Performance Improvement of the Microwave Discharge Ion Thruster
- Paper number
IAC-06-C4.4.10
- Author
Mr. Tatsuya NAKAI, University of Tokyo, Japan
- Coauthor
Dr. Kazutaka Nishiyama, Japan Aerospace Exploration Agency (JAXA), Japan
- Coauthor
Dr. Hitoshi Kuninaka, Japan Aerospace Exploration Agency (JAXA)/ISAS, Japan
- Year
2006
- Abstract
Japan’s HAYABUSA asteroid explorer has microwave discharge ion engines "µ10", which have electro-static grids of effective diameter 10cm and established 25,800 hours the total numbers of space operational time to generate 1,400m/s delta-V with 22kg xenon propellant. In order to adapt to a wide variety of the space flights as well as advance the technology of the ion engine, the "µ20" is under research and development. The "µ20" has a 20cm diameter grid and aims to achieve 30mN/kW thrust power ratio. Magnetic field and propellant injection method of the ion source has been optimized. The performance is highly dependent on the propellant injection method. The summary of the propellant injection method optimization will be described below. Some of gas ports were ready on the yoke (end plate) and their combinations used in the tests. Although more than 10 patterns have been evaluated, only two remarkable results will be shown herein. All the ports are cylinders 5mm in diameter and 5mm in length. The propellant was injected to downstream direction in parallel to the thruster center axis. The total mass flow rate of xenon was controlled with one controller and the propellant feeders were evenly divided before being connected to the ports.The vacuum pressures near the thruster in the test facility were 6.0×10 −5 Pa without load and 1.0×10 −3 Pa with 10sccm xenon flow, respectively. The beam extraction was carried out with a screen voltage of 1200V, an accelerator voltage of -350V and a decelerator voltage of 0V. The flow rates were varied to 8.6sccm, 9.6sccm and 10.7sccm. In the worst performance case that we have investigated so far, although the beam currents gradually increase as the flow rates increase, the current is very small, about 420mA at microwave power of 100W, as if it was generated by a relatively smaller thruster. The contribution of ion beam production at outer discharge chamber is probably small. The best performance in this reseach has its peak at a flow rate of 9.6sccm. The ion beam current at the nominal operating power of 100W is as large as the target value of 500mA, and 20
- Abstract document
- Manuscript document
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