Development and characterization of a diverging cusped field thruster and a lanthanum hexaboride hollow cathode

A low power, magnetically confined plasma thruster has been developed and undergone preliminary characterization. The design employs cusped magnetic fields arranged in a divergent fashion to confine electron flow to an anode while providing efficient acceleration of an ion beam, similar to traditional Hall type thrusters. The design, referred to as a Diverging Cusped Field (DCF) thruster, employs aspects of both existing cusped field thrusters and traditional Hall thrusters while including several unique design features aimed at increasing performance. In addition to supporting competitive thrust and efficiency performance, the DCF magnetic arrangement confines the discharge plasma away from the channel walls in order to reduce wall erosion and promote long lifetimes. The thruster has demonstrated performance levels comparable to typical commercial Hall thrusters. Specifically, a nominal anode efficiency of 44.5% has been achieved while providing 13.4mN of thrust at xenon mass flow rate of 8.5sccm and consuming 242W of anode power. The corresponding nominal specific impulse was 1640s. Preliminary observations suggest that the arrangement successfully contains the plasma away from the channel walls throughout the majority of the discharge chamber. Unique aspects of the DCF discharge include an apparent bi-modal operating spectrum and an irregular beam profile. While efficient operation has been observed in both operating modes, the transitions are shown to be accompanied by variations in both ionization efficiency and ion energy distribution. The emitted plume was observed to be conical in shape, with a hollow interior and concentrated ion flux diverging at roughly 32°. In addition to the DCF thruster, a small lanthanum hexaboride (LaB6) hollow cathode has been developed for use with plasma thrusters within the MIT Space Propulsion Laboratory.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Courtney, Daniel George

Advisor dc:contributor.advisor

• Manuel Martínez-Sánchez.

• Aeronautics and Astronautics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/45239

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/45239