Nonlinear Optical Diagnostics of Nitramine Combustion

The specific technical achievements of this Office of Naval Research contract are as follows. The use of a high pressure, motorized combustion vessel allowed control of the spatial location of the burning propellant surface and data acquisition from the thin (100 micron), near-surface reaction zone. Resolution of the temperature and species profiles in the reaction zone, required for further insight, was provided by a major advance, the implementation of Line CARS, a 1-D imaging geometry, that allows single shot (10 nsec) measurement of the large temperature and concentration gradients near the surface with a spatial resolution of 25 microns. Partial funding of the Line CARS work was provided under ARO Contract DAAL03-87-C-0005. An internal heater was designed and implemented in the motorized vessel that allowed the preheated strand to sustain combustion at low pressure (1 atm) with expanded reaction zones and increased spatial resolution. CARS was used to study the concentration profile of NO immediately above the surface of a nitramine flame at 2 atm pressure. Degenerate four wave mixing (DFWM) was investigated for diagnostics of minor combustion species in propellant flames. jg p.5