Initial Review On A Water Based Hall Effect Thruster

This thesis represents a first feasibility study to adapt a Hall effect thruster (HET) currently available in the Sitael lineup to allow it to use water like propellant. Electrolysis process splits H2O in H2 and O2, then the generated gases are respectively employed to feed the cathode and anode. This concept could be revolutionary as it allows to significantly decrease the costs of the propellant and reduces safety risks for propellant's handling on the ground. An overview of the water thruster state of art is given. Then a potential propulsion system architecture to support operation of a HET with water is proposed; it follows a discussion on the possible ways to guarantee a correct mass flow rate at the right pressure for both oxygen at the anode side and hydrogen at the cathode side. A detailed study of the electrolysis technique is carried out. A suitable HET candidate from SITAEL's thruster portfolio is identified, which is foreseen to be the subject of future experimental campaigns. Then, the behavior of oxygen plasma is explored by considering the advantages and disadvantages in terms of thrust, specific impulse and efficiency compared to the more common xenon propellant. Lastly, a numerical 1-D stationary model is implemented in order to estimate plasma characteristics evolution along the channel in SITAEL's HET. Two different cases are analyzed: the first one is carried out with xenon, in the second one the thruster is supposed to be operated with oxygen on the anode side and hydrogen on the cathode side. The first case is to understand and check what are the nominal performance of the xenon fed thruster, the latter gives the expected performance with oxygen fed thruster. Final results remark how much difference there is between an heavy and atomic gas and light and molecular propellant. It follows a discussion to suggest possible way to increase the oxygen ionization and to improve the overall performance of the oxygen fed HET. The exploration of the behavior of hydrogen fed neutralizer is left to subsequent studies.