Plasma Accelerator Single Cathode Modulated Thrust
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Solution Overview
Problem
Current plasma thrusters for space propulsion, such as gridded ion engines, Hall thrusters, and multi-stage plasma accelerators, face limitations including high complexity, high power consumption, thermal issues, and reduced lifetime due to the need for multiple active cathodes and high voltage biases, which restrict their operational efficiency and longevity.
Innovation Solution
A plasma accelerator configuration using a single active cathode for both plasma discharge and neutralization, with a conductive discharge chamber and multiple power supplies, employs a control grid to modulate the plasma stream exhaust and thrust, and a multiple-mirror magnetic field configuration to enhance ionization efficiency and reduce electron motion instability, thereby lowering electric power and propellant consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If gridded ion engines use multiple active cathodes and high voltage biases for plasma discharge and neutralization, then plasma stream generation and thrust delivery are improved, but device complexity and power consumption increase
Solution Approach 1:
The patent combines the plasma discharge function and the neutralization function into a single active cathode, eliminating the need for separate cathodes for each function. This merging reduces the number of components, simplifies the electrical system with fewer power supplies, and decreases overall power consumption while maintaining effective plasma generation and beam neutralization
Solution Approach 2:
The single active cathode performs multiple functions: it generates plasma through electron emission and ionization, and simultaneously provides electrons for neutralizing the ion beam space charge. This multi-functional design reduces device complexity and eliminates the need for multiple specialized components
2Force
If gridded ion engines use multiple active cathodes and high voltage biases, then thrust delivery is improved, but thermal issues and component lifetime are worsened
Solution Approach 1:
By merging the discharge and neutralization functions into one cathode, the patent reduces the total number of high-stress components. Fewer cathodes mean fewer thermal sources and fewer components subject to thermal stress and charged particle bombardment, thereby extending system lifetime while maintaining thrust performance
Solution Approach 2:
The patent uses the single cathode design to convert the potential harm of multiple thermal sources into a benefit by reducing overall thermal load and simplifying thermal management, which indirectly protects other components from thermal stress and extends their operational life
3Productivity
If gridded ion engines use multiple active cathodes, then plasma stream generation and neutralization are improved, but electric power consumption increases
Solution Approach 1:
The patent merges plasma generation and beam neutralization into a single cathode operation, eliminating the redundant power consumption associated with running multiple cathodes. This single cathode efficiently performs both functions, reducing overall electrical power requirements while maintaining effective plasma stream generation
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 configuration simplifies the system, reduces power consumption, and extends the thruster's operational life by allowing throttle control with lower voltages, minimizing wear, and increasing ionization efficiency, making it more suitable for satellite maneuvers and space missions.
Implementation Method 1
an electron source, which is negatively biased with respect to the electrically conductive walls of the discharge chamber and provides electrons for both working gas ionization and outflowing ion beam neutralization
Implementation Method 2
a multiple-mirror magnetic field configuration to enhance ionization efficiency and reduce electron motion instability
Implementation Method 3
a first power supply connected between this active cathode and the discharge chamber walls providing an acceleration voltage V AC for electrons and ions
Implementation Method 4
The plasma composed of electrons and ions is produced inside the discharge chamber by neutral gas atom collisional ionization by electrons emitted from active cathodes
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a plasma accelerator that produces and controls a plasma stream exhaust, in particular for space propulsion. The ions are produced inside the discharge chamber by working gas collisional ionization by electrons from a single electron source placed outside, also employed for ion beam neutralization. The ion motion is directed outwards through the exit side by the electric field between a cathode grid and the walls of the plasma chamber. The acceleration voltage imparts energy to the ion flux and an electrically biased control grid modulates the ion outflow from the discharge chamber and the electron inflow from the electron source. This allows electrical control of throttle and/or modulation of thrust delivered along the longitudinal direction of the thruster axis. Several plasma accelerators could be clustered together to provide controlled non-axial thrust using the individual control of throttle.