Field ionization test chamber for carbon nanotube-based miniature ion thruster applications
Crosby, Bryan D.
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Electric propulsion for micro- and nano-satellites is an increasingly viable solution for station keeping and end-of-life operations. In particular, microelectromechanical systems (MEMS) electrodes for use in a field ionization electric propulsion thruster are starting to show compelling evidence as a viable plasma generator electrode. This was determined by utilizing a bell jar pressure chamber and a proof-of-concept field ionization electrode characterization fixture complete with an accelerator mesh grid, and a beam current data acquisition suite. The complete field ionization electrode characterization apparatus enables the user to view the generated ion plasma and collect beam current, and enables future work to incorporate a thrust stand and a cathode/anode gap micrometer. Beam current collected from a series of experiments comparing angled-wall etched nozzles with and without carbon nanotube (CNT) deposition showed a distinct improvement in maximum collected current. Mass utilization efficiency and specific impulse for a CNT electrode were found to be 0.31% and 17.5 seconds, respectively, at 560V. This is marginal in comparison to thrusters in industry; however, it shows a successful apparatus and test fixture proof of concept.
Approved for public release; distribution is unlimitedReissued 27 Sep 2018 to reflect updated abstract on pages i and v.