Electrokinetically Pumped Liquid Propellant Microthrusters for Orbital Station Keeping

For most orbital maneuvers, small satellites in the sub-10 kg range require thrusters capable of spanning the micro-Newton to milli-Newton force range. At this scale, electrokinetic (EK) pumping offers precise metering of monergolic or hypergolic liquid propellants under purely electrical control at pressures and flow rates well-suited to microthruster applications. We have demonstrated direct and indirect EK pumping for delivery of anhydrous hydrazine and hydrogen peroxide monopropellants, respectively, into capillary-based microthrusters with integrated in-line catalyst beds. Catalytic decomposition generates gases which accelerate through a plasma-formed converging-diverging nozzle, producing thrust. Specific impulses up to 190 s have been shown for hydrazine in non-optimized nozzles.