Nickel-Alloy Capillary Flow Regulation for Electric Thrusters
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Solution Overview
Problem
Current flow controller technology for electric propulsion systems, particularly in space electric thrusters, is limited in providing a wide range of propellant gas flow rates due to material degradation and thermal limitations, leading to reduced performance and potential leaks.
Innovation Solution
A thermo-capillary device with a capillary conduit made from a nickel-based alloy, such as Inconel, which withstands high temperatures and maintains structural integrity, allowing for a wider range of propellant fluid flow while controlling dimensions and shaping, thereby overcoming material degradation issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If stainless steel capillary conduit is used, then ease of manufacture and initial ductility are improved, but reliability deteriorates due to material degradation at high temperatures
Solution Approach 1:
The patent applies composite materials by combining nickel-based alloy with specific chromium and iron content ratios. The nickel-chromium-iron composite structure provides both thermal stability at high temperatures and resistance to degradation, while maintaining sufficient ductility for manufacturing processes like bending and brazing.
Solution Approach 2:
The patent changes the material parameters by specifying precise compositional ranges: nickel content of 72-80%, chromium of 14-17%, and iron of 6-10%. These parameter changes transform the material properties to achieve optimal balance between thermal resistance, ductility, and manufacturability.
2Productivity
If higher electric current is applied to increase flow range, then productivity is improved, but reliability deteriorates due to accelerated material degradation
Solution Approach 1:
The patent changes the thermal and mechanical parameters of the capillary conduit material to withstand higher operating temperatures generated by higher electric currents. The nickel-chromium-iron alloy maintains structural integrity at elevated temperatures, enabling the system to operate at higher currents (0-4A) to achieve wider flow ranges without premature failure.
3Volume of moving object
If capillary conduit dimensions are reduced to control size, then volume is improved, but strength deteriorates due to increased resistivity and temperature
Solution Approach 1:
The patent uses nickel-chromium-iron composite alloy that maintains high strength-to-volume ratio. The specific composition provides enhanced creep resistance and structural stability at high temperatures, allowing the capillary conduit to be manufactured in small dimensions (several hundred micrometers diameter) while maintaining sufficient mechanical strength and electrical conductivity.
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
The nickel-based alloy conduit enables a broader range of propellant gas flow rates with improved thermal resistance and reduced material degradation, enhancing the performance and reliability of electric thrusters by maintaining flow control across varying operating conditions.
Implementation Method 1
such an electric current passing through the capillary conduit causes heating of the capillary conduit by the Joule effect
Data Source
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Figure 2
AI summary
Device (52) for regulating the rate of flow of propellant fluid for an electric thruster, of the thermo-capillary device type comprising at least one capillary duct that is electrically conductive and capable of regulating the rate of flow of propellant fluid under the action of a change in temperature of the duct, characterized in that said at least one capillary duct comprises a nickel-based alloy.