William Brabston
(Advisor: Prof. Mitchell Walker)
will propose a doctoral thesis entitled,
Analysis of the Ionization Mechanisms of an N2/O2 Air Mixture in a Hall Effect Thruster
On
Thursday, October 24th at 2:00 p.m.
Montgomery Knight Building, Room 317 (MK317)
Abstract
There is a growing interest for satellites to access very low Earth orbit (VLEO); however, VLEO is currently prohibitive due to its high atmospheric density imposing a strong drag force on satellites. This drag force is life-limiting to the satellites as it rapidly depletes on-board propellant, typically xenon or krypton, used in a Hall effect thruster (HET) to counter the drag and maintain the VLEO orbit. Air-breathing electric propulsion (ABEP), consisting of the collection and subsequent ionization and acceleration of atmospheric air in a HET, offers a potential solution to enable long-term access to VLEO by providing an indefinite propellant supply.
The electron-impact ionization of air in a HET is governed by distinct reaction mechanisms that vary from traditional atomic xenon and krypton mechanisms, due to the molecular nature of air. As a result, the ionization of molecular species in HETs is not fully understood and preliminary testing demonstrates that air-operated HETs experience degraded performance and efficiency that currently do not meet key benchmarks to enable access to VLEO. This research seeks to address these deficiencies.
There are four primary goals in this proposal. The first goal is to develop an energy flow model to visualize and understand the unique molecular energy sinks and pathways in the ionization and acceleration of air in a HET. Second, is to investigate and produce a kinetic model of the dominant reaction mechanisms of air across a variety of operational setpoints and plasma conditions. Third, is to develop an analytical efficiency model to quantify the effect of distinct molecular energy sinks on overall HET performance and efficiency. Finally, the last goal is to apply experimental data to the aforementioned models to determine how the composition in an air mixture influences the species production, energy distribution, and overall performance and efficiency when used as a propellant in a HET. This proposed work seeks to inform molecular HET ionization model assumptions, provide a framework for the analysis of experimental molecular HET data, and influence optimized molecular HET design to enable VLEO access.
Committee
- Prof. Mitchell Walker – School of Aerospace Engineering (advisor)
- Prof. Wenting Sun – School of Aerospace Engineering
- Prof. Sedina Tsikata – School of Mechanical Engineering