Overview and research status of the JAXA 150-mN Ion Engine

Paper number

IAC-06-C4.4.01

Author

Dr. Shoji Kitamura, Japan Aerospace Exploration Agency (JAXA), Japan

Coauthor

Dr. Yasushi Ohkawa, Japan Aerospace Exploration Agency (JAXA), Japan

Coauthor

Mr. Yukio Hayakawa, Japan Aerospace Exploration Agency (JAXA), Japan

Coauthor

Mr. Hideki Yoshida, Japan Aerospace Exploration Agency (JAXA), Japan

Coauthor

Mr. Katsuhiro Miyazaki, Japan Aerospace Exploration Agency (JAXA), Japan

Year

2006

Abstract

Research of the 150-mN-class ion engine has been conducted at the Institute of Aerospace Technology of the Japan Aerospace Exploration Agency.  The objective of this research is to establish basic xenon ion propulsion technology for future applications requiring high thrust levels. There are great demands for ion engines with such high thrust levels.
   The ion thruster under development has a discharge-chamber with ring-cusp magnets and an ion accelerating system with three grids of a 35-cm beam diameter.  With repeated design improvements and fabrications so far, the thruster has already achieved the target value of ion production cost less than 140 W/A with a good margin at 150-mN operations.  Thrusting capability tests were also conducted, and wide thrust range from 80 to 200 mN was obtained at 1.8 to 4.6-kW power consumption.
   Main hollow cathodes are one of the critical parts of ion thrusters in terms of their lives.  One of the serious problems occurring to them was erosion of a keeper electrode and an orifice plate due to ion sputtering.  To overcome this, the material of the keeper and the orifice was changed from metal to graphite.  Preliminary tests of the new hollow cathodes were conducted.  After the tests, the cathodes were disassembled and inspected, and no problems were found on them.  At present, a cathode life test is being prepared to confirm endurance of the cathode.
   Electron emission characteristics of neutralizer hollow cathodes were obtained in ion beam neutralizing operation.  In this operation, the ion thruster including the neutralizer was electrically isolated from the ground, and the engine floating voltage was measured with changing the propellant flow rate.  Results showed that the engine floating voltage was almost constant at 16 to 17 V for the flow rate range of about 100 to 250 mAeq., and the voltage did not depend on the beam current.  This electron emission capability is enough for 150-mN class ion thrusters.
   The ion propulsion system using the 150-mN thrusters will require very high levels of electric power, and thus the power-processing unit is one of the critical components in the system in point of high power.  Preliminary research on the power-processing unit has been started, and trial fabrication of a lab-model power-processing unit has been conducted.  In an operation test of the power-processing unit with a thruster, we attained an overall power efficiency of 0.88.

Abstract document

IAC-06-C4.4.01.pdf

Manuscript document

IAC-06-C4.4.01.pdf (🔒 authorized access only).

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