Solid Expellant Plasma Generator with Decomposition Matching
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Solution Overview
Problem
Existing plasma generators for spacecraft propulsion, such as electrodynamic tethers, are limited by their reliance on sensitive components, high electrical power, and contamination issues, and require complex systems like high pressure vessels and regulated power, which are not suitable for space applications.
Innovation Solution
A solid expellant plasma generator using a stainless steel housing with a copper-clad carbon electrode rod and a block of poly(butyl methacrylate) with poly(tetraethylene glycol diacrylate) crosslinks, where the electrode and expellant decompose at the same rate, maintaining a stable plasma discharge, and operates efficiently with unregulated power, reducing mass and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hollow cathode plasma generators are used, then plasma generation capability is achieved, but device complexity increases due to high pressure vessels and plumbing requirements
Solution Approach 1:
The patent removes the complex pressure vessel and plumbing subsystems by extracting the high-pressure gas storage and delivery functions. Instead, it uses a solid expellant block that delivers gas directly at the discharge point through simple capillary channels, eliminating the need for pressure regulators, valves, and extensive plumbing while maintaining plasma generation capability
Solution Approach 2:
The invention changes the physical state of the expellant from gaseous (requiring pressure vessels) to solid (block form). This parameter change fundamentally simplifies the system by eliminating pressure containment requirements while maintaining the ability to supply expellant gas to the plasma discharge through controlled sublimation or decomposition
2Reliability
If electron guns or hollow cathodes are used, then plasma contactor function is provided, but sensitivity to contamination increases requiring special conditioning
Solution Approach 1:
The solid expellant block is designed as a consumable component that is replaced rather than maintained. This disposable approach eliminates the need for complex contamination control systems, as the solid block can be simply swapped out if contaminated, unlike sensitive electron guns or hollow cathodes that require elaborate conditioning procedures
Solution Approach 2:
The solid expellant material inherently protects the electrode from contamination by providing a fresh supply of expellant gas directly at the discharge point. The design self-regulates to maintain optimal performance without requiring external contamination control measures or conditioning procedures
3Reliability
If hollow cathode plasma generators are used, then plasma generation is achieved, but mass consumption increases due to pressure vessels and associated pluming
Solution Approach 1:
The patent extracts and removes the heavy pressure vessel, pressure regulators, valves, and extensive plumbing from the system. By using a solid expellant block with simple capillary channels, the design eliminates these mass-intensive components while maintaining plasma generation capability, significantly reducing overall system mass
Solution Approach 2:
Changing the expellant from gaseous to solid state eliminates the need for pressure containment structures. This parameter change fundamentally reduces system mass by removing thick-walled pressure vessels and associated heavy plumbing, while the solid block provides sufficient expellant supply through its controlled sublimation or decomposition
4Reliability
If conventional plasma generators are used, then plasma discharge is achieved, but electrical power consumption increases due to complex regulation systems
Solution Approach 1:
The solid expellant plasma generator is self-regulating, automatically adjusting expellant flow to match power input without external control systems. The capillary channels and solid block design create inherent flow regulation that adapts to varying power levels, eliminating the need for electrically-powered pressure regulators, valves, and control electronics that would increase power consumption
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 solution provides a robust, contamination-insensitive plasma generator capable of emitting high currents with minimal expellant mass and power usage, eliminating the need for complex plumbing and on-orbit conditioning, and achieving efficient ionization and stable operation.
Implementation Method 1
The heat generated by the discharge, in turn, vaporizes additional expellant, which replenishes the expanding cloud and maintains the conditions required for the electrical discharge to function
Implementation Method 2
The heat generated by the discharge, in turn, vaporizes additional expellant, which replenishes the expanding cloud
Data Source
AI summary
An improved solid expellant plasma generator has been developed. The plasma generator includes a support housing, an electrode rod located in the central portion of the housing, and a mass of solid expellant material that surrounds the electrode rod within the support housing. The electrode rod and the solid expellant material are made of separate materials that are selected so that the electrode and the solid expellant material decompose at the same rate when the plasma generator is ignited. This maintains a point of discharge of the plasma at the interface between the electrode and the solid expellant material.