ETD

• Hall-effect Thruster
• I2HET
• Iodine

Hall-effect thrusters are devices which exploit plasma phenomena to ionize a propellant and to accelerate it thus to generate thrust. These devices are typically employed in space platforms to perform a variety of in-orbit maneuvers and eventually for deep-space exploration. The implementation of this technology has been made possible by the need of reducing the propellant consumption. Hall-effect thrusters currently operate using xenon. This element features several advantageous properties for electric propulsion. Yet, as resources of xenon tend to become less and less available and therefore its price tends to fluctuate, space missions definitely require alternatives. Among all the options, iodine possesses several features which make it a promising alternative propellant for electric propulsion applications in a xenon-replacement perspective.
The present dissertation deals with the development of an iodine feeding system for Hall-effect thrusters. An analysis of the employed methodologies to control the gas feeding flow is provided. A 1-D thermal fluid model is developed and discussed to theoretically analyze the gas generation mechanism. The model guided the design of the feeding system described throughout this document. A series of experimental activities have been performed and they are reported together with the related results. The feeding system performance have been measured. As a result, the selected architecture of the system revealed the viability of generating iodine vapor with low power consumption in accordance with the design choice. The outcomes of the experimental campaign allowed to calibrate the theoretical model. A major
contribution of calibration process consisted in using a gas kinetics approach to model the iodine transport properties. Afterwards, a series of preliminary propulsion tests have been performed by coupling the feeding system with a thruster unit. The results of these experiments are reported and discussed. Lastly, initial activities concerning the realization of an improved feeding system are described.