Micro-Chemical Monopropellant Thruster
Final rept. 1 Aug 2004-1 Feb 2006
SURREY SATELLITE TECHNOLOGY LIMITED GUILFORD (UNITED KINGDOM) SURREY SPACE CENTRE
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This report summarises the work completed under EOARD contract 043022 Micro-Chemical Monopropellant Thruster. The research was carried out at the Surrey Space Centre, University of Surrey and the testing was conducted at the Surrey Satellite Technology Ltd Propulsion Test Site, Westcott, Bucks. The need to extend the on-orbit capabilities of nanosatellites has led to the requirement for a miniaturised propulsion system. The mass, power and volume constraints placed on this system by the host nanosatellite platform lead to the selection of a chemical propulsion system. In order to optimize the thrust available and minimise complexity a monopropellant system is a favorable solution. The research has considered the miniaturisation of two key components of a monopropellant thruster the decomposition chamber and the nozzle. The focus was the extent of miniaturisation that was possible, while maintaining the use of a conventional approach in terms of manufacture and testing. Hydrogen peroxide was selected as the propellant due to its favorable handling characteristics and previous use at the Surrey Space Centre. The geometry and morphology of a decomposition chamber are critical to the overall performance of the thruster. As the magnitude of thrust generated by the thruster reduces, the mass flow rate of propellant reduces together with the associated dimensions of the complete system. Empirical guidelines exist for the design of a decomposition chamber for a thruster of conventional size, however it is uncertain as to whether these remain applicable at thrust levels below 1 N. Two different catalyst morphologies were considered in decomposition chambers of various diameter and length. A manganese oxide catalyst, supported on a high density alumina foam was used to assess the performance of a monolithic catalyst bed and a silver powder was used to investigate the performance of a compressed powder catalyst bed.
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