Space electric propulsion is required not only for orbit raising and transfer, position control, and station keeping, but also for spacecraft attitude control, advanced thermal material testing, and end-of-life de-orbiting that is much more fuel efficient than conventional chemical rockets. FEEP thruster is one type of ion propulsion system that provides a low thrust of the order of micro-Newton (µN) to milli-Newton (mN) that is primarily used for precise spacecraft attitude control with extremely high efficiency and small impulse bits based on the exhaust velocity of an ejected ion from a thruster.
This thesis report includes a mathematical and 3D CAD model of a FEEP thruster with the overarching goal of investigating and analyzing the thruster’s parametric performance. To accomplish this, a MATLAB program was used to simulate the change in thrust and exhaust velocity over time using various types of liquid metal as a propellant, assuming the fuel mass is equal to the atomic mass of the propellant, the wet mass of the spacecraft is assumed to be 4kg, and the charge of an ion is assumed to be 1.602 × 10−19 while the supplied voltage is held constant at 10 kV. Furthermore, because the porous crown emitter is the heart of the FEEP thruster, its stiffness and topology optimization were investigated.
The simulation results show that the thrust value of the FEEP thruster over time ranges from 0.213µN to 211mN during stable ion flow rate and mass expulsion of indium propellant, implying that the result is comparable to realistic FEEP parameters. Furthermore, as expected, increasing the voltage between the emitter and extractor electrodes and decreasing the mass expulsion of the propellant increased the thrust value of the FEEP thruster.
Table of Contents
1 Introduction
1.1 Motivation
1.2 Electric propulsion overview
1.2.1 Rocket equation
1.2.2 Specific impulse
1.2.3 Energy and thrust efficiency
1.2.4 Types of electric propulsion
1.2.5 General application of EP
1.3 Thesis objectives and contributions
1.4 Thesis scope and outline
2 FEEP background and literature review
2.1 Field emission theory
2.1.1 Emitter critical current and impedance
2.1.2 Emitter onset voltage and Taylor cone
2.1.3 Emitter surface stability
2.2 Filed emission electric propulsion overview
2.2.1 FEEP thruster description
2.2.2 FEEP mission application
2.2.3 FEEP operational consideration
3 Field Emission Electric Propulsion modeling
3.1 Modeling Overview
3.1.1 Shape propellant flow model
3.1.2 Propellant flow equation of motion
3.1.3 Ion formation model
3.2 FEEP thruster preliminary design
3.2.1 Thruster head component
3.2.2 Propellant tank components
3.2.3 Electronics (DCIU/PPU)
3.2.4 Cathode neutralizer component
3.2.5 FEEP thruster 3D model assembly
3.2.6 FEEP thruster integration with CubeSat
4 Parametric analysis of FEEP system
4.1 Performance parametric analysis
4.1.1 Thrust change of FEEP over time
4.1.2 Thrust change of FEEP over voltage
4.2 FEEP thruster design parameter optimization
4.2.1 Crown emitter topology optimization
5 Conclusion and future work
5.1 Summary
5.2 Future work
Objectives and Topics
This thesis aims to develop a comprehensive mathematical and 3D CAD model of a Field Emission Electric Propulsion (FEEP) system to analyze its parametric performance. The research focuses on identifying how various thruster parameters, such as propellant type and electrical voltage, influence the overall efficiency, thrust output, and operational stability of the thruster in micro-satellite environments.
- Mathematical modeling of Field Emission Electric Propulsion systems.
- 3D CAD design and structural topology optimization of FEEP thruster components.
- Parametric performance analysis concerning propellant mass, exhaust velocity, and ion flow.
- Investigation of operational requirements for micro-satellite integration.
Excerpt from the Book
2.1 Field emission theory
The mechanism for emitting ions in a FEEP thruster is the same as that used in liquid metal ion sources (LMIS). A strong electrostatic field is applied to a liquid metal surface, which is usually adhered to a solid metal support structure as depicted in Figure 2.1. Due to the combined action of this field and surface tension, the liquid metal surface deforms and, depending on the geometry of the support structure (single needle or capillary, capillary slit, pool), assumes an equilibrium configuration consisting of a single or multiple conical structures, the Taylor cones (apex angle 98.6 deg).
At the apices of these cones (diameter < 10^-8 m), the field is high enough (10^9 - 10^10 V/m), so that ions can be field-evaporated directly from the liquid without the transitional vapor phase. This process of emitting electrons from liquid or solid surfaces into a vacuum, a fluid (such as air), or any non-conductive or weakly conducting dielectric is referred to as field emission. Ions emitted from the apices are replenished by hydrodynamic flow from a liquid metal reservoir, resulting in a continuous ion beam emitted from each cone. The stream of metal to the tip introduces additional hydrodynamic forces, resulting in the actual geometry of the emission sites being that of a Taylor cone elongated at the apex in the shape of a jet with a tip width of a few nanometers [13].
Summary of Chapters
1 Introduction: Provides an overview of space electric propulsion, discusses the current motivations for miniaturized propulsion systems, and outlines the research objectives.
2 FEEP background and literature review: Establishes the theoretical foundation for field emission thrusters, covering ion source mechanisms, Taylor cone physics, and existing thruster technologies.
3 Field Emission Electric Propulsion modeling: Details the mathematical modeling of propellant flow and ion formation, alongside the preliminary 3D design of FEEP components.
4 Parametric analysis of FEEP system: Presents the results of simulation studies regarding thrust variations over time and voltage, and discusses topology optimization of the crown emitter.
5 Conclusion and future work: Summarizes the thesis findings and suggests potential future improvements, such as advanced optimization algorithms for thruster design.
Keywords
CubeSat, Electric Propulsion, Emitter, FEEP, Thruster, Satellite, Spacecraft, Field Emission, Taylor Cone, Ion Source, Modeling, Parametric Analysis, Topology Optimization, Propellant Flow, Micro-propulsion
Frequently Asked Questions
What is the primary focus of this research?
The work focuses on the mathematical modeling and parametric performance analysis of Field Emission Electric Propulsion (FEEP) systems designed for small satellite applications.
What are the key themes addressed in the thesis?
Key themes include field emission physics, propulsion system design, 3D structural modeling, and performance optimization based on propellant and electrical inputs.
What is the main objective of this study?
The primary goal is to provide a comprehensive model of a FEEP thruster and to analyze how different design parameters affect its propulsion performance.
Which scientific methodology is utilized?
The research employs a combined approach of theoretical fluid dynamics modeling, 3D CAD design, and numerical parametric simulations to evaluate thruster behavior.
What topics are covered in the main body?
The main body covers field emission theory, the specific operational requirements for FEEP thrusters, 3D design concepts, and performance simulations under various scenarios.
How would you characterize this work through keywords?
The work is characterized by terms such as FEEP, CubeSat, Field Emission, Thruster, Ion Source, and Parametric Analysis.
Why is the Taylor cone essential to the FEEP system?
The Taylor cone is the physical structure formed by the liquid metal propellant under an intense electric field, which enables the stable field evaporation of ions at the apex.
What is the significance of the crown emitter in this study?
The crown emitter is a critical component that allows for multiple emission sites, facilitating higher thrust output while maintaining the compact size requirements of CubeSats.
- Quote paper
- Dinaol Gadisa (Author), 2023, Modeling and Parametric Performance Analysis of Field Emission Electric Propulsion, Munich, GRIN Verlag, https://www.grin.com/document/1335759
