Design and fabrication of a MEMS-based millinewton level hydrazine thruster

A MEMS-based millinewton level hydrazine thruster was designed and tested in this research. The microthruster was composed of a microvalve, a microreactor, and a micronozzle. The detailed considerations of system and component designs were presented. For the microreactor, iridium coated micro catalytic bed was fabricated with a high flow path surface to volume ratio of 84mm²/mm³. The microreactor successfully proceeded hydrazine dissociation reactions and achieved desired ammonia dissociations over 90% at the hydrazine flow rates of interest. Bonded with the micronozzle, the microreactor/nozzle assembly produced an optimum performance at the hydrazine flow rate of 0.625mg/s, where a vacuum thrust of 0.99 mN was observed with a specific impulse close to 162s. A deficiency of 35% was estimated and considered mainly from the heat loss and viscous loss in microchannels. More effective thermal management should be developed in the future design. In addition, research on ICP etching control would be necessary to produce smoother surface to reduce the friction loss. This preliminary test result demonstrated the feasibility of utilizing hydrazine on MENS-based microthruster's operations.