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A newly developed power processing unit (PPU) offers the advantages of smaller size and lighter weight than conventional PPUs. The thrust performance of a magnetic layer type Hall thruster developed at Kyushu University with this new PPU was investigated; it showed a good performance as compared with conventional power supplies. The thrust to power ratio was improved to 58 mN/kW at discharge voltage of 150 V and anode xenon mass flow rate of 1.0 mg/s.

A new ignition system utilizing discharge plasma for reaction control system (RCS) thrusters with green monopropellant is designed and evaluated experimentally in this study. The discharge plasma ignition system laboratory model (DPI-LM) is designed for one of hydroxyl ammonium nitrate (HAN) based monopropellant, SHP163; moreover, the DPI-LM is in substitution for conventional solid catalyst. Objectives of this study are (1) to design and build of DPI-LM and (2) evaluate basic propellant ignition characteristics in terms of successful and stable propellant ignition conditions, power consumption, and fundamental lifetime estimation. In addition, in order to generate discharge plasma prior to propellant ignition, a noble gas is used. Effect of noble gas type, argon and helium, on propellant ignition characteristics are also evaluated. Argon gas shows better propellant ignition with wide ranges of argon and SHP163 mass flow rates. It is considered that the propellant ignition strongly connects to discharge plasma diffusion condition prior to ignition. The power consumption at an argon mass flow rate of 0.075 g/s and a SHP163 mass flow rate of 0.3 g/s is approximately 270 W. The electrode degradation as a function of accumulated experiment time is evaluated as simplified lifetime estimation. The results of the degradation is only 0.1 % in electrode mass at 2000s , and the stable propellant ignition keeps at an accumulated time of 2000 s. Nomenclature I (t) = instantenous discharge current PW = power consumption t p,i = beginning time of the phase t p,f = end time of the phase V (t) = instantenous discharge voltage Δt p = duration of the phase 1 Graduate Student, Department of Aerospace Engineering, tiizuka@astak3.sd.tmu.ac.jp, Student Member.