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Details of Grant 

EPSRC Reference: EP/M506783/1
Title: Development of a modelling tool for performance optimization in pulsed plasma thrusters
Principal Investigator: Vaughan, Professor A
Other Investigators:
Gabriel, Professor SB Golosnoy, Dr I
Researcher Co-Investigators:
Project Partners:
Department: Electronics and Computer Science
Organisation: University of Southampton
Scheme: Technology Programme
Starts: 01 August 2014 Ends: 31 October 2015 Value (£): 39,337
EPSRC Research Topic Classifications:
Design & Testing Technology Manufacturing Machine & Plant
EPSRC Industrial Sector Classifications:
Related Grants:
Panel History:  
Summary on Grant Application Form
The overall aim of the project is to develop a numerical model for pulsed plasma thrusters that will allow their performance

to be optimized. This model involves several parts including, ablation of the solid Teflon propellant and subsequent

ionization of the resulting vapour creating a plasma, through which a discharge current flows between the two electrodes.

The interaction of this current with the self-induced magnetic field produces JxB forces, which accelerate the plasma to a

high velocity. In order to develop the numerical otimisation tool a plasma model is required and this is envisaged as the

most challenging part of the modelling. The academic contribution lies in how this plasma is to be modelled and in

particular three key aspects of this modelling:

1) how the current sheet attaches at the electrodes

2) how the geometry of the current sheet changes as electrons tends to diffuse away

3) what assumptions are made in terms of the thermodynamic state of the plasma

The former two are closely related to the calculation of the dimensions of the current sheet whilst the latter deals with the

fact that the plasma is unlikely to be in a state of equilibrium (LTE) but in a highly non-equilibrium state with the electrons

far from being Maxwellian. If one couples these three together one can arrive at the plasma resistance, which is a key

input to the overall numerical model ( a modified snowplow model) which represents the PPT as an RLC circuit but with

parameters that vary in both space and time.

The novelty of the university contribution to the overall project goal of a numerical optimization tool is in the approach to the

plasma modelling, in particular in allowing for a non-equilibrium distribution for the electrons, examining the current

emission of electrons from the cathode together with current attachment at the cathode and non-uniform distribution of

electrons density in the sheet, which have never been investigated before and the effects that these will have on the overall

optimisation of the performance using the numerical tool.

The first step will be to critically examine the previous plasma modelling approaches that have been published in the

literature. This will allow us to identify exactly where the gaps are and crystallize our detailed methodology. Nevertheless

our current view is that the key aspects seem to lie in cathode emission and current attachment and the non-equilibrium

nature of the electrons.

Our approach will be to start with the simplifying assumption of a given gas mass flow from the ablating solid surface,

giving us the upstream boundary and avoiding solving for the ablation of the Teflon. This then reduces the problem in effect

to one of a gas fed PPT on which there has been significant fundamental research at Princeton University and allowing us to use these results. For the non-equilibrium electron distribution, we will begin with the existing drift-diffusion numerical

model for a dielectric barrier discharge, which assumes a swarm distribution, and modify the electron distribution (initial

ideas include using bi-Maxwellian and/or primary plus a Maxwellian) or solving the conservation equations for

concentration and energy of electrons . For the electron emission, it will be assumed that two mechanisms are possible,

field emission and ion bombardment although a third one of explosive spots will also be looked at. To estimate the current

sheet thickness, previous modelling approaches will be used and also a semi-empirical approach based on

Key Findings
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Potential use in non-academic contexts
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Date Materialised
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Further Information:  
Organisation Website: http://www.soton.ac.uk