Liquid Metal Ion Source Pulsed Voltage Control
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Solution Overview
Problem
Liquid metal-ion and electron sources in space propulsion and focused ion beam systems face inefficiencies due to high liquid metal consumption and droplet generation, leading to pulsating ion beams and increased fuel consumption, especially when operating above critical current thresholds.
Innovation Solution
A method involving a periodically varying operating voltage between the emitter and extractor electrodes, with specific voltage thresholds and pulse frequencies to prevent droplet generation, allowing for reduced liquid metal consumption and efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high current is applied above critical current threshold to achieve relevant thrust power, then thrust power is improved, but droplet generation increases leading to high liquid metal consumption
Solution Approach 1:
The patent applies periodic pulsed voltage instead of continuous DC voltage to the emitter. By operating in pulsed mode with duty cycles below 10%, the system achieves thrust power during the pulse while allowing the liquid metal cone to recover between pulses, preventing droplet generation and reducing propellant consumption significantly compared to continuous operation above critical current threshold
Solution Approach 2:
The patent changes the voltage application mode from continuous DC to periodic pulsed voltage, and controls the duty cycle to remain below 10%. This parameter change allows the system to operate efficiently at low average currents while still achieving relevant thrust power during the pulse peaks, avoiding the droplet generation that occurs at continuously high currents
2Loss of substance
If very pointed needle emitter is used to improve efficiency and reduce droplet generation, then droplet generation is reduced, but device complexity increases
Solution Approach 1:
The patent uses periodic pulsed voltage operation to prevent droplet generation without requiring complex emitter geometries. The pulsed operation mode with controlled duty cycle below 10% allows standard capillary or needle emitters to operate efficiently without the droplet formation issues that would otherwise require very pointed or specially shaped emitters
Solution Approach 2:
The patent enables the use of simpler, more robust emitter geometries (standard capillaries or needles) by operating in pulsed mode. While the emitter does consume liquid metal, the pulsed operation below 10% duty cycle extends emitter lifetime significantly, making these simpler geometries viable without requiring the precision-manufactured very pointed needles that would otherwise be needed
3Stability of the object's composition
If continuous DC voltage is applied to maintain steady ion beam, then beam continuity is improved, but liquid metal consumption increases due to droplet generation
Solution Approach 1:
The patent applies periodic pulsed voltage with duty cycles below 10% to create a pulsed ion beam. While the beam is not continuously steady, the high repetition frequency and controlled duty cycle provide sufficient time-averaged stability for propulsion applications, while dramatically reducing liquid metal consumption by preventing droplet generation that occurs in continuous DC operation
Solution Approach 2:
The patent maintains continuous useful action by operating at high pulse repetition frequencies where the pulsed ion beam provides sufficient time-averaged thrust. The continuous supply of liquid metal to the emitter ensures the cone is always ready to emit, and the pulsed operation maintains beam effectiveness while reducing consumption to acceptable levels
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
This approach significantly reduces liquid metal consumption by preventing droplet formation and maintaining efficient ion or electron beam generation, extending system lifetime and reducing propellant loss.
Implementation Method 1
A heater is used to heat up the emitter to a temperature at which the metallic propellant is liquid
Implementation Method 2
When a high voltage is applied between the emitter and extractor, a liquid metal cone is formed on the emitter tip having an atomic tip which extends toward the extractor
Implementation Method 3
At this point, the electric field is large enough that, depending on the polarity, ions are emitted when operating as a liquid metal-ion source
Implementation Method 4
electrons are emitted when operating as liquid metal-ion sources
Implementation Method 5
An extractor, e.g. configured as a perforated electrode, is arranged by being spaced therefrom
Data Source
AI summary
The invention relates to a liquid metal-ion beam system (1) or liquid metal electron beam system, including:a conductive emitter electrode (2),a conductive extractor electrode (3) opposite to the emitter electrode (2),a liquid metal reservoir (4) which is fluidically connected to the emitter electrode (2) for transporting liquid metal to the emitter electrode (2),a control unit (5) which is configured to apply a periodically varying operating voltage between emitter electrode (2) and extractor electrode (3).