Operational Characteristics of an Iodine Propellant Feed System for Electric Propulsion

The paper aims to study an iodine propellant feed system for electric propulsion. Firstly, comparisons of different previous design schemes are carried out, and a design scheme consisting of an iodine reservoir, a Bang-Bang controller, and a thermal throttle is proposed. Then, a simulation model is established using AMESim software to describe the design scheme, and the simulation results and the experimental data are compared. Finally, the effects of the inlet pressure of the thermal throttle and the temperature of the gaseous iodine in the thermal throttle on the flow rate of the gaseous iodine are studied. The operational performance of the Bang-Bang controller and the thermal throttle, and the effect of temperature in the iodine reservoir are analyzed. The results show that if the output flow rate of the gaseous iodine is 0.2 mg/s−3 mg/s with an error of ±10%, the inlet pressure error of the thermal throttle must be ±50 Pa, or the temperature error of the gaseous iodine must be ±15 K; if the high and low threshold pressures of the Bang-Bang controller are changed, the flow rate of the gaseous iodine can be various from 0.2 mg/s to 3 mg/s discontinuously, and the errors of the most output flow rate of the gaseous iodine are less than ±10%. In addition, the output flow rate has an accuracy of ±10% when the temperature change in the iodine reservoir is ±5 K. It is indicated that the design scheme can reduce the difficulty of temperature control in the iodine reservoir and further improve the accuracy of the output flow rate of the gaseous iodine.