Conceptual Propellant Feed System for Electrospray Thrusters and an Exploration into 3D Printed Millifluidic Manifolds

The miniaturization of satellites has led to a new era of miniaturized spacecraft technology, which includes propulsion systems. The full potential of CubeSats will be realized once they are equipped with miniaturized thrusters. One option being developed at the University of Tennessee Space Institute (UTSI) is a miniature electrospray device, Micro Scalable Thrusters for Adaptive Mission Profiles in Space (µSTAMPS). This device operates via electrospray principles and utilizes an ionic liquid (IL) propellant. µSTAMPS aims to provide CubeSats with maneuvering capabilities, including rapid deorbiting, station-keeping, and collision avoidance maneuvers (CAMs). An internal propellant reservoir can deliver enough propellant for CAMs; however, to achieve additional applications, an external propellant feed system is required. The focus of this thesis is to initiate the development of such a system. The first prototype employs a FEP bladder tank, a peristaltic pump, and an MSLA 3P printed (3DP) millifluidic propellant routing manifold (PRM). Primary goals were to develop a leak-free bladder tank to deliver 100 grams of IL and fabricate a 3DP millifluidic PRM to simultaneously distribute propellant to four thrusters. Seal strength tests (ASTM F88) were performed to determine the required tank thickness, which ended up being 0.1 in. However, the assembled prototype failed before any pressurization tests could commence. It was concluded that the current tank design was not ideal. The fabrication of the PRMs began with a comparison of print accuracy between Elegoo’s Mars 2 Pro (M2P) and Mars 4 Ultra (M4U). Test prints were performed with various support strategies; it was found that the PRMs should be printed with lightweight supports at a support density of 80%. PRMs were then fabricated on both printers with differing orientations and channel designs. These iterations were subjected to several flow tests; the ideal orientation was to print the wide face of the PRM perpendicular to the bed with an inlet on the wide face. However, the current method of fabrication does not allow simultaneous flow through each channel due to internal deformations. Overall, while the initial prototype faced challenges, the project lays a foundation for future improvements which will ensure the success of µSTAMPS.