Basic MATLAB simulation of ion propulsion rocket by chlorine as propellant via negative ion pair thrusting

Abstract

Ion propulsion rocketry is increasingly becoming popular by ion-ion pair thrusting concept, because they need low propellant, and design thrust around 1.5 N with low electric power and high efficiency. Basic MATLAB simulation of negative ion-negative ion pair propulsion has been explained in this article. Negative ion plasma has been obtained from electronegative gas, e.g. chlorine, by attachment of electron. Formation of large stable negative ion is achievable due to high electron affinity of chlorine. Electron affinity is a measure of energy exchange due to the addition of electron to a neutral atom to form a negative ion. When the neutral chlorine picks up electrons and forms chloride (Cl^-) ion, the energy released due to exothermic reaction is -349 kJ/mol (i.e., -3.6 eV/atom). Mechanism of attachment of electron to chlorine involves the formation of intermediates. Due to that, the high repulsive force is created between the same negative ions. Average distance between any neighbouring ions is important for rocket thrust calculation, and is determined by propellant exhaust velocity. Mass flow rate of propellant is assessed from the ratio of total mass of propellant needed for operation to time periods. This accelerates negative ions to a high velocity in the thrust vector direction with a significantly intense magnetic field and the exhaust of negative ions through nozzle. On comparing with theoretical value and earlier method (xenon ion-electron), this method is capable of achieving required thrust with low electric power (1 kW).