Overview and research status of the JAXA 150-mN ion engine

In this work a computer code called P RIMA was further developed and utilized to study the motion of primary electrons in a two -dimensional, axisymmetric discharge chamber of an ion engine. Primary electrons are key to ion engine performance in that they produce the ions that produce the thrus t. Maxwell equations are solved to determine the magnetic field and the equations of motion are solved to determine the trajectory of the primary electrons. A study was conducted to gain insights as to what constitutes a good magnetic field. This was done by looking at three types of ideal magnetic fields and several, ring -cusp configurations. The actual discharge chamber design parameters studied are the discharge chamber shape and the number of magnetic rings.

Primary electron modeling in the discharge chamber of an ion engine

Numerical Simulation of Characteristics of CEX Ions in Ion Thruster Optical System

Enhancing the confinement of primary electrons within the discharge chamber of an ion engine improves the eciency with which ions are produced. Consequently, this improves the ion engine’s performance. The confinement of electrons can be achieved by the application of a static magnetic field. A properly designed magnetic field makes it more dicult for electrons to be absorbed by the anode biased chamber walls. Understanding how to increase the confinement of primary electrons in the discharge chamber by altering the shape of the magnetic field is the objective of this work. The type of magnet circuit considered in this work is that composed of samarium cobalt, ring magnets. From this computational study guidelines are deduced that provide information on the proper spacing of these magnets for maximum primary electron confinement in an axisymmetric discharge chamber constructed of walls that do not interact with the magnetic field. To keep the guidelines as general as possible, ring cusp pairs are studied. The guidelines obtained for these ring cusp pairs can be applied to more complex ring-cusp configurations. Three types of ring-cusp pair arrangements are studied. The first arrangement studied is a front-back wall pair of magnetic rings which face one another, the second configuration studied is a front-side wall pair of magnetic rings at varying angles to one another, and the third configuration investigated is a side-back wall pair of magnet rings at 90 to one another. A fourth study looks at the eect of the radial oset for both the front-back wall and the front-side wall pairings. For these configurations, guidelines on the positioning and orientations of the magnet rings that provide maximum electron containment within the discharge chamber are found. To check the validity of the guidelines obtained from the pair configuration surveys, more complex ring-cusp configurations are studied. The results indicate that the guidelines obtained with the simple pair configurations are applicable to more complex magnetic circuits.

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Computational Study of Ring-Cusp Magnet Configurations that Provide Maximum Electron Confinement

∗ Presented as Paper IEPC-01-000 at the 27 International Electric Propulsion Conference, Pasadena, CA, 15-19 October, 2001. † Copyright  2001 by the Electric Rocket Propulsion Society. All rights reserved. ‡ Professor, Senior Member AIAA This paper describes the current status of electric propulsion technology development and related studies in Japan. Ion engine systems (IES) onboard the Engineering Test Satellite VI (ETS-VI) and the Communications and Broadcasting Engineering Test Satellite (COMETS), and a quasisteady MPD thruster onboard the Space Flyer Unit (SFU) were successfully demonstrated. The National Space Development Agency of Japan (NASDA) is to launch an improved IES onboard the Engineering Test Satellite VIII (ETS-VIII) in 2003. 1.8 kW/ 250 mN-class hydrazine DC arcjet thrusters are to be used on the Data Relay Test Satellite (DRTS). The Institute of Space and Astronautical Science (ISAS) is developing the sample and return space mission from an asteroid, the MUSES-C, which is scheduled to be launched in 2002 and to bring back some specimens to the Earth in 2007 from an extraterrestrial object. In the MUSES-C mission, a cathode-less microwave discharge ion engine system is ready as a primary propulsion in the interplanetary space. Electric propulsion studies at universities, research institutes and industries are also aiming at applications as well as fundamental physics.

T. Maeda

Papers

5,000-hour endurance test of a 35-cm xenon ion thruster

Performance characteristics of a 35-cm diameter xenon ion thruster