| الوصف: |
The focus of this research work is to develop plasma global models, to support the investigations on argon and carbon dioxide helicon plasma thruster, carried out at CISAS research center. These models have been applied in three different and consecutive research programs, the EU FP7 HpH.com program, the AO7048 ESA program, and the SAPERE-STRONG MIUR program. The models have been developed for the most general case of an electronegative magnetized discharge, therefore encompass all types of cold non magnetized or electropositive discharges. Furthermore, the models employs results from particle in cell simulations of the plasma exhaust plume, in order to account properly for the plasma detachment and acceleration provided by the so called magnetic nozzle effect. The simulations are in agreement with performed experiments on the laboratory set up, and allow prediction of the thruster propulsive performances. The viability of plasma assisted combustion for monopropellant propulsion applications, is also investigated. An experimental proof of concept is provided with a nitrous oxide gliding arc experiment, carried out at Drexel Plasma Institute. The experiment shows that the plasma is effective in promoting catalytic decomposition and combustion of the gas. A global model is developed to investigate the mechanism of nitrous oxide plasma assisted dissociation; the model implements non-equilibrium neutral gas phase reaction rates and a vibrational energy equation for the estimation of the vibrational temperature. The model is able to reveal the mechanism of plasma catalysis, and predicts good performances for an hypothetical nitrous oxide microwave discharge thruster. |