Characterization of direct current discharge based electric microthrusters
Date
2017
Authors
Wright, William Patrick
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Abstract
In this work, a novel electrostatic microthruster concept, based on a direct current gaseous
discharge, is proposed. The design draws inspiration from the previously developed
CorIon system, which utilizes a coupling of the corona ionization mechanism and the
acceleration mechanism. The new design is an attempt to develop a space propulsion
system for use on microsatellites, such as CubeSats. A proof of concept system is tested
to determine if the direct current discharge can be used as a plasma generator for use in
electric space propulsion systems. A system representative of the proposed microthruster
concept is tested to determine if it operates in a way that will generate thrust, and
boundaries on the systems stable operating parameters are ascertained. Lifetime, re-
peatability and erosion tests are performed on both the proof of concept system, and
the microthruster design to determine if the system is an improvement on the CorIon
system. A thrust measurement stand is designed and constructed that utilizes a novel
magnetic coupling mechanism to measure the thrust produced by a microthruster. The
thrust measurement stand is tested with a cold gas thruster to study the thrust stands
repeatability characteristics, and if it produces the expected results for such a system. A
theoretical model for the thrust measurement stand is developed, so that the output of
the thrust stand can be predicted for various loading conditions. Thrust measurements
are performed on the microthruster design as different operating parameters are varied.
Measurements of the power used by the microthruster design are taken as different op-
erating parameters are varied. Ion current density measurements of the microthruster
design are performed as different operating parameters are varied. Ion current density
distribution measurements of the microthruster design are performed. Simulations of
the microthruster design are developed, using COMSOL Multiphysics, to con rm the
hypothesized mechanism of operation of the microthruster design, and to explain the
trends observed in experimental data. Two types of simulation are constructed: a base
case, where general features in the physical quantities extracted from the simulations are
discussed, and simulations where operating parameters are varied, to study the effects
these parameters have on the extracted physical quantities. Thrust values are extracted
from the simulations and compared with the experimentally measured thrust. Future
research to be conducted involving the novel microthruster design is listed.
Description
A thesis submitted in fullment of the requirements for the degree of Doctor of Philosophy School of Physics to the Faculty of Science, University of the Witwatersrand,
Johannesburg, March 2017.
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Citation
Wright, William Patrick (2017) Characterization of direct current discharge based electric microthrusters, University of the Witwatersrand, Johannesburg, https://hdl.handle.net/10539/25133