ION thrusters require efficient ionization of propellant atoms, which can be accomplished by a variety of plasma generation methods. These include DC electron discharges, RF and microwave

Presented as Paper 4486 at the 42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, Sacramento, California, 9–12 July 2006; received 8 July 2006; revision received 5 February 2007; accepted for publication 7 February 2007. Copyright© 2007 by the American Institute of Aeronautics and Astronautics, Inc. The US Government has a royalty-free license to exercise all rights under the copyright claimed herein for Governmental purposes. All other rights are reserved by the copyright owner. Copies of this paper may be made for personal or internal use, on condition that the copier pay the $10.00 per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923; include the code 0748-4658/07 $10.00 in correspondence with the CCC.∗ Senior Research Scientist, Advanced Propulsion Group, Jet Propulsion