Measurement of multispecies concentration and gas temperature in an ammonium-dinitramide-based thruster by tunable diode lasers

In this paper, quantitative experiments were made to measure the concentration of key intermediate products (CO, N2O, and NO) and the gas temperature for combustion flow based on near-infrared and mid-infrared laser absorption spectroscopy. This paper used the developed diagnostic system to study two main ignition modes of a real 1-Newton thruster based on ammonium dinitramide (ADN): steady-state firing and pulse-mode firing over a feed pressure of 5-12 bar. The steady-state firing experiments distinguished the whole process into catalytic decomposition stage and combustion stage, experimentally demonstrating the combustion kinetics mechanism of an ADN monopropellant. Experiments for pulse-mode firing showed the measured multispecies concentration and temperature were consistent with pulse trains, verifying good performance for the thruster pulse-mode firing operation. The performance of the thruster was given based on the optical measurements, and characteristic velocity for the ADN-based thruster standard operation was higher than the corresponding 1-Newton hydrazine thruster. (C) 2018 Optical Society of America