupted closed bomb (extinguished at pressures between 35 and 100 MPa) has been performed. This work was undertaken to investigate mechanisms associated with the apparent burning rate augmentation of M30 under conditions of plasma ignition compared to conventional ignition. Burning rate augmentation of solid propellants with plasma ignition was found to occur during, but not after, the plasma event. The following factors are evidence of a more forceful process for plasma ignition compared to conventional ignition: a) the initial pressure rise was greater with plasma ignition; b) metals from the closed bomb hardware, and stripping of NQ from M30 propellants was observed in the perforations; c) irregular surface burning (possibly due to ablation). And hot embedded particles have been observed in grains after plasma, but not conventional, ignition. Extensive chemical analyses of extinguished grains have been performed, but no significant differences were revealed between plasma and conventional ignition, quite possibly because any early chemical interactions are obscured by normal burning processes occurring later.