The assessment of the different magnetic field topologies found in plasma propulsion thrusters using a finite element code

Abstract

Electrical thrusters can be used as a useful alternative to the chemical thrusters, the major dominant in the spacecraft industry due to their high specific impulse, and thus low fuel consumption, which results in smaller fuel weight. The Hall Effect Thruster is included in the electrostatic category as the plasma is formed inside the chamber of the thruster. It is based of electrons thrown into a chamber from an external cathode towards an inner anode, inducing an axial electrostatic potential an ionizing the injected neutral gas. A magnetic field is also induced, in order to prevent electrons from reaching the anode too quickly and also accelerate the ionized heavy particles that will generate thrust. On the other hand, the Helicon Plasma Thruster could be considered as an interesting alternative based on the energy source energy in the form of Helicon Plasma Sources. From the point of view of the energy, the HPT behaves as an electrothermal thruster, heating the plasma with RF waves radiated from an antenna and supersonically expanding it in a magnetic nozzle. From the thrust generation point of view, the HPT behaves as an electromagnetic thruster, due to the interaction between the azimuthal plasma currents during the supersonic expansion and the magnetic field lines, that produces an action-reaction force that accelerates the plasma and confers thrust to the vehicle. This bachelor thesis is focused on the analysis of the infuence of the different magnetic elements (such as solenoids, coils or even permanent magnets, etc. used in the design of the magnetic circuits of both thrusters) on the magnetic field topology. To perform the study, an open-source, finite-element method code is used. This code allows to calculate the magnetic field of different magnetic circuits to evaluate their infuence. In the case of the Hall thruster, the different parameters to get the desire magnetic element configuration and intensity have to been developed by trial and error configuration. On the other hand, in the case of the HPT, actual information implemented in a prototype performed by EP2 and Sener is used. In a first approximation, punctual elements are taken into consideration, and in further analysis filling factor are included so as to add more realism to the model.