Field Emission Thruster Calibration for Small Satellites
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Solution Overview
Problem
Existing field emission propulsion systems for spacecraft, particularly those using liquid metal ion sources, face challenges in miniaturization, efficiency, and control of thrust vector due to uncontrolled emitter firing and manufacturing tolerances, making them unsuitable for small satellites.
Innovation Solution
A field emission propulsion system with individually controllable extractor electrodes and a calibration process to set specific ion current levels, allowing for precise control of thrust vector and emission timing, using a common emitter voltage for ion emitters and adjustable extractor electrode voltages to compensate for component tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common extractor electrode is used for all liquid metal ion emitters, then the device complexity is reduced, but the control precision of individual emitters deteriorates
Solution Approach 1:
The common extractor electrode is divided into multiple independently controllable segments. Each segment can be individually activated or deactivated to control specific ion emitters, enabling precise firing sequences while maintaining a segmented version of the common electrode structure.
Solution Approach 2:
The extractor electrode transitions from a static common structure to a dynamic segmented structure where individual segments can be independently controlled in time and space, allowing adaptive control of emitter firing sequences based on operational requirements.
2Manufacturing precision
If individual extractor electrode voltage sources are used for each emitter, then the control precision of thrust vector is improved, but the device complexity increases
Solution Approach 1:
The voltage control system is segmented into individual voltage sources for each extractor electrode segment, allowing independent control of each segment's potential. This enables precise control of ion emission from specific emitters while maintaining manageable system complexity through modular voltage source design.
Solution Approach 2:
Different voltage sources provide locally optimized control for each extractor electrode segment, allowing tailored voltage profiles for different regions of the emitter array. This enables precise local control of ion emission characteristics while maintaining overall system coherence.
3Device complexity
If manufacturing tolerances are not compensated, then the device complexity is reduced, but the thrust vector prediction accuracy deteriorates
Solution Approach 1:
The system performs preliminary characterization of each ion emitter's properties during assembly or initial operation. This advance measurement of emitter characteristics allows the control system to pre-calculate compensation factors for manufacturing tolerances, improving thrust vector prediction accuracy before actual operation begins.
Solution Approach 2:
The system implements feedback mechanisms that monitor actual emitter performance and adjust voltage control parameters accordingly. This continuous feedback loop compensates for manufacturing tolerances by adapting the control strategy based on measured emitter behavior, thereby improving thrust vector prediction accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables high-efficiency, controlled propulsion with a variable thrust range, reducing system losses and installation space, and improving thrust direction precision for small satellites.
Implementation Method 1
field emission propulsion system for spacecraft, comprising a control unit, a propulsion assembly with several field emission propulsion units comprising an ion source with multiple ion emitters and extractor electrodes arranged in a field arrangement
Implementation Method 2
the ion emitter can be supplied with a common emitter voltage or potential, while the extractor electrodes are electrically isolated from one another and can be driven by extractor electrode voltage sources with individually adjustable extractor electrode voltages
Data Source
Figure 1
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AI summary
The invention relates to a field emission propulsion system (1) for spacecraft, comprising: a control unit (4); a propulsion assembly (2) with a plurality of field emission propulsion units (23) that comprise an ion source with a plurality of ion emitters (222) and extraction electrodes (24), associated with said ion emitters (222) and arranged in a field arrangement; and a plurality of extraction electrode voltage sources (43), each associated with the extraction electrodes (24) to operate same, controlled by the control unit (4), using an individual extraction electrode voltage.