Pulsed Plasma Microthrusters
Pulsed plasma thrusters (PPT) have been used for several decades to provide
attitude control for small satellites. The advantage of these thrusters is
simplicity, since they use a solid Teflon propellant. The disadvantage is that
they have electrical efficiencies of 10% or less. These thrusters are becoming
important as potential propulsion systems for a smaller class of communication
satellites that will be launched in large numbers (e.g., 77 in the Motorola
Iridium System) into low earth orbit to provide continuous global coverage. In
this application electrical efficiency is very important since the power
available for propulsion is limited.
These thrusters have many of the characteristics of plasma opening switches
(POS) that have been under study at UTSI for several years. We have developed a
computational capability for the POS that can easily be adapted to pulsed plasma
thrusters. Initial studies using our code suggested that the performance could
be improved by better utilization of the electrothermal expansion of the plasma.
An experiment has been designed to test new thruster configurations utilizing a
two-beam laser interferometer to measure the exhaust velocity. Mr. Thomas
Walloschek, a visiting MS student from the University of Stuttgart, is
performing some initial experiments to determine whether the efficiency of these
devices can be substantially improved. A proposal was submitted to AFOSR to
continue this research investigation.
Investigator: Dr. D. R. Keefer
Sponsor: AFOSR
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