Global model of microwave plasma assisted N2O dissociation for monopropellant propulsion

Abstract

A global numerical model is developed to study the capability of a Microwave Electro-thermal thruster (MET) to operate with Nitrous Oxide gas (N2O), for spacecraft monopropellant thruster applications. N2O is a "green" propellant with interesting properties but highly inert when used as monopropellant; the non-equilibrium activation effect of the plasma is able to promote combustion of the gas. The model is self-consistent and features different temperatures for the vibrational modes of the mixture in order to account for possible vibrational activation effects of the plasma; a detailed kinetic scheme is presented, comprising rates for vibrational energy exchanges between the modes. The model shows that good theoretical efficiencies can be achieved by operating the MET with N2O, with thrust to power ratios up to 1 mN/W and specific impulse up to 200 s. The main channels of plasma assisted dissociation are examined, and the role of vibrational non-equilibrium is addressed.