For most orbital maneuvers, small satellites weighing less than 10 kg require propulsion systems capable of producing thrust in the micro-Newton to milli-Newton force range. At this scale, electrokinetic (EK) pumping offers a method to precisely meter liquid propellants under purely electrical control at pressures and flow rates well-suited for microthruster applications. After exploring a variety of materials and surface treatments for the electrokinetic pumping media, the authors have demonstrated EK pumping of anhydrous hydrazine using both packed-capillary and larger sintered-monolith pump designs. Hydrogen peroxide has proven difficult to directly pump electrokinetically, but they have shown the utility of delivering peroxide and other electrokinetically incompatible liquids indirectly using in-line reservoirs with fluidic isolation to separate the pump working fluid from the propellant. Directly- and indirectly-pumped propellants have been delivered to novel capillary microthrusters with integrated catalyst beds and plasma-formed micronozzle structures. Specific impulses up to 190 s have been shown for hydrazine in non-optimized capillary thrusters at a mass flow rate of 1.5 mg/s. Controlled thrust pulses with a maximum continuous thrust of 1.5 mN, minimum impulse bit of 7 muN-s, and average specific impulse of 110 s have been demonstrated with the electrokinetically pumped microthruster assembly.
Electrokinetic pumping of liquid propellants for small satellite microthruster applications
Elektrokinetisches Pumpen von Flüssigtreibstoffen für kleine Satelliten-Mikroschubantriebsanwendungen
2008
10 Seiten, 13 Bilder, 1 Tabelle, 40 Quellen
Aufsatz (Konferenz)
Englisch