Summary
In mono-propulsion systems, a propellant is flowed across a catalyst to promote a chemical reaction and generate thrust. Conventional catalyst manufacturing methods entail (a) coating the inner walls of the thruster nozzle with a catalyst (generally undesirable due to limited catalyst-propellant contact), or (b) inserting a metal or graphite foam coated with a catalyst material into the thruster chamber. Method (b), while superior in terms of thrust generation, also possesses several limitations. Metal/graphite foams are difficult and expensive to procure, stochastic/random in nature (e.g., possess high variability in terms of geometric and other properties), and must be jammed into the thruster chamber using a compression plunger during installation – a process that often leads to catalyst damage. A new manufacturing method that improves repeatability, thruster reactivity, and tailorability (e.g., mechanical, chemical, and fluid flow) while reducing cost and lead time is thus highly desirable. To address this need, NASA and EOS developed methods to additively manufacture (AM) ultra-fine lattice structure propulsion catalysts.