Ignition of composite solid propellant at subatmospheric pressures

Abstract

The ignition of composite solid propellants by CO 2 laser irradiation at low pressures has been investigated experimentally. Three ignition modes are found at subatmospheric pressures: self-sustaining ignition, non-self-sustaining ignition, and pulsating ignition. Here, the self-sustaining and the non-self-sustaining ignition modes have been studied. Samples of an ammonium perchlorate polybutadiene propellant were ignited. The incipient flame was detected with a phototransistor, and the temperatures at the surface and in the solid phase were measured by means of Type K thermocouples. Aspects of surface regression were recorded by photography. It is found that non-self-sustaining ignition occurs in the lower pressure range and with the higher incident heat flux from the laser. At ignition, the heat loss into the solid phase in the non-self-sustaining mode is much larger than that in the self-sustaining one. It is concluded that these ignition modes are determined independently of the exposure time after the flame's appearance.