Design and evaluation of a propellant feed system for electric propulsion systems using aromatic hydrocarbons

The use of aromatic hydrocarbons as plasma thruster propellants represents a promising alternative to xenon, providing storage advantages, low ionization losses, high specific thrust, as well as low post-ionization fragmentation. However, using aromatic hydrocarbons requires significant changes at propulsion system level, in terms of storage and feeding system, and for the experimental setup, since conventional vacuum facilities for electric propulsion are designed to operate with inert gaseous propellants. The focus of the proposed project is on the design, prototyping, and evaluation of the propellant feed system based on the aromatic hydrocarbon naphthalene. After reviewing existing feed system technologies, a design was implemented considering the physical and chemical properties of the candidate propellant and the flow theory along the system. The idea is to control the flow rate by regulating the temperature and thereby controlling the sublimation inside the tank. A complete mechanical and thermal design of the feed system was developed, manufactured and assembled, and evaluated in a vacuum chamber setup. In particular, controlling and measuring the flow of the propellant was demonstrated, as this is the key for subsequent evaluation of the thruster performance. Future work may include enhancements to the design and testing setup, along with a focused investigation of the pipe effect and its integration with the thruster.