R&D of Hall Thruster toward Japanese All-Electric Propulsion Satellite
To increase communication capability of geostationary satellites with suppressing the cost, the all-electric propulsion system is considered as one of the solutions. JAXA strongly recognizes the importance of all-electric propulsion technology, and as a result, the launch of Engineering Test Satellite 9 (ETS-9) is being prepared in the early 2020s to enable Japanese all-electric propulsion satellite with high throughput communication capability. The satellite bus of ETS-9 features high-power and medium size satellite bus whose weight is a 4,500kg and its electric power exceeds 25 kW. For orbit raising maneuvers from a launch orbit, two or three Hall thrusters will be simultaneously used, and they are mounted on a swingable arms to optimize thrust vector suitable for orbit raising. After reaching a geostationary orbit, thrust vectors are changed to conduct station keeping operation.
Technological R&Ds for ETS-9 started from 2015 at JAXA. Along with new satellite bus system consisting of high-power solar paddles, power control unit, and structural/thermal design that is scalable up to 6,000 kg, a 6-kW-class hall thruster system is identified as a strategic sub-system and is intensively under development. A Hall thruster head was designed by IHI Aerospace, IHI, JAXA and TMU, and testing of breadboard models were conducted not only to select appropriate channel-magnetic field design but also to evaluate erosion profiles during the initial 500 hours of continuous thruster operation. Typical thruster performance was obtained at Georgia Institute of Technology, showing a thrust of 359 mN and an Isp of 1710 s at an input power to the thruster head of 6 kW (for orbital raising), and 83 mN/1710s for a reduced input power of 1.8 kW (for station keeping). The specification for ETS-9 is, however, still to be determined since appropriate contingency plan such as back-up thruster system is necessary based on related evaluations in particular life tests which are planned in this fiscal year.
My personal expectation is that ETS-9’s Hall thruster with some diagnostics devices will provide a good opportunity to clarify the so-called facility effect by comparing in vacuum chambers and its flight data. I hope to share some of ETS-9’s flight data with the EP community so that ETS-9 will be beneficial not only for Japanse industry but also for the world’s EP community.