Main directions of solid propellant micro-propulsion activity at LAAS

Solid propellant micro-thruster is an alternative option to cold gas and field emission electric propulsion systems for space. It can also be used for autonomous Micro-Air-Vehicles (MAV) micro-propulsion in complement to electrical motor. It is simple, cheap and requires low power to ignite the micro-combustion of a few milli-grammes of a solid propellant. This paper presents two concepts of solid propellant micro-thruster. The first one is a sandwich of three parts: a combustion chamber (with one or several wafers), an igniter and a convergent-divergent nozzle. They produce force thrust between 0.28mN and 14mN making them good candidates for station keeping or orbit maneuvers for micro-spacecraft. The second one is a planar structure, more powerful in comparison with the first structure. It is designed to deliver thrusts between 10mN and 50mN for civil and military applications, like the stabilization of MAV during stationary fly. It is made of three layers : (i) a combustion chamber and a micro-nozzle are micromachined on the same silicon wafer; (ii) a ceramic reservoir is reported on the top; (iii) a Pyrex glass seals the back side of the structure. The design, the micro-fabrication and the characterization of both structures are reported.