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
- Acronyms
- 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
- 2.1 Field emission theory
- 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
- 3.1 Modeling Overview
- 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
- 4.1 Performance parametric analysis
- 5 Conclusion and future work
- 5.1 Summary
- 5.2 Future work
- A List of Appendices
- A.1 FEEP thruster developmental milestone
- A.2 Summary of FEEP performance
- A.3 The preliminary FEEP thruster requirements
- A.4 Preliminary FEEP thruster component dimensions
- A.5 Previous FEEP performance test
- A.5.1 Performance test of single porous Tungsten crown emitter [104]
- A.5.2 Performance test of cluster of 3 porous Tungsten crown emitter [104]
- A.6 Space experience of ARCS Indium LMIS thruster
- A.7 Crown multi-emitter manufacturing process
Objectives & Key Themes
This thesis focuses on the modeling and parametric performance analysis of a Field Emission Electric Propulsion (FEEP) thruster. The overarching goal is to investigate and analyze the thruster's parametric performance through mathematical and 3D CAD modeling, as well as simulation, to understand its behavior with various liquid metal propellants.
- Establish a mathematical model and preliminary design for a FEEP system.
- Investigate the parametric performance of FEEP thrusters using different propellants.
- Analyze the operational considerations and mission applications of FEEP thrusters.
- Optimize the design parameters, particularly the crown emitter topology, for improved performance.
- Utilize MATLAB simulations to study thrust and exhaust velocity variations.
Excerpt from the Book
Field emission electric propulsion (FEEP)
Field emission electric propulsion (FEEP): Field emission electric propulsion is an advanced electrostatic propulsion based on field ionization of a liquid metal and subsequent acceleration of the ions by a strong electric field [5]. The schematic FEEP system, shown in Fig. 1.6, is comprised of an emitter, accelerator, neutralizer, and propellant reservoir, and it uses liquid metal as a propellant, such as caesium, indium, or mercury. These propellants have low ionization potential (3.78 eV for Cs and 4.16 eV for Rb), low melting point(28.7 °C for Cs and 38.9 °C for Rb) and very good wetting capabilities. The actual thrust is generated by exhausting a beam composed primarily of singly-ionized cesium or rubidium atoms produced by field evaporation at the emitter’s tip. An accelerating electrode (accelerator) is placed directly in front of the emitter and is made of a metal (usually stainless steel) plate with two sharp blades machined into it. When a potential difference of 10kV is applied between the emitter and the accelerator, or when the combined effects of electrostatic force and surface tension are applied, the liquid metal’s free surface enters a regime of local instability, resulting in the formation of a series of protruding cusps or Taylor cone at the tip of the emitter. When the electric field reaches 10^9 V/m, the atoms at the tip of the cusps spontaneously ionize and an ion jet is extracted by the electric field, while electrons are rejected in the bulk of the liquid accelerated to high velocities—typically 100km/s or more. An external source of electrons (neutralizer) provides negative charges to keep the thruster assembly electrically neutral. Taylor cone is crucial in FEEP which is currently of great interest in the electric propulsion scientific community due to its unique features: 1μN to 1mN thrust range, near instantaneous switch on/off capability, and high-resolution throttleability (better than one part in 10^3), which enables accurate thrust modulation in both continuous and pulsed modes. This propulsion system, which is currently being tested for several scientific missions onboard drag-free satellites, has also been proposed for attitude control and orbit maintenance on commercial small satellites and constellations [55]. This type of electrostatic propulsion system is the focus of this thesis report, which will be discussed in greater detail in chapter 3 in terms of modeling and parametric performance analysis.
Chapter Summaries
Chapter 1: Introduction: This chapter provides an introduction to electric propulsion, including its types and applications, as well as the motivation for and contribution of this work.
Chapter 2: FEEP background and literature review: This chapter presents the theoretical foundation for the FEEP thruster, its operating principle, major components, functions, and emitter characteristics.
Chapter 3: Field Emission Electric Propulsion modeling: In this chapter, the mathematical and CAD modeling of major components of the FEEP thruster, with detailed discussions, are provided.
Chapter 4: Parametric analysis of FEEP system: This chapter covers the parametric performance of the field emission electric propulsion system, as well as parametric studies and analysis.
Chapter 5: Conclusion and future work: This chapter summarizes the findings and provides recommendations for future work regarding the FEEP system.
Keywords
CubeSat, electric propulsion, emitter, FEEP, thruster, satellite, spacecraft, modeling, parametric analysis, ion propulsion, Taylor cone, thrust, specific impulse, optimization
Frequently Asked Questions
What is this work generally about?
This thesis focuses on the modeling and parametric performance analysis of a Field Emission Electric Propulsion (FEEP) system, a type of advanced electric propulsion for spacecraft, with a particular emphasis on its design and operational characteristics.
What are the central thematic areas?
The central thematic areas include electric propulsion overview, field emission theory, FEEP thruster design and modeling, parametric performance analysis of FEEP systems, and optimization of thruster components.
What is the primary goal or research question?
The primary goal is to establish a comprehensive mathematical model and a preliminary design for a FEEP system, and to thoroughly investigate its parametric performance using various liquid metal propellants through simulation and analysis.
Which scientific method is used?
The scientific method employed involves mathematical modeling, 3D CAD modeling of the FEEP thruster's components, and parametric performance analysis conducted via MATLAB simulations to study changes in thrust and exhaust velocity.
What is covered in the main part?
The main part of the thesis covers the theoretical background of FEEP, detailed mathematical and CAD modeling of its components, a description of the thruster's design, and a comprehensive parametric analysis of the FEEP system's performance.
Which keywords characterize the work?
Key terms characterizing this work include electric propulsion, FEEP, thruster, modeling, parametric analysis, CubeSat, emitter, satellite, spacecraft, ion propulsion, Taylor cone, thrust, specific impulse, and optimization.
What is a Field Emission Electric Propulsion (FEEP) thruster?
A FEEP thruster is an advanced electrostatic propulsion system that generates thrust by field ionizing a liquid metal and accelerating the resulting ions with a strong electric field. It typically uses liquid metals like caesium or indium as propellant.
What role does the "Taylor cone" play in FEEP operation?
The Taylor cone is a crucial phenomenon in FEEP, referring to the conical shape formed by the liquid metal propellant's free surface at the emitter tip under the combined effects of electrostatic force and surface tension, which facilitates the stable extraction of ions.
How is the FEEP thruster integrated with CubeSats?
The thesis discusses the integration of the FEEP thruster into CubeSat missions, highlighting its low-cost, high-performance capabilities for de-orbiting, orbit control, attitude control, and other advanced maneuvers for small satellites.
What propellants are typically used in FEEP systems?
Common propellants for FEEP systems are liquid metals with low ionization potential and good wetting capabilities, such as caesium, indium, gallium, rubidium, and mercury.
- 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
