Study of Hall Thruster Discharge Channel Wall Erosion via Optical Diagnostics.

Hall Thruster;Channel Wall Erosion;Optical Diagnostics;LIF;CRDS;Aerospace Engineering;Engineering;Aerospace Engineering

Huang, WenshengSmith, Timothy B. ;

University of Michigan

关键词: Hall Thruster;    Channel Wall Erosion;    Optical Diagnostics;    LIF;    CRDS;    Aerospace Engineering;    Engineering;    Aerospace Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/86567/davhuang_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

This dissertation describes the use of optical diagnostics to study the Hall thruster channel wall erosion problem. The novel use of two-axis laser-induced fluorescence velocimetry produced velocity distribution function maps of the ions bombarding the channel walls of a 6 kW Hall thruster. This is the first published instance of the use of laser-induced fluorescence to study the bombarding particles near the discharge channel walls in a Hall thruster. Additionally, the dissertation demonstrated the first successful use of boron cavity ring-down spectroscopy to study channel wall erosion in a Hall thruster environment to measure the channel wall erosion rate. The combination of data from the two optical diagnostics highlighted the importance of the erosion zone length as a key parameter that drives channel wall erosion.The length of the erosion zone was found to scale roughly with the discharge voltage of the Hall thruster. There are also subtle signs that the erosion zone length decreases slightly with increasing anode mass flow rate. A simple engineering erosion model was formulated to produce a scaling equation that can be used to correlate the relative erosion rate across different discharge voltages and anode mass flow rates for the 6-kW Hall thruster with symmetric magnetic field topology. The equation shows that, to a first-order approximation, the erosion rate scales linearly with the anode mass flow rate and with the square of the discharge voltage.However, the key result of this dissertation is not the determination of the power to which the discharge voltage is raised. Instead, it is the method used to derive the scaling equation. The said method highlights the importance of determining the scaling relationship between the length of the erosion zone and the controlling parameters. This method has not been previously used because the diagnostics needed to study the aforementioned scaling relationship has not been previously available. Thus, it can be said that the truly original contribution of this dissertation to the study of the channel wall erosion problem is the development of the two optical diagnostics and a demonstration of their potential use.