A numerical model of the ion thruster hollow cathode plasma
A numerical model of the ion thruster hollow cathode plasma
Electric propulsion (EP) devices such as gridded and Hall effect ion thrusters (HET) offer significant mass savings compared to chemical rockets. In addition to enhancing existing mission possibilities, it is also true that cutting edge EP systems are an enabling technology for certain high ΔV missions. Although ion and HET thrusters are currently used operationally, there still remains a need for further understanding of the physics associated by the devices in order to enhancing performance and reliability.
The hollow cathode (HC) is a device commonly used in electron bombardment ion thrusters to provide a primary ionising current source, while a secondary cathode is often used as a plume neutraliser. Although HCs are often used, the internal plasma physics is still poorly understood and they exhibit operational modes the cause of which has not been fully explained. This is primarily due to the difficulties associated with recording experimental data from within the very small scale cylindrical cathode.
In order to gain further understanding of the hollow cathode internal physics, a numerical model was developed. Due to the degree of rarefaction and low density, the neutral flow was modelled using a Direct Simulation Monte Carlo (DSMC) model. It was found that the flow was rarefied in the cathode plume, and numerically transitional in Knudsen number within the ‘throat’ (tip) of the hollow cathode.
Due to the predicted plasma density in the cathode, a Particle-in-Cell (PIC), Monte Carlo Collision (MCC) model was then added to the existing neutral gas model. This was validated against some standard test cases and experimental data for cathode conditions. It was found that the hollow cathode plasma exhibits a dense emitting region extending a short distance inside.
University of Southampton
Crawford, Francis T. A
b15429f3-105b-447f-8f16-dc0eec07d0a3
2004
Crawford, Francis T. A
b15429f3-105b-447f-8f16-dc0eec07d0a3
Crawford, Francis T. A
(2004)
A numerical model of the ion thruster hollow cathode plasma.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Electric propulsion (EP) devices such as gridded and Hall effect ion thrusters (HET) offer significant mass savings compared to chemical rockets. In addition to enhancing existing mission possibilities, it is also true that cutting edge EP systems are an enabling technology for certain high ΔV missions. Although ion and HET thrusters are currently used operationally, there still remains a need for further understanding of the physics associated by the devices in order to enhancing performance and reliability.
The hollow cathode (HC) is a device commonly used in electron bombardment ion thrusters to provide a primary ionising current source, while a secondary cathode is often used as a plume neutraliser. Although HCs are often used, the internal plasma physics is still poorly understood and they exhibit operational modes the cause of which has not been fully explained. This is primarily due to the difficulties associated with recording experimental data from within the very small scale cylindrical cathode.
In order to gain further understanding of the hollow cathode internal physics, a numerical model was developed. Due to the degree of rarefaction and low density, the neutral flow was modelled using a Direct Simulation Monte Carlo (DSMC) model. It was found that the flow was rarefied in the cathode plume, and numerically transitional in Knudsen number within the ‘throat’ (tip) of the hollow cathode.
Due to the predicted plasma density in the cathode, a Particle-in-Cell (PIC), Monte Carlo Collision (MCC) model was then added to the existing neutral gas model. This was validated against some standard test cases and experimental data for cathode conditions. It was found that the hollow cathode plasma exhibits a dense emitting region extending a short distance inside.
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Published date: 2004
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Local EPrints ID: 465690
URI: http://eprints.soton.ac.uk/id/eprint/465690
PURE UUID: e39f191b-531d-4a3b-8a1d-38ed0d5ba85d
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Date deposited: 05 Jul 2022 02:35
Last modified: 16 Mar 2024 20:19
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Author:
Francis T. A Crawford
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