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Disparate Electrospray Systems for Undergraduate and Graduate Education

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2019 ASEE Annual Conference & Exposition


Tampa, Florida

Publication Date

June 15, 2019

Start Date

June 15, 2019

End Date

October 19, 2019

Conference Session

Aerospace Engineering Education

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Paper Authors


Amelia Greig California Polytechnic State University, San Luis Obispo

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Dr Amelia Greig has degrees in Mechanical and Aerospace Engineering, and Science from the University of Adelaide, and a PhD in Physics from the Australian National University. She teaches courses in spacecraft propulsion and the space environment at Cal Poly San Luis Obispo, and also leads the Aerospace Engineering Department’s micro-propulsion research activities.

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Alex Powaser California Polytechnic State University, San Luis Obispo

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Alex is a graduate student in Aerospace Engineering at California Polytechnic State Universtiy, San Luis Obispo. His thesis work is on developing a colloid thruster to be used at Cal Poly's undergraduate laboratory. While being a student, Alex enjoys teaching various labs and lectures for the university as well. Outside of the classroom, he enjoys an active leadership role in CRU (formally known as Campus Crusade for Christ) and other hobbies such as playing guitar, being an amateur woodworker, and exploring California's Central Coast with his fiancée.

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Douglas Howe California Polytechnic State University, San Luis Obispo


Will Alan McGehee California Polytechnic State University

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Will McGehee is currently attending California Polytechnic State University (Cal Poly) in pursuit of his Master's Degree in Aerospace Engineering. He completed his undergraduate degree in Aerospace Engineering at Cal Poly as well. His thesis encompasses the design and initial operational testing of an electrospray (aka colloid) thruster for current and future research efforts at Cal Poly in the field of micro-propulsion. He has experience in electrical systems, micro-fabrication, and diagnostic techniques used in testing of micro-propulsion thrusters. Additionally, he has experience in the design, fabrication, and assembly of systems including electrical, composite, and traditional material components.

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In support of its “Learn by Doing” pedagogical philosophy, the Aerospace Engineering Department at California Polytechnic State University in San Luis Obispo, CA has developed electrospray thruster platforms for both graduate research education and course based undergraduate education purposes. Having numerous applications in precision attitude control and propulsion of small satellite platforms, electrospray thrusters are low thrust, high efficiency devices that use electrostatic fields to accelerate droplets of non-volatile liquid propellants. These thrusters present unique educational opportunities to expose students to comparatively novel technologies in a laboratory setting, requiring only modest university resources and development time.

Two thruster platforms, one research oriented and one education oriented, were developed in parallel with disparate design considerations. The research-oriented platform has fidelity to practical applications, ensuring modularity to support a wide variety of potential research studies. The research system can function as a single emitter system to study the formation of Taylor cones, backscatter effects, and the electrostatic principles involved, or as a linear array to study the interactions of the emitter tips with each other. The modularity of the design exposes research students to the fundamental processes involved with electrospray thrusters, with the fidelity of the system to practical applications ensuring a high quality of research can be undertaken.

In contrast, the educational electrospray thruster is low cost to construct and maintain, focuses on demonstration of core principles, and provides students a highly interactive experience. The educational platform has a planar array of ten emitters followed by an extractor grid and an accelerator grid using glycerol as a propellant. A collector plate downstream collects the expelled propellant so students can measure total mass used, which when combined with the time of operation and electrical conditions is used to calculate thruster performance. This indirect method of gathering force data is an inexpensive alternative to using a precision thrust balance, and by using the principles of operation of the thruster to calculate thrust rather than just measuring it directly, the students gain a deeper understanding of electrospray thruster technologies and propulsion principles.

Greig, A., & Powaser, A., & Howe, D., & McGehee, W. A. (2019, June), Disparate Electrospray Systems for Undergraduate and Graduate Education Paper presented at 2019 ASEE Annual Conference & Exposition , Tampa, Florida. 10.18260/1-2--32669

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