1-D ANALYSIS OF THE PLASMA PLUME OF A HOLLOW CATHODE WITH MAGNETIC NOZZLE

Small spacecraft with limited on-board resources would benefit greatly from the development of a low power, low cost micro thruster that will be able to offer propellant savings over conventional alternatives and enable higher energy missions. Such kind of a thruster would also be beneficial in the development of all-electric spacecraft whereby the normally separate reaction control system and primary electric propulsion system were able to operate from a common propellant management system and it can be used as a main thruster for micro-small satellites. Hollow cathode have recently been investigated as potential standalone micro thrusters and the Thrust measurements suggest that in some cases, hollow cathodes are able to generate specific impulse of over 1000-s depending on the operating conditions and propellant used. Knowing that the HC can produce thrust the thesis work will emphasize on improvement in the thrust production from HC with a magnetic nozzle creating a new path in the field of electric propulsion in the micro thruster development region. For this a one-dimensional (1-D) model for the study of the plasma plume generated by the hollow cathode with a magnetic nozzle has been developed and the fluid equations of the model have been solved numerically, under the assumptions of an axial magnetic field and that all the parameters vary only in the axial direction. The plasma is assumed to be quasi-neutral. The variation of the plasma parameters as the plasma expands in the magnetic nozzle has been investigated for a xenon mass flowrate of 1.5 mg/s, 30 A of current and 50-mT of maximum applied magnetic field. In the energy equation for ions and neutrals, heat flow and thermal conductivity have been considered low and hence neglected. Finally, thrust using the magnetic nozzle has been computed and compared with the thrust without magnetic nozzle, finding that the application of the magnetic field allows for significantly higher thrust production