This paper presents the development status at Delft University of Technology of a low-pressure micro-resistojet based on a sublimating solid propellant. In this particular type of electro-thermal thruster the propellant is water, stored as a solid and operated at very low pressure, under sublimation conditions. The steam is then expelled at high Knudsen numbers, through microchannels. The particle velocity is increased in the microchannels not by geometrical expansion as in conventional thermal propulsion concepts, but by thermal energy of the walls, transferred to the particles through collisions. The Direct Simulation Monte Carlo numerical simulations presented in the paper show that it is theoretically possible to achieve a specific impulse of 63.7 s up to 110.7 s with a plenum pressure of 50 to 300 Pa and a microchannel wall temperature of up to 900 K. A model of the tank was also designed and simulated using, in this case, the COMSOL Multiphysics 4.4 software. The sublimation is controlled inside the tank according to the mass flow needed by the plenum to keep the thermodynamic state required. These designs and simulations are based on DelFFi mission requirements and, in particular, the need to perform a basic formation flying demonstration. Additionally, the results show that by controlling the heater chip temperature, the tank temperature and the mass flow rate one can easily control the thrust and specific impulse allowing an optimal correlation between them. This opens the way to a better understanding of the operational principle of this concept and to its possible use in future demonstration missions.
|Conference||IAF 66th international astronautical congress, IAC2015, Jerusalem, Israel|
|Period||12/10/15 → 16/10/15|