Cold Gas Micro Propulsion

This thesis describes the development of a micro propulsion system. The trend of miniaturization of satellites requires small sized propulsion systems. For particular missions it is important to maintain an accurate distance between multiple satellites. Satellites drift apart due to differences in mass, area and position of the satellites. A miniaturized propulsion system of a cold gas blow-down rocket engine is presented. The system consists of two parts; the low pressure storage system and the feeding and thruster system. The feeding and thruster system can generate the thrust required for position corrections of the satellite. It consists of several functional modules; an active valve, a particle filter, a nozzle and an electronic module. A nozzle is needed which can deliver a thrust in the mN range. The nozzle is used to increase the efficiency of the propulsion system. We explored the fabrication of a 3D conical converging-diverging nozzle shape by means of MST techniques. These techniques are: deep reactive ion etching, femtosecond laser machining and a technique which uses powder blasting in combination with a heat treatment. It is shown that the latter two methods are most promising. The valve has to be very leak-tight to ensure a successful satellite mission. In conventional valves a low leak-rate is obtained by a large and forceful actuator. To allow for smaller valves a novel design is presented requiring low force – and thus a smaller actuator - while still promising to be leak-tight. A flexible thin film membrane is pulled over a valve seat pattern to make a leak-tight seal. Due to the flexibility of this membrane it can deform and adjust to the surface topography. A lot of progress has been made in the manufacturing of this novel valve