Model for Ammonia Solar Thermal Thruster

Abstract

This work is an attempt to investigate the nozzle expansion characteristics of a solar thruster that uses ammonia as the propellant. For this purpose we have developed a state-to-state kinetic model to study the dissociation of ammonia in a supersonic nozzle expansion. The properties of the thruster depend on the ammonia dissociation degree in the reservoir, which can be very far from equilibrium due to the very slow dissociation kinetics at the thruster working conditions (less than 2000 K). We have extended the calculation for higher temperatures (greater than 2500 K) where ammonia dissociation is higher. Because of the presence of some hydrogen atoms, non-Boltzmann distributions have been observed.