Date of Award

12-2013

Degree Name

MS in Aerospace Engineering

Department

Aerospace Engineering

Advisor

Dr. Kira Abercromby

Abstract

To support the research of miniature ion propulsion, Cal Poly's Miniature Xenon

Ion (MiXI) thruster has been modeled and tested. Using ANSYS Fluent, a two-

dimensional model of the transient thermal environment of MiXI-CP-V3 was

created. Validation testing was conducted in order to assess the accuracy of the

thermal model. During testing, temperature was measured at eight locations

across MiXI. From the test data it was determined that the thermal model did a

poor job of predicting temperature due to incident radiation at the four locations

nearest the keeper electrode. The four remaining locations were affected mostly

by conduction and followed a trend that closely resembled the test data. The

difference between the test data and the model's predicted temperature varied

depending on time and location; the difference between the predicted data and

the test data fell within 10C, for most of the operation but reached 27.1C at

one location. The thermal model was used to assess ways to shunt heat transfer

to the permanent magnets in order to postpone demagnetization, which occurs at

300C. Sheathing the entire keeper electrode with Macor was shown to reduce the

temperature by as much as 13.3C at certain times and locations. Due to its lower

thermal conductivity, it was hypothesized that a thruster made of titanium would

impede heat transfer to the magnets, however, the model showed an increase in

temperature rise when properties of certain titanium alloys are applied. Applying

a thermally insulative coatings to the anode was considered, but not modeled

because the available coatings have a melting point below 350C.

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